diff --git a/CHANGES.ja.md b/CHANGES.ja.md
index 5c1fa8960d..cc1bfc9e02 100644
--- a/CHANGES.ja.md
+++ b/CHANGES.ja.md
@@ -1,9 +1,463 @@
 変更点
 ======
 
-4.21 (2025 年 07 月 18 日)
+4.47 (2026 年 07 月 09 日)
 -----------------
 
+- 新しい型
+  * `CursorResponse` クラス
+
+
+4.46 (2026 年 06 月 15 日)
+--------------------------
+
+- `AuthorizationFailRequest.Reason` 列挙型
+  * `INVALID_SCOPE` を追加。
+  * `UNAUTHORIZED_CLIENT` を追加。
+  * `TEMPORARILY_UNAVAILABLE` を追加。
+
+- `TokenFailRequest.Reason` 列挙型
+  * `INVALID_CLIENT` を追加。
+  * `UNAUTHORIZED_CLIENT` を追加。
+  * `INVALID_SCOPE` を追加。
+
+
+4.45 (2026 年 05 月 18 日)
+--------------------------
+
+- `AccessRight` 列挙型
+    * `MODIFY_SERVICE`、`CREATE_CLIENT`、`ADMIN` が `USE_INTROSPECTION` を含むように修正。
+
+
+4.44 (2026 年 05 月 10 日)
+--------------------------
+
+- `AuthleteApi` インターフェース
+    * `backchannelLogoutToken(BackchannelLogoutTokenRequest)` メソッドを追加。
+    * `backchannelLogoutToken(BackchannelLogoutTokenRequest, Options)` メソッドを追加。
+
+- `Client` クラス
+    * `getBackchannelLogoutUri()` メソッドを追加。
+    * `setBackchannelLogoutUri(URI)` メソッドを追加。
+    * `isBackchannelLogoutSessionRequired()` メソッドを追加。
+    * `setBackchannelLogoutSessionRequired(boolean)` メソッドを追加。
+
+- `Service` クラス
+    * `isBackchannelLogoutSupported()` メソッドを追加。
+    * `setBackchannelLogoutSupported(boolean)` メソッドを追加。
+    * `isBackchannelLogoutSessionSupported()` メソッドを追加。
+    * `setBackchannelLogoutSessionSupported(boolean)` メソッドを追加。
+
+- 新しい型
+    * `BackchannelLogoutTokenRequest` クラス
+    * `BackchannelLogoutTokenResponse` クラス
+
+
+4.43 (2026 年 04 月 17 日)
+--------------------------
+
+- `AccessRight` 列挙型
+    * `USE_INTROSPECTION` を追加。
+    * `VIEW_AUDIT_LOG` を追加。
+
+
+4.42 (2026 年 04 月 14 日)
+--------------------------
+
+- `Service` クラス
+    * `getClientAttesterRoots()` メソッドを追加。
+    * `setClientAttesterRoots(String[])` メソッドを追加。
+    * `isClientAttesterRootsEnabled()` メソッドを追加。
+    * `setClientAttesterRootsEnabled(boolean)` メソッドを追加。
+    * `isClientAttesterRootsOnly()` メソッドを追加。
+    * `setClientAttesterRootsOnly(boolean)` メソッドを追加。
+    * `getKeyAttesterRoots()` メソッドを追加。
+    * `setKeyAttesterRoots(String[])` メソッドを追加。
+    * `isKeyAttesterRootsEnabled()` メソッドを追加。
+    * `setKeyAttesterRootsEnabled(boolean)` メソッドを追加。
+    * `isKeyAttesterRootsOnly()` メソッドを追加。
+    * `setKeyAttesterRootsOnly(boolean)` メソッドを追加。
+
+
+4.41 (2026 年 03 月 28 日)
+--------------------------
+
+- `Client` クラス
+    * `getHaipVersion()` メソッドを追加。
+    * `setHaipVersion(String)` メソッドを追加。
+
+- `Service` クラス
+    * `getHaipVersion()` メソッドを追加。
+    * `setHaipVersion(String)` メソッドを追加。
+
+
+4.40 (2026 年 03 月 24 日)
+--------------------------
+
+- `Service` クラス
+    * `getAuthorizationCodeDuration()` メソッドを追加。
+    * `setAuthorizationCodeDuration(long)` メソッドを追加。
+
+
+4.39 (2026 年 03 月 20 日)
+--------------------------
+
+- `AuthleteApi` インターフェース
+    * `attestationChallenge(AttestationChallengeRequest)` メソッドを追加。
+    * `attestationChallenge(AttestationChallengeRequest, Options)` メソッドを追加。
+
+- `BackchannelAuthenticationResponse` クラス
+    * `getAttestationChallenge()` メソッドを追加。
+    * `setAttestationChallenge(String)` メソッドを追加。
+
+- `DeviceAuthorizationResponse` クラス
+    * `getAttestationChallenge()` メソッドを追加。
+    * `setAttestationChallenge(String)` メソッドを追加。
+
+- `ErrorCode` 列挙型
+    * `use_attestation_challenge` を追加。
+    * `use_fresh_attestation` を追加。
+    * `invalid_client_attestation` を追加。
+
+- `PushedAuthReqResponse` クラス
+    * `getAttestationChallenge()` メソッドを追加。
+    * `setAttestationChallenge(String)` メソッドを追加。
+
+- `RevocationResponse` クラス
+    * `getAttestationChallenge()` メソッドを追加。
+    * `setAttestationChallenge(String)` メソッドを追加。
+
+- `Service` クラス
+    * `getChallengeEndpoint()` メソッドを追加。
+    * `setChallengeEndpoint(URI)` メソッドを追加。
+    * `getAttestationChallengeTimeWindow()` メソッドを追加。
+    * `setAttestationChallengeTimeWindow(long)` メソッドを追加。
+
+- `TokenResponse` クラス
+    * `getAttestationChallenge()` メソッドを追加。
+    * `setAttestationChallenge(String)` メソッドを追加。
+
+- 新しい型
+    * `AttestationChallengeRequest` クラス
+    * `AttestationChallengeResponse` クラス
+
+
+4.38 (2026 年 03 月 04 日)
+--------------------------
+
+- `TokenUpdateRequest` クラス
+    * `getRefreshToken()` メソッドを追加。
+    * `setRefreshToken(String)` メソッドを追加。
+    * `getRefreshTokenHash()` メソッドを追加。
+    * `setRefreshTokenHash(String)` メソッドを追加。
+
+
+4.37 (2026 年 03 月 02 日)
+--------------------------
+
+- `ClientAssertionType` 列挙型
+    * `JWT_SPIFFE` を追加。
+
+
+4.36 (2026 年 02 月 26 日)
+--------------------------
+
+- `ClientAuthMethod` 列挙型
+    * `SPIFFE_JWT` を追加。
+
+- `Client` クラス
+    * `getSpiffeId()` メソッドを追加。
+    * `setSpiffeId(URI)` メソッドを追加。
+    * `getSpiffeBundleEndpoint()` メソッドを追加。
+    * `setSpiffeBundleEndpoint(URI)` メソッドを追加。
+
+
+4.35 (2026 年 01 月 10 日)
+--------------------------
+
+- `CredentialDeferredIssueRequest` クラス
+    * `isDenied()` メソッドを追加。
+    * `setDenied(boolean)` メソッドを追加。
+    * `getInterval()` メソッドを追加。
+    * `setInterval(int)` メソッドを追加。
+
+- `CredentialDeferredIssueResponse.Action` 列挙型
+    * `ACCEPTED` を追加。
+    * `ACCEPTED_JWT` を追加。
+
+- `CredentialSingleIssueRequest` クラス
+    * `isDenied()` メソッドを追加。
+    * `setDenied(boolean)` メソッドを追加。
+    * `getInterval()` メソッドを追加。
+    * `setInterval(int)` メソッドを追加。
+
+
+4.34 (2026 年 01 月 03 日)
+--------------------------
+
+- `AuthzDetailsElement` クラス
+    * デフォルトコンストラクタを明示的に追加。
+    * コピーコンストラクタ (`AuthzDetailsElement(AuthzDetailsElement)`) を追加。
+
+- `CredentialRequestInfo` クラス
+    * `getCredentialConfigurationId()` メソッドを追加。
+    * `setCredentialConfigurationId(String)` メソッドを追加。
+    * `getCredentialIdentifier()` メソッドを追加。
+    * `setCredentialIdentifier(String)` メソッドを追加。
+
+
+4.33 (2025 年 12 月 13 日)
+--------------------------
+
+- `Service` クラス
+    * `isCimdMetadataPolicyEnabled()` メソッドを追加。
+    * `setCimdMetadataPolicyEnabled(boolean)` メソッドを追加。
+    * `getCimdMetadataPolicy()` メソッドを追加。
+    * `setCimdMetadataPolicy(String)` メソッドを追加。
+
+
+4.32 (2025 年 12 月 01 日)
+--------------------------
+
+- `Service` クラス
+    * `isHttpAliasProhibited()` メソッドを追加。
+    * `setHttpAliasProhibited(boolean)` メソッドを追加。
+
+
+4.31 (2025 年 11 月 25 日)
+--------------------------
+
+- `Service` クラス
+    * `isCimdAllowlistEnabled()` メソッドを追加。
+    * `setCimdAllowlistEnabled(boolean)` メソッドを追加。
+    * `getCimdAllowlist()` メソッドを追加。
+    * `setCimdAllowlist(String[])` メソッドを追加。
+    * `isCimdWhitelistEnabled()` メソッドを削除。
+    * `setCimdWhitelistEnabled(boolean)` メソッドを削除。
+    * `getCimdWhitelist()` メソッドを削除。
+    * `setCimdWhitelist(String[])` メソッドを削除。
+
+
+4.30 (2025 年 11 月 20 日)
+--------------------------
+
+- `AuthorizationRequest` クラス
+    * `getCimdOptions()` メソッドを追加。
+    * `setCimdOptions(CimdOptions)` メソッドを追加。
+
+- `BackchannelAuthenticationRequest` クラス
+    * `getCimdOptions()` メソッドを追加。
+    * `setCimdOptions(CimdOptions)` メソッドを追加。
+
+- `DeviceAuthorizationRequest` クラス
+    * `getCimdOptions()` メソッドを追加。
+    * `setCimdOptions(CimdOptions)` メソッドを追加。
+
+- `Service` クラス
+    * `isCimdWhitelistEnabled()` メソッドを追加。
+    * `setCimdWhitelistEnabled(boolean)` メソッドを追加。
+    * `getCimdWhitelist()` メソッドを追加。
+    * `setCimdWhitelist(String[])` メソッドを追加。
+    * `isCimdAlwaysRetrieved()` メソッドを追加。
+    * `setCimdAlwaysRetrieved(boolean)` メソッドを追加。
+    * `isCimdHttpPermitted()` メソッドを追加。
+    * `setCimdHttpPermitted(boolean)` メソッドを追加。
+    * `isCimdQueryPermitted()` メソッドを追加。
+    * `setCimdQueryPermitted(boolean)` メソッドを追加。
+
+- `TokenRequest` クラス
+    * `getCimdOptions()` メソッドを追加。
+    * `setCimdOptions(CimdOptions)` メソッドを追加。
+
+- 新しい型
+    * `CimdOptions` クラス
+
+
+4.29 (2025 年 11 月 18 日)
+--------------------------
+
+- `AuthorizationResponse` クラス
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `BackchannelAuthenticationCompleteResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `BackchannelAuthenticationResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `Client` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `getMetadataDocumentExpiresAt()` メソッドを追加。
+    * `setMetadataDocumentExpiresAt(long)` メソッドを追加。
+    * `getMetadataDocumentUpdatedAt()` メソッドを追加。
+    * `setMetadataDocumentUpdatedAt(long)` メソッドを追加。
+    * `isDiscoveredByMetadataDocument()` メソッドを追加。
+    * `setDiscoveredByMetadataDocument(boolean)` メソッドを追加。
+    * `getClientSource()` メソッドを追加。
+    * `setClientSource(ClientSource)` メソッドを追加。
+    * `updateClientSource()` メソッドを追加。
+
+- `ClientMetadataControl` クラス
+    * `isMetadataDocumentLocationPreferred()` メソッドを追加。
+    * `setMetadataDocumentLocationPreferred(boolean)` メソッドを追加。
+
+- `DeviceAuthorizationResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `DeviceVerificationResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `IntrospectionResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `Service` クラス
+    * `isClientIdMetadataDocumentSupported()` メソッドを追加。
+    * `setClientIdMetadataDocumentSupported(boolean)` メソッドを追加。
+
+- `TokenCreateRequest` クラス
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `TokenInfo` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `TokenIssueResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `TokenResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- `UserInfoResponse` クラス
+    * `getMetadataDocumentLocation()` メソッドを追加。
+    * `setMetadataDocumentLocation(URI)` メソッドを追加。
+    * `isMetadataDocumentUsed()` メソッドを追加。
+    * `setMetadataDocumentUsed(boolean)` メソッドを追加。
+
+- 新しい型
+    * `ClientSource` 列挙型
+
+
+4.28 (2025 年 11 月 05 日)
+--------------------------
+
+- `ErrorCode` 列挙型
+    * `unknown_credential_configuration` を追加。
+    * `unknown_credential_identifier` を追加。
+    * `invalid_nonce` を追加。
+    * `credential_request_denied` を追加。
+    * `invalid_notification_id` を追加。
+    * `invalid_notification_request` を追加。
+
+
+4.27 (2025 年 11 月 04 日)
+--------------------------
+
+- `AuthleteApi` インターフェース
+    * `credentialNonce(CredentialNonceRequest)` メソッドを追加。
+    * `credentialNonce(CredentialNonceRequest, Options)` メソッドを追加。
+
+- 新しい型
+    * `CredentialNonceRequest` クラス
+    * `CredentialNonceResponse` クラス
+
+- その他
+    * PR #143: fix spotbugs-annotations dependency
+
+
+4.26 (2025 年 11 月 03 日)
+--------------------------
+
+- `CredentialIssuerMetadata` クラス
+    * `getNotificationEndpoint()` メソッドを追加。
+    * `setNotificationEndpoint(URI)` メソッドを追加。
+    * `getNonceEndpoint()` メソッドを追加。
+    * `setNonceEndpoint(URI)` メソッドを追加。
+    * `getCredentialRequestEncryptionJwks()` メソッドを追加。
+    * `setCredentialRequestEncryptionJwks(String)` メソッドを追加。
+    * `getCredentialRequestEncryptionEncValuesSupported()` メソッドを追加。
+    * `setCredentialRequestEncryptionEncValuesSupported(JWEEnc[])` メソッドを追加。
+    * `getCredentialRequestEncryptionZipValuesSupported()` メソッドを追加。
+    * `setCredentialRequestEncryptionZipValuesSupported(JWEEnc[])` メソッドを追加。
+    * `isRequireCredentialRequestEncryption()` メソッドを追加。
+    * `setRequireCredentialRequestEncryption(boolean)` メソッドを追加。
+    * `getCredentialResponseEncryptionZipValuesSupported()` メソッドを追加。
+    * `setCredentialResponseEncryptionZipValuesSupported(JWEEnc[])` メソッドを追加。
+    * `getBatchSize()` メソッドを追加。
+    * `setBatchSize(int)` メソッドを追加。
+    * `getDisplay()` メソッドを追加。
+    * `setDisplay(String)` メソッドを追加。
+
+- 新しい型
+    * `JWEZip` 列挙型
+
+
+4.25 (2025 年 10 月 30 日)
+--------------------------
+
+- `Service` クラス
+    * `getOid4vciVersion()` メソッドを追加。
+    * `setOid4vciVersion(String)` メソッドを追加。
+
+
+4.24 (2025 年 10 月 06 日)
+--------------------------
+
+- `TokenResponse` クラス
+    * `getAdditionalClaims()` メソッドを追加
+    * `setAdditionalClaims(String)` メソッドを追加
+    * カスタムクレームを処理するために Native SSO のトークンレスポンスに追加されたクレームへのアクセスをサポート
+
+
+4.23 (2025 年 10 月 03 日)
+--------------------------
+
+- `ApiResponse` クラス
+    * `getResponseHeaders()` メソッドを追加。
+    * `setResponseHeaders(Map<String, List<String>>)` メソッドを追加。
+    * Authlete の API 呼び出しから HTTP レスポンスヘッダーを取り出す機能をサポート。
+
+- `Client` クラス
+    * `isInScopeForTokenMigration()` メソッドを追加。
+    * `setInScopeForTokenMigration(boolean)` メソッドを追加。
+
+- `com.neovisionaries:nv-cipher` と `com.neovisionaries:nv-digest` を依存関係から削除。
+
+
+4.22 (2025 年 08 月 14 日)
+--------------------------
+
+- nimbus-jose-jwt を バージョン 10.0.2 に更新。
+
+
+4.21 (2025 年 07 月 18 日)
+--------------------------
+
 - Authlete API V3 における HTTP URLConnection のサポートを追加。
 - checkstyle 用の設定ファイルを追加。
 - spotbugs 用の設定ファイルを追加。
diff --git a/CHANGES.md b/CHANGES.md
index 134f0b1e8a..3f05fed0bd 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,460 @@
 CHANGES
 =======
 
+4.47 (2026-07-09)
+-----------------
+
+- New types
+  * `CursorResponse` class
+
+
+4.46 (2026-06-15)
+-----------------
+
+- `AuthorizationFailRequest.Reason` enum
+  * Added `INVALID_SCOPE`
+  * Added `UNAUTHORIZED_CLIENT`
+  * Added `TEMPORARILY_UNAVAILABLE`
+
+- `TokenFailRequest.Reason` enum
+  * Added `INVALID_CLIENT`
+  * Added `UNAUTHORIZED_CLIENT`
+  * Added `INVALID_SCOPE`
+
+
+4.45 (2026-05-18)
+-----------------
+
+- `AccessRight` enum
+    * Fixed `MODIFY_SERVICE`, `CREATE_CLIENT`, and `ADMIN` to include `USE_INTROSPECTION`.
+
+
+4.44 (2026-05-10)
+-----------------
+
+- `AuthleteApi` interface
+    * Added the `backchannelLogoutToken(BackchannelLogoutTokenRequest)` method.
+    * Added the `backchannelLogoutToken(BackchannelLogoutTokenRequest, Options)` method.
+
+- `Client` class
+    * Added the `getBackchannelLogoutUri()` method.
+    * Added the `setBackchannelLogoutUri(URI)` method.
+    * Added the `isBackchannelLogoutSessionRequired()` method.
+    * Added the `setBackchannelLogoutSessionRequired(boolean)` method.
+
+- `Service` class
+    * Added the `isBackchannelLogoutSupported()` method.
+    * Added the `setBackchannelLogoutSupported(boolean)` method.
+    * Added the `isBackchannelLogoutSessionSupported()` method.
+    * Added the `setBackchannelLogoutSessionSupported(boolean)` method.
+
+- New types
+    * `BackchannelLogoutTokenRequest` class
+    * `BackchannelLogoutTokenResponse` class
+
+
+4.43 (2026-04-17)
+-----------------
+
+- `AccessRight` enum
+    * Added `USE_INTROSPECTION`.
+    * Added `VIEW_AUDIT_LOG`.
+
+
+4.42 (2026-04-14)
+-----------------
+
+- `Service` class
+    * Added the `getClientAttesterRoots()` method.
+    * Added the `setClientAttesterRoots(String[])` method.
+    * Added the `isClientAttesterRootsEnabled()` method.
+    * Added the `setClientAttesterRootsEnabled(boolean)` method.
+    * Added the `isClientAttesterRootsOnly()` method.
+    * Added the `setClientAttesterRootsOnly(boolean)` method.
+    * Added the `getKeyAttesterRoots()` method.
+    * Added the `setKeyAttesterRoots(String[])` method.
+    * Added the `isKeyAttesterRootsEnabled()` method.
+    * Added the `setKeyAttesterRootsEnabled(boolean)` method.
+    * Added the `isKeyAttesterRootsOnly()` method.
+    * Added the `setKeyAttesterRootsOnly(boolean)` method.
+
+
+4.41 (2026-03-28)
+-----------------
+
+- `Client` class
+    * Added the `getHaipVersion()` method.
+    * Added the `setHaipVersion(String)` method.
+
+- `Service` class
+    * Added the `getHaipVersion()` method.
+    * Added the `setHaipVersion(String)` method.
+
+
+4.40 (2026-03-24)
+-----------------
+
+- `Service` class
+    * Added the `getAuthorizationCodeDuration()` method.
+    * Added the `setAuthorizationCodeDuration(long)` method.
+
+
+4.39 (2026-03-20)
+-----------------
+
+- `AuthleteApi` interface
+    * Added the `attestationChallenge(AttestationChallengeRequest)` method.
+    * Added the `attestationChallenge(AttestationChallengeRequest, Options)` method.
+
+- `BackchannelAuthenticationResponse` class
+    * Added the `getAttestationChallenge()` method.
+    * Added the `setAttestationChallenge(String)` method.
+
+- `DeviceAuthorizationResponse` class
+    * Added the `getAttestationChallenge()` method.
+    * Added the `setAttestationChallenge(String)` method.
+
+- `ErrorCode` enum
+    * Added `use_attestation_challenge`.
+    * Added `use_fresh_attestation`.
+    * Added `invalid_client_attestation`.
+
+- `PushedAuthReqResponse` class
+    * Added the `getAttestationChallenge()` method.
+    * Added the `setAttestationChallenge(String)` method.
+
+- `RevocationResponse` class
+    * Added the `getAttestationChallenge()` method.
+    * Added the `setAttestationChallenge(String)` method.
+
+- `Service` class
+    * Added the `getChallengeEndpoint()` method.
+    * Added the `setChallengeEndpoint(URI)` method.
+    * Added the `getAttestationChallengeTimeWindow()` method.
+    * Added the `setAttestationChallengeTimeWindow(long)` method.
+
+- `TokenResponse` class
+    * Added the `getAttestationChallenge()` method.
+    * Added the `setAttestationChallenge(String)` method.
+
+- New types
+    * `AttestationChallengeRequest` class
+    * `AttestationChallengeResponse` class
+
+
+4.38 (2026-03-04)
+-----------------
+
+- `TokenUpdateRequest` class
+    * Added the `getRefreshToken()` method.
+    * Added the `setRefreshToken(String)` method.
+    * Added the `getRefreshTokenHash()` method.
+    * Added the `setRefreshTokenHash(String)` method.
+
+
+4.37 (2026-03-02)
+-----------------
+
+- `ClientAssertionType` enum
+    * Added `JWT_SPIFFE`.
+
+
+4.36 (2026-02-26)
+-----------------
+
+- `ClientAuthMethod` enum
+    * Added `SPIFFE_JWT`.
+
+- `Client` class
+    * Added the `getSpiffeId()` method.
+    * Added the `setSpiffeId(URI)` method.
+    * Added the `getSpiffeBundleEndpoint()` method.
+    * Added the `setSpiffeBundleEndpoint(URI)` method.
+
+
+4.35 (2026-01-10)
+-----------------
+
+- `CredentialDeferredIssueRequest` class
+    * Added the `isDenied()` method.
+    * Added the `setDenied(boolean)` method.
+    * Added the `getInterval()` method.
+    * Added the `setInterval(int)` method.
+
+- `CredentialDeferredIssueResponse.Action` enum
+    * Added `ACCEPTED`.
+    * Added `ACCEPTED_JWT`.
+
+- `CredentialSingleIssueRequest` class
+    * Added the `isDenied()` method.
+    * Added the `setDenied(boolean)` method.
+    * Added the `getInterval()` method.
+    * Added the `setInterval(int)` method.
+
+
+4.34 (2026-01-03)
+-----------------
+
+- `AuthzDetailsElement` class
+    * Added the default constructor explicitly.
+    * Added a copy constructor (`AuthzDetailsElement(AuthzDetailsElement)`).
+
+- `CredentialRequestInfo` class
+    * Added the `getCredentialConfigurationId()` method.
+    * Added the `setCredentialConfigurationId(String)` method.
+    * Added the `getCredentialIdentifier()` method.
+    * Added the `setCredentialIdentifier(String)` method.
+
+
+4.33 (2025-12-13)
+-----------------
+
+- `Service` class
+    * Added the `isCimdMetadataPolicyEnabled()` method.
+    * Added the `setCimdMetadataPolicyEnabled(boolean)` method.
+    * Added the `getCimdMetadataPolicy()` method.
+    * Added the `setCimdMetadataPolicy(String)` method.
+
+
+4.32 (2025-12-01)
+-----------------
+
+- `Service` class
+    * Added the `isHttpAliasProhibited()` method.
+    * Added the `setHttpAliasProhibited(boolean)` method.
+
+
+4.31 (2025-11-25)
+-----------------
+
+- `Service` class
+    * Added the `isCimdAllowlistEnabled()` method.
+    * Added the `setCimdAllowlistEnabled(boolean)` method.
+    * Added the `getCimdAllowlist()` method.
+    * Added the `setCimdAllowlist(String[])` method.
+    * Removed the `isCimdWhitelistEnabled()` method.
+    * Removed the `setCimdWhitelistEnabled(boolean)` method.
+    * Removed the `getCimdWhitelist()` method.
+    * Removed the `setCimdWhitelist(String[])` method.
+
+
+4.30 (2025-11-20)
+-----------------
+
+- `AuthorizationRequest` class
+    * Added the `getCimdOptions()` method.
+    * Added the `setCimdOptions(CimdOptions)` method.
+
+- `BackchannelAuthenticationRequest` class
+    * Added the `getCimdOptions()` method.
+    * Added the `setCimdOptions(CimdOptions)` method.
+
+- `DeviceAuthorizationRequest` class
+    * Added the `getCimdOptions()` method.
+    * Added the `setCimdOptions(CimdOptions)` method.
+
+- `Service` class
+    * Added the `isCimdWhitelistEnabled()` method.
+    * Added the `setCimdWhitelistEnabled(boolean)` method.
+    * Added the `getCimdWhitelist()` method.
+    * Added the `setCimdWhitelist(String[])` method.
+    * Added the `isCimdAlwaysRetrieved()` method.
+    * Added the `setCimdAlwaysRetrieved(boolean)` method.
+    * Added the `isCimdHttpPermitted()` method.
+    * Added the `setCimdHttpPermitted(boolean)` method.
+    * Added the `isCimdQueryPermitted()` method.
+    * Added the `setCimdQueryPermitted(boolean)` method.
+
+- `TokenRequest` class
+    * Added the `getCimdOptions()` method.
+    * Added the `setCimdOptions(CimdOptions)` method.
+
+- New types
+    * `CimdOptions` class
+
+
+4.29 (2025-11-18)
+-----------------
+
+- `AuthorizationResponse` class
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `BackchannelAuthenticationCompleteResponse`  class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `BackchannelAuthenticationResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `Client` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `getMetadataDocumentExpiresAt()` method.
+    * Added the `setMetadataDocumentExpiresAt(long)` method.
+    * Added the `getMetadataDocumentUpdatedAt()` method.
+    * Added the `setMetadataDocumentUpdatedAt(long)` method.
+    * Added the `isDiscoveredByMetadataDocument()` method.
+    * Added the `setDiscoveredByMetadataDocument(boolean)` method.
+    * Added the `getClientSource()` method.
+    * Added the `setClientSource(ClientSource)` method.
+    * Added the `updateClientSource()` method.
+
+- `ClientMetadataControl` class
+    * Added the `isMetadataDocumentLocationPreferred()` method.
+    * Added the `setMetadataDocumentLocationPreferred(boolean)` method.
+
+- `DeviceAuthorizationResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `DeviceVerificationResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `IntrospectionResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `Service` class
+    * Added the `isClientIdMetadataDocumentSupported()` method.
+    * Added the `setClientIdMetadataDocumentSupported(boolean)` method.
+
+- `TokenCreateRequest` class
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `TokenInfo` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `TokenIssueResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `TokenResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- `UserInfoResponse` class
+    * Added the `getMetadataDocumentLocation()` method.
+    * Added the `setMetadataDocumentLocation(URI)` method.
+    * Added the `isMetadataDocumentUsed()` method.
+    * Added the `setMetadataDocumentUsed(boolean)` method.
+
+- New types
+    * `ClientSource` enum
+
+
+4.28 (2025-11-05)
+-----------------
+
+- `ErrorCode` enum
+    * Added `unknown_credential_configuration`
+    * Added `unknown_credential_identifier`
+    * Added `invalid_nonce`
+    * Added `credential_request_denied`
+    * Added `invalid_notification_id`
+    * Added `invalid_notification_request`
+
+
+4.27 (2025-11-04)
+-----------------
+
+- `AuthleteApi` interface
+    * Added the `credentialNonce(CredentialNonceRequest)` method.
+    * Added the `credentialNonce(CredentialNonceRequest, Options)` method.
+
+- New types
+    * `CredentialNonceRequest` class
+    * `CredentialNonceResponse` class
+
+- Others
+    * PR #143: fix spotbugs-annotations dependency
+
+
+4.26 (2025-11-03)
+-----------------
+
+- `CredentialIssuerMetadata` class
+    * Added the `getNotificationEndpoint()` method.
+    * Added the `setNotificationEndpoint(URI)` method.
+    * Added the `getNonceEndpoint()` method.
+    * Added the `setNonceEndpoint(URI)` method.
+    * Added the `getCredentialRequestEncryptionJwks()` method.
+    * Added the `setCredentialRequestEncryptionJwks(String)` method.
+    * Added the `getCredentialRequestEncryptionEncValuesSupported()` method.
+    * Added the `setCredentialRequestEncryptionEncValuesSupported(JWEEnc[])` method.
+    * Added the `getCredentialRequestEncryptionZipValuesSupported()` method.
+    * Added the `setCredentialRequestEncryptionZipValuesSupported(JWEEnc[])` method.
+    * Added the `isRequireCredentialRequestEncryption()` method.
+    * Added the `setRequireCredentialRequestEncryption(boolean)` method.
+    * Added the `getCredentialResponseEncryptionZipValuesSupported()` method.
+    * Added the `setCredentialResponseEncryptionZipValuesSupported(JWEEnc[])` method.
+    * Added the `getBatchSize()` method.
+    * Added the `setBatchSize(int)` method.
+    * Added the `getDisplay()` method.
+    * Added the `setDisplay(String)` method.
+
+- New types
+    * `JWEZip` enum
+
+
+4.25 (2025-10-30)
+-----------------
+
+- `Service` class
+    * Added the `getOid4vciVersion()` method.
+    * Added the `setOid4vciVersion(String)` method.
+
+
+4.24 (2025-10-06)
+-----------------
+
+- `TokenResponse` class
+    * Added the `getAdditionalClaims()` method.
+    * Added the `setAdditionalClaims(String)` method.
+    * Enables access to additional claims data in Native SSO token responses for custom claim handling
+
+
+4.23 (2025-10-03)
+----------
+
+- `ApiResponse` class
+    * Added the `getResponseHeaders()` method.
+    * Added the `setResponseHeaders(Map<String, List<String>>)` method.
+    * Added support for extracting HTTP response headers from Authlete API calls.
+
+- `Client` class
+    * Added the `isInScopeForTokenMigration()` method.
+    * Added the `setInScopeForTokenMigration(boolean)` method.
+
+- Removed `com.neovisionaries:nv-cipher` and `com.neovisionaries:nv-digest` dependencies.
+
+
+4.22 (2025-08-14)
+-----------------
+
+- Updated nimbus-jose-jwt to v10.0.2.
+
+
 4.21 (2025-07-18)
 -----------------
 
diff --git a/README.ja.md b/README.ja.md
index c8ba4a3633..05c14a7c18 100644
--- a/README.ja.md
+++ b/README.ja.md
@@ -54,8 +54,6 @@ JavaDoc
 
   <code>https://authlete.github.io/authlete-java-common/</code>
 
-  <code>https://authlete.github.io/authlete-java-common/index.html?overview-summary.html</code> [FRAMES]
-
 
 説明
 ----
@@ -364,12 +362,21 @@ settings.setReadTimeout(5000);
   - `credentialBatchIssue(CredentialBatchIssueRequest)`
   - `credentialDeferredParse(CredentialDeferredParseRequest)`
   - `credentialDeferredIssue(CredentialDeferredIssueRequest)`
+  - `credentialNonce(CredentialNonceRequest)`
 
   22. OpenID Connect Native SSO for Mobile Apps 1.0 に関するメソッド群
 
   - `nativeSso(NativeSsoRequest)`
   - `nativeSsoLogout(NativeSsoLogoutRequest)`
 
+  23. OAuth 2.0 Attestation-Based Client Authentication に関するメソッド群
+
+  - `attestationChallenge(AttestationChallengeRequest)`
+
+  24. OpenID Connect Back-Channel Logout 1.0 に関するメソッド群
+
+  - `backchannelLogoutToken(BackchannelLogoutTokenRequest)`
+
 *例*
 
 次のコードは既存のサービスのリストを取得する例です。
diff --git a/README.md b/README.md
index 0fc3e0dd7f..79f92da732 100644
--- a/README.md
+++ b/README.md
@@ -55,8 +55,6 @@ JavaDoc
 
   <code>https://authlete.github.io/authlete-java-common/</code>
 
-  <code>https://authlete.github.io/authlete-java-common/index.html?overview-summary.html</code> [FRAMES]
-
 
 Description
 -----------
@@ -375,12 +373,21 @@ Methods in `AuthleteApi` interface can be divided into some categories.
   - `credentialBatchIssue(CredentialBatchIssueRequest)`
   - `credentialDeferredParse(CredentialDeferredParseRequest)`
   - `credentialDeferredIssue(CredentialDeferredIssueRequest)`
+  - `credentialNonce(CredentialNonceRequest)`
 
   22. Methods for OpenID Connect Native SSO for Mobile Apps 1.0
 
   - `nativeSso(NativeSsoRequest)`
   - `nativeSsoLogout(NativeSsoLogoutRequest)`
 
+  23. Methods for OAuth 2.0 Attestation-Based Client Authentication
+
+  - `attestationChallenge(AttestationChallengeRequest)`
+
+  24. Methods for OpenID Connect Back-Channel Logout 1.0
+
+  - `backchannelLogoutToken(BackchannelLogoutTokenRequest)`
+
 *Examples*
 
 The following code snippet is an example to get the list of your existing
diff --git a/pom.xml b/pom.xml
index f23eb457cc..d7d6f96709 100644
--- a/pom.xml
+++ b/pom.xml
@@ -4,7 +4,7 @@
 
     <groupId>com.authlete</groupId>
     <artifactId>authlete-java-common</artifactId>
-    <version>4.21-SNAPSHOT</version>
+    <version>4.48-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>${project.groupId}:${project.artifactId}</name>
     <description>
@@ -32,7 +32,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <git.connection>scm:git:git@github.com:authlete/authlete-java-common.git</git.connection>
         <git.url>git@github.com:authlete/authlete-java-common.git</git.url>
-        <nimbus.version>9.31</nimbus.version>
+        <nimbus.version>10.0.2</nimbus.version>
     </properties>
 
     <scm>
@@ -43,12 +43,6 @@
     </scm>
 
     <dependencies>
-        <dependency>
-            <groupId>com.neovisionaries</groupId>
-            <artifactId>nv-cipher</artifactId>
-            <version>1.3</version>
-        </dependency>
-
         <dependency>
             <groupId>com.google.code.gson</groupId>
             <artifactId>gson</artifactId>
@@ -68,23 +62,34 @@
             <scope>test</scope>
         </dependency>
 
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>2.19.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>2.19.2</version>
+        </dependency>
+
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-annotations</artifactId>
-            <version>2.18.2</version>
+            <version>2.19.2</version>
         </dependency>
 
         <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <version>4.13.1</version>
-            <scope>test</scope>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>1.19.0</version>
         </dependency>
 
         <dependency>
-            <groupId>com.neovisionaries</groupId>
-            <artifactId>nv-digest</artifactId>
-            <version>1.5</version>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.13.1</version>
             <scope>test</scope>
         </dependency>
 
@@ -128,7 +133,7 @@
         <dependency>
             <groupId>com.github.spotbugs</groupId>
             <artifactId>spotbugs-annotations</artifactId>
-            <version>RELEASE</version>
+            <version>4.9.6</version>
             <scope>compile</scope>
         </dependency>
     </dependencies>
@@ -213,6 +218,7 @@
                         <extensions>true</extensions>
                         <configuration>
                             <publishingServerId>authlete</publishingServerId>
+                            <autoPublish>true</autoPublish>
                         </configuration>
                     </plugin>
                 </plugins>
diff --git a/src/main/java/com/authlete/common/api/AccessRight.java b/src/main/java/com/authlete/common/api/AccessRight.java
index 5897387237..49441f104c 100644
--- a/src/main/java/com/authlete/common/api/AccessRight.java
+++ b/src/main/java/com/authlete/common/api/AccessRight.java
@@ -49,20 +49,24 @@ public enum AccessRight
     MODIFY_CLIENT(true, true, VIEW_CLIENT),
     /** can view the details of this service */
     VIEW_SERVICE(false, true, VIEW_CLIENT),
+    /** can use the introspection endpoint */
+    USE_INTROSPECTION(false, true),
     /** can use the non-destructive service API calls (auth endpoint, token endpoint, etc.) */
-    USE_SERVICE(false, true, VIEW_SERVICE, VIEW_CLIENT),
+    USE_SERVICE(false, true, USE_INTROSPECTION, VIEW_SERVICE, VIEW_CLIENT),
     /** can create new clients on this service */
-    CREATE_CLIENT(false, true, USE_SERVICE, VIEW_SERVICE, MODIFY_CLIENT, VIEW_CLIENT),
+    CREATE_CLIENT(false, true, USE_INTROSPECTION, USE_SERVICE, VIEW_SERVICE, MODIFY_CLIENT, VIEW_CLIENT),
     /** can modify this service */
-    MODIFY_SERVICE(false, true, USE_SERVICE, VIEW_SERVICE, CREATE_CLIENT, MODIFY_CLIENT, VIEW_CLIENT),
+    MODIFY_SERVICE(false, true, USE_INTROSPECTION, USE_SERVICE, VIEW_SERVICE, CREATE_CLIENT, MODIFY_CLIENT, VIEW_CLIENT),
     /** can view default service parameters */
     VIEW_DEFAULT_SERVICE(false, false),
     /** can create additional services */
     CREATE_SERVICE(false, false, VIEW_DEFAULT_SERVICE),
+    /** can view audit logs */
+    VIEW_AUDIT_LOG(false, false),
     /** can delete a specific service */
     DELETE_SERVICE(false, true),
     /** can call administrative functions on the Authlete server */
-    ADMIN(false, false, VIEW_DEFAULT_SERVICE, CREATE_SERVICE, DELETE_SERVICE, USE_SERVICE, VIEW_SERVICE, MODIFY_SERVICE, CREATE_CLIENT, MODIFY_CLIENT, VIEW_CLIENT)
+    ADMIN(false, false, VIEW_DEFAULT_SERVICE, CREATE_SERVICE, DELETE_SERVICE, USE_INTROSPECTION, USE_SERVICE, VIEW_SERVICE, MODIFY_SERVICE, CREATE_CLIENT, MODIFY_CLIENT, VIEW_CLIENT)
     ;
 
 
diff --git a/src/main/java/com/authlete/common/api/AuthleteApi.java b/src/main/java/com/authlete/common/api/AuthleteApi.java
index c29d265040..d77cd7fcc1 100644
--- a/src/main/java/com/authlete/common/api/AuthleteApi.java
+++ b/src/main/java/com/authlete/common/api/AuthleteApi.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2025 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,8 @@
 import com.authlete.common.dto.AuthorizationIssueResponse;
 import com.authlete.common.dto.AuthorizationRequest;
 import com.authlete.common.dto.AuthorizationResponse;
+import com.authlete.common.dto.AttestationChallengeRequest;
+import com.authlete.common.dto.AttestationChallengeResponse;
 import com.authlete.common.dto.AuthorizationTicketInfoRequest;
 import com.authlete.common.dto.AuthorizationTicketInfoResponse;
 import com.authlete.common.dto.AuthorizationTicketUpdateRequest;
@@ -36,6 +38,8 @@
 import com.authlete.common.dto.BackchannelAuthenticationIssueResponse;
 import com.authlete.common.dto.BackchannelAuthenticationRequest;
 import com.authlete.common.dto.BackchannelAuthenticationResponse;
+import com.authlete.common.dto.BackchannelLogoutTokenRequest;
+import com.authlete.common.dto.BackchannelLogoutTokenResponse;
 import com.authlete.common.dto.Client;
 import com.authlete.common.dto.ClientAuthorizationGetListRequest;
 import com.authlete.common.dto.ClientAuthorizationUpdateRequest;
@@ -58,6 +62,8 @@
 import com.authlete.common.dto.CredentialIssuerMetadataResponse;
 import com.authlete.common.dto.CredentialJwtIssuerMetadataRequest;
 import com.authlete.common.dto.CredentialJwtIssuerMetadataResponse;
+import com.authlete.common.dto.CredentialNonceRequest;
+import com.authlete.common.dto.CredentialNonceResponse;
 import com.authlete.common.dto.CredentialOfferCreateRequest;
 import com.authlete.common.dto.CredentialOfferCreateResponse;
 import com.authlete.common.dto.CredentialOfferInfoRequest;
@@ -4567,6 +4573,45 @@ CredentialDeferredIssueResponse credentialDeferredIssue(
             CredentialDeferredIssueRequest request, Options options) throws AuthleteApiException;
 
 
+    /**
+     * Call Authlete's {@code /vci/nonce} API.
+     *
+     * @param request
+     *         Request parameters passed to the API.
+     *
+     * @return
+     *         Response from the API.
+     *
+     * @since 4.27
+     * @since Authlete 3.0.22
+     */
+    default CredentialNonceResponse credentialNonce(
+            CredentialNonceRequest request) throws AuthleteApiException
+    {
+        return credentialNonce(request, null);
+    }
+
+
+    /**
+     * Call Authlete's {@code /vci/nonce} API.
+     *
+     * @param request
+     *         Request parameters passed to the API.
+     *
+     * @param options
+     *         Request options.
+     *
+     * @return
+     *         Response from the API.
+     *
+     * @since 4.27
+     * @since Authlete 3.0.22
+     */
+    CredentialNonceResponse credentialNonce(
+            CredentialNonceRequest request, Options options) throws AuthleteApiException;
+
+
+
     /**
      * Call Authlete's {@code /idtoken/reissue} API.
      *
@@ -4801,4 +4846,80 @@ NativeSsoResponse nativeSso(
      */
     NativeSsoLogoutResponse nativeSsoLogout(
             NativeSsoLogoutRequest request, Options options) throws AuthleteApiException;
+
+
+    /**
+     * Call Authlete's {@code /attestation/challenge} API.
+     *
+     * @param request
+     *         Request parameters passed to the API.
+     *
+     * @return
+     *         Response from the API.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    default AttestationChallengeResponse attestationChallenge(
+            AttestationChallengeRequest request) throws AuthleteApiException
+    {
+        return attestationChallenge(request, null);
+    }
+
+
+    /**
+     * Call Authlete's {@code /attestation/challenge} API.
+     *
+     * @param request
+     *         Request parameters passed to the API.
+     *
+     * @param options
+     *         Request options.
+     *
+     * @return
+     *         Response from the API.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    AttestationChallengeResponse attestationChallenge(
+            AttestationChallengeRequest request, Options options) throws AuthleteApiException;
+
+
+    /**
+     * Call Authlete's {@code /backchannel/logout/token} API.
+     *
+     * @param request
+     *         Request parameters passed to the API.
+     *
+     * @return
+     *         Response from the API.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     */
+    default BackchannelLogoutTokenResponse backchannelLogoutToken(
+            BackchannelLogoutTokenRequest request) throws AuthleteApiException
+    {
+        return backchannelLogoutToken(request, null);
+    }
+
+
+    /**
+     * Call Authlete's {@code /backchannel/logout/token} API.
+     *
+     * @param request
+     *         Request parameters passed to the API.
+     *
+     * @param options
+     *         Request options.
+     *
+     * @return
+     *         Response from the API.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     */
+    BackchannelLogoutTokenResponse backchannelLogoutToken(
+            BackchannelLogoutTokenRequest request, Options options) throws AuthleteApiException;
 }
diff --git a/src/main/java/com/authlete/common/api/AuthleteApiImpl.java b/src/main/java/com/authlete/common/api/AuthleteApiImpl.java
index 518d357f65..71c60a8784 100644
--- a/src/main/java/com/authlete/common/api/AuthleteApiImpl.java
+++ b/src/main/java/com/authlete/common/api/AuthleteApiImpl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2017-2025 Authlete, Inc.
+ * Copyright (C) 2017-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@
 import com.authlete.common.conf.AuthleteApiVersion;
 import com.authlete.common.conf.AuthleteConfiguration;
 import com.authlete.common.dto.ApiResponse;
+import com.authlete.common.dto.AttestationChallengeRequest;
+import com.authlete.common.dto.AttestationChallengeResponse;
 import com.authlete.common.dto.AuthorizationFailRequest;
 import com.authlete.common.dto.AuthorizationFailResponse;
 import com.authlete.common.dto.AuthorizationIssueRequest;
@@ -41,6 +43,8 @@
 import com.authlete.common.dto.BackchannelAuthenticationIssueResponse;
 import com.authlete.common.dto.BackchannelAuthenticationRequest;
 import com.authlete.common.dto.BackchannelAuthenticationResponse;
+import com.authlete.common.dto.BackchannelLogoutTokenRequest;
+import com.authlete.common.dto.BackchannelLogoutTokenResponse;
 import com.authlete.common.dto.Client;
 import com.authlete.common.dto.ClientAuthorizationDeleteRequest;
 import com.authlete.common.dto.ClientAuthorizationGetListRequest;
@@ -66,6 +70,8 @@
 import com.authlete.common.dto.CredentialIssuerMetadataResponse;
 import com.authlete.common.dto.CredentialJwtIssuerMetadataRequest;
 import com.authlete.common.dto.CredentialJwtIssuerMetadataResponse;
+import com.authlete.common.dto.CredentialNonceRequest;
+import com.authlete.common.dto.CredentialNonceResponse;
 import com.authlete.common.dto.CredentialOfferCreateRequest;
 import com.authlete.common.dto.CredentialOfferCreateResponse;
 import com.authlete.common.dto.CredentialOfferInfoRequest;
@@ -141,6 +147,7 @@
  */
 class AuthleteApiImpl extends AuthleteApiBasicImpl
 {
+    private static final String ATTESTATION_CHALLENGE_API_PATH            = "/api/attestation/challenge";
     private static final String AUTH_AUTHORIZATION_API_PATH               = "/api/auth/authorization";
     private static final String AUTH_AUTHORIZATION_FAIL_API_PATH          = "/api/auth/authorization/fail";
     private static final String AUTH_AUTHORIZATION_ISSUE_API_PATH         = "/api/auth/authorization/issue";
@@ -190,6 +197,7 @@ class AuthleteApiImpl extends AuthleteApiBasicImpl
     private static final String BC_AUTHENTICATION_COMPLETE_API_PATH       = "/api/backchannel/authentication/complete";
     private static final String BC_AUTHENTICATION_FAIL_API_PATH           = "/api/backchannel/authentication/fail";
     private static final String BC_AUTHENTICATION_ISSUE_API_PATH          = "/api/backchannel/authentication/issue";
+    private static final String BC_LOGOUT_TOKEN_API_PATH                  = "/api/backchannel/logout/token";
     private static final String DEVICE_AUTHORIZATION_API_PATH             = "/api/device/authorization";
     private static final String DEVICE_COMPLETE_API_PATH                  = "/api/device/complete";
     private static final String DEVICE_VERIFICATION_API_PATH              = "/api/device/verification";
@@ -204,6 +212,7 @@ class AuthleteApiImpl extends AuthleteApiBasicImpl
     private static final String FEDERATION_CONFIGURATION_API_PATH         = "/api/federation/configuration";
     private static final String FEDERATION_REGISTRATION_API_PATH          = "/api/federation/registration";
     private static final String VCI_METADATA_API_PATH                     = "/api/vci/metadata";
+    private static final String VCI_NONCE_API_PATH                        = "/api/vci/nonce";
     private static final String VCI_JWT_ISSUER_API_PATH                   = "/api/vci/jwtissuer";
     private static final String VCI_JWKS_API_PATH                         = "/api/vci/jwks";
     private static final String VCI_OFFER_CREATE_API_PATH                 = "/api/vci/offer/create";
@@ -221,7 +230,7 @@ class AuthleteApiImpl extends AuthleteApiBasicImpl
     private final String mServiceOwnerAuth;
     private final String mServiceAuth;
 
-    
+
     /**
      * The constructor with an instance of {@link AuthleteConfiguration}.
      *
@@ -1704,6 +1713,21 @@ public CredentialDeferredIssueResponse credentialDeferredIssue(
     }
 
 
+    @Override
+    public CredentialNonceResponse credentialNonce(
+            CredentialNonceRequest request, Options options) throws AuthleteApiException
+    {
+        // Note that the /vci/nonce API is not available in Authlete 2.x,
+        // so the executeApiCall below will throw an exception.
+
+        return executeApiCall(
+                new ServicePostApiCaller<CredentialNonceResponse>(
+                        CredentialNonceResponse.class, request,
+                        VCI_NONCE_API_PATH)
+                        .setOptions(options));
+    }
+
+
     @Override
     public IDTokenReissueResponse idTokenReissue(
             IDTokenReissueRequest request, Options options) throws AuthleteApiException
@@ -1792,4 +1816,34 @@ public NativeSsoLogoutResponse nativeSsoLogout(
                         NATIVE_SSO_LOGOUT_API_PATH)
                         .setOptions(options));
     }
+
+
+    @Override
+    public AttestationChallengeResponse attestationChallenge(
+            AttestationChallengeRequest request, Options options) throws AuthleteApiException
+    {
+        // Note that the /attestation/challenge API is not available in Authlete 2.x,
+        // so the executeApiCall below will throw an exception.
+
+        return executeApiCall(
+                new ServicePostApiCaller<AttestationChallengeResponse>(
+                        AttestationChallengeResponse.class, request,
+                        ATTESTATION_CHALLENGE_API_PATH)
+                        .setOptions(options));
+    }
+
+
+    @Override
+    public BackchannelLogoutTokenResponse backchannelLogoutToken(
+            BackchannelLogoutTokenRequest request, Options options) throws AuthleteApiException
+    {
+        // Note that the /backchannel/logout/token API is not available in
+        // Authlete 2.x, so the executeApiCall below will throw an exception.
+
+        return executeApiCall(
+                new ServicePostApiCaller<BackchannelLogoutTokenResponse>(
+                        BackchannelLogoutTokenResponse.class, request,
+                        BC_LOGOUT_TOKEN_API_PATH)
+                        .setOptions(options));
+    }
 }
diff --git a/src/main/java/com/authlete/common/api/AuthleteApiImplV3.java b/src/main/java/com/authlete/common/api/AuthleteApiImplV3.java
index cdbaa66b8c..fbf9857b61 100644
--- a/src/main/java/com/authlete/common/api/AuthleteApiImplV3.java
+++ b/src/main/java/com/authlete/common/api/AuthleteApiImplV3.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2025 Authlete, Inc.
+ * Copyright (C) 2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,8 @@
 import com.authlete.common.conf.AuthleteApiVersion;
 import com.authlete.common.conf.AuthleteConfiguration;
 import com.authlete.common.dto.ApiResponse;
+import com.authlete.common.dto.AttestationChallengeRequest;
+import com.authlete.common.dto.AttestationChallengeResponse;
 import com.authlete.common.dto.AuthorizationFailRequest;
 import com.authlete.common.dto.AuthorizationFailResponse;
 import com.authlete.common.dto.AuthorizationIssueRequest;
@@ -42,6 +44,8 @@
 import com.authlete.common.dto.BackchannelAuthenticationIssueResponse;
 import com.authlete.common.dto.BackchannelAuthenticationRequest;
 import com.authlete.common.dto.BackchannelAuthenticationResponse;
+import com.authlete.common.dto.BackchannelLogoutTokenRequest;
+import com.authlete.common.dto.BackchannelLogoutTokenResponse;
 import com.authlete.common.dto.Client;
 import com.authlete.common.dto.ClientAuthorizationDeleteRequest;
 import com.authlete.common.dto.ClientAuthorizationGetListRequest;
@@ -67,6 +71,8 @@
 import com.authlete.common.dto.CredentialIssuerMetadataResponse;
 import com.authlete.common.dto.CredentialJwtIssuerMetadataRequest;
 import com.authlete.common.dto.CredentialJwtIssuerMetadataResponse;
+import com.authlete.common.dto.CredentialNonceRequest;
+import com.authlete.common.dto.CredentialNonceResponse;
 import com.authlete.common.dto.CredentialOfferCreateRequest;
 import com.authlete.common.dto.CredentialOfferCreateResponse;
 import com.authlete.common.dto.CredentialOfferInfoRequest;
@@ -142,6 +148,7 @@
  */
 public class AuthleteApiImplV3 extends AuthleteApiBasicImpl
 {
+    private static final String ATTESTATION_CHALLENGE_API_PATH                = "/api/%d/attestation/challenge";
     private static final String AUTH_AUTHORIZATION_API_PATH                   = "/api/%d/auth/authorization";
     private static final String AUTH_AUTHORIZATION_FAIL_API_PATH              = "/api/%d/auth/authorization/fail";
     private static final String AUTH_AUTHORIZATION_ISSUE_API_PATH             = "/api/%d/auth/authorization/issue";
@@ -191,6 +198,7 @@ public class AuthleteApiImplV3 extends AuthleteApiBasicImpl
     private static final String BACKCHANNEL_AUTHENTICATION_COMPLETE_API_PATH  = "/api/%d/backchannel/authentication/complete";
     private static final String BACKCHANNEL_AUTHENTICATION_FAIL_API_PATH      = "/api/%d/backchannel/authentication/fail";
     private static final String BACKCHANNEL_AUTHENTICATION_ISSUE_API_PATH     = "/api/%d/backchannel/authentication/issue";
+    private static final String BACKCHANNEL_LOGOUT_TOKEN_API_PATH             = "/api/%d/backchannel/logout/token";
     private static final String DEVICE_AUTHORIZATION_API_PATH                 = "/api/%d/device/authorization";
     private static final String DEVICE_COMPLETE_API_PATH                      = "/api/%d/device/complete";
     private static final String DEVICE_VERIFICATION_API_PATH                  = "/api/%d/device/verification";
@@ -207,6 +215,7 @@ public class AuthleteApiImplV3 extends AuthleteApiBasicImpl
     private static final String VCI_JWKS_API_PATH                             = "/api/%d/vci/jwks";
     private static final String VCI_JWT_ISSUER_API_PATH                       = "/api/%d/vci/jwtissuer";
     private static final String VCI_METADATA_API_PATH                         = "/api/%d/vci/metadata";
+    private static final String VCI_NONCE_API_PATH                            = "/api/%d/vci/nonce";
     private static final String VCI_OFFER_CREATE_API_PATH                     = "/api/%d/vci/offer/create";
     private static final String VCI_OFFER_INFO_API_PATH                       = "/api/%d/vci/offer/info";
     private static final String VCI_SINGLE_PARSE_API_PATH                     = "/api/%d/vci/single/parse";
@@ -1569,6 +1578,18 @@ public CredentialDeferredIssueResponse credentialDeferredIssue(
     }
 
 
+    @Override
+    public CredentialNonceResponse credentialNonce(
+            CredentialNonceRequest request, Options options) throws AuthleteApiException
+    {
+        return executeApiCall(
+                new PostApiCaller<CredentialNonceResponse>(
+                        CredentialNonceResponse.class, request,
+                        VCI_NONCE_API_PATH, mServiceId)
+                        .setOptions(options));
+    }
+
+
     @Override
     public IDTokenReissueResponse idTokenReissue(
             IDTokenReissueRequest request, Options options) throws AuthleteApiException
@@ -1652,4 +1673,28 @@ public NativeSsoLogoutResponse nativeSsoLogout(
                         NATIVE_SSO_LOGOUT_API_PATH, mServiceId)
                         .setOptions(options));
     }
+
+
+    @Override
+    public AttestationChallengeResponse attestationChallenge(
+            AttestationChallengeRequest request, Options options) throws AuthleteApiException
+    {
+        return executeApiCall(
+                new PostApiCaller<AttestationChallengeResponse>(
+                        AttestationChallengeResponse.class, request,
+                        ATTESTATION_CHALLENGE_API_PATH, mServiceId)
+                        .setOptions(options));
+    }
+
+
+    @Override
+    public BackchannelLogoutTokenResponse backchannelLogoutToken(
+            BackchannelLogoutTokenRequest request, Options options) throws AuthleteApiException
+    {
+        return executeApiCall(
+                new PostApiCaller<BackchannelLogoutTokenResponse>(
+                        BackchannelLogoutTokenResponse.class, request,
+                        BACKCHANNEL_LOGOUT_TOKEN_API_PATH, mServiceId)
+                        .setOptions(options));
+    }
 }
diff --git a/src/main/java/com/authlete/common/conf/AuthletePropertiesConfiguration.java b/src/main/java/com/authlete/common/conf/AuthletePropertiesConfiguration.java
index e5f5cc1d93..2ecc26b2ec 100644
--- a/src/main/java/com/authlete/common/conf/AuthletePropertiesConfiguration.java
+++ b/src/main/java/com/authlete/common/conf/AuthletePropertiesConfiguration.java
@@ -19,7 +19,7 @@
 import java.util.logging.Logger;
 import com.authlete.common.util.PropertiesLoader;
 import com.authlete.common.util.TypedProperties;
-import com.neovisionaries.security.AESCipher;
+import com.authlete.common.util.security.AESCipher;
 
 
 /**
diff --git a/src/main/java/com/authlete/common/dto/ApiResponse.java b/src/main/java/com/authlete/common/dto/ApiResponse.java
index 4349368559..238bc2c9bb 100644
--- a/src/main/java/com/authlete/common/dto/ApiResponse.java
+++ b/src/main/java/com/authlete/common/dto/ApiResponse.java
@@ -17,6 +17,8 @@
 
 
 import java.io.Serializable;
+import java.util.List;
+import java.util.Map;
 
 
 /**
@@ -32,6 +34,7 @@ public class ApiResponse implements Serializable
 
     private String resultCode;
     private String resultMessage;
+    private Map<String, List<String>> responseHeaders;
 
 
     /**
@@ -81,4 +84,33 @@ public void setResultMessage(String message)
     {
         this.resultMessage = message;
     }
+
+
+    /**
+     * Get the HTTP response headers returned from an Authlete API call.
+     *
+     * @return
+     *         A map of HTTP response headers. May be {@code null} or empty.
+     *
+     * @since 4.23
+     */
+    public Map<String, List<String>> getResponseHeaders()
+    {
+        return responseHeaders;
+    }
+
+
+    /**
+     * Set the HTTP response headers returned from an Authlete API call.
+     *
+     * @param responseHeaders
+     *         A map of HTTP response headers where each key is a header name
+     *         and the corresponding value is a list of header values.
+     *
+     * @since 4.23
+     */
+    public void setResponseHeaders(Map<String, List<String>> responseHeaders)
+    {
+        this.responseHeaders = responseHeaders;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/AttestationChallengeRequest.java b/src/main/java/com/authlete/common/dto/AttestationChallengeRequest.java
new file mode 100644
index 0000000000..6c89203fd6
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/AttestationChallengeRequest.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2026 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.dto;
+
+
+import java.io.Serializable;
+
+
+/**
+ * Request to Authlete's {@code /attestation/challenge} API.
+ *
+ * <p>
+ * The Authlete API is supposed to be used from within the implementation of
+ * the challenge endpoint of the authorization server.
+ * </p>
+ *
+ * @since 4.39
+ * @since Authlete 3.0.28
+ *
+ * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+ *      OAuth 2.0 Attestation-Based Client Authentication</a>
+ */
+public class AttestationChallengeRequest implements Serializable
+{
+    private static final long serialVersionUID = 1L;
+
+
+    private boolean pretty;
+
+
+
+    /**
+     * Get the flag indicating whether the challenge response is written in the
+     * pretty format or not.
+     *
+     * @return
+     *         {@code true} if the challenge response is written in the pretty
+     *         format.
+     */
+    public boolean isPretty()
+    {
+        return pretty;
+    }
+
+
+    /**
+     * Set the flag indicating whether the challenge response is written in the
+     * pretty format or not.
+     *
+     * @param pretty
+     *         {@code true} to write the challenge response in the pretty format.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AttestationChallengeRequest setPretty(boolean pretty)
+    {
+        this.pretty = pretty;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/AttestationChallengeResponse.java b/src/main/java/com/authlete/common/dto/AttestationChallengeResponse.java
new file mode 100644
index 0000000000..b3ad5a306e
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/AttestationChallengeResponse.java
@@ -0,0 +1,249 @@
+/*
+ * Copyright (C) 2026 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.dto;
+
+
+/**
+ * Response from Authlete's {@code /attestation/challenge} API.
+ *
+ * <p>
+ * The Authlete API is supposed to be used from within the implementation
+ * the challenge endpoint of the authorization server.
+ * </p>
+ *
+ * <p>
+ * Authlete's {@code /attestation/challenge} API returns JSON which can be
+ * mapped to this class. The authorization server implementation should
+ * retrieve the value of the <code>{@link #getAction() action}</code>
+ * response parameter from the API response and take the following steps
+ * according to the value.
+ * </p>
+ *
+ * <h3><code>OK</code></h3>
+ *
+ * <p>
+ * When the value of the <code>{@link #getAction() action}</code> response
+ * parameter is <code>{@link Action#OK OK}</code>, it means that Authlete
+ * could prepare a challenge response successfully.
+ * <p>
+ *
+ * </p>
+ * In this case, the implementation of the challenge endpoint of the
+ * authorization server should return an HTTP response with the HTTP status
+ * code "{@code 200 OK}" and the content type "{@code application/json}".
+ * The message body of the response has been prepared by Authlete's
+ * {@code /attestation/challenge} API and it is available as the
+ * <code>{@link #getResponseContent() responseContent}</code> response
+ * parameter.
+ * </p>
+ *
+ * <p>
+ * The implementation of the challenge endpoint can construct an HTTP response
+ * by doing like below.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;">
+ * 200 OK
+ * Content-Type: application/json
+ * Cache-Control: no-store
+ * (Other HTTP headers)
+ *
+ * <i>(the value of the {@link #getResponseContent() responseContent} response parameter)</i></pre>
+ *
+ * <p>
+ * Note that the <a href=
+ * "https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/"
+ * >OAuth 2.0 Attestation-Based Client Authentication</a> specification
+ * requires the response to include the {@code Cache-Control} header including
+ * the value {@code no-store}.
+ * </p>
+ *
+ * <h3><code>INTERNAL_SERVER_ERROR</code></h3>
+ *
+ * <p>
+ * When the value of the <code>{@link #getAction() action}</code> response
+ * parameter is <code>{@link Action#INTERNAL_SERVER_ERROR INTERNAL_SERVER_ERROR}</code>,
+ * it means that an unexpected error has occurred on Authlete side or the
+ * service has not been set up properly yet.
+ * </p>
+ *
+ * </p>
+ * In this case, a simple implementation of the challenge endpoint would return
+ * an HTTP response with the HTTP status code "{@code 500 Internal Server Error}"
+ * and the content type "{@code application/json}". The message body (= error
+ * information in the JSON format) of the response has been prepared by Authlete's
+ * {@code /attestation/challenge} API and it is available as the
+ * <code>{@link #getResponseContent() responseContent}</code> response parameter.
+ * </p>
+ *
+ * <p>
+ * Such simple implementation of the challenge endpoint can construct an HTTP
+ * response by doing like below.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;">
+ * 500 Internal Server Error
+ * Content-Type: application/json
+ * (Other HTTP headers)
+ *
+ * <i>(the value of the {@link #getResponseContent() responseContent} response parameter)</i></pre>
+ *
+ * <p>
+ * However, in real commercial deployments, it is rare for an authorization
+ * server to return "{@code 500 Internal Server Error}" when it encounters an
+ * unexpected internal error. It's up to implementations of authorization
+ * servers what they actually return in the case of internal server error.
+ * </p>
+ *
+ * @since 4.39
+ * @since Authlete 3.0.28
+ *
+ * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+ *      OAuth 2.0 Attestation-Based Client Authentication</a>
+ */
+public class AttestationChallengeResponse extends ApiResponse
+{
+    private static final long serialVersionUID = 1L;
+
+
+    /**
+     * The next action that the implementation of the challenge endpoint
+     * should take after getting a response from Authlete's
+     * {@code /attestation/challenge} API.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    public enum Action
+    {
+        /**
+         * A challenge response has been prepared successfully. The
+         * implementation of the challenge endpoint should return an HTTP
+         * response with the HTTP status code "{@code 200 OK}" and the content
+         * type "{@code application/json}".
+         */
+        OK,
+
+        /**
+         * An unexpected error occurred on Authlete side or the service has
+         * not been set up properly yet. A simple implementation of the
+         * challenge endpoint would return an HTTP response with the HTTP
+         * status code "{@code 500 Internal Server Error}" and the content
+         * type "{@code application/json}".
+         */
+        INTERNAL_SERVER_ERROR,
+    }
+
+
+    private Action action;
+    private String responseContent;
+    private String attestationChallenge;
+
+
+    /**
+     * Get the next action that the implementation of the challenge endpoint
+     * should take after getting a response from Authlete's
+     * {@code /attestation/challenge} API.
+     *
+     * @return
+     *         The next action.
+     */
+    public Action getAction()
+    {
+        return action;
+    }
+
+
+    /**
+     * Set the next action that the implementation of the challenge endpoint
+     * should take after getting a response from Authlete's
+     * {@code /attestation/challenge} API.
+     *
+     * @param action
+     *         The next action.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AttestationChallengeResponse setAction(Action action)
+    {
+        this.action = action;
+
+        return this;
+    }
+
+
+    /**
+     * Get the content that the implementation of the challenge endpoint should
+     * use when it constructs a response.
+     *
+     * @return
+     *         The response content in the JSON format.
+     */
+    public String getResponseContent()
+    {
+        return responseContent;
+    }
+
+
+    /**
+     * Set the content that the implementation of the challenge endpoint should
+     * use when it constructs a response.
+     *
+     * @param content
+     *         The response content in the JSON format.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AttestationChallengeResponse setResponseContent(String content)
+    {
+        this.responseContent = content;
+
+        return this;
+    }
+
+
+    /**
+     * Get the {@code attestation_challenge} value generated by the
+     * {@code /attestation/challenge} API.
+     *
+     * @return
+     *         The generated {@code attestation_challenge} value.
+     */
+    public String getAttestationChallenge()
+    {
+        return attestationChallenge;
+    }
+
+
+    /**
+     * Set the {@code attestation_challenge} value generated by the
+     * {@code /attestation/challenge} API.
+     *
+     * @param challenge
+     *         The generated {@code attestation_challenge} value.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AttestationChallengeResponse setAttestationChallenge(String challenge)
+    {
+        this.attestationChallenge = challenge;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/AuthorizationFailRequest.java b/src/main/java/com/authlete/common/dto/AuthorizationFailRequest.java
index 4a690ba4a0..47b7ae2028 100644
--- a/src/main/java/com/authlete/common/dto/AuthorizationFailRequest.java
+++ b/src/main/java/com/authlete/common/dto/AuthorizationFailRequest.java
@@ -261,6 +261,40 @@ public enum Reason
          * @since 2.62
          */
         INVALID_TARGET,
+
+        /**
+         * The requested scope is invalid, unknown, or malformed.
+         *
+         * <p>
+         * Using this reason will result in {@code error=invalid_scope}.
+         * </p>
+         *
+         * @since 4.46
+         */
+        INVALID_SCOPE,
+
+        /**
+         * The client is not authorized to request an authorization code using this method.
+         *
+         * <p>
+         *  Using this reason will result in {@code error=unauthorized_client}.
+         * </p>
+         * @since 4.46
+         */
+        UNAUTHORIZED_CLIENT,
+
+        /**
+         * The authorization server is currently unable to handle the request due to a temporary overloading or maintenance
+         * of the server. (This error code is needed because a 503 Service Unavailable HTTP status code cannot be returned
+         * to the client via an HTTP redirect.)
+         *
+         * <p>
+         *  Using this reason will result in {@code error=temporarily_unavailable}.
+         * </p>
+         *
+         * @since 4.46
+         */
+        TEMPORARILY_UNAVAILABLE,
     }
 
 
diff --git a/src/main/java/com/authlete/common/dto/AuthorizationIssueRequest.java b/src/main/java/com/authlete/common/dto/AuthorizationIssueRequest.java
index 2a298dfc95..24ec702ad6 100644
--- a/src/main/java/com/authlete/common/dto/AuthorizationIssueRequest.java
+++ b/src/main/java/com/authlete/common/dto/AuthorizationIssueRequest.java
@@ -1,11 +1,11 @@
 /*
- * Copyright (C) 2014-2025 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
- *     http://www.apache.org/licenses/LICENSE-2.0
+ *     https://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
@@ -45,9 +45,9 @@
  * is required unless the authorization request has come with
  * {@code response_type=none} (which means the client application
  * did not request any token to be returned). See "<a href=
- * "http://openid.net/specs/oauth-v2-multiple-response-types-1_0.html#none"
+ * "https://openid.net/specs/oauth-v2-multiple-response-types-1_0.html#none"
  * >4. None Response Type</a>" in <a href=
- * "http://openid.net/specs/oauth-v2-multiple-response-types-1_0.html"
+ * "https://openid.net/specs/oauth-v2-multiple-response-types-1_0.html"
  * >OAuth 2.0 Multiple Response Type Encoding Practices</a> for
  * details about {@code response_type=none}.
  * </p>
@@ -73,7 +73,7 @@
  * <p>
  * The claims of the end-user (= pieces of information about the
  * end-user) in JSON format. See
- * <a href="http://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
+ * <a href="https://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
  * >OpenID Connect Core 1.0, 5.1. Standard Claims</a> for details
  * about the format.
  * </p>
@@ -122,7 +122,7 @@
  * If you add <code>"offline_access"</code> scope although it is not
  * included in the original request, keep in mind that the specification
  * requires explicit consent from the user for the scope (<a href=
- * "http://openid.net/specs/openid-connect-core-1_0.html#OfflineAccess"
+ * "https://openid.net/specs/openid-connect-core-1_0.html#OfflineAccess"
  * >OpenID Connect Core 1.0, 11. Offline Access</a>). When
  * <code>"offline_access"</code> is included in the original request, the
  * current implementation of Authlete's {@code /auth/authorization} API
@@ -234,7 +234,7 @@
  *
  * @see AuthorizationResponse
  *
- * @see <a href="http://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
+ * @see <a href="https://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
  *      >OpenID Connect Core 1.0, 5.1. Standard Claims</a>
  *
  * @author Takahiko Kawasaki
@@ -659,7 +659,7 @@ public String getClaims()
      * </p>
      *
      * <p>
-     * See <a href="http://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
+     * See <a href="https://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
      * >OpenID Connect Core 1.0, 5.1. Standard Claims</a> for further details
      * about the format.
      * </p>
@@ -670,7 +670,7 @@ public String getClaims()
      * @return
      *         {@code this} object.
      *
-     * @see <a href="http://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
+     * @see <a href="https://openid.net/specs/openid-connect-core-1_0.html#StandardClaims"
      *      >OpenID Connect Core 1.0, 5.1. Standard Claims</a>
      */
     public AuthorizationIssueRequest setClaims(String claims)
@@ -750,7 +750,7 @@ public Property[] getProperties()
      * Keys listed below should not be used and they would be ignored on
      * the server side even if they were used. It's because they are reserved
      * in <a href="https://tools.ietf.org/html/rfc6749">RFC 6749</a> and
-     * <a href="http://openid.net/specs/openid-connect-core-1_0.html"
+     * <a href="https://openid.net/specs/openid-connect-core-1_0.html"
      * >OpenID Connect Core 1.0</a>.
      * </p>
      *
@@ -835,7 +835,7 @@ public String[] getScopes()
      * If you add <code>"offline_access"</code> scope although it is not
      * included in the original request, keep in mind that the specification
      * requires explicit consent from the user for the scope (<a href=
-     * "http://openid.net/specs/openid-connect-core-1_0.html#OfflineAccess"
+     * "https://openid.net/specs/openid-connect-core-1_0.html#OfflineAccess"
      * >OpenID Connect Core 1.0, 11. Offline Access</a>). When
      * <code>"offline_access"</code> is included in the original request, the
      * current implementation of Authlete's /api/auth/authorization API checks
@@ -1657,7 +1657,7 @@ public AuthorizationIssueRequest setAccessTokenDuration(long duration)
      * claim.
      *
      * <p>
-     * This parameter needs to be provided only if you want to support the
+     * This parameter needs to be provided if you want to support the
      * "<a href="https://openid.net/specs/openid-connect-native-sso-1_0.html"
      * >OpenID Connect Native SSO for Mobile Apps 1.0</a>" specification
      * (a.k.a. "Native SSO"). To enable support for the Native SSO specification,
@@ -1669,10 +1669,28 @@ public AuthorizationIssueRequest setAccessTokenDuration(long duration)
      * <b>NOTE</b>: When the response from the {@code /auth/authorization} API
      * contains the {@code nativeSsoRequested} property with a value of
      * {@code true} (see {@link AuthorizationResponse#isNativeSsoRequested()}),
-     * the {@code sessionId} request parameter must be provided to the
+     * this {@code sessionId} request parameter must be provided to the
      * {@code /auth/authorization/issue} API.
      * </p>
      *
+     * <p>
+     * Also, if your server's
+     * <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code> metadata
+     * parameter is set to {@code true} (see
+     * {@link Service#isBackchannelLogoutSessionSupported()}), this
+     * {@code sessionId} request parameter should be provided. See the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification for the metadata
+     * parameter.
+     * </p>
+     *
+     * <p>
+     * In the current Authlete implementation, this {@code sessionId} request
+     * parameter is recognized only when Native SSO is requested or the
+     * <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code> server
+     * metadata parameter is set to {@code true}.
+     * </p>
+     *
      * @return
      *         The session ID of the user's authentication session.
      *
@@ -1683,6 +1701,10 @@ public AuthorizationIssueRequest setAccessTokenDuration(long duration)
      *      >OpenID Connect Native SSO for Mobile Apps 1.0</a>
      * @see AuthorizationResponse#isNativeSsoRequested()
      * @see Service#isNativeSsoSupported()
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html"
+     *      >OpenID Connect Back-Channel Logout 1.0</a>
+     * @see Service#isBackchannelLogoutSessionSupported()
      */
     public String getSessionId()
     {
@@ -1696,7 +1718,7 @@ public String getSessionId()
      * claim.
      *
      * <p>
-     * This parameter needs to be provided only if you want to support the
+     * This parameter needs to be provided if you want to support the
      * "<a href="https://openid.net/specs/openid-connect-native-sso-1_0.html"
      * >OpenID Connect Native SSO for Mobile Apps 1.0</a>" specification
      * (a.k.a. "Native SSO"). To enable support for the Native SSO specification,
@@ -1708,10 +1730,28 @@ public String getSessionId()
      * <b>NOTE</b>: When the response from the {@code /auth/authorization} API
      * contains the {@code nativeSsoRequested} property with a value of
      * {@code true} (see {@link AuthorizationResponse#isNativeSsoRequested()}),
-     * the {@code sessionId} request parameter must be provided to the
+     * this {@code sessionId} request parameter must be provided to the
      * {@code /auth/authorization/issue} API.
      * </p>
      *
+     * <p>
+     * Also, if your server's
+     * <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code> metadata
+     * parameter is set to {@code true} (see
+     * {@link Service#isBackchannelLogoutSessionSupported()}), this
+     * {@code sessionId} request parameter should be provided. See the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification for the metadata
+     * parameter.
+     * </p>
+     *
+     * <p>
+     * In the current Authlete implementation, this {@code sessionId} request
+     * parameter is recognized only when Native SSO is requested or the
+     * <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code> server
+     * metadata parameter is set to {@code true}.
+     * </p>
+     *
      * @param sessionId
      *         The session ID of the user's authentication session.
      *
@@ -1725,6 +1765,10 @@ public String getSessionId()
      *      >OpenID Connect Native SSO for Mobile Apps 1.0</a>
      * @see AuthorizationResponse#isNativeSsoRequested()
      * @see Service#isNativeSsoSupported()
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html"
+     *      >OpenID Connect Back-Channel Logout 1.0</a>
+     * @see Service#isBackchannelLogoutSessionSupported()
      */
     public AuthorizationIssueRequest setSessionId(String sessionId)
     {
diff --git a/src/main/java/com/authlete/common/dto/AuthorizationRequest.java b/src/main/java/com/authlete/common/dto/AuthorizationRequest.java
index 5c2aeabd00..4a0d2f696e 100644
--- a/src/main/java/com/authlete/common/dto/AuthorizationRequest.java
+++ b/src/main/java/com/authlete/common/dto/AuthorizationRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2023 Authlete, Inc.
+ * Copyright (C) 2014-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,7 +50,7 @@
  */
 public class AuthorizationRequest implements Serializable
 {
-    private static final long serialVersionUID = 3L;
+    private static final long serialVersionUID = 4L;
 
 
     /**
@@ -69,6 +69,15 @@ public class AuthorizationRequest implements Serializable
     private String context;
 
 
+    /**
+     * Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private CimdOptions cimdOptions;
+
+
     /**
      * Get the value of {@code parameters} which are the request
      * parameters that the OAuth 2.0 authorization endpoint of the
@@ -184,4 +193,49 @@ public AuthorizationRequest setContext(String context)
 
         return this;
     }
+
+
+    /**
+     * Get options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @return
+     *         Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public CimdOptions getCimdOptions()
+    {
+        return cimdOptions;
+    }
+
+
+    /**
+     * Set options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @param options
+     *         Options for CIMD processing.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public AuthorizationRequest setCimdOptions(CimdOptions options)
+    {
+        this.cimdOptions = options;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/AuthorizationResponse.java b/src/main/java/com/authlete/common/dto/AuthorizationResponse.java
index 2b949d692c..e2117a4ee8 100644
--- a/src/main/java/com/authlete/common/dto/AuthorizationResponse.java
+++ b/src/main/java/com/authlete/common/dto/AuthorizationResponse.java
@@ -1021,7 +1021,7 @@
  */
 public class AuthorizationResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 21L;
+    private static final long serialVersionUID = 22L;
 
 
     /**
@@ -1161,6 +1161,11 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 1.1
      */
@@ -1756,6 +1761,75 @@ public void setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the flag which indicates whether the value of the {@code client_id}
+     * request parameter included in the authorization request is the location
+     * of the client's metadata document.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * <p>
+     * When this flag is {@code true}, {@code client.}{@link
+     * Client#getMetadataDocumentLocation() getMetadataDocumentLocation()}
+     * returns the location of the client's metadata document.
+     * </p>
+     *
+     * @return
+     *         {@code true} if the value of the {@code client_id} request
+     *         parameter is the location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the value of the {@code client_id}
+     * request parameter included in the authorization request is the location
+     * of the client's metadata document.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * <p>
+     * When this flag is {@code true}, {@code client.}{@link
+     * Client#getMetadataDocumentLocation() getMetadataDocumentLocation()}
+     * returns the location of the client's metadata document.
+     * </p>
+     *
+     * @param used
+     *         {@code true} to indicate that the value of the {@code client_id}
+     *         request parameter is the location of the client's metadata
+     *         document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentUsed(boolean used)
+    {
+        metadataDocumentUsed = used;
+    }
+
+
     /**
      * Get the list of ACRs (Authentication Context Class References)
      * requested by the client application. The value come from (1)
diff --git a/src/main/java/com/authlete/common/dto/AuthzDetailsElement.java b/src/main/java/com/authlete/common/dto/AuthzDetailsElement.java
index be8b29d4d9..f69bf8ab8b 100644
--- a/src/main/java/com/authlete/common/dto/AuthzDetailsElement.java
+++ b/src/main/java/com/authlete/common/dto/AuthzDetailsElement.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2021 Authlete, Inc.
+ * Copyright (C) 2019-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,7 @@
  */
 public class AuthzDetailsElement implements Serializable
 {
-    private static final long serialVersionUID = 4L;
+    private static final long serialVersionUID = 5L;
 
 
     private String type;
@@ -42,6 +42,43 @@ public class AuthzDetailsElement implements Serializable
     private String otherFields;
 
 
+    /**
+     * The default constructor.
+     */
+    public AuthzDetailsElement()
+    {
+    }
+
+
+    /**
+     * The copy constructor.
+     *
+     * @param element
+     *         The source instance.
+     *
+     * @since 4.34
+     */
+    public AuthzDetailsElement(AuthzDetailsElement element)
+    {
+        if (element != null)
+        {
+            this.type        = element.type;
+            this.locations   = copy(element.locations);
+            this.actions     = copy(element.actions);
+            this.dataTypes   = copy(element.dataTypes);
+            this.identifier  = element.identifier;
+            this.privileges  = copy(element.privileges);
+            this.otherFields = element.otherFields;
+        }
+    }
+
+
+    private static String[] copy(String[] source)
+    {
+        return (source != null) ? source.clone() : null;
+    }
+
+
     /**
      * Get the type of this element.
      *
diff --git a/src/main/java/com/authlete/common/dto/BackchannelAuthenticationCompleteResponse.java b/src/main/java/com/authlete/common/dto/BackchannelAuthenticationCompleteResponse.java
index 67326120b9..c4bb60e36a 100644
--- a/src/main/java/com/authlete/common/dto/BackchannelAuthenticationCompleteResponse.java
+++ b/src/main/java/com/authlete/common/dto/BackchannelAuthenticationCompleteResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018-2023 Authlete, Inc.
+ * Copyright (C) 2018-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -139,7 +139,7 @@
  */
 public class BackchannelAuthenticationCompleteResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 8L;
+    private static final long serialVersionUID = 9L;
 
 
     /**
@@ -218,6 +218,22 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * Whether the client's metadata document was used.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 2.0.0
      */
@@ -581,18 +597,129 @@ public BackchannelAuthenticationCompleteResponse setClientEntityIdUsed(boolean u
 
 
     /**
-     * Get the client identifier used in the backchannel authentication
-     * request.
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public BackchannelAuthenticationCompleteResponse setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
      *
      * <p>
-     * When {@link #isClientIdAliasUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientIdAlias()} does. Otherwise,
-     * if {@link #isClientEntityIdUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientEntityId()}{@code .toString()}
-     * does. In other cases, this method returns the string representation of
-     * the value returned from {@link #getClientId()}.
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
      * </p>
      *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public BackchannelAuthenticationCompleteResponse setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+
+        return this;
+    }
+
+
+    /**
+     * Get the client identifier used in the backchannel authentication
+     * request.
+     *
+     * <ol>
+     * <li>When {@link #isClientEntityIdUsed()} returns {@code true}, this
+     *     method returns the same value as {@link #getClientIdAlias()} does.
+     *
+     * <li>Otherwise, if {@link #isClientEntityIdUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getClientEntityId()}{@code .toString()} does.
+     *
+     * <li>Otherwise, if {@link #isMetadataDocumentUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getMetadataDocumentLocation()}{@code .toString()} does.
+     *
+     * <li>In other cases, this method returns the string representation of
+     *     the value returned from {@link #getClientId()}.
+     * </ol>
+     *
      * @return
      *         The client identifier used in the backchannel authentication
      *         request.
@@ -607,6 +734,10 @@ else if (clientEntityIdUsed)
         {
             return clientEntityId.toString();
         }
+        else if (metadataDocumentUsed)
+        {
+            return metadataDocumentLocation.toString();
+        }
         else
         {
             return String.valueOf(clientId);
diff --git a/src/main/java/com/authlete/common/dto/BackchannelAuthenticationRequest.java b/src/main/java/com/authlete/common/dto/BackchannelAuthenticationRequest.java
index 68f0151cfb..6aa3157c7a 100644
--- a/src/main/java/com/authlete/common/dto/BackchannelAuthenticationRequest.java
+++ b/src/main/java/com/authlete/common/dto/BackchannelAuthenticationRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018-2024 Authlete, Inc.
+ * Copyright (C) 2018-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -124,7 +124,7 @@
  */
 public class BackchannelAuthenticationRequest implements Serializable
 {
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = 3L;
 
 
     /**
@@ -181,6 +181,15 @@ public class BackchannelAuthenticationRequest implements Serializable
     private String oauthClientAttestationPop;
 
 
+    /**
+     * Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private CimdOptions cimdOptions;
+
+
     /**
      * Get the value of {@code parameters} which are the request parameters
      * that the backchannel authentication endpoint of the OpenID provider
@@ -446,4 +455,49 @@ public BackchannelAuthenticationRequest setOauthClientAttestationPop(String jwt)
 
         return this;
     }
+
+
+    /**
+     * Get options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @return
+     *         Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public CimdOptions getCimdOptions()
+    {
+        return cimdOptions;
+    }
+
+
+    /**
+     * Set options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @param options
+     *         Options for CIMD processing.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public BackchannelAuthenticationRequest setCimdOptions(CimdOptions options)
+    {
+        this.cimdOptions = options;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/BackchannelAuthenticationResponse.java b/src/main/java/com/authlete/common/dto/BackchannelAuthenticationResponse.java
index 73d6afb732..0828ba2016 100644
--- a/src/main/java/com/authlete/common/dto/BackchannelAuthenticationResponse.java
+++ b/src/main/java/com/authlete/common/dto/BackchannelAuthenticationResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018-2023 Authlete, Inc.
+ * Copyright (C) 2018-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -594,11 +594,39 @@
  * </dd>
  * </dl>
  *
+ * <br/>
+ * <hr>
+ * <h3>Attestation Challenge (Authlete 3.0.28 onwards)</h3>
+ *
+ * <p>
+ * Since version 3.0.28, Authlete recognizes the {@code challenge} claim in
+ * Client Attestation PoP JWTs. If the {@code challenge} claim is required
+ * (= if the service's challenge endpoint is configured), the Authlete API
+ * checks whether the {@code challenge} claim in the presented Client
+ * Attestation PoP JWT is identical to the expected value.
+ * </p>
+ *
+ * <p>
+ * If the {@code attestationChallenge} response parameter from the API is not
+ * null, its value is the expected attestation challenge value for Client
+ * Attestation PoP JWT. The expected value needs to be conveyed to the client
+ * application as the value of the {@code OAuth-Client-Attestation-Challenge}
+ * HTTP header.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;"
+ * >OAuth-Client-Attestation-Challenge: (The value returned from {@link #getAttestationChallenge()})</pre>
+ *
+ * <p>
+ * See <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/"
+ * >OAuth 2.0 Attestation-Based Client Authentication</a> for details.
+ * </p>
+ *
  * @since 2.32
  */
 public class BackchannelAuthenticationResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 11L;
+    private static final long serialVersionUID = 13L;
 
 
     /**
@@ -682,6 +710,22 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * Whether the client's metadata document was used.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 2.0.0
      */
@@ -812,6 +856,16 @@ public enum Action
      */
     private String ticket;
 
+    /**
+     * The expected attestation challenge value for Client Attestation PoP JWT,
+     * which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private String attestationChallenge;
+
 
     /**
      * Get the next action that the implementation of the backchannel
@@ -1087,18 +1141,129 @@ public BackchannelAuthenticationResponse setClientEntityIdUsed(boolean used)
 
 
     /**
-     * Get the client identifier used in the backchannel authentication
-     * request.
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public BackchannelAuthenticationResponse setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
      *
      * <p>
-     * When {@link #isClientIdAliasUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientIdAlias()} does. Otherwise,
-     * if {@link #isClientEntityIdUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientEntityId()}{@code .toString()}
-     * does. In other cases, this method returns the string representation of
-     * the value returned from {@link #getClientId()}.
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
      * </p>
      *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public BackchannelAuthenticationResponse setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+
+        return this;
+    }
+
+
+    /**
+     * Get the client identifier used in the backchannel authentication
+     * request.
+     *
+     * <ol>
+     * <li>When {@link #isClientEntityIdUsed()} returns {@code true}, this
+     *     method returns the same value as {@link #getClientIdAlias()} does.
+     *
+     * <li>Otherwise, if {@link #isClientEntityIdUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getClientEntityId()}{@code .toString()} does.
+     *
+     * <li>Otherwise, if {@link #isMetadataDocumentUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getMetadataDocumentLocation()}{@code .toString()} does.
+     *
+     * <li>In other cases, this method returns the string representation of
+     *     the value returned from {@link #getClientId()}.
+     * </ol>
+     *
      * @return
      *         The client identifier used in the backchannel authentication
      *         request.
@@ -1113,6 +1278,10 @@ else if (clientEntityIdUsed)
         {
             return clientEntityId.toString();
         }
+        else if (metadataDocumentUsed)
+        {
+            return metadataDocumentLocation.toString();
+        }
         else
         {
             return String.valueOf(clientId);
@@ -2218,4 +2387,75 @@ public BackchannelAuthenticationResponse setTicket(String ticket)
 
         return this;
     }
+
+
+    /**
+     * Get the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * backchannel authentication endpoint should add the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header in the response
+     * from the endpoint to the client application, using the value of this
+     * response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @return
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public String getAttestationChallenge()
+    {
+        return attestationChallenge;
+    }
+
+
+    /**
+     * Set the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * backchannel authentication endpoint should add the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header in the response
+     * from the endpoint to the client application, using the value of this
+     * response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @param challenge
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public BackchannelAuthenticationResponse setAttestationChallenge(String challenge)
+    {
+        this.attestationChallenge = challenge;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/BackchannelLogoutTokenRequest.java b/src/main/java/com/authlete/common/dto/BackchannelLogoutTokenRequest.java
new file mode 100644
index 0000000000..13f9caa876
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/BackchannelLogoutTokenRequest.java
@@ -0,0 +1,193 @@
+/*
+ * Copyright (C) 2026 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.authlete.common.dto;
+
+
+import java.io.Serializable;
+
+
+/**
+ * Request to Authlete's
+ * <code>/api<wbr>/<i>{serivce-id}</i><wbr>/backchannel<wbr>/logout<wbr>/token</code>
+ * API.
+ *
+ * <p>
+ * The Authlete API generates a <a href=
+ * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+ * >Logout Token</a> that complies with the <a href=
+ * https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID Connect
+ * Back-Channel Logout 1.0</a> specification.
+ * </p>
+ *
+ * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+ *      OpenID Connect Back-Channel Logout 1.0</a>
+ *
+ * @since 4.43
+ * @since Authlete 3.0.32
+ */
+public class BackchannelLogoutTokenRequest implements Serializable
+{
+    private static final long serialVersionUID = 1L;
+
+
+    /**
+     * The client identifier.
+     */
+    private String clientIdentifier;
+
+
+    /**
+     * The subject of the end-user.
+     */
+    private String subject;
+
+
+    /**
+     * The session ID.
+     */
+    private String sessionId;
+
+
+    /**
+     * Get the client identifier.
+     * This request parameter is mandatory.
+     *
+     * @return
+     *         The client identifier.
+     */
+    public String getClientIdentifier()
+    {
+        return clientIdentifier;
+    }
+
+
+    /**
+     * Set the client identifier.
+     * This request parameter is mandatory.
+     *
+     * @param identifier
+     *         The client identifier.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public BackchannelLogoutTokenRequest setClientIdentifier(String identifier)
+    {
+        this.clientIdentifier = identifier;
+
+        return this;
+    }
+
+
+    /**
+     * Get the subject of the end-user. At least one of this {@code subject}
+     * request parameter or the {@code sessionId} request parameter is
+     * required.
+     *
+     * <p>
+     * This value is used as the value of the {@code sub} claim in the
+     * Logout Token.
+     * </p>
+     *
+     * @return
+     *         The subject of the end-user.
+     */
+    public String getSubject()
+    {
+        return subject;
+    }
+
+
+    /**
+     * Set the subject of the end-user. At least one of this {@code subject}
+     * request parameter or the {@code sessionId} request parameter is
+     * required.
+     *
+     * <p>
+     * This value is used as the value of the {@code sub} claim in the
+     * Logout Token.
+     * </p>
+     *
+     * @param subject
+     *         The subject of the end-user.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public BackchannelLogoutTokenRequest setSubject(String subject)
+    {
+        this.subject = subject;
+
+        return this;
+    }
+
+
+    /**
+     * Get the session ID. At least one of this {@code sessionId} request
+     * parameter or the {@code subject} request parameter is required.
+     *
+     * <p>
+     * This value is used as the value of the {@code sid} claim in the
+     * Logout Token.
+     * </p>
+     *
+     * <p>
+     * If the <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code>
+     * server metadata parameter of your server is {@code true} (= if the
+     * <code>backchannel<wbr>Logout<wbr>Session<wbr>Supported</code> property
+     * of your {@link Service} is {@code true}), this request parameter should
+     * be included.
+     * </p>
+     *
+     * @return
+     *         The session ID.
+     */
+    public String getSessionId()
+    {
+        return sessionId;
+    }
+
+
+    /**
+     * Set the session ID. At least one of this {@code sessionId} request
+     * parameter or the {@code subject} request parameter is required.
+     *
+     * <p>
+     * This value is used as the value of the {@code sid} claim in the
+     * Logout Token.
+     * </p>
+     *
+     * <p>
+     * If the <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code>
+     * server metadata parameter of your server is {@code true} (= if the
+     * <code>backchannel<wbr>Logout<wbr>Session<wbr>Supported</code> property
+     * of your {@link Service} is {@code true}), this request parameter should
+     * be included.
+     * </p>
+     *
+     * @param sessionId
+     *         The session ID.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public BackchannelLogoutTokenRequest setSessionId(String sessionId)
+    {
+        this.sessionId = sessionId;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/BackchannelLogoutTokenResponse.java b/src/main/java/com/authlete/common/dto/BackchannelLogoutTokenResponse.java
new file mode 100644
index 0000000000..ae95324920
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/BackchannelLogoutTokenResponse.java
@@ -0,0 +1,230 @@
+/*
+ * Copyright (C) 2026 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.authlete.common.dto;
+
+
+import java.net.URI;
+
+
+/**
+ * Response from Authlete's
+ * <code>/api<wbr>/<i>{serivce-id}</i><wbr>/backchannel<wbr>/logout<wbr>/token</code>
+ * API.
+ *
+ * <p>
+ * The Authlete API generates a <a href=
+ * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+ * >Logout Token</a> that complies with the <a href=
+ * https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID Connect
+ * Back-Channel Logout 1.0</a> specification.
+ * </p>
+ *
+ * <p>
+ * If the value of the {@code action} parameter in the response from the
+ * Authlete API is {@link Action#OK OK}, it indicates that a Logout Token has
+ * been generated successfully. In this case, your server is expected to send
+ * a <a href=
+ * "https://openid.net/specs/openid-connect-backchannel-1_0.html#BCRequest"
+ * >Back-Channel Logout Request</a> containing the generated Logout Token to
+ * the client's Backchannel Logout URI.
+ * <p>
+ *
+ * <p>
+ * The {@code logoutToken} parameter in the API response contains the generated
+ * Logout Token, and the <code>backchannel<wbr>Logout<wbr>Uri</code> parameter
+ * contains the client's Back-Channel Logout URI, which corresponds to the
+ * <code>backchannel_<wbr>logout_<wbr>uri</code> client metadata parameter.
+ * Using these values, the Back-Channel Logout Request can be constructed as
+ * follows.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;">
+ * POST {@link #getBackchannelLogoutUri()} HTTP/1.1
+ * Content-Type: application/x-www-form-urlencoded
+ * Content-Length: ...
+ *
+ * <i>logout_token={@link #getLogoutToken()}</i></pre>
+ * <br/>
+ *
+ * <p>
+ * Note that the Authlete API does not verify whether the client's
+ * <code>backchannel_<wbr>logout_<wbr>uri</code> metadata parameter is
+ * configured properly. Therefore, the value of the
+ * <code>backchannel<wbr>Logout<wbr>Uri</code> response parameter may not be
+ * a valid HTTP-accessible URL. It may even be {@code null}.
+ * </p>
+ *
+ * <p>
+ * Also note that the API call does not revoke any refresh tokens. If necessary,
+ * the client itself should trigger refresh token revocation (e.g., by calling
+ * the revocation endpoint).
+ * </p>
+ *
+ * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+ *      OpenID Connect Back-Channel Logout 1.0</a>
+ *
+ * @since 4.43
+ * @since Authlete 3.0.32
+ */
+public class BackchannelLogoutTokenResponse extends ApiResponse
+{
+    private static final long serialVersionUID = 1L;
+
+
+    /**
+     * The next action that the API caller should take.
+     */
+    public enum Action
+    {
+        /**
+         * A Logout Token has been generated successfully. The API caller is
+         * expected to send a Back-Channel Logout Request to the client.
+         */
+        OK,
+
+
+        /**
+         * There is an error on Authlete's side, such as a database access error.
+         */
+        SERVER_ERROR,
+
+
+        /**
+         * The API call is invalid. For example, the mandatory request parameter
+         * {@code clientIdentifier} is missing.
+         */
+        CALLER_ERROR,
+    }
+
+
+    /**
+     * The next action that the API caller should take.
+     */
+    private Action action;
+
+
+    /**
+     * The generated Logout Token.
+     */
+    private String logoutToken;
+
+
+    /**
+     * The client's Back-Channel Logout URI.
+     */
+    private URI backchannelLogoutUri;
+
+
+    /**
+     * Get the next action that the API caller should take. In practice, this
+     * value represents the result of the API call.
+     *
+     * @return
+     *         The next action that the API caller should take.
+     */
+    public Action getAction()
+    {
+        return action;
+    }
+
+
+    /**
+     * Set the next action that API caller should take. In practice, this
+     * value represents the result of the API call.
+     *
+     * @param action
+     *         The next action that the API caller should take.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public BackchannelLogoutTokenResponse setAction(Action action)
+    {
+        this.action = action;
+
+        return this;
+    }
+
+
+    /**
+     * Get the issued <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>.
+     *
+     * @return
+     *         The issued Logout Token.
+     */
+    public String getLogoutToken()
+    {
+        return logoutToken;
+    }
+
+
+    /**
+     * Set the issued <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>.
+     *
+     * @param logoutToken
+     *         The issued Logout Token.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public BackchannelLogoutTokenResponse setLogoutToken(String logoutToken)
+    {
+        this.logoutToken = logoutToken;
+
+        return this;
+    }
+
+
+    /**
+     * Get the client's Back-Channel Logout URI, which corresponds to the
+     * <code>backchannel_<wbr>logout_<wbr>uri</code> client metadata
+     * parameter defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1&#x2E;0</a> specification.
+     *
+     * @return
+     *         The client's Back-Channel Logout URI.
+     */
+    public URI getBackchannelLogoutUri()
+    {
+        return backchannelLogoutUri;
+    }
+
+
+    /**
+     * Set the client's Back-Channel Logout URI, which corresponds to the
+     * <code>backchannel_<wbr>logout_<wbr>uri</code> client metadata
+     * parameter defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1&#x2E;0</a> specification.
+     *
+     * @param uri
+     *         The client's Back-Channel Logout URI.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public BackchannelLogoutTokenResponse setBackchannelLogoutUri(URI uri)
+    {
+        this.backchannelLogoutUri = uri;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/CimdOptions.java b/src/main/java/com/authlete/common/dto/CimdOptions.java
new file mode 100644
index 0000000000..a02389ed3e
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/CimdOptions.java
@@ -0,0 +1,300 @@
+/*
+ * Copyright (C) 2025 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.dto;
+
+
+import java.io.Serializable;
+
+
+/**
+ * Options for <a href=
+ * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+ * >OAuth Client ID Metadata Document</a> (CIMD).
+ *
+ * @since 4.30
+ * @since Authlete 3.0.22
+ *
+ * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+ *      OAuth Client ID Metadata Document</a>
+ */
+public class CimdOptions implements Serializable
+{
+    private static final long serialVersionUID = 1L;
+
+
+    /**
+     * Whether to always retrieve client metadata in the CIMD context
+     * regardless of the cache's validity.
+     */
+    private boolean alwaysRetrieved;
+
+
+    /**
+     * Whether to allow the {@code http} scheme in client IDs in the CIMD
+     * context.
+     */
+    private boolean httpPermitted;
+
+
+    /**
+     * Whether to allow a query component in client IDs in the CIMD context.
+     */
+    private boolean queryPermitted;
+
+
+    /**
+     * Get the flag that indicates whether Authlete should always fetch the
+     * client metadata from the location specified by the client ID, regardless
+     * of whether a cached copy already exists and has not yet expired.
+     *
+     * <p>
+     * Under normal circumstances, client metadata retrieved from the location
+     * referenced by the client ID is stored in the database with an expiration
+     * time calculated using HTTP caching mechanisms (see <a href=
+     * "https://www.rfc-editor.org/rfc/rfc9111.html">RFC 9111 HTTP Caching</a>).
+     * Until that expiration time is reached, Authlete does not attempt to
+     * retrieve the client metadata again.
+     * </p>
+     *
+     * <p>
+     * When this flag is set to {@code true}, Authlete retrieves the client
+     * metadata regardless of the cache's validity.
+     * </p>
+     *
+     * <p>
+     * If this flag is included in an Authlete API call and its value is
+     * {@code true}, it takes precedence over the corresponding service
+     * configuration (see {@link Service#isCimdAlwaysRetrieved()}).
+     * </p>
+     *
+     * <p>
+     * This flag is effective only when the service supports CIMD (see {@link
+     * Service#isClientIdMetadataDocumentSupported()}) and CIMD is actually
+     * used to resolve client metadata. For example, if the client ID in a
+     * request does not appear to be a valid URI, CIMD will not be used even
+     * if the service is configured to support it. In such cases, this flag
+     * has no effect.
+     * </p>
+     *
+     * <p>
+     * Client metadata retrieval is performed only in the initiating request
+     * of an authorization flow, and not in any subsequent requests. For
+     * example, in the authorization code flow, metadata may be retrieved
+     * during the authorization request, but not during the subsequent token
+     * request. In contrast, in the client credentials flow, metadata retrieval
+     * may occur because the token request itself is the initiating request
+     * in the flow.
+     * </p>
+     *
+     * @return
+     *         {@code true} if Authlete attempts to retrieve client metadata
+     *         regardless of the cache's validity.
+     */
+    public boolean isAlwaysRetrieved()
+    {
+        return alwaysRetrieved;
+    }
+
+
+    /**
+     * Set the flag that indicates whether Authlete should always fetch the
+     * client metadata from the location specified by the client ID, regardless
+     * of whether a cached copy already exists and has not yet expired.
+     *
+     * <p>
+     * Under normal circumstances, client metadata retrieved from the location
+     * referenced by the client ID is stored in the database with an expiration
+     * time calculated using HTTP caching mechanisms (see <a href=
+     * "https://www.rfc-editor.org/rfc/rfc9111.html">RFC 9111 HTTP Caching</a>).
+     * Until that expiration time is reached, Authlete does not attempt to
+     * retrieve the client metadata again.
+     * </p>
+     *
+     * <p>
+     * When this flag is set to {@code true}, Authlete retrieves the client
+     * metadata regardless of the cache's validity.
+     * </p>
+     *
+     * <p>
+     * If this flag is included in an Authlete API call and its value is
+     * {@code true}, it takes precedence over the corresponding service
+     * configuration (see {@link Service#isCimdAlwaysRetrieved()}).
+     * </p>
+     *
+     * <p>
+     * This flag is effective only when the service supports CIMD (see {@link
+     * Service#isClientIdMetadataDocumentSupported()}) and CIMD is actually
+     * used to resolve client metadata. For example, if the client ID in a
+     * request does not appear to be a valid URI, CIMD will not be used even
+     * if the service is configured to support it. In such cases, this flag
+     * has no effect.
+     * </p>
+     *
+     * <p>
+     * Client metadata retrieval is performed only in the initiating request
+     * of an authorization flow, and not in any subsequent requests. For
+     * example, in the authorization code flow, metadata may be retrieved
+     * during the authorization request, but not during the subsequent token
+     * request. In contrast, in the client credentials flow, metadata retrieval
+     * may occur because the token request itself is the initiating request
+     * in the flow.
+     * </p>
+     *
+     * @param always
+     *         {@code true} to instruct Authlete to retrieve client metadata
+     *         regardless of the cache's validity.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CimdOptions setAlwaysRetrieved(boolean always)
+    {
+        this.alwaysRetrieved = always;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether the {@code http} scheme in the client
+     * ID is permitted.
+     *
+     * <p>
+     * The specification requires the {@code https} scheme, but if this flag is
+     * set to {@code true}, Authlete also allows the {@code http} scheme. The
+     * main purpose of this option is to make development easier for developers
+     * who run CIMD-enabled servers and a web server publishing client metadata
+     * on their local machines without TLS.
+     * </p>
+     *
+     * <p>
+     * Given this purpose, it is not recommended to enable this option in
+     * production environments unless an allowlist is used (see {@link
+     * Service#isCimdAllowlistEnabled()}).
+     * </p>
+     *
+     * <p>
+     * If this flag is included in an Authlete API call and its value is
+     * {@code true}, it takes precedence over the corresponding service
+     * configuration (see {@link Service#isCimdHttpPermitted()}).
+     * </p>
+     *
+     * @return
+     *         {@code true} if the {@code http} scheme in the client ID is
+     *         permitted.
+     */
+    public boolean isHttpPermitted()
+    {
+        return httpPermitted;
+    }
+
+
+    /**
+     * Set the flag that indicates whether the {@code http} scheme in the client
+     * ID is permitted.
+     *
+     * <p>
+     * The specification requires the {@code https} scheme, but if this flag is
+     * set to {@code true}, Authlete also allows the {@code http} scheme. The
+     * main purpose of this option is to make development easier for developers
+     * who run CIMD-enabled servers and a web server publishing client metadata
+     * on their local machines without TLS.
+     * </p>
+     *
+     * <p>
+     * Given this purpose, it is not recommended to enable this option in
+     * production environments unless an allowlist is used (see {@link
+     * Service#isCimdAllowlistEnabled()}).
+     * </p>
+     *
+     * <p>
+     * If this flag is included in an Authlete API call and its value is
+     * {@code true}, it takes precedence over the corresponding service
+     * configuration (see {@link Service#isCimdHttpPermitted()}).
+     * </p>
+     *
+     * @param permitted
+     *         {@code true} to permit the {@code http} scheme in the client ID.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CimdOptions setHttpPermitted(boolean permitted)
+    {
+        this.httpPermitted = permitted;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether a query component in the client ID
+     * is permitted.
+     *
+     * <p>
+     * Although the specification states that a client ID <i>"SHOULD NOT
+     * include a query string component,"</i> it does technically allow it.
+     * However, query components are prone to misuse. Therefore, Authlete does
+     * not allow them by default. Setting this flag to {@code true} relaxes
+     * that restriction.
+     * </p>
+     *
+     * <p>
+     * If this flag is included in an Authlete API call and its value is
+     * {@code true}, it takes precedence over the corresponding service
+     * configuration (see {@link Service#isCimdQueryPermitted()}).
+     * </p>
+     *
+     * @return
+     *         {@code true} if a query component in the client ID is permitted.
+     */
+    public boolean isQueryPermitted()
+    {
+        return queryPermitted;
+    }
+
+
+    /**
+     * Set the flag that indicates whether a query component in the client ID
+     * is permitted.
+     *
+     * <p>
+     * Although the specification states that a client ID <i>"SHOULD NOT
+     * include a query string component,"</i> it does technically allow it.
+     * However, query components are prone to misuse. Therefore, Authlete does
+     * not allow them by default. Setting this flag to {@code true} relaxes
+     * that restriction.
+     * </p>
+     *
+     * <p>
+     * If this flag is included in an Authlete API call and its value is
+     * {@code true}, it takes precedence over the corresponding service
+     * configuration (see {@link Service#isCimdQueryPermitted()}).
+     * </p>
+     *
+     * @param permitted
+     *         {@code true} to permit a query component in the client ID.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CimdOptions setQueryPermitted(boolean permitted)
+    {
+        this.queryPermitted = permitted;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/Client.java b/src/main/java/com/authlete/common/dto/Client.java
index 63ca8992f7..7209308ea8 100644
--- a/src/main/java/com/authlete/common/dto/Client.java
+++ b/src/main/java/com/authlete/common/dto/Client.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2024 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@
 import com.authlete.common.types.ApplicationType;
 import com.authlete.common.types.ClientAuthMethod;
 import com.authlete.common.types.ClientRegistrationType;
+import com.authlete.common.types.ClientSource;
 import com.authlete.common.types.ClientType;
 import com.authlete.common.types.DeliveryMode;
 import com.authlete.common.types.FapiMode;
@@ -80,10 +81,16 @@
  *
  * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
  *      >OpenID for Verifiable Credential Issuance</a>
+ *
+ * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+ *      >OAuth Client ID Metadata Document</a>
+ *
+ * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html"
+ *      >OpenID Connect Back-Channel Logout 1.0</a>
  */
 public class Client implements Serializable
 {
-    private static final long serialVersionUID = 38L;
+    private static final long serialVersionUID = 42L;
 
 
     /*
@@ -583,6 +590,13 @@ public class Client implements Serializable
      */
     private boolean mtlsEndpointAliasesUsed;
 
+    /**
+     * Indicates if the client is in scope for token migration.
+     *
+     * @since Authlete 4.23
+     */
+    private boolean inScopeForTokenMigration;
+
 
     /*
      * For OpenID Federation 1.0.
@@ -638,6 +652,7 @@ public class Client implements Serializable
      */
     private boolean explicitlyRegistered;
 
+
     /*
      * For Verifiable Credentials
      */
@@ -653,6 +668,98 @@ public class Client implements Serializable
     private boolean credentialResponseEncryptionRequired;
 
 
+    /*
+     * For OAuth Client ID Metadata Document
+     */
+
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * The time at which the metadata document will expire.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private long metadataDocumentExpiresAt;
+
+    /**
+     * The time at which the metadata document was updated.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private long metadataDocumentUpdatedAt;
+
+    /**
+     * Whether the client was discovered by Client ID Metadata Document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean discoveredByMetadataDocument;
+
+
+    /**
+     * The source of this client.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private ClientSource clientSource;
+
+
+    /**
+     * The SPIFFE ID.
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     */
+    private URI spiffeId;
+
+
+    /**
+     * The SPIFFE Bundle Endpoint.
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     */
+    private URI spiffeBundleEndpoint;
+
+
+    /**
+     * The HAIP version to comply with.
+     *
+     * @since 4.41
+     * @since Authlete 3.0.29
+     */
+    private String haipVersion;
+
+
+    /**
+     * The Back-Channel Logout URI.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     */
+    private URI backchannelLogoutUri;
+
+
+    /**
+     * The flag indicating whether this client requires Logout Tokens to
+     * include the {@code sid} claim.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     */
+    private boolean backchannelLogoutSessionRequired;
+
+
     /**
      * Get the client number.
      *
@@ -5209,6 +5316,710 @@ public Client setMtlsEndpointAliasesUsed(boolean mtlsEndpointAliasesUsed)
     }
 
 
+    /**
+     * Get the value that indicates whether this Client is inscope for token migration.
+     *
+     * @return
+     *         The value that indicates whether this Client is in scope for token migration.
+     *
+     * @since Authlete 4.23
+     */
+    public boolean isInScopeForTokenMigration()
+    {
+        return inScopeForTokenMigration;
+    }
+
+
+    /**
+     * Sets the flag that indicates that this Client is in scope for token migration.
+     *
+     * @param inScopeForTokenMigration
+     *         The new value for the flag to indicates whether this Client is in scope for token migration.
+     *
+     * @return
+     *         The {@link Client} after setting the provided property.
+     *
+     * @since Authlete 4.23
+     */
+    public Client setInScopeForTokenMigration(boolean inScopeForTokenMigration)
+    {
+        this.inScopeForTokenMigration = inScopeForTokenMigration;
+
+        return this;
+    }
+
+
+    /**
+     * Get the location of the client's metadata document.
+     *
+     * <p>
+     * This property is available only when the client was discovered using
+     * the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>. The mechanism is used only
+     * when the service supports it.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document.
+     *
+     * <p>
+     * This property is available only when the client was discovered using
+     * the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>. The mechanism is used only
+     * when the service supports it.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Client setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+
+        return this;
+    }
+
+
+    /**
+     * Get the expiration time of the client's metadata document. The value is
+     * represented as milliseconds elapsed since the Unix epoch (1970-01-01).
+     *
+     * <p>
+     * This property is meaningful only when the client was discovered using
+     * the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>. The mechanism is used only
+     * when the service supports it.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         The expiration time of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public long getMetadataDocumentExpiresAt()
+    {
+        return metadataDocumentExpiresAt;
+    }
+
+
+    /**
+     * Set the expiration time of the client's metadata document. The value is
+     * represented as milliseconds elapsed since the Unix epoch (1970-01-01).
+     *
+     * <p>
+     * This property is meaningful only when the client was discovered using
+     * the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>. The mechanism is used only
+     * when the service supports it.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param expiresAt
+     *         The expiration time of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Client setMetadataDocumentExpiresAt(long expiresAt)
+    {
+        this.metadataDocumentExpiresAt = expiresAt;
+
+        return this;
+    }
+
+
+    /**
+     * Get the time at which the client was last updated with its metadata
+     * document.
+     *
+     * <p>
+     * This property is meaningful only when the client was discovered using
+     * the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>. The mechanism is used only
+     * when the service supports it.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         The time at which the client was last updated with its metadata
+     *         document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public long getMetadataDocumentUpdatedAt()
+    {
+        return metadataDocumentUpdatedAt;
+    }
+
+
+    /**
+     * Set the time at which the client was last updated with its metadata
+     * document.
+     *
+     * <p>
+     * This property is meaningful only when the client was discovered using
+     * the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>. The mechanism is used only
+     * when the service supports it.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param updatedAt
+     *         The time at which the client was last updated with its metadata
+     *         document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Client setMetadataDocumentUpdatedAt(long updatedAt)
+    {
+        this.metadataDocumentUpdatedAt = updatedAt;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether this client was discovered and
+     * registered by the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     *
+     * @return
+     *         {@code true} if this client was discovered and registered by
+     *         the mechanism defined in OAuth Client ID Metadata Document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isDiscoveredByMetadataDocument()
+    {
+        return discoveredByMetadataDocument;
+    }
+
+
+    /**
+     * Set the flag indicating whether this client was discovered and
+     * registered by the mechanism defined in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     *
+     * @param discovered
+     *         {@code true} to indicate that this client was discovered and
+     *         registered by the mechanism defined in OAuth Client ID Metadata
+     *         Document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Client setDiscoveredByMetadataDocument(boolean discovered)
+    {
+        this.discoveredByMetadataDocument = discovered;
+
+        return this;
+    }
+
+
+    /**
+     * Get the source of this client.
+     *
+     * @return
+     *         The source of this client.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see #updateClientSource()
+     */
+    public ClientSource getClientSource()
+    {
+        return clientSource;
+    }
+
+
+    /**
+     * Set the source of this client.
+     *
+     * @param source
+     *         The source of this client.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see #updateClientSource()
+     */
+    public Client setClientSource(ClientSource source)
+    {
+        this.clientSource = source;
+
+        return this;
+    }
+
+
+    /**
+     * Update the {@code clientSource} property according to the current
+     * values of registration-related fields.
+     *
+     * <ol>
+     * <li>{@link ClientSource#DYNAMIC_REGISTRATION DYNAMIC_REGISTRATION}
+     *     if {@link #isDynamicallyRegistered()} returns {@code true}.
+     *
+     * <li>{@link ClientSource#AUTOMATIC_REGISTRATION AUTOMATIC_REGISTRATION}
+     *     if {@link #isAutomaticallyRegistered()} returns {@code true}.
+     *
+     * <li>{@link ClientSource#EXPLICIT_REGISTRATION EXPLICIT_REGISTRATION}
+     *     if {@link #isExplicitlyRegistered()} returns {@code true}.
+     *
+     * <li>{@link ClientSource#METADATA_DOCUMENT METADATA_DOCUMENT}
+     *     if {@link #isDiscoveredByMetadataDocument()} returns {@code true}.
+     *
+     * <li>{@link ClientSource#STATIC_REGISTRATION STATIC_REGISTRATION}
+     *     in other cases.
+     * </ol>
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     */
+    public Client updateClientSource()
+    {
+        return updateClientSource(this);
+    }
+
+
+    private static Client updateClientSource(Client client)
+    {
+        if (client == null)
+        {
+            return null;
+        }
+
+        // Derive the client source from fields.
+        ClientSource cs = deriveClientSource(client);
+
+        return client.setClientSource(cs);
+    }
+
+
+    private static ClientSource deriveClientSource(Client client)
+    {
+        if (client == null)
+        {
+            return null;
+        }
+
+        if (client.isDynamicallyRegistered())
+        {
+            // RFC 7591: OAuth 2.0 Dynamic Client Registration Protocol, or
+            // OpenID Connect Dynamic Client Registration 1.0.
+            return ClientSource.DYNAMIC_REGISTRATION;
+        }
+        else if (client.isAutomaticallyRegistered())
+        {
+            // Automatic registration defined in OpenID Federation 1.0.
+            return ClientSource.AUTOMATIC_REGISTRATION;
+        }
+        else if (client.isExplicitlyRegistered())
+        {
+            // Explicit registration defined in OpenID Federation 1.0.
+            return ClientSource.EXPLICIT_REGISTRATION;
+        }
+        else if (client.isDiscoveredByMetadataDocument())
+        {
+            // Discovery using OAuth Client ID Metadata Document.
+            return ClientSource.METADATA_DOCUMENT;
+        }
+        else
+        {
+            // Static registration.
+            return ClientSource.STATIC_REGISTRATION;
+        }
+    }
+
+
+    /**
+     * Get the SPIFFE ID. This property corresponds to the {@code spiffe_id}
+     * client metadata.
+     *
+     * <p>
+     * The value of this property is compared against the SPIFFE ID contained
+     * in the SVID presented by the client during SPIFFE Client Authentication.
+     * </p>
+     *
+     * <p>
+     * According to the <a href=
+     * "https://github.com/spiffe/spiffe/blob/main/standards/SPIFFE-ID.md">SPIFFE
+     * ID specification</a>, the characters allowed in the path component of a
+     * SPIFFE ID are limited to {@code [a-zA-Z0-9.-_]}. However, in the value
+     * of this property (i.e., in the value of the {@code spiffe_id} client
+     * metadata), the final path segment may be specified using a wildcard
+     * {@code *} (e.g., <code>spiffe://<wbr>example.com/<wbr>workload/*</code>).
+     * When comparing it with the SPIFFE ID in the SVID, the wildcard is taken
+     * into account.
+     * </p>
+     *
+     * @return
+     *         The SPIFFE ID.
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://spiffe.io/">SPIFFE</a>
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-spiffe-client-auth/">
+     *      OAuth SPIFFE Client Authentication</a>
+     */
+    public URI getSpiffeId()
+    {
+        return spiffeId;
+    }
+
+
+    /**
+     * Set the SPIFFE ID. This property corresponds to the {@code spiffe_id}
+     * client metadata.
+     *
+     * <p>
+     * The value of this property is compared against the SPIFFE ID contained
+     * in the SVID presented by the client during SPIFFE Client Authentication.
+     * </p>
+     *
+     * <p>
+     * According to the <a href=
+     * "https://github.com/spiffe/spiffe/blob/main/standards/SPIFFE-ID.md">SPIFFE
+     * ID specification</a>, the characters allowed in the path component of a
+     * SPIFFE ID are limited to {@code [a-zA-Z0-9.-_]}. However, in the value
+     * of this property (i.e., in the value of the {@code spiffe_id} client
+     * metadata), the final path segment may be specified using a wildcard
+     * {@code *} (e.g., <code>spiffe://<wbr>example.com/<wbr>workload/*</code>).
+     * When comparing it with the SPIFFE ID in the SVID, the wildcard is taken
+     * into account.
+     * </p>
+     *
+     * @param spiffeId
+     *         The SPIFFE ID.
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://spiffe.io/">SPIFFE</a>
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-spiffe-client-auth/">
+     *      OAuth SPIFFE Client Authentication</a>
+     */
+    public Client setSpiffeId(URI spiffeId)
+    {
+        this.spiffeId = spiffeId;
+
+        return this;
+    }
+
+
+    /**
+     * Get the SPIFFE Bundle Endpoint. This property corresponds to the
+     * {@code spiffe_bundle_endpoint} client metadata.
+     *
+     * <p>
+     * The authorization server retrieves the SPIFFE Bundle from the location
+     * indicated by this property (i.e., by the {@code spiffe_bundle_endpoint}
+     * client metadata) in order to verify the SVID presented by the client
+     * during SPIFFE Client Authentication. The SPIFFE Bundle is, in essence,
+     * a JWK Set.
+     * </p>
+     *
+     * @return
+     *         The SPIFFE Bundle Endpoint.
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://spiffe.io/">SPIFFE</a>
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-spiffe-client-auth/">
+     *      OAuth SPIFFE Client Authentication</a>
+     */
+    public URI getSpiffeBundleEndpoint()
+    {
+        return spiffeBundleEndpoint;
+    }
+
+
+    /**
+     * Set the SPIFFE Bundle Endpoint. This property corresponds to the
+     * {@code spiffe_bundle_endpoint} client metadata.
+     *
+     * <p>
+     * The authorization server retrieves the SPIFFE Bundle from the location
+     * indicated by this property (i.e., by the {@code spiffe_bundle_endpoint}
+     * client metadata) in order to verify the SVID presented by the client
+     * during SPIFFE Client Authentication. The SPIFFE Bundle is, in essence,
+     * a JWK Set.
+     * </p>
+     *
+     * @param endpoint
+     *         The SPIFFE Bundle Endpoint.
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://spiffe.io/">SPIFFE</a>
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-spiffe-client-auth/">
+     *      OAuth SPIFFE Client Authentication</a>
+     */
+    public Client setSpiffeBundleEndpoint(URI endpoint)
+    {
+        this.spiffeBundleEndpoint = endpoint;
+
+        return this;
+    }
+
+
+    /**
+     * Get the HAIP version to comply with. Valid values for this property are
+     * as follows:
+     *
+     * <ul>
+     * <li>{@code "1.0"}
+     * </ul>
+     *
+     * <p>
+     * If this property is set, requests from this client undergo additional
+     * validation based on the specified version of the <a href=
+     * "https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >HAIP</a> specification.
+     * </p>
+     *
+     * <p>
+     * Note that even if this property is not set, additional validation based
+     * on the HAIP specification is performed if the {@link Service}'s
+     * {@code haipVersion} is set or if a scope with the {@code haip} attribute
+     * is included in the request.
+     * </p>
+     *
+     * @return
+     *         The HAIP version to comply with.
+     *
+     * @since 4.41
+     * @since Authlete 3.0.29
+     *
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     */
+    public String getHaipVersion()
+    {
+        return haipVersion;
+    }
+
+
+    /**
+     * Set the HAIP version to comply with. Valid values for this property are
+     * as follows:
+     *
+     * <ul>
+     * <li>{@code "1.0"}
+     * </ul>
+     *
+     * <p>
+     * If this property is set, requests from this client undergo additional
+     * validation based on the specified version of the <a href=
+     * "https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >HAIP</a> specification.
+     * </p>
+     *
+     * <p>
+     * Note that even if this property is not set, additional validation based
+     * on the HAIP specification is performed if the {@link Service}'s
+     * {@code haipVersion} is set or if a scope with the {@code haip} attribute
+     * is included in the request.
+     * </p>
+     *
+     * @param version
+     *         The HAIP version to comply with.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.41
+     * @since Authlete 3.0.29
+     *
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     */
+    public Client setHaipVersion(String version)
+    {
+        this.haipVersion = version;
+
+        return this;
+    }
+
+
+    /**
+     * Get the Back-Channel Logout URI. This property corresponds to the
+     * <code>backchannel_<wbr>logout_<wbr>uri</code> client metadata parameter
+     * defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * @return
+     *         The Back-Channel Logout URI.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     */
+    public URI getBackchannelLogoutUri()
+    {
+        return backchannelLogoutUri;
+    }
+
+
+    /**
+     * Set the Back-Channel Logout URI. This property corresponds to the
+     * <code>backchannel_<wbr>logout_<wbr>uri</code> client metadata parameter
+     * defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * @param uri
+     *         The Back-Channel Logout URI.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     */
+    public Client setBackchannelLogoutUri(URI uri)
+    {
+        this.backchannelLogoutUri = uri;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether this client requires <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>s to include the {@code sid} claim. This property
+     * corresponds to the <code>backchannel_<wbr>logout_<wbr>sesssion_<wbr>required</code>
+     * client metadata parameter defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * @return
+     *         The flag indicating whether this client requires Logout Tokens
+     *         to include the {@code sid} claim.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     */
+    public boolean isBackchannelLogoutSessionRequired()
+    {
+        return backchannelLogoutSessionRequired;
+    }
+
+
+    /**
+     * Set the flag indicating whether this client requires <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>s to include the {@code sid} claim. This property
+     * corresponds to the <code>backchannel_<wbr>logout_<wbr>sesssion_<wbr>required</code>
+     * client metadata parameter defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * @param required
+     *         {@code true} to require Logout Tokens to include the {@code sid}
+     *         claim.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     */
+    public Client setBackchannelLogoutSessionRequired(boolean required)
+    {
+        this.backchannelLogoutSessionRequired = required;
+
+        return this;
+    }
+
+
     /**
      * Get a {@code Map} instance that represents a set of standard client
      * metadata.
@@ -5502,6 +6313,26 @@ public Map<String, Object> toStandardMetadata(ClientMetadataControl control)
         // response_modes
         put(metadata, "response_modes", getResponseModes(), nullIncluded);
 
+        //----------------------------------------------------------------------
+        // OAuth SPIFFE Client Authentication
+        //----------------------------------------------------------------------
+
+        // spiffe_id
+        put(metadata, "spiffe_id", getSpiffeId(), nullIncluded);
+
+        // spiffe_bundle_endpoint
+        put(metadata, "spiffe_bundle_endpoint", getSpiffeBundleEndpoint(), nullIncluded);
+
+        //----------------------------------------------------------------------
+        // OpenID Connect Back-Channel Logout 1.0
+        //----------------------------------------------------------------------
+
+        // backchannel_logout_uri
+        put(metadata, "backchannel_logout_uri", getBackchannelLogoutUri(), nullIncluded);
+
+        // backchannel_logout_session_required
+        put(metadata, "backchannel_logout_session_required", isBackchannelLogoutSessionRequired(), falseIncluded);
+
         //----------------------------------------------------------------------
         // Custom Metadata
         //----------------------------------------------------------------------
@@ -5528,6 +6359,12 @@ else if (control.isEntityIdPreferred() && getEntityId() != null)
             // Use the entity ID as the value of "client_id".
             value = getEntityId().toString();
         }
+        // If "metadata document location" is preferred and available.
+        else if (control.isMetadataDocumentLocationPreferred() && getMetadataDocumentLocation() != null)
+        {
+            // Use the metadata document location as the value of "client_id".
+            value = getMetadataDocumentLocation().toString();
+        }
         else
         {
             // Use the original numeric client ID as the value of "client_id".
diff --git a/src/main/java/com/authlete/common/dto/CredentialDeferredIssueRequest.java b/src/main/java/com/authlete/common/dto/CredentialDeferredIssueRequest.java
index 586316c0d6..a8f419fa39 100644
--- a/src/main/java/com/authlete/common/dto/CredentialDeferredIssueRequest.java
+++ b/src/main/java/com/authlete/common/dto/CredentialDeferredIssueRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -26,7 +26,7 @@
  * The Authlete API is supposed to be called by the implementation of the
  * <b>deferred credential endpoint</b>. The endpoint is defined in the "<a href=
  * "https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
- * >OpenID for Verifiable Credential Issuance</a>" (OID4VCI) specification.
+ * >OpenID for Verifiable Credential Issuance 1.0</a>" (OID4VCI) specification.
  * </p>
  *
  * <p>
@@ -41,14 +41,59 @@
  * </ol>
  *
  * <p>
- * The role of the {@code /vci/deferred/issue} API is to issue a credential.
+ * The {@code /vci/deferred/issue} API is used for one of the following purposes:
  * </p>
  *
+ * <ol>
+ * <li>To issue a credential
+ * <li>To deny the deferred credential request
+ * <li>To notify that the requested credential is not ready yet
+ * </ol>
+ *
+ * <h3>Issuing a credential</h3>
+ *
  * <p>
- * If the credential for the transaction ID is not ready, the implementation
- * of the deferred credential endpoint should prepare an error response with
- * {@code "error":"issuance_pending"} manually and return it to the request
- * sender, without calling the {@code /vci/deferred/issue} API.
+ * To issue a credential, the {@code order} request parameter must be set up
+ * properly, and both the {@code denied} and {@code order.issuanceDeferred}
+ * request parameters must be set to {@code false}.
+ * </p>
+ *
+ * <h3>Denying a deferred credential request</h3>
+ *
+ * <p>
+ * To deny the deferred credential request, the {@code denied} request parameter
+ * in the API call must be set to {@code true}. In this case, Authlete prepares
+ * a response containing {@code "error":"credential_request_denied"} and returns
+ * <code>"action":"{@link CredentialDeferredIssueResponse.Action#BAD_REQUEST BAD_REQUEST}"</code>.
+ * </p>
+ *
+ * <p>
+ * Note that the {@code credential_request_denied} error code does not exist in
+ * OID4VCI 1.0 ID1. Therefore, you should not call the API with {@code denied}
+ * set to {@code true} when the target specification version is "1.0-ID1".
+ * </p>
+ *
+ * <h3>Notifying that the credential is not ready yet</h3>
+ *
+ * <p>
+ * To notify that the requested credential is not ready yet, the
+ * {@code order.issuanceDeferred} request parameter in the API call must be
+ * set to {@code true}. In this case, Authlete will do one of the following:
+ * </p>
+ *
+ * <ol>
+ * <li>
+ * Prepare an error response with the {@code issuance_pending} error code for
+ * OID4VCI 1.0 ID1.
+ * <li>
+ * Prepare a successful response containing the {@code transaction_id} and
+ * {@code interval} parameters for OID4VCI 1.0 Final or later.
+ * </ol>
+ *
+ * <p>
+ * Note that if the Authlete Server version is older than 3.0.25 and the target
+ * specification version is "1.0-ID1", you need to manually construct an error
+ * response as shown below, without using the {@code /vci/deferred/issue} API.
  * </p>
  *
  * <pre>
@@ -61,15 +106,38 @@
  * }
  * </pre>
  *
+ * <h3>Interval handling</h3>
+ *
+ * <p>
+ * If the {@code interval} request parameter in the API call is present and its
+ * value is positive, it is used as the value of the {@code interval} response
+ * parameter in the deferred credential response. If the {@code interval}
+ * request parameter is missing, zero, or negative, Authlete uses the default
+ * value.
+ * </p>
+ *
+ * <p>
+ * Note that the {@code interval} response parameter does not exist in OID4VCI
+ * 1.0 ID1. Therefore, you don't have to care about the {@code interval} request
+ * parameter if the target specification version is "1.0-ID1".
+ * </p>
+ *
+ * <h3>Important note</h3>
+ *
+ * <p>
+ * In all cases, the {@code order.requestIdentifier} request parameter must be
+ * set properly.
+ * </p>
+ *
  * @since 3.70
  * @since Authlete 3.0
  *
- * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
- *      >OpenID for Verifiable Credential Issuance</a>
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+ *      OpenID for Verifiable Credential Issuance 1.0</a>
  */
 public class CredentialDeferredIssueRequest implements Serializable
 {
-    private static final long serialVersionUID = 1L;
+    private static final long serialVersionUID = 2L;
 
 
     /**
@@ -78,6 +146,26 @@ public class CredentialDeferredIssueRequest implements Serializable
     private CredentialIssuanceOrder order;
 
 
+    /**
+     * The flag that indicates whether to deny the deferred credential request.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    private boolean denied;
+
+
+    /**
+     * The minimum amount of time in seconds that the Wallet SHOULD wait after
+     * receiving the response before sending a new request to the Deferred
+     * Credential Endpoint.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    private int interval;
+
+
     /**
      * Get the credential order that provides an instruction for issuing a
      * credential.
@@ -107,4 +195,160 @@ public CredentialDeferredIssueRequest setOrder(CredentialIssuanceOrder order)
 
         return this;
     }
+
+
+    /**
+     * Get the flag that indicates whether to deny the deferred credential
+     * request.
+     *
+     * <p>
+     * If this parameter is set to {@code true}, the response content prepared
+     * by Authlete will contain {@code "error":"credential_request_denied"}
+     * like below.
+     * </p>
+     *
+     * <pre>
+     * {
+     *     "error": "credential_request_denied"
+     * }
+     * </pre>
+     *
+     * <p>
+     * Note that the {@code credential_request_denied} error code does not
+     * exist in OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @return
+     *         {@code true} for generating a response content containing
+     *         {@code "error":"credential_request_denied"}.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public boolean isDenied()
+    {
+        return denied;
+    }
+
+
+    /**
+     * Set the flag that indicates whether to deny the deferred credential
+     * request.
+     *
+     * <p>
+     * If this parameter is set to {@code true}, the response content prepared
+     * by Authlete will contain {@code "error":"credential_request_denied"}
+     * like below.
+     * </p>
+     *
+     * <pre>
+     * {
+     *     "error": "credential_request_denied"
+     * }
+     * </pre>
+     *
+     * <p>
+     * Note that the {@code credential_request_denied} error code does not
+     * exist in OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @param denied
+     *         {@code true} for generating a response content containing
+     *         {@code "error":"credential_request_denied"}.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public CredentialDeferredIssueRequest setDenied(boolean denied)
+    {
+        this.denied = denied;
+
+        return this;
+    }
+
+
+    /**
+     * Get the minimum amount of time in seconds that the Wallet SHOULD wait
+     * after receiving the response before sending a new request to the
+     * Deferred Credential Endpoint.
+     *
+     * <p>
+     * The value of this parameter is used as the value of the {@code interval}
+     * parameter in the deferred credential response. However, the
+     * {@code interval} parameter is included in the deferred credential
+     * response only when the following conditions are met:
+     * </p>
+     *
+     * <ul>
+     * <li>
+     * The value of the {@code order.issuanceDeferred} request parameter is
+     * {@code true}.
+     * </li>
+     *
+     * <li>
+     * The version of the OID4VCI specification is 1.0-Final or later (that is,
+     * the {@code oid4vciVersion} property of {@link Service} is set and its
+     * value is not {@code "1.0-ID1"}).
+     * </li>
+     * </ul>
+     *
+     * @return
+     *         The minimum amount of time in seconds that the Wallet SHOULD
+     *         wait after receiving the response before sending a new request
+     *         to the Deferred Credential Endpoint.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public int getInterval()
+    {
+        return interval;
+    }
+
+
+    /**
+     * Set the minimum amount of time in seconds that the Wallet SHOULD wait
+     * after receiving the response before sending a new request to the
+     * Deferred Credential Endpoint.
+     *
+     * <p>
+     * The value of this parameter is used as the value of the {@code interval}
+     * parameter in the deferred credential response. However, the
+     * {@code interval} parameter is included in the deferred credential
+     * response only when the following conditions are met:
+     * </p>
+     *
+     * <ul>
+     * <li>
+     * The value of the {@code order.issuanceDeferred} request parameter is
+     * {@code true}.
+     * </li>
+     *
+     * <li>
+     * The version of the OID4VCI specification is 1.0-Final or later (that is,
+     * the {@code oid4vciVersion} property of {@link Service} is set and its
+     * value is not {@code "1.0-ID1"}).
+     * </li>
+     * </ul>
+     *
+     * @param interval
+     *         The minimum amount of time in seconds that the Wallet SHOULD
+     *         wait after receiving the response before sending a new request
+     *         to the Deferred Credential Endpoint.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public CredentialDeferredIssueRequest setInterval(int interval)
+    {
+        this.interval = interval;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/CredentialDeferredIssueResponse.java b/src/main/java/com/authlete/common/dto/CredentialDeferredIssueResponse.java
index e22a1efb37..3121285169 100644
--- a/src/main/java/com/authlete/common/dto/CredentialDeferredIssueResponse.java
+++ b/src/main/java/com/authlete/common/dto/CredentialDeferredIssueResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -71,6 +71,51 @@
  * </pre>
  *
  * <hr>
+ * <h3>{@code action} = {@link Action#ACCEPTED ACCEPTED}</h3>
+ *
+ * <p>
+ * The {@code action} value {@link Action#ACCEPTED ACCEPTED} means that
+ * the requested credential is not ready yet. In this case, the
+ * implementation of the deferred credential endpoint should return a
+ * successful response to the request sender. The HTTP status code and the
+ * content type of the response should be 202 and {@code application/json},
+ * respectively. The value of the {@code responseContent} parameter can
+ * be used as the message body of the response. It contains the
+ * "{@code transaction_id}" parameter that conforms to the specification
+ * of "Deferred Credential Response".
+ * </p>
+ *
+ * <pre>
+ * HTTP/1.1 202 Accepted
+ * Content-Type: application/json
+ * Cache-Control: no-store
+ *
+ * (Put the value of the "responseContent" parameter here.)
+ * </pre>
+ *
+ * <hr>
+ * <h3>{@code action} = {@link Action#ACCEPTED_JWT ACCEPTED_JWT}</h3>
+ *
+ * <p>
+ * The {@code action} value {@link Action#ACCEPTED_JWT ACCEPTED_JWT} means
+ * that the requested credential is not ready yet and the deferred credential
+ * response should be encrypted. In this case, the implementation of the
+ * deferred credential endpoint should return a successful response to the
+ * request sender. The HTTP status code and the content type of the response
+ * should be 202 and {@code application/jwt}, respectively. The value of the
+ * {@code responseContent} parameter is an encrypted JWT and can be used
+ * as the message body of the response.
+ * </p>
+ *
+ * <pre>
+ * HTTP/1.1 202 Accepted
+ * Content-Type: application/jwt
+ * Cache-Control: no-store
+ *
+ * (Put the value of the "responseContent" parameter here.)
+ * </pre>
+ *
+ * <hr>
  * <h3>{@code action} = {@link Action#BAD_REQUEST BAD_REQUEST}</h3>
  *
  * <p>
@@ -169,7 +214,7 @@
  */
 public class CredentialDeferredIssueResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = 3L;
 
 
     /**
@@ -197,12 +242,42 @@ public enum Action
          */
         OK_JWT,
 
+        /**
+         * The requested credential is not ready yet. The implementation of
+         * the deferred credential endpoint should return a successful response
+         * with the HTTP status code "202 Accepted" and the content type
+         * {@code application/json}.
+         *
+         * @since 4.35
+         * @since Authlete 3.0.25
+         */
+        ACCEPTED,
+
+        /**
+         * The requested credential is not ready yet and the deferred
+         * credential response should be encrypted. The implementation of the
+         * deferred credential endpoint should return a successful response
+         * with the HTTP status code "202 Accepted" and the content type
+         * {@code application/jwt}.
+         *
+         * @since 4.35
+         * @since Authlete 3.0.25
+         */
+        ACCEPTED_JWT,
+
         /**
          * The original deferred credential request is wrong. This can happen,
          * for example, when the process for encrypting the deferred credential
          * response with the encryption parameters specified in the deferred
          * credential request failed.
          *
+         * <p>
+         * Since Authlete 3.0.25, this action is returned also when the
+         * credential issuer has decided not to issue a credential for the
+         * presented transaction ID (that is, when the {@code /vci/deferred/issue}
+         * API is called with {@code denied} set to {@code true}).
+         * </p>
+         *
          * @since 3.86
          */
         BAD_REQUEST,
diff --git a/src/main/java/com/authlete/common/dto/CredentialDeferredParseResponse.java b/src/main/java/com/authlete/common/dto/CredentialDeferredParseResponse.java
index 778bfda188..3891482730 100644
--- a/src/main/java/com/authlete/common/dto/CredentialDeferredParseResponse.java
+++ b/src/main/java/com/authlete/common/dto/CredentialDeferredParseResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -33,14 +33,15 @@
  * The {@code action} value {@link Action#OK OK} means that the deferred
  * credential request is valid. In this case, the implementation of the
  * deferred credential endpoint should call the {@code /vci/deferred/issue}
- * API in order to issue a verifiable credential, or return the
- * {@code issuance_pending} error if the verifiable credential is not ready
- * yet.
+ * API in order to issue a verifiable credential, deny the deferred credential
+ * request, or notify that the requested credential is not ready yet.
  * </p>
  *
  * <p>
- * The following is an example error response telling the request sender
- * that the verifiable credential is not ready yet.
+ * Note that if the Authlete Server version is older than 3.0.25 and the
+ * target specification version is "1.0-ID1", you need to manually construct
+ * an error response containing {@code "error":"issuance_pending"}, as shown
+ * below, without using the {@code /vci/deferred/issue} API.
  * </p>
  *
  * <pre>
diff --git a/src/main/java/com/authlete/common/dto/CredentialIssuerMetadata.java b/src/main/java/com/authlete/common/dto/CredentialIssuerMetadata.java
index 0a002df1b8..7b0fb32090 100644
--- a/src/main/java/com/authlete/common/dto/CredentialIssuerMetadata.java
+++ b/src/main/java/com/authlete/common/dto/CredentialIssuerMetadata.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023-2024 Authlete, Inc.
+ * Copyright (C) 2023-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,26 +18,103 @@
 
 import static com.authlete.common.util.MapUtils.put;
 import static com.authlete.common.util.MapUtils.putJsonObject;
+import static com.authlete.common.util.MapUtils.putJsonArray;
 import java.io.Serializable;
 import java.net.URI;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import com.authlete.common.types.JWEAlg;
 import com.authlete.common.types.JWEEnc;
+import com.authlete.common.types.JWEZip;
+import com.nimbusds.jose.jwk.JWKSet;
 
 
 /**
  * A class that represents the set of credential issuer metadata.
- * The set consists of the following.
+ * The set consists of the following:
+ *
+ * <blockquote>
+ * <table border="1" cellpadding="5" style="border-collapse: collapse;">
+ *   <tr bgcolor="orange">
+ *     <th rowspan="2">Parameter</th>
+ *     <th colspan="2">Spec Version</th>
+ *   </tr>
+ *   <tr>
+ *     <td align="center">1.0-ID1</td>
+ *     <td align="center">1.0-Final</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code credential_issuer}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code authorization_servers}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code credential_endpoint}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code batch_credential_endpoint}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">deprecated</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code deferred_credential_endpoint}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code notification_endpoint}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code nonce_endpoint}</td>
+ *     <td align="center"></td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code credential_request_encryption}</td>
+ *     <td align="center"></td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code credential_response_encryption}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code batch_credential_issuance}</td>
+ *     <td align="center"></td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code display}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@code credential_configurations_supported}</td>
+ *     <td align="center">&check;</td>
+ *     <td align="center">&check;</td>
+ *   </tr>
+ * </table>
+ * </blockquote>
+ *
+ * <p>
+ * The following parameters, which existed in the 1.0-ID1 version but have
+ * removed from the 1.0-Final version, are not supported by Authlete
+ * from the beginning:
+ * </p>
  *
  * <ul>
- * <li>{@code credential_issuer}
- * <li>{@code authorization_servers}
- * <li>{@code credential_endpoint}
- * <li>{@code batch_credential_endpoint}
- * <li>{@code deferred_credential_endpoint}
- * <li>{@code credential_response_encryption}
- * <li>{@code credential_configurations_supported}
+ * <li>{@code credential_identifiers_supported}</li>
+ * <li>{@code signed_metadata}</li>
  * </ul>
  *
  * <p>
@@ -76,14 +153,14 @@
  * @since Authlete 3.0
  *
  * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
- *      >OpenID for Verifiable Credential Issuance</a>
+ *      >OpenID for Verifiable Credential Issuance 1.0</a>
  *
- * @see <a href="https://openid.github.io/OpenID4VCI/openid-4-verifiable-credential-issuance-wg-draft.html"
- *      >OpenID for Verifiable Credential Issuance, Working Draft</a>
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0-ID1.html"
+ *      >OpenID for Verifiable Credential Issuance 1.0, Implementer's Draft 1</a>
  */
 public class CredentialIssuerMetadata implements Serializable
 {
-    private static final long serialVersionUID = 4L;
+    private static final long serialVersionUID = 5L;
 
 
     /**
@@ -119,6 +196,22 @@ public class CredentialIssuerMetadata implements Serializable
     private URI deferredCredentialEndpoint;
 
 
+    /**
+     * The URL of the notification endpoint.
+     *
+     * @since 4.26
+     */
+    private URI notificationEndpoint;
+
+
+    /**
+     * The URL of the nonce endpoint.
+     *
+     * @since 4.26
+     */
+    private URI nonceEndpoint;
+
+
     /**
      * The supported JWE alg algorithms for credential response encryption.
      *
@@ -127,6 +220,40 @@ public class CredentialIssuerMetadata implements Serializable
     private JWEAlg[] credentialResponseEncryptionAlgValuesSupported;
 
 
+    /**
+     * A JSON Web Key Set containing private keys for credential request
+     * encryption.
+     *
+     * @since 4.26
+     */
+    private String credentialRequestEncryptionJwks;
+
+
+    /**
+     * The supported JWE enc algorithms for credential request encryption.
+     *
+     * @since 4.26
+     */
+    private JWEEnc[] credentialRequestEncryptionEncValuesSupported;
+
+
+    /**
+     * The supported JWE zip algorithms for credential request encryption.
+     *
+     * @since 4.26
+     */
+    private JWEZip[] credentialRequestEncryptionZipValuesSupported;
+
+
+    /**
+     * The boolean flag indicating whether credential request encryption is
+     * required.
+     *
+     * @since 4.26
+     */
+    private boolean requireCredentialRequestEncryption;
+
+
     /**
      * The supported JWE enc algorithms for credential response encryption.
      *
@@ -135,6 +262,14 @@ public class CredentialIssuerMetadata implements Serializable
     private JWEEnc[] credentialResponseEncryptionEncValuesSupported;
 
 
+    /**
+     * The supported JWE zip algorithms for credential response encryption.
+     *
+     * @since 4.26
+     */
+    private JWEZip[] credentialResponseEncryptionZipValuesSupported;
+
+
     /**
      * The boolean flag indicating whether credential response encryption is
      * required.
@@ -144,6 +279,23 @@ public class CredentialIssuerMetadata implements Serializable
     private boolean requireCredentialResponseEncryption;
 
 
+    /**
+     * The maximum array size for the {@code proofs} parameter in a credential
+     * request.
+     *
+     * @since 4.26
+     */
+    private int batchSize;
+
+
+    /**
+     * The credential issuer's display properties in JSON array format.
+     *
+     * @since 4.26
+     */
+    private String display;
+
+
     /**
      * A JSON object describing supported credential configurations.
      */
@@ -176,9 +328,18 @@ public CredentialIssuerMetadata(CredentialIssuerMetadata metadata)
         credentialEndpoint                             = metadata.getCredentialEndpoint();
         batchCredentialEndpoint                        = metadata.getBatchCredentialEndpoint();
         deferredCredentialEndpoint                     = metadata.getDeferredCredentialEndpoint();
+        notificationEndpoint                           = metadata.getNotificationEndpoint();
+        nonceEndpoint                                  = metadata.getNonceEndpoint();
+        credentialRequestEncryptionJwks                = metadata.getCredentialRequestEncryptionJwks();
+        credentialRequestEncryptionEncValuesSupported  = metadata.getCredentialRequestEncryptionEncValuesSupported();
+        credentialRequestEncryptionZipValuesSupported  = metadata.getCredentialRequestEncryptionZipValuesSupported();
+        requireCredentialRequestEncryption             = metadata.isRequireCredentialRequestEncryption();
         credentialResponseEncryptionAlgValuesSupported = metadata.getCredentialResponseEncryptionAlgValuesSupported();
         credentialResponseEncryptionEncValuesSupported = metadata.getCredentialResponseEncryptionEncValuesSupported();
+        credentialResponseEncryptionZipValuesSupported = metadata.getCredentialResponseEncryptionZipValuesSupported();
         requireCredentialResponseEncryption            = metadata.isRequireCredentialResponseEncryption();
+        batchSize                                      = metadata.getBatchSize();
+        display                                        = metadata.getDisplay();
         credentialsSupported                           = metadata.getCredentialsSupported();
     }
 
@@ -323,6 +484,11 @@ public CredentialIssuerMetadata setCredentialEndpoint(URI endpoint)
      * this property should be omitted.
      * </p>
      *
+     * <p>
+     * NOTE: This metadata parameter was deprecated and is not available in the
+     * 1.0-Final version of the OID4VCI specification.
+     * </p>
+     *
      * @return
      *         The URL of the batch credential endpoint.
      */
@@ -341,10 +507,16 @@ public URI getBatchCredentialEndpoint()
      * this property should be omitted.
      * </p>
      *
+     * <p>
+     * NOTE: This metadata parameter was deprecated and is not available in the
+     * 1.0-Final version of the OID4VCI specification.
+     * </p>
+     *
      * @param endpoint
      *         The URL of the batch credential endpoint.
      *
      * @return
+     *         {@code this} object.
      */
     public CredentialIssuerMetadata setBatchCredentialEndpoint(URI endpoint)
     {
@@ -399,6 +571,284 @@ public CredentialIssuerMetadata setDeferredCredentialEndpoint(URI endpoint)
     }
 
 
+    /**
+     * Get the URL of the notification endpoint. This property corresponds to
+     * the {@code notification_endpoint} metadata.
+     *
+     * @return
+     *         The URL of the notification endpoint.
+     *
+     * @since 4.26
+     */
+    public URI getNotificationEndpoint()
+    {
+        return notificationEndpoint;
+    }
+
+
+    /**
+     * Set the URL of the notification endpoint. This property corresponds to
+     * the {@code notification_endpoint} metadata.
+     *
+     * @param endpoint
+     *         The URL of the notification endpoint.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setNotificationEndpoint(URI endpoint)
+    {
+        this.notificationEndpoint = endpoint;
+
+        return this;
+    }
+
+
+    /**
+     * Get the URL of the nonce endpoint. This property corresponds to the
+     * {@code nonce_endpoint} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @return
+     *         The URL of the nonce endpoint.
+     *
+     * @since 4.26
+     */
+    public URI getNonceEndpoint()
+    {
+        return nonceEndpoint;
+    }
+
+
+    /**
+     * Set the URL of the nonce endpoint. This property corresponds to the
+     * {@code nonce_endpoint} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @param endpoint
+     *         The URL of the nonce endpoint.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setNonceEndpoint(URI endpoint)
+    {
+        this.nonceEndpoint = endpoint;
+
+        return this;
+    }
+
+
+    /**
+     * Get the JWK Set for credential request encryption.
+     *
+     * <p>
+     * The public part of this JWK Set is used as the value of the
+     * {@code credential_request_encryption.jwks} metadata.
+     * </p>
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @return
+     *         The JWK Set for credential request encryption.
+     *
+     * @since 4.26
+     */
+    public String getCredentialRequestEncryptionJwks()
+    {
+        return credentialRequestEncryptionJwks;
+    }
+
+
+    /**
+     * Set the JWK Set for credential request encryption.
+     *
+     * <p>
+     * The public part of this JWK Set is used as the value of the
+     * {@code credential_request_encryption.jwks} metadata.
+     * </p>
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @param jwks
+     *         The JWK Set for credential request encryption.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setCredentialRequestEncryptionJwks(String jwks)
+    {
+        this.credentialRequestEncryptionJwks = jwks;
+
+        return this;
+    }
+
+
+    /**
+     * Get the supported JWE {@code enc} algorithms for credential request
+     * encryption. This property corresponds to the
+     * {@code credential_request_encryption.enc_values_supported} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @return
+     *         The supported JWE {@code enc} algorithms for credential request
+     *         encryption.
+     *
+     * @since 4.26
+     */
+    public JWEEnc[] getCredentialRequestEncryptionEncValuesSupported()
+    {
+        return credentialRequestEncryptionEncValuesSupported;
+    }
+
+
+    /**
+     * Set the supported JWE {@code enc} algorithms for credential request
+     * encryption. This property corresponds to the
+     * {@code credential_request_encryption.enc_values_supported} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @param encs
+     *         The supported JWE {@code enc} algorithms for credential request
+     *         encryption.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setCredentialRequestEncryptionEncValuesSupported(JWEEnc[] encs)
+    {
+        this.credentialRequestEncryptionEncValuesSupported = encs;
+
+        return this;
+    }
+
+
+    /**
+     * Get the supported JWE {@code zip} algorithms for credential request
+     * encryption. This property corresponds to the
+     * {@code credential_request_encryption.zip_values_supported} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @return
+     *         The supported JWE {@code zip} algorithms for credential request
+     *         encryption.
+     *
+     * @since 4.26
+     */
+    public JWEZip[] getCredentialRequestEncryptionZipValuesSupported()
+    {
+        return credentialRequestEncryptionZipValuesSupported;
+    }
+
+
+    /**
+     * Set the supported JWE {@code zip} algorithms for credential request
+     * encryption. This property corresponds to the
+     * {@code credential_request_encryption.zip_values_supported} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @param zips
+     *         The supported JWE {@code zip} algorithms for credential request
+     *         encryption.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setCredentialRequestEncryptionZipValuesSupported(JWEZip[] zips)
+    {
+        this.credentialRequestEncryptionZipValuesSupported = zips;
+
+        return this;
+    }
+
+
+    /**
+     * Get the boolean flag indicating whether credential request encryption
+     * is required. This property corresponds to the
+     * {@code credential_request_encryption.encryption_required} metadata.
+     *
+     * <p>
+     * If this flag is {@code true}, every credential request to the credential
+     * issuer must be encrypted.
+     * </p>
+     *
+     * @return
+     *         {@code true} if credential request encryption is required.
+     *
+     * @since 4.26
+     */
+    public boolean isRequireCredentialRequestEncryption()
+    {
+        return requireCredentialRequestEncryption;
+    }
+
+
+    /**
+     * Set the boolean flag indicating whether credential request encryption
+     * is required. This property corresponds to the
+     * {@code credential_request_encryption.encryption_required} metadata.
+     *
+     * <p>
+     * If this flag is {@code true}, every credential request to the credential
+     * issuer must be encrypted
+     * </p>
+     *
+     * @param required
+     *         {@code true} to require credential request encryption.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setRequireCredentialRequestEncryption(boolean required)
+    {
+        this.requireCredentialRequestEncryption = required;
+
+        return this;
+    }
+
+
     /**
      * Get the supported JWE {@code alg} algorithms for credential response
      * encryption. This property corresponds to the
@@ -478,6 +928,55 @@ public CredentialIssuerMetadata setCredentialResponseEncryptionEncValuesSupporte
     }
 
 
+    /**
+     * Get the supported JWE {@code zip} algorithms for credential response
+     * encryption. This property corresponds to the
+     * {@code credential_response_encryption.zip_values_supported} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @return
+     *         The supported JWE {@code zip} algorithms for credential response
+     *         encryption.
+     *
+     * @since 4.26
+     */
+    public JWEZip[] getCredentialResponseEncryptionZipValuesSupported()
+    {
+        return credentialResponseEncryptionZipValuesSupported;
+    }
+
+
+    /**
+     * Set the supported JWE {@code zip} algorithms for credential response
+     * encryption. This property corresponds to the
+     * {@code credential_response_encryption.zip_values_supported} metadata.
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @param zips
+     *         The supported JWE {@code zip} algorithms for credential response
+     *         encryption.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setCredentialResponseEncryptionZipValuesSupported(JWEZip[] zips)
+    {
+        this.credentialResponseEncryptionZipValuesSupported = zips;
+
+        return this;
+    }
+
+
     /**
      * Get the boolean flag indicating whether credential response encryption
      * is required. This property corresponds to the
@@ -525,6 +1024,152 @@ public CredentialIssuerMetadata setRequireCredentialResponseEncryption(boolean r
     }
 
 
+    /**
+     * Get the maximum array size for the {@code proofs} parameter in a
+     * credential request. This property corresponds to the
+     * {@code batch_credential_issuance.batch_size} metadata.
+     *
+     * <p>
+     * If the value of this property is 2 or greater, the
+     * {@code batch_credential_issuance} parameter will appear in the response
+     * from the credential metadata endpoint.
+     * </p>
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @return
+     *         The maximum array size for the {@code proofs} parameter in a
+     *         credential request.
+     *
+     * @since 4.26
+     */
+    public int getBatchSize()
+    {
+        return batchSize;
+    }
+
+
+    /**
+     * Set the maximum array size for the {@code proofs} parameter in a
+     * credential request. This property corresponds to the
+     * {@code batch_credential_issuance.batch_size} metadata.
+     *
+     * <p>
+     * If the value of this property is 2 or greater, the
+     * {@code batch_credential_issuance} parameter will appear in the response
+     * from the credential metadata endpoint.
+     * </p>
+     *
+     * <p>
+     * NOTE: This metadata parameter exists in the 1.0-Final version of the
+     * OID4VCI specification but is not available in the 1.0-ID1 version.
+     * </p>
+     *
+     * @param batchSize
+     *         The maximum array size for the {@code proofs} parameter in a
+     *         credential request.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setBatchSize(int batchSize)
+    {
+        this.batchSize = batchSize;
+
+        return this;
+    }
+
+
+    /**
+     * Get the display properties of this credential issuer in JSON array format.
+     *
+     * <p>
+     * The following is an example of {@code display} value excerpted from <a href=
+     * "https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#appendix-I.1"
+     * >Appendix I.1. Credential IssuerMetadata</a> of the OID4VCI specification.
+     * </p>
+     *
+     * <pre style="width: stretch; margin-left: 1em; margin-right: 1em; border: 1px solid black;">
+     * [
+     *   {
+     *     "name": "Example University",
+     *     "locale": "en-US",
+     *     "logo": {
+     *       "uri": "https://university.example.edu/public/logo.png",
+     *       "alt_text":"a square logo of a university"
+     *     }
+     *   },
+     *   {
+     *     "name": "Example Université",
+     *     "locale": "fr-FR",
+     *     "logo": {
+     *       "uri": "https://university.example.edu/public/logo.png",
+     *       "alt_text":"Un logo universitaire carré"
+     *     }
+     *   }
+     * ]</pre>
+     *
+     * @return
+     *         The display properties.
+     *
+     * @since 4.26
+     */
+    public String getDisplay()
+    {
+        return display;
+    }
+
+
+    /**
+     * Set the display properties of this credential issuer in JSON array format.
+     *
+     * <p>
+     * The following is an example of {@code display} value excerpted from <a href=
+     * "https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#appendix-I.1"
+     * >Appendix I.1. Credential IssuerMetadata</a> of the OID4VCI specification.
+     * </p>
+     *
+     * <pre style="width: stretch; margin-left: 1em; margin-right: 1em; border: 1px solid black;">
+     * [
+     *   {
+     *     "name": "Example University",
+     *     "locale": "en-US",
+     *     "logo": {
+     *       "uri": "https://university.example.edu/public/logo.png",
+     *       "alt_text":"a square logo of a university"
+     *     }
+     *   },
+     *   {
+     *     "name": "Example Université",
+     *     "locale": "fr-FR",
+     *     "logo": {
+     *       "uri": "https://university.example.edu/public/logo.png",
+     *       "alt_text":"Un logo universitaire carré"
+     *     }
+     *   }
+     * ]</pre>
+     *
+     * @param display
+     *         The display properties.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.26
+     */
+    public CredentialIssuerMetadata setDisplay(String display)
+    {
+        this.display = display;
+
+        return this;
+    }
+
+
     /**
      * Get the information about supported credential configurations in the
      * JSON format. This property corresponds to the
@@ -609,8 +1254,15 @@ public boolean isEmpty()
                (credentialEndpoint                             == null) &&
                (batchCredentialEndpoint                        == null) &&
                (deferredCredentialEndpoint                     == null) &&
+               (notificationEndpoint                           == null) &&
+               (nonceEndpoint                                  == null) &&
+               (credentialRequestEncryptionJwks                == null) &&
+               (credentialRequestEncryptionEncValuesSupported  == null) &&
+               (credentialRequestEncryptionZipValuesSupported  == null) &&
                (credentialResponseEncryptionAlgValuesSupported == null) &&
                (credentialResponseEncryptionEncValuesSupported == null) &&
+               (credentialResponseEncryptionZipValuesSupported == null) &&
+               (display                                        == null) &&
                (credentialsSupported                           == null);
     }
 
@@ -696,20 +1348,60 @@ public Map<String, Object> toMap()
         put(map, "credential_endpoint",            credentialEndpoint,             false);
         put(map, "batch_credential_endpoint",      batchCredentialEndpoint,        false);
         put(map, "deferred_credential_endpoint",   deferredCredentialEndpoint,     false);
+        put(map, "notification_endpoint",          notificationEndpoint,           false);
+        put(map, "nonce_endpoint",                 nonceEndpoint,                  false);
+        put(map, "credential_request_encryption",  credentialRequestEncryption(),  false);
         put(map, "credential_response_encryption", credentialResponseEncryption(), false);
+        put(map, "batch_credential_issuance",      batchCredentialIssuance(),      false);
+        putDisplay(map);                           // display
+        putCredentialConfigurationsSupported(map); // credential_configurations_supported
+
+        return map;
+    }
+
+
+    private Map<String, Object> credentialRequestEncryption()
+    {
+        if (credentialRequestEncryptionJwks                      == null ||
+            credentialRequestEncryptionEncValuesSupported        == null ||
+            credentialRequestEncryptionEncValuesSupported.length == 0)
+        {
+            return null;
+        }
+
+        Map<String, Object> map = new LinkedHashMap<>();
+
+        put(map, "jwks",                 credentialRequestEncryptionPublicJwks(),       true);
+        put(map, "enc_values_supported", credentialRequestEncryptionEncValuesSupported, true);
+        put(map, "zip_values_supported", credentialRequestEncryptionZipValuesSupported, false);
+        put(map, "encryption_required",  requireCredentialRequestEncryption,            true);
+
+        return map;
+    }
+
+
+    private Map<String, Object> credentialRequestEncryptionPublicJwks()
+    {
+        if (credentialRequestEncryptionJwks == null)
+        {
+            return null;
+        }
+
+        JWKSet jwks;
 
         try
         {
-            // Parse the value of 'credentialsSupported' as a JSON object.
-            putJsonObject(map, "credential_configurations_supported", credentialsSupported, false);
+            // Parse the string as a JWK Set.
+            jwks = JWKSet.parse(credentialRequestEncryptionJwks);
         }
         catch (Exception cause)
         {
             throw new IllegalStateException(
-                    "The value of the 'credentialsSupported' property failed to be parsed as a JSON object.", cause);
+                    "The value of the 'credentialRequestEncryptionJwks' property failed to be parsed as a JWK Set.", cause);
         }
 
-        return map;
+        // Public keys only.
+        return jwks.toJSONObject(true);
     }
 
 
@@ -727,8 +1419,74 @@ private Map<String, Object> credentialResponseEncryption()
 
         put(map, "alg_values_supported", credentialResponseEncryptionAlgValuesSupported, true);
         put(map, "enc_values_supported", credentialResponseEncryptionEncValuesSupported, true);
+        put(map, "zip_values_supported", credentialResponseEncryptionZipValuesSupported, false);
         put(map, "encryption_required",  requireCredentialResponseEncryption,            true);
 
         return map;
     }
+
+
+    private Map<String, Object> batchCredentialIssuance()
+    {
+        // OpenID for Verifiable Credential Issuance 1.0
+        // 12.2.4. Credential Issuer Metadata Parameters
+        //
+        //   batch_credential_issuance:
+        //
+        //     OPTIONAL. Object containing information about the Credential
+        //     Issuer's support for issuance of multiple Credentials in a batch
+        //     in the Credential Endpoint. The presence of this parameter means
+        //     that the issuer supports more than one key proof in the proofs
+        //     parameter in the Credential Request so can issue more than one
+        //     Verifiable Credential for the same Credential Dataset in a
+        //     single request/response.
+        //
+        //       batch_size:
+        //         REQUIRED. Integer value specifying the maximum array size
+        //         for the proofs parameter in a Credential Request. It MUST
+        //         be 2 or greater.
+        //
+        if (batchSize < 2)
+        {
+            return null;
+        }
+
+        // {
+        //   "batch_size": batchSize
+        // }
+        Map<String, Object> value = new LinkedHashMap<>();
+        value.put("batch_size", batchSize);
+
+        return value;
+    }
+
+
+    private void putDisplay(Map<String, Object> map)
+    {
+        try
+        {
+            // Parse the value of 'display as a JSON array.
+            putJsonArray(map, "display", display, false);
+        }
+        catch (Exception cause)
+        {
+            throw new IllegalStateException(
+                    "The value of the 'display' property failed to be parsed as a JSON array.", cause);
+        }
+    }
+
+
+    private void putCredentialConfigurationsSupported(Map<String, Object> map)
+    {
+        try
+        {
+            // Parse the value of 'credentialsSupported' as a JSON object.
+            putJsonObject(map, "credential_configurations_supported", credentialsSupported, false);
+        }
+        catch (Exception cause)
+        {
+            throw new IllegalStateException(
+                    "The value of the 'credentialsSupported' property failed to be parsed as a JSON object.", cause);
+        }
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/CredentialNonceRequest.java b/src/main/java/com/authlete/common/dto/CredentialNonceRequest.java
new file mode 100644
index 0000000000..1e8687355c
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/CredentialNonceRequest.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2025 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.dto;
+
+
+import java.io.Serializable;
+
+
+/**
+ * Request to Authlete's {@code /vci/nonce} API.
+ *
+ * <p>
+ * The Authlete API is supposed to be used from within the implementation of
+ * the nonce endpoint of the credential issuer.
+ * </p>
+ *
+ * @since 4.27
+ * @since Authlete 3.0.22
+ *
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-nonce-endpoint">
+ *      OpenID for Verifiable Credential Issuance 1.0,
+ *      Section 7. Nonce Endpoint</a>
+ */
+public class CredentialNonceRequest implements Serializable
+{
+    private static final long serialVersionUID = 1L;
+
+
+    private boolean pretty;
+
+
+
+    /**
+     * Get the flag indicating whether the nonce response is written in the pretty
+     * format or not.
+     *
+     * @return
+     *         {@code true} if the nonce response is written in the pretty format.
+     */
+    public boolean isPretty()
+    {
+        return pretty;
+    }
+
+
+    /**
+     * Set the flag indicating whether the nonce response is written in the pretty
+     * format or not.
+     *
+     * @param pretty
+     *         {@code true} to write the nonce response in the pretty format.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CredentialNonceRequest setPretty(boolean pretty)
+    {
+        this.pretty = pretty;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/CredentialNonceResponse.java b/src/main/java/com/authlete/common/dto/CredentialNonceResponse.java
new file mode 100644
index 0000000000..4bd7c91070
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/CredentialNonceResponse.java
@@ -0,0 +1,283 @@
+/*
+ * Copyright (C) 2025 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.dto;
+
+
+/**
+ * Response from Authlete's {@code /vci/nonce} API.
+ *
+ * <p>
+ * The Authlete API is supposed to be used from within the implementation
+ * the nonce endpoint of the credential issuer.
+ * </p>
+ *
+ * <p>
+ * Authlete's {@code /vci/nonce} API returns JSON which can be mapped to
+ * this class. The credential issuer implementation should retrieve the value
+ * of the <code>{@link #getAction() action}</code> response parameter from
+ * the API response and take the following steps according to the value.
+ * </p>
+ *
+ * <h3><code>OK</code></h3>
+ *
+ * <p>
+ * When the value of the <code>{@link #getAction() action}</code> response
+ * parameter is <code>{@link Action#OK OK}</code>, it means that Authlete
+ * could prepare a nonce response successfully.
+ * <p>
+ *
+ * </p>
+ * In this case, the implementation of the nonce endpoint of the credential
+ * issuer should return an HTTP response with the HTTP status code
+ * "{@code 200 OK}" and the content type "{@code application/json}". The
+ * message body of the response has been prepared by Authlete's {@code /vci/nonce}
+ * API and it is available as the
+ * <code>{@link #getResponseContent() responseContent}</code> response parameter.
+ * </p>
+ *
+ * <p>
+ * The implementation of the nonce endpoint can construct an HTTP response by
+ * doing like below.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;">
+ * 200 OK
+ * Content-Type: application/json
+ * Cache-Control: no-store
+ * (Other HTTP headers)
+ *
+ * <i>(the value of the {@link #getResponseContent() responseContent} response parameter)</i></pre>
+ *
+ * <p>
+ * Note that the <a href=
+ * "https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
+ * >OpenID for Verifiable Credential Issuance 1.0</a> specification requires
+ * the response to include the {@code Cache-Control} header including the
+ * value {@code no-store}.
+ * </p>
+ *
+ * <h3><code>NOT_FOUND</code></h3>
+ *
+ * <p>
+ * When the value of the <code>{@link #getAction() action}</code> response
+ * parameter is <code>{@link Action#NOT_FOUND NOT_FOUND}</code>, it means that
+ * the service configuration has not enabled the feature of Verifiable
+ * Credentials and so the nonce endpoint should not be accessed.
+ * </p>
+ *
+ * </p>
+ * In this case, the implementation of the nonce endpoint of the credential
+ * issuer should return an HTTP response with the HTTP status code
+ * "{@code 404 Not Found}" and the content type "{@code application/json}".
+ * The message body (= error information in the JSON format) of the response
+ * has been prepared by Authlete's {@code /vci/nonce} API and it is available
+ * as the <code>{@link #getResponseContent() responseContent}</code> response
+ * parameter.
+ * </p>
+ *
+ * <p>
+ * The implementation of the nonce endpoint can construct an HTTP response by
+ * doing like below.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;">
+ * 404 Not Found
+ * Content-Type: application/json
+ * (Other HTTP headers)
+ *
+ * <i>(the value of the {@link #getResponseContent() responseContent} response parameter)</i></pre>
+ *
+ * <h3><code>INTERNAL_SERVER_ERROR</code></h3>
+ *
+ * <p>
+ * When the value of the <code>{@link #getAction() action}</code> response
+ * parameter is <code>{@link Action#INTERNAL_SERVER_ERROR INTERNAL_SERVER_ERROR}</code>,
+ * it means that an unexpected error has occurred on Authlete side or the
+ * service has not been set up properly yet.
+ * </p>
+ *
+ * </p>
+ * In this case, a simple implementation of the nonce endpoint would return
+ * an HTTP response with the HTTP status code "{@code 500 Internal Server Error}"
+ * and the content type "{@code application/json}". The message body (= error
+ * information in the JSON format) of the response has been prepared by Authlete's
+ * {@code /vci/nonce} API and it is available as the <code>{@link #getResponseContent()
+ * responseContent}</code> response parameter.
+ * </p>
+ *
+ * <p>
+ * Such simple implementation of the nonce endpoint can construct an HTTP response
+ * by doing like below.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;">
+ * 500 Internal Server Error
+ * Content-Type: application/json
+ * (Other HTTP headers)
+ *
+ * <i>(the value of the {@link #getResponseContent() responseContent} response parameter)</i></pre>
+ *
+ * <p>
+ * However, in real commercial deployments, it is rare for a credential issuer
+ * to return "{@code 500 Internal Server Error}" when it encounters an
+ * unexpected internal error. It's up to implementations of credential issuers
+ * what they actually return in the case of internal server error.
+ * </p>
+ *
+ * @since 4.27
+ * @since Authlete 3.0.22
+ *
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+ *      OpenID for Verifiable Credential Issuance 1.0</a>
+ */
+public class CredentialNonceResponse extends ApiResponse
+{
+    private static final long serialVersionUID = 1L;
+
+
+    /**
+     * The next action that the implementation of the nonce endpoint
+     * should take after getting a response from Authlete's
+     * {@code /vci/nonce} API.
+     *
+     * @since 4.27
+     * @since Authlete 3.0.22
+     */
+    public enum Action
+    {
+        /**
+         * A nonce response has been prepared successfully. The implementation
+         * of the nonce endpoint should return an HTTP response with the HTTP
+         * status code "{@code 200 OK}" and the content type
+         * "{@code application/json}".
+         */
+        OK,
+
+        /**
+         * The feature of Verifiable Credentials is not enabled. The
+         * implementation of the nonce endpoint should return an HTTP response
+         * with the HTTP status code "{@code 404 Not Found}" and the content
+         * type "{@code application/json}" to indicate that the endpoint should
+         * not be accessed.
+         */
+        NOT_FOUND,
+
+        /**
+         * An unexpected error occurred on Authlete side or the service has
+         * not been set up properly yet. A simple implementation of the nonce
+         * endpoint would return an HTTP response with the HTTP status code
+         * "{@code 500 Internal Server Error}" and the content type
+         * "{@code application/json}".
+         */
+        INTERNAL_SERVER_ERROR,
+    }
+
+
+    private Action action;
+    private String responseContent;
+    private String cnonce;
+
+
+    /**
+     * Get the next action that the implementation of the nonce endpoint should
+     * take after getting a response from Authlete's {@code /vci/nonce} API.
+     *
+     * @return
+     *         The next action.
+     */
+    public Action getAction()
+    {
+        return action;
+    }
+
+
+    /**
+     * Set the next action that the implementation of the nonce endpoint should
+     * take after getting a response from Authlete's {@code /vci/nonce} API.
+     *
+     * @param action
+     *         The next action.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CredentialNonceResponse setAction(Action action)
+    {
+        this.action = action;
+
+        return this;
+    }
+
+
+    /**
+     * Get the content that the implementation of the nonce endpoint should use
+     * when it constructs a response.
+     *
+     * @return
+     *         The response content in the JSON format.
+     */
+    public String getResponseContent()
+    {
+        return responseContent;
+    }
+
+
+    /**
+     * Set the content that the implementation of the nonce endpoint should use
+     * when it constructs a response.
+     *
+     * @param content
+     *         The response content in the JSON format.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CredentialNonceResponse setResponseContent(String content)
+    {
+        this.responseContent = content;
+
+        return this;
+    }
+
+
+    /**
+     * Get the {@code c_nonce} value generated by the {@code /vci/nonce} API.
+     *
+     * @return
+     *         The generated {@code c_nonce} value.
+     */
+    public String getCnonce()
+    {
+        return cnonce;
+    }
+
+
+    /**
+     * Set the {@code c_nonce} value generated by the {@code /vci/nonce} API.
+     *
+     * @param cnonce
+     *         The generated {@code c_nonce} value.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CredentialNonceResponse setCnonce(String cnonce)
+    {
+        this.cnonce = cnonce;
+
+        return this;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/CredentialRequestInfo.java b/src/main/java/com/authlete/common/dto/CredentialRequestInfo.java
index 97644f91bd..7f0a6d020e 100644
--- a/src/main/java/com/authlete/common/dto/CredentialRequestInfo.java
+++ b/src/main/java/com/authlete/common/dto/CredentialRequestInfo.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023-2024 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -32,12 +32,12 @@
  * @since 3.66
  * @since Authlete 3.0
  *
- * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
- *      >OpenID for Verifiable Credential Issuance</a>
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+ *      OpenID for Verifiable Credential Issuance 1.0</a>
  */
 public class CredentialRequestInfo implements Serializable
 {
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = 3L;
 
 
     /**
@@ -72,6 +72,25 @@ public class CredentialRequestInfo implements Serializable
     private String details;
 
 
+    /**
+     * The {@code credential_configuration_id} parameter in the credential
+     * request.
+     *
+     * @since 4.34
+     * @since Authlete 3.0.25
+     */
+    private String credentialConfigurationId;
+
+
+    /**
+     * The {@code credential_identifier} parameter in the credential request.
+     *
+     * @since 4.34;
+     * @since Authlete 3.0.25
+     */
+    private String credentialIdentifier;
+
+
     /**
      * Get the identifier of the credential request.
      *
@@ -118,9 +137,18 @@ public CredentialRequestInfo setIdentifier(String identifier)
     /**
      * Get the value of the {@code format} parameter in the credential request.
      *
+     * <p>
+     * This {@code format} property is available only when the supported OID4VCI
+     * specification version is {@code "1.0-ID1"} (i.e., when the Service's
+     * {@code oid4vciVersion} is unset or set to {@code "1.0-ID1"}) and the
+     * credential request contains the {@code format} parameter. Note that in
+     * the final version of the specification, the {@code format} parameter is
+     * deprecated.
+     * </p>
+     *
      * @return
      *         The value of the {@code format} parameter in the credential request.
-     *         Such as {@code "vc+sd-jwt"}.
+     *         Such as {@code "dc+sd-jwt"}.
      */
     public String getFormat()
     {
@@ -131,9 +159,18 @@ public String getFormat()
     /**
      * Set the value of the {@code format} parameter in the credential request.
      *
+     * <p>
+     * This {@code format} property is available only when the supported OID4VCI
+     * specification version is {@code "1.0-ID1"} (i.e., when the Service's
+     * {@code oid4vciVersion} is unset or set to {@code "1.0-ID1"}) and the
+     * credential request contains the {@code format} parameter. Note that in
+     * the final version of the specification, the {@code format} parameter is
+     * deprecated.
+     * </p>
+     *
      * @param format
      *         The value of the {@code format} parameter in the credential request.
-     *         Such as {@code "jwt_vc_json"} and {@code "vc+sd-jwt"}.
+     *         Such as {@code "jwt_vc_json"} and {@code "dc+sd-jwt"}.
      *
      * @return
      *         {@code this} object.
@@ -233,11 +270,18 @@ public CredentialRequestInfo setBindingKeys(String[] bindingKeys)
      *
      * <p>
      * The value is almost the same as the credential request except that it
-     * does not contain the {@code "format"} parameter, the {@code "proof"}
-     * parameter, the {@code "proofs"} parameter, and the
-     * {@code credential_response_encryption} parameter.
+     * does not contain the following parameters:
      * </p>
      *
+     * <ul>
+     * <li>{@code credential_configuration_id}
+     * <li>{@code credential_identifier}
+     * <li>{@code credential_response_encryption}
+     * <li>{@code format}
+     * <li>{@code proof}
+     * <li>{@code proofs}
+     * </ul>
+     *
      * <p>
      * For example, when the original credential request holds the following:
      * </p>
@@ -299,4 +343,114 @@ public CredentialRequestInfo setDetails(String details)
 
         return this;
     }
+
+
+    /**
+     * Get the value of the {@code credential_configuration_id} parameter in
+     * the credential request.
+     *
+     * <p>
+     * This property is not available when the supported OID4VCI specification
+     * version is {@code "1.0-ID1"} (i.e., when the Service's
+     * {@code oid4vciVersion} is unset or set to {@code "1.0-ID1"}), because
+     * the {@code credential_configuration_id} parameter does not exist in
+     * OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @return
+     *         The value of the {@code credential_configuration_id} parameter
+     *         in the credential request.
+     *
+     * @since 4.34
+     * @since Authlete 3.0.25
+     */
+    public String getCredentialConfigurationId()
+    {
+        return credentialConfigurationId;
+    }
+
+
+    /**
+     * Set the value of the {@code credential_configuration_id} parameter in
+     * the credential request.
+     *
+     * <p>
+     * This property is not available when the supported OID4VCI specification
+     * version is {@code "1.0-ID1"} (i.e., when the Service's
+     * {@code oid4vciVersion} is unset or set to {@code "1.0-ID1"}), because
+     * the {@code credential_configuration_id} parameter does not exist in
+     * OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @param id
+     *         The value of the {@code credential_configuration_id} parameter
+     *         in the credential request.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.34
+     * @since Authlete 3.0.25
+     */
+    public CredentialRequestInfo setCredentialConfigurationId(String id)
+    {
+        this.credentialConfigurationId = id;
+
+        return this;
+    }
+
+
+    /**
+     * Get the value of the {@code credential_identifier} parameter in the
+     * credential request.
+     *
+     * <p>
+     * This property is not available when the supported OID4VCI specification
+     * version is {@code "1.0-ID1"} (i.e., when the Service's
+     * {@code oid4vciVersion} is unset or set to {@code "1.0-ID1"}), because
+     * Authlete does not support the {@code credential_identifier} parameter
+     * for OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @return
+     *         The value of the {@code credential_identifier} parameter in the
+     *         credential request.
+     *
+     * @since 4.34
+     * @since Authlete 3.0.25
+     */
+    public String getCredentialIdentifier()
+    {
+        return credentialIdentifier;
+    }
+
+
+    /**
+     * Set the value of the {@code credential_identifier} parameter in the
+     * credential request.
+     *
+     * <p>
+     * This property is not available when the supported OID4VCI specification
+     * version is {@code "1.0-ID1"} (i.e., when the Service's
+     * {@code oid4vciVersion} is unset or set to {@code "1.0-ID1"}), because
+     * Authlete does not support the {@code credential_identifier} parameter
+     * for OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @param identifier
+     *         The value of the {@code credential_identifier} parameter in the
+     *         credential request.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.34
+     * @since Authlete 3.0.25
+     */
+    public CredentialRequestInfo setCredentialIdentifier(String identifier)
+    {
+        this.credentialIdentifier = identifier;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/CredentialSingleIssueRequest.java b/src/main/java/com/authlete/common/dto/CredentialSingleIssueRequest.java
index a1a36d61af..e116ca52c3 100644
--- a/src/main/java/com/authlete/common/dto/CredentialSingleIssueRequest.java
+++ b/src/main/java/com/authlete/common/dto/CredentialSingleIssueRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -26,7 +26,7 @@
  * The Authlete API is supposed to be called by the implementation of the
  * <b>credential endpoint</b>. The endpoint is defined in the "<a href=
  * "https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
- * >OpenID for Verifiable Credential Issuance</a>" (OID4VCI) specification.
+ * >OpenID for Verifiable Credential Issuance 1.0</a>" (OID4VCI) specification.
  * </p>
  *
  * <p>
@@ -49,12 +49,12 @@
  * @since 3.67
  * @since Authlete 3.0
  *
- * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html"
- *      >OpenID for Verifiable Credential Issuance</a>
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+ *      OpenID for Verifiable Credential Issuance 1.0</a>
  */
 public class CredentialSingleIssueRequest implements Serializable
 {
-    private static final long serialVersionUID = 1L;
+    private static final long serialVersionUID = 2L;
 
 
     /**
@@ -69,6 +69,26 @@ public class CredentialSingleIssueRequest implements Serializable
     private CredentialIssuanceOrder order;
 
 
+    /**
+     * The flag that indicates whether to deny the credential request.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    private boolean denied;
+
+
+    /**
+     * The minimum amount of time in seconds that the Wallet SHOULD wait after
+     * receiving the response before sending a new request to the Deferred
+     * Credential Endpoint.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    private int interval;
+
+
     /**
      * Get the access token that was presented at the credential endpoint.
      *
@@ -127,4 +147,158 @@ public CredentialSingleIssueRequest setOrder(CredentialIssuanceOrder order)
 
         return this;
     }
+
+
+    /**
+     * Get the flag that indicates whether to deny the credential request.
+     *
+     * <p>
+     * If this parameter is set to {@code true}, the response content prepared
+     * by Authlete will contain {@code "error":"credential_request_denied"}
+     * like below.
+     * </p>
+     *
+     * <pre>
+     * {
+     *     "error": "credential_request_denied"
+     * }
+     * </pre>
+     *
+     * <p>
+     * Note that the {@code credential_request_denied} error code does not
+     * exist in OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @return
+     *         {@code true} for generating a response content containing
+     *         {@code "error":"credential_request_denied"}.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public boolean isDenied()
+    {
+        return denied;
+    }
+
+
+    /**
+     * Set the flag that indicates whether to deny the credential request.
+     *
+     * <p>
+     * If this parameter is set to {@code true}, the response content prepared
+     * by Authlete will contain {@code "error":"credential_request_denied"}
+     * like below.
+     * </p>
+     *
+     * <pre>
+     * {
+     *     "error": "credential_request_denied"
+     * }
+     * </pre>
+     *
+     * <p>
+     * Note that the {@code credential_request_denied} error code does not
+     * exist in OID4VCI 1.0 ID1.
+     * </p>
+     *
+     * @param denied
+     *         {@code true} for generating a response content containing
+     *         {@code "error":"credential_request_denied"}.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public CredentialSingleIssueRequest setDenied(boolean denied)
+    {
+        this.denied = denied;
+
+        return this;
+    }
+
+
+    /**
+     * Get the minimum amount of time in seconds that the Wallet SHOULD wait
+     * after receiving the response before sending a new request to the
+     * Deferred Credential Endpoint.
+     *
+     * <p>
+     * The value of this parameter is used as the value of the {@code interval}
+     * parameter in the credential response. However, the {@code interval}
+     * parameter is included in the credential response only when the following
+     * conditions are met:
+     * </p>
+     *
+     * <ul>
+     * <li>
+     * The value of the {@code order.issuanceDeferred} request parameter is
+     * {@code true}.
+     * </li>
+     *
+     * <li>
+     * The version of the OID4VCI specification is 1.0-Final or later (that is,
+     * the {@code oid4vciVersion} property of {@link Service} is set and its
+     * value is not {@code "1.0-ID1"}).
+     * </li>
+     * </ul>
+     *
+     * @return
+     *         The minimum amount of time in seconds that the Wallet SHOULD
+     *         wait after receiving the response before sending a new request
+     *         to the Deferred Credential Endpoint.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public int getInterval()
+    {
+        return interval;
+    }
+
+
+    /**
+     * Set the minimum amount of time in seconds that the Wallet SHOULD wait
+     * after receiving the response before sending a new request to the
+     * Deferred Credential Endpoint.
+     *
+     * <p>
+     * The value of this parameter is used as the value of the {@code interval}
+     * parameter in the credential response. However, the {@code interval}
+     * parameter is included in the credential response only when the following
+     * conditions are met:
+     * </p>
+     *
+     * <ul>
+     * <li>
+     * The value of the {@code order.issuanceDeferred} request parameter is
+     * {@code true}.
+     * </li>
+     *
+     * <li>
+     * The version of the OID4VCI specification is 1.0-Final or later (that is,
+     * the {@code oid4vciVersion} property of {@link Service} is set and its
+     * value is not {@code "1.0-ID1"}).
+     * </li>
+     * </ul>
+     *
+     * @param interval
+     *         The minimum amount of time in seconds that the Wallet SHOULD
+     *         wait after receiving the response before sending a new request
+     *         to the Deferred Credential Endpoint.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.35
+     * @since Authlete 3.0.25
+     */
+    public CredentialSingleIssueRequest setInterval(int interval)
+    {
+        this.interval = interval;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/CredentialSingleIssueResponse.java b/src/main/java/com/authlete/common/dto/CredentialSingleIssueResponse.java
index c91f0f67d3..64940b10c6 100644
--- a/src/main/java/com/authlete/common/dto/CredentialSingleIssueResponse.java
+++ b/src/main/java/com/authlete/common/dto/CredentialSingleIssueResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -292,6 +292,13 @@ public enum Action
          * with the encryption parameters specified in the credential request
          * failed.
          *
+         * <p>
+         * Since Authlete 3.0.25, this action is returned also when the
+         * credential issuer has decided not to issue a credential for the
+         * presented transaction ID (that is, when the {@code /vci/single/issue}
+         * API is called with {@code denied} set to {@code true}).
+         * </p>
+         *
          * @since 3.86
          */
         BAD_REQUEST,
diff --git a/src/main/java/com/authlete/common/dto/CursorResponse.java b/src/main/java/com/authlete/common/dto/CursorResponse.java
new file mode 100644
index 0000000000..6683c58c42
--- /dev/null
+++ b/src/main/java/com/authlete/common/dto/CursorResponse.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2014 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.dto;
+
+
+import java.io.Serializable;
+
+
+/**
+ * Response from Authlete's cursor based APIs.
+ *
+ * @author Kyle Gonzalez
+ * @since Authlete 3.0.34
+ */
+public class CursorResponse<T extends Serializable> implements Serializable
+{
+    private static final long serialVersionUID = 1L;
+
+    /**
+     * The total number of entities, in situations where this is expensive to calculate it can be omitted and set to {@code null}.
+     */
+    private Integer totalCount = null;
+
+    /**
+     * The requested max limit of entities to return in this payload.
+     */
+    private int limit;
+
+    /**
+     * The array of entities that have been returned.
+     */
+    private T[] entities;
+
+    /**
+     * The opaque cursor token which is required for the next list request. If there are no further entities to retrieve this property will be {@code null}.
+     */
+    private String nextCursor;
+
+
+    public CursorResponse()
+    {
+
+    }
+
+
+    public CursorResponse(T[] entities, int limit, String nextCursor)
+    {
+        this.entities = entities;
+        this.limit = limit;
+        this.nextCursor = nextCursor;
+    }
+
+
+    public CursorResponse(T[] entities, int limit, String nextCursor, Integer totalCount)
+    {
+        this(entities, limit, nextCursor);
+        this.totalCount = totalCount;
+    }
+
+
+    /**
+     * Get the list of entities that match the list conditions.
+     *
+     * @return Array of entities that match, otherwise an empty array
+     */
+    public T[] getEntities()
+    {
+        return entities;
+    }
+
+
+    /**
+     * Get the interpreted limit of entities that will be return from the single call.
+     *
+     * @return the maximum amount of entities that could be returned from this single call
+     */
+    public int getLimit()
+    {
+        return limit;
+    }
+
+
+    /**
+     * Get the total count of entities available from this endpoint given the provided conditions.
+     *
+     * @return the maximum available amount of entities that can be retrieved at this point in time
+     */
+    public Integer getTotalCount()
+    {
+        return totalCount;
+    }
+
+
+    /**
+     * The next {@code cursor} that should be provided to this endpoint to retrieve the next portion of entities.
+     * If {@code null} it means all entities have been iterated over already and there are no further entities to retrieve.
+     *
+     * @return the next cursor value to be used if more entities can be retrieved, otherwise {@code null}
+     */
+    public String getNextCursor()
+    {
+        return nextCursor;
+    }
+}
diff --git a/src/main/java/com/authlete/common/dto/DeviceAuthorizationRequest.java b/src/main/java/com/authlete/common/dto/DeviceAuthorizationRequest.java
index 236b44d120..1c1c8ebd68 100644
--- a/src/main/java/com/authlete/common/dto/DeviceAuthorizationRequest.java
+++ b/src/main/java/com/authlete/common/dto/DeviceAuthorizationRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2024 Authlete, Inc.
+ * Copyright (C) 2019-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -124,7 +124,7 @@
  */
 public class DeviceAuthorizationRequest implements Serializable
 {
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = 3L;
 
 
     /**
@@ -181,6 +181,15 @@ public class DeviceAuthorizationRequest implements Serializable
     private String oauthClientAttestationPop;
 
 
+    /**
+     * Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private CimdOptions cimdOptions;
+
+
     /**
      * Get the value of {@code parameters} which are the request parameters
      * that the device authorization endpoint of the authorization server
@@ -446,4 +455,49 @@ public DeviceAuthorizationRequest setOauthClientAttestationPop(String jwt)
 
         return this;
     }
+
+
+    /**
+     * Get options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @return
+     *         Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public CimdOptions getCimdOptions()
+    {
+        return cimdOptions;
+    }
+
+
+    /**
+     * Set options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @param options
+     *         Options for CIMD processing.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public DeviceAuthorizationRequest setCimdOptions(CimdOptions options)
+    {
+        this.cimdOptions = options;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/DeviceAuthorizationResponse.java b/src/main/java/com/authlete/common/dto/DeviceAuthorizationResponse.java
index 347db34018..18bd97bcf7 100644
--- a/src/main/java/com/authlete/common/dto/DeviceAuthorizationResponse.java
+++ b/src/main/java/com/authlete/common/dto/DeviceAuthorizationResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2023 Authlete, Inc.
+ * Copyright (C) 2019-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -166,11 +166,39 @@
  *
  * </dl>
  *
+ * <br/>
+ * <hr>
+ * <h3>Attestation Challenge (Authlete 3.0.28 onwards)</h3>
+ *
+ * <p>
+ * Since version 3.0.28, Authlete recognizes the {@code challenge} claim in
+ * Client Attestation PoP JWTs. If the {@code challenge} claim is required
+ * (= if the service's challenge endpoint is configured), the Authlete API
+ * checks whether the {@code challenge} claim in the presented Client
+ * Attestation PoP JWT is identical to the expected value.
+ * </p>
+ *
+ * <p>
+ * If the {@code attestationChallenge} response parameter from the API is not
+ * null, its value is the expected attestation challenge value for Client
+ * Attestation PoP JWT. The expected value needs to be conveyed to the client
+ * application as the value of the {@code OAuth-Client-Attestation-Challenge}
+ * HTTP header.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;"
+ * >OAuth-Client-Attestation-Challenge: (The value returned from {@link #getAttestationChallenge()})</pre>
+ *
+ * <p>
+ * See <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/"
+ * >OAuth 2.0 Attestation-Based Client Authentication</a> for details.
+ * </p>
+ *
  * @since 2.42
  */
 public class DeviceAuthorizationResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 9L;
+    private static final long serialVersionUID = 11L;
 
 
     /**
@@ -249,6 +277,22 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * Whether the client's metadata document was used.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 2.0.0
      */
@@ -354,6 +398,16 @@ public enum Action
      */
     private String[] warnings;
 
+    /**
+     * The expected attestation challenge value for Client Attestation PoP JWT,
+     * which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private String attestationChallenge;
+
 
     /**
      * Get the next action that the implementation of the device authorization
@@ -622,17 +676,128 @@ public DeviceAuthorizationResponse setClientEntityIdUsed(boolean used)
 
 
     /**
-     * Get the client identifier used in the device authorization request.
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public DeviceAuthorizationResponse setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
      *
      * <p>
-     * When {@link #isClientIdAliasUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientIdAlias()} does. Otherwise,
-     * if {@link #isClientEntityIdUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientEntityId()}{@code .toString()}
-     * does. In other cases, this method returns the string representation of
-     * the value returned from {@link #getClientId()}.
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
      * </p>
      *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public DeviceAuthorizationResponse setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+
+        return this;
+    }
+
+
+    /**
+     * Get the client identifier used in the device authorization request.
+     *
+     * <ol>
+     * <li>When {@link #isClientEntityIdUsed()} returns {@code true}, this
+     *     method returns the same value as {@link #getClientIdAlias()} does.
+     *
+     * <li>Otherwise, if {@link #isClientEntityIdUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getClientEntityId()}{@code .toString()} does.
+     *
+     * <li>Otherwise, if {@link #isMetadataDocumentUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getMetadataDocumentLocation()}{@code .toString()} does.
+     *
+     * <li>In other cases, this method returns the string representation of
+     *     the value returned from {@link #getClientId()}.
+     * </ol>
+     *
      * @return
      *         The client identifier used in the device authorization request.
      */
@@ -646,6 +811,10 @@ else if (clientEntityIdUsed)
         {
             return clientEntityId.toString();
         }
+        else if (metadataDocumentUsed)
+        {
+            return metadataDocumentLocation.toString();
+        }
         else
         {
             return String.valueOf(clientId);
@@ -1536,4 +1705,75 @@ public DeviceAuthorizationResponse setClientAttributes(Pair[] attributes)
 
         return this;
     }
+
+
+    /**
+     * Get the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * device authorization endpoint should add the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header in the response
+     * from the endpoint to the client application, using the value of this
+     * response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @return
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public String getAttestationChallenge()
+    {
+        return attestationChallenge;
+    }
+
+
+    /**
+     * Set the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * device authorization endpoint should add the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header in the response
+     * from the endpoint to the client application, using the value of this
+     * response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @param challenge
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public DeviceAuthorizationResponse setAttestationChallenge(String challenge)
+    {
+        this.attestationChallenge = challenge;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/DeviceVerificationResponse.java b/src/main/java/com/authlete/common/dto/DeviceVerificationResponse.java
index 5487dda579..c8023dbaa2 100644
--- a/src/main/java/com/authlete/common/dto/DeviceVerificationResponse.java
+++ b/src/main/java/com/authlete/common/dto/DeviceVerificationResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2023 Authlete, Inc.
+ * Copyright (C) 2019-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -76,7 +76,7 @@
  */
 public class DeviceVerificationResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 9L;
+    private static final long serialVersionUID = 10L;
 
 
     /**
@@ -148,6 +148,22 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * Whether the client's metadata document was used.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 2.0.0
      */
@@ -453,18 +469,129 @@ public DeviceVerificationResponse setClientEntityIdUsed(boolean used)
 
 
     /**
-     * Get the client identifier used in the device authorization request for
-     * the user code.
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public DeviceVerificationResponse setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
      *
      * <p>
-     * When {@link #isClientIdAliasUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientIdAlias()} does. Otherwise,
-     * if {@link #isClientEntityIdUsed()} returns {@code true}, this method
-     * returns the same value as {@link #getClientEntityId()}{@code .toString()}
-     * does. In other cases, this method returns the string representation of
-     * the value returned from {@link #getClientId()}.
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
      * </p>
      *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public DeviceVerificationResponse setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+
+        return this;
+    }
+
+
+    /**
+     * Get the client identifier used in the device authorization request for
+     * the user code.
+     *
+     * <ol>
+     * <li>When {@link #isClientEntityIdUsed()} returns {@code true}, this
+     *     method returns the same value as {@link #getClientIdAlias()} does.
+     *
+     * <li>Otherwise, if {@link #isClientEntityIdUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getClientEntityId()}{@code .toString()} does.
+     *
+     * <li>Otherwise, if {@link #isMetadataDocumentUsed()} returns {@code true},
+     *     this method returns the same value as
+     *     {@link #getMetadataDocumentLocation()}{@code .toString()} does.
+     *
+     * <li>In other cases, this method returns the string representation of
+     *     the value returned from {@link #getClientId()}.
+     * </ol>
+     *
      * @return
      *         The client identifier used in the device authorization request
      *         for the user code.
@@ -479,6 +606,10 @@ else if (clientEntityIdUsed)
         {
             return clientEntityId.toString();
         }
+        else if (metadataDocumentUsed)
+        {
+            return metadataDocumentLocation.toString();
+        }
         else
         {
             return String.valueOf(clientId);
diff --git a/src/main/java/com/authlete/common/dto/IntrospectionResponse.java b/src/main/java/com/authlete/common/dto/IntrospectionResponse.java
index e199151417..fa19e6f426 100644
--- a/src/main/java/com/authlete/common/dto/IntrospectionResponse.java
+++ b/src/main/java/com/authlete/common/dto/IntrospectionResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2024 Authlete, Inc.
+ * Copyright (C) 2014-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -268,7 +268,7 @@
  */
 public class IntrospectionResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 23L;
+    private static final long serialVersionUID = 24L;
 
 
     /**
@@ -442,6 +442,25 @@ public enum Action
     private boolean clientEntityIdUsed;
 
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+
+    /**
+     * Flag which indicates whether the location of the client's metadata
+     * document was used when the request for the access token was made.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
+
     /**
      * Confirmation hash for MTLS-bound access tokens. Currently only the S256
      * type is supported and is assumed.
@@ -1091,6 +1110,100 @@ public void setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+    }
+
+
     /**
      * Get the client certificate thumbprint used to validate the access token.
      *
diff --git a/src/main/java/com/authlete/common/dto/PushedAuthReqResponse.java b/src/main/java/com/authlete/common/dto/PushedAuthReqResponse.java
index 467f1e7382..33b6997561 100644
--- a/src/main/java/com/authlete/common/dto/PushedAuthReqResponse.java
+++ b/src/main/java/com/authlete/common/dto/PushedAuthReqResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019-2023 Authlete, Inc.
+ * Copyright (C) 2019-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -262,11 +262,39 @@
  * 2.0 Demonstrating Proof of Possession (DPoP)</a> for details.
  * </p>
  *
+ * <br/>
+ * <hr>
+ * <h3>Attestation Challenge (Authlete 3.0.28 onwards)</h3>
+ *
+ * <p>
+ * Since version 3.0.28, Authlete recognizes the {@code challenge} claim in
+ * Client Attestation PoP JWTs. If the {@code challenge} claim is required
+ * (= if the service's challenge endpoint is configured), the Authlete API
+ * checks whether the {@code challenge} claim in the presented Client
+ * Attestation PoP JWT is identical to the expected value.
+ * </p>
+ *
+ * <p>
+ * If the {@code attestationChallenge} response parameter from the API is not
+ * null, its value is the expected attestation challenge value for Client
+ * Attestation PoP JWT. The expected value needs to be conveyed to the client
+ * application as the value of the {@code OAuth-Client-Attestation-Challenge}
+ * HTTP header.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;"
+ * >OAuth-Client-Attestation-Challenge: (The value returned from {@link #getAttestationChallenge()})</pre>
+ *
+ * <p>
+ * See <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/"
+ * >OAuth 2.0 Attestation-Based Client Authentication</a> for details.
+ * </p>
+ *
  * @since 2.51
  */
 public class PushedAuthReqResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = 3L;
 
 
     /**
@@ -353,6 +381,16 @@ public static enum Action
      */
     private String dpopNonce;
 
+    /**
+     * The expected attestation challenge value for Client Attestation PoP JWT,
+     * which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private String attestationChallenge;
+
 
     /**
      * Get the next action that the authorization server should take.
@@ -549,6 +587,77 @@ public PushedAuthReqResponse setDpopNonce(String dpopNonce)
     }
 
 
+    /**
+     * Get the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * pushed authorization request endpoint should add the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header in the response
+     * from the endpoint to the client application, using the value of this
+     * response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @return
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public String getAttestationChallenge()
+    {
+        return attestationChallenge;
+    }
+
+
+    /**
+     * Set the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * pushed authorization request endpoint should add the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header in the response
+     * from the endpoint to the client application, using the value of this
+     * response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @param challenge
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public PushedAuthReqResponse setAttestationChallenge(String challenge)
+    {
+        this.attestationChallenge = challenge;
+
+        return this;
+    }
+
+
     /**
      * Get the summary of this instance.
      */
diff --git a/src/main/java/com/authlete/common/dto/RevocationResponse.java b/src/main/java/com/authlete/common/dto/RevocationResponse.java
index 9d1e963050..b97867cf38 100644
--- a/src/main/java/com/authlete/common/dto/RevocationResponse.java
+++ b/src/main/java/com/authlete/common/dto/RevocationResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015 Authlete, Inc.
+ * Copyright (C) 2015-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -199,6 +199,34 @@
  * </dd>
  * </dl>
  *
+ * <br/>
+ * <hr>
+ * <h3>Attestation Challenge (Authlete 3.0.28 onwards)</h3>
+ *
+ * <p>
+ * Since version 3.0.28, Authlete recognizes the {@code challenge} claim in
+ * Client Attestation PoP JWTs. If the {@code challenge} claim is required
+ * (= if the service's challenge endpoint is configured), the Authlete API
+ * checks whether the {@code challenge} claim in the presented Client
+ * Attestation PoP JWT is identical to the expected value.
+ * </p>
+ *
+ * <p>
+ * If the {@code attestationChallenge} response parameter from the API is not
+ * null, its value is the expected attestation challenge value for Client
+ * Attestation PoP JWT. The expected value needs to be conveyed to the client
+ * application as the value of the {@code OAuth-Client-Attestation-Challenge}
+ * HTTP header.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;"
+ * >OAuth-Client-Attestation-Challenge: (The value returned from {@link #getAttestationChallenge()})</pre>
+ *
+ * <p>
+ * See <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/"
+ * >OAuth 2.0 Attestation-Based Client Authentication</a> for details.
+ * </p>
+ *
  * @see <a href="http://tools.ietf.org/html/rfc7009">RFC 7009, OAuth 2.0 Token Revocation</a>
  *
  * @author Takahiko Kawasaki
@@ -208,7 +236,7 @@
  */
 public class RevocationResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 1L;
+    private static final long serialVersionUID = 2L;
 
 
     /**
@@ -250,6 +278,16 @@ public enum Action
     private Action action;
     private String responseContent;
 
+    /**
+     * The expected attestation challenge value for Client Attestation PoP JWT,
+     * which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private String attestationChallenge;
+
 
     /**
      * Get the next action that the service implementation should take.
@@ -289,6 +327,70 @@ public void setResponseContent(String responseContent)
     }
 
 
+    /**
+     * Get the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * revocation endpoint should add the {@code OAuth-Client-Attestation-Challenge}
+     * HTTP header in the response from the endpoint to the client application,
+     * using the value of this response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @return
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public String getAttestationChallenge()
+    {
+        return attestationChallenge;
+    }
+
+
+    /**
+     * Set the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * revocation endpoint should add the {@code OAuth-Client-Attestation-Challenge}
+     * HTTP header in the response from the endpoint to the client application,
+     * using the value of this response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @param challenge
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public void setAttestationChallenge(String challenge)
+    {
+        this.attestationChallenge = challenge;
+    }
+
+
     /**
      * Get the summary of this instance.
      */
diff --git a/src/main/java/com/authlete/common/dto/Service.java b/src/main/java/com/authlete/common/dto/Service.java
index 3ffdf39496..5837ec016a 100644
--- a/src/main/java/com/authlete/common/dto/Service.java
+++ b/src/main/java/com/authlete/common/dto/Service.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2025 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -330,7 +330,7 @@
  */
 public class Service implements Serializable
 {
-    private static final long serialVersionUID = 83L;
+    private static final long serialVersionUID = 93L;
 
 
     /*
@@ -738,6 +738,25 @@ public class Service implements Serializable
     private long idTokenDuration;
 
 
+    /**
+     * Duration of authorization code in seconds.
+     *
+     * <p>
+     * A value of {@code 0} means that this property is not set and that the
+     * implementation falls back to the default configuration on the server.
+     * </p>
+     *
+     * <p>
+     * For FAPI 2.0, the lifetime of authorization codes is capped to 60
+     * seconds. See OpenID FAPI 2.0 Security Profile for details.
+     * </p>
+     *
+     * @since 4.40
+     * @since Authlete 3.0.29
+     */
+    private long authorizationCodeDuration;
+
+
     /**
      * Duration of authorization response JWTs.
      *
@@ -1883,6 +1902,207 @@ public class Service implements Serializable
     private boolean nativeSsoSupported;
 
 
+    /**
+     * The version of the OpenID for Verifiable Credential Issuance specification
+     * to support.
+     *
+     * @since 4.25
+     * @since Authlete 3.0.22
+     */
+    private String oid4vciVersion;
+
+
+    /**
+     * Whether to support <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean clientIdMetadataDocumentSupported;
+
+
+    /**
+     * Whether to enable the allowlist for client IDs in the CIMD context.
+     *
+     * @since 4.31
+     * @since Authlete 3.0.22
+     */
+    private boolean cimdAllowlistEnabled;
+
+
+    /**
+     * The allowlist for client IDs in the CIMD context.
+     *
+     * @since 4.31
+     * @since Authlete 3.0.22
+     */
+    private String[] cimdAllowlist;
+
+
+    /**
+     * Whether to always retrieve client metadata in the CIMD context
+     * regardless of the cache's validity.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private boolean cimdAlwaysRetrieved;
+
+
+    /**
+     * Whether to allow the {@code http} scheme in client IDs in the CIMD
+     * context.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private boolean cimdHttpPermitted;
+
+
+    /**
+     * Whether to allow a query component in client IDs in the CIMD context.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private boolean cimdQueryPermitted;
+
+
+    /**
+     * Whether to apply the metadata policy to client metadata that is obtained
+     * through the CIMD mechanism.
+     *
+     * @since 4.33
+     * @since Authlete 3.0.23
+     */
+    private boolean cimdMetadataPolicyEnabled;
+
+
+    /**
+     * The metadata policy applied to client metadata that is obtained through
+     * the CIMD mechanism.
+     *
+     * @since 4.33
+     * @since Authlete 3.0.23
+     */
+    private String cimdMetadataPolicy;
+
+
+    /**
+     * Whether to prohibit client ID aliases that start with {@code https://}
+     * or {@code http://}.
+     *
+     * @since 4.32
+     * @since Authlete 3.0.22
+     */
+    private boolean httpAliasProhibited;
+
+
+    /**
+     * The challenge endpoint defined in
+     * OAuth 2&#x2E;0 Attestation-Based Client Authentication.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private URI challengeEndpoint;
+
+
+    /**
+     * The time window of attestation challenges in seconds.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private long attestationChallengeTimeWindow;
+
+
+    /**
+     * The HAIP version to comply with.
+     *
+     * @since 4.41
+     * @since Authlete 3.0.29
+     */
+    private String haipVersion;
+
+
+    /**
+     * The trusted root certificates for Client Attestation JWT.
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    private String[] clientAttesterRoots;
+
+
+    /**
+     * Whether to enable the trusted root certificates for Client Attestation JWT.
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    private boolean clientAttesterRootsEnabled;
+
+
+    /**
+     * Whether to refer to only the trusted root certificates for Client
+     * Attestation JWT, without referring to system-installed ones.
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    private boolean clientAttesterRootsOnly;
+
+
+    /**
+     * The trusted root certificates for Key Attestation JWT.
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    private String[] keyAttesterRoots;
+
+
+    /**
+     * Whether to enable the trusted root certificates for Key Attestation JWT.
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    private boolean keyAttesterRootsEnabled;
+
+
+    /**
+     * Whether to refer to only the trusted root certificates for Key
+     * Attestation JWT, without referring to system-installed ones.
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    private boolean keyAttesterRootsOnly;
+
+
+    /**
+     * Whether to support the OpenID Connect Back-Channel Logout 1&#x2E;0
+     * specification.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     */
+    private boolean backchannelLogoutSupported;
+
+
+    /**
+     * Whether to support the {@code sid} claim in Logout Tokens.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     */
+    private boolean backchannelLogoutSessionSupported;
+
+
     /**
      * Get the service number.
      *
@@ -2971,6 +3191,39 @@ public Service setIdTokenDuration(long duration)
     }
 
 
+    /**
+     * Get the duration of authorization code in seconds.
+     *
+     * @return
+     *         The duration of authorization code in seconds.
+     *
+     * @since 3.0.29
+     */
+    public long getAuthorizationCodeDuration()
+    {
+        return authorizationCodeDuration;
+    }
+
+
+    /**
+     * Set the duration of authorization code in seconds.
+     *
+     * @param duration
+     *         The duration of authorization code in seconds.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 3.0.29
+     */
+    public Service setAuthorizationCodeDuration(long duration)
+    {
+        this.authorizationCodeDuration = duration;
+
+        return this;
+    }
+
+
     /**
      * Get the duration of authorization response JWTs.
      *
@@ -4234,6 +4487,8 @@ public Service setErrorUriOmitted(boolean omitted)
      *         {@code false} if the feature is disabled.
      *
      * @since 2.2
+     *
+     * @see #isHttpAliasProhibited()
      */
     public boolean isClientIdAliasEnabled()
     {
@@ -4260,6 +4515,8 @@ public boolean isClientIdAliasEnabled()
      *         {@code this} object.
      *
      * @since 2.2
+     *
+     * @see #isHttpAliasProhibited()
      */
     public Service setClientIdAliasEnabled(boolean enabled)
     {
@@ -11092,13 +11349,37 @@ public Service setPreAuthorizedGrantAnonymousAccessSupported(boolean supported)
 
 
     /**
-     * Get the duration of {@code c_nonce} in seconds.
+     * Get the duration (in 1.0-ID1) or validity period (time window)
+     * (in 1.0-Final) of {@code c_nonce} in seconds.
+     *
+     * <p>
+     * The method of generating {@code c_nonce} differs between OID4VCI 1.0-ID1
+     * and OID4VCI 1.0-Final.
+     * </p>
      *
      * <p>
-     * {@code c_nonce} is issued from the token endpoint of an authorization
-     * server in the pre-authorized code flow, and from the credential endpoint
-     * and the batch credential endpoint of a credential issuer. This property
-     * is used as the lifetime of the {@code c_nonce}.
+     * In 1.0-ID1, the {@code c_nonce} is issued from the token endpoint or the
+     * credential endpoint. In Authlete's implementation, the {@code c_nonce}
+     * for 1.0-ID1 is associated with an access token.
+     * </p>
+     *
+     * <p>
+     * For {@code c_nonce} in 1.0-ID1, this {@code cnonceDuration} property is
+     * used as the lifetime of {@code c_nonce}.
+     * </p>
+     *
+     * <p>
+     * In contrast, in 1.0-Final, the {@code c_nonce} is issued from the nonce
+     * endpoint. Requests to this endpoint do not include an access token, so
+     * the server cannot determine who the requester is. As a result, the
+     * {@code c_nonce} cannot be generated per access token or per client
+     * application. Consequently, the same {@code c_nonce} value is returned to
+     * anyone who accesses the endpoint within the same time window.
+     * </p>
+     *
+     * <p>
+     * For {@code c_nonce} in 1.0-Final, this {@code cnonceDuration} property
+     * specifies the validity period (time window) in seconds.
      * </p>
      *
      * <p>
@@ -11114,12 +11395,14 @@ public Service setPreAuthorizedGrantAnonymousAccessSupported(boolean supported)
      * </p>
      *
      * <p>
+     * NOTE:
      * The {@code getCNonceDuration()} method added by the version 3.63 has
      * been renamed to {@code getCnonceDuration()} by the version 3.90.
      * </p>
      *
      * @return
-     *         The duration of {@code c_nonce} in seconds.
+     *         The duration of {@code c_nonce} in seconds in OID4VCI 1.0-ID1, or
+     *         the validity period (time window) in seconds in OID4VCI 1.0-Final.
      *
      * @since 3.90
      * @since Authlete 3.0
@@ -11134,13 +11417,37 @@ public long getCnonceDuration()
 
 
     /**
-     * Set the duration of {@code c_nonce} in seconds.
+     * Set the duration (in 1.0-ID1) or validity period (time window)
+     * (in 1.0-Final) of {@code c_nonce} in seconds.
+     *
+     * <p>
+     * The method of generating {@code c_nonce} differs between OID4VCI 1.0-ID1
+     * and OID4VCI 1.0-Final.
+     * </p>
+     *
+     * <p>
+     * In 1.0-ID1, the {@code c_nonce} is issued from the token endpoint or the
+     * credential endpoint. In Authlete's implementation, the {@code c_nonce}
+     * for 1.0-ID1 is associated with an access token.
+     * </p>
+     *
+     * <p>
+     * For {@code c_nonce} in 1.0-ID1, this {@code cnonceDuration} property is
+     * used as the lifetime of {@code c_nonce}.
+     * </p>
+     *
+     * <p>
+     * In contrast, in 1.0-Final, the {@code c_nonce} is issued from the nonce
+     * endpoint. Requests to this endpoint do not include an access token, so
+     * the server cannot determine who the requester is. As a result, the
+     * {@code c_nonce} cannot be generated per access token or per client
+     * application. Consequently, the same {@code c_nonce} value is returned to
+     * anyone who accesses the endpoint within the same time window.
+     * </p>
      *
      * <p>
-     * {@code c_nonce} is issued from the token endpoint of an authorization
-     * server in the pre-authorized code flow, and from the credential endpoint
-     * and the batch credential endpoint of a credential issuer. This property
-     * is used as the lifetime of the {@code c_nonce}.
+     * For {@code c_nonce} in 1.0-Final, this {@code cnonceDuration} property
+     * specifies the validity period (time window) in seconds.
      * </p>
      *
      * <p>
@@ -11156,12 +11463,14 @@ public long getCnonceDuration()
      * </p>
      *
      * <p>
+     * NOTE:
      * The {@code setCNonceDuration(long)} method added by the version 3.63 has
      * been renamed to {@code setCnonceDuration(long)} by the version 3.90.
      * </p>
      *
      * @param duration
-     *         The duration of {@code c_nonce} in seconds.
+     *         The duration of {@code c_nonce} in seconds in OID4VCI 1.0-ID1, or
+     *         the validity period (time window) in seconds in OID4VCI 1.0-Final.
      *
      * @return
      *         {@code this} object.
@@ -11962,4 +12271,1698 @@ public Service setNativeSsoSupported(boolean supported)
 
         return this;
     }
+
+
+    /**
+     * Get the version of the OpenID for Verifiable Credential Issuance
+     * specification to support.
+     *
+     * <p>
+     * Valid values are as follows:
+     * </p>
+     *
+     * <blockquote>
+     * <table border="1" cellpadding="5" style="border-collapse: collapse;">
+     *   <tr bgcolor="orange">
+     *     <th>Value</th>
+     *     <th>Specification</th>
+     *   </tr>
+     *   <tr>
+     *     <td>null</td>
+     *     <td rowspan="2">
+     *       <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0-ID1.html">
+     *       OpenID for Verifiable Credential Issuance 1.0, Implementer's Draft 1</a>
+     *     </td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code "1.0-ID1"}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code "1.0"}</td>
+     *     <td rowspan="2">
+     *       <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *       OpenID for Verifiable Credential Issuance 1.0, Final</a>
+     *     </td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code "1.0-Final"}</td>
+     *   </tr>
+     * </table>
+     * </blockquote>
+     *
+     * @return
+     *         The version of the OpenID for Verifiable Credential Issuance
+     *         specification to support.
+     *
+     * @since 4.25
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://www.authlete.com/developers/oid4vci/">
+     *      OpenID for Verifiable Credential Issuance</a>
+     */
+    public String getOid4vciVersion()
+    {
+        return oid4vciVersion;
+    }
+
+
+    /**
+     * Set the version of the OpenID for Verifiable Credential Issuance
+     * specification to support.
+     *
+     * <p>
+     * Valid values are as follows:
+     * </p>
+     *
+     * <blockquote>
+     * <table border="1" cellpadding="5" style="border-collapse: collapse;">
+     *   <tr bgcolor="orange">
+     *     <th>Value</th>
+     *     <th>Specification</th>
+     *   </tr>
+     *   <tr>
+     *     <td>null</td>
+     *     <td rowspan="2">
+     *       <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0-ID1.html">
+     *       OpenID for Verifiable Credential Issuance 1.0, Implementer's Draft 1</a>
+     *     </td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code "1.0-ID1"}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code "1.0"}</td>
+     *     <td rowspan="2">
+     *       <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *       OpenID for Verifiable Credential Issuance 1.0, Final</a>
+     *     </td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code "1.0-Final"}</td>
+     *   </tr>
+     * </table>
+     * </blockquote>
+     *
+     * @param version
+     *         The version of the OpenID for Verifiable Credential Issuance
+     *         specification to support.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.25
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://www.authlete.com/developers/oid4vci/">
+     *      OpenID for Verifiable Credential Issuance</a>
+     */
+    public Service setOid4vciVersion(String version)
+    {
+        this.oid4vciVersion = version;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag to determine to support <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     *
+     * <p>
+     * This flag corresponds to the {@code client_id_metadata_document_supported}
+     * metadata parameter.
+     * </p>
+     *
+     * @return
+     *         {@code true} if OAuth Client ID Metadata Document is supported.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isClientIdMetadataDocumentSupported()
+    {
+        return clientIdMetadataDocumentSupported;
+    }
+
+
+    /**
+     * Set the flag to determine to support <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     *
+     * <p>
+     * This flag corresponds to the {@code client_id_metadata_document_supported}
+     * metadata parameter.
+     * </p>
+     *
+     * @param supported
+     *         {@code true} to support OAuth Client ID Metadata Document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setClientIdMetadataDocumentSupported(boolean supported)
+    {
+        this.clientIdMetadataDocumentSupported = supported;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether the allowlist for client IDs
+     * in the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> context is enabled or not.
+     *
+     * <p>
+     * If the allowlist is enabled, the client ID in a request must match at
+     * least one entry in the allowlist to be considered a valid client ID
+     * in the CIMD context.
+     * </p>
+     *
+     * @return
+     *         {@code true} if the allowlist for client IDs in the CIMD
+     *         context is enabled.
+     *
+     * @since 4.31
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isCimdAllowlistEnabled()
+    {
+        return cimdAllowlistEnabled;
+    }
+
+
+    /**
+     * Set the flag that indicates whether the allowlist for client IDs
+     * in the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> context is enabled or not.
+     *
+     * <p>
+     * If the allowlist is enabled, the client ID in a request must match at
+     * least one entry in the allowlist to be considered a valid client ID
+     * in the CIMD context.
+     * </p>
+     *
+     * @param enabled
+     *         {@code true} to enable the allowlist for client IDs in the
+     *         CIMD context.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.31
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setCimdAllowlistEnabled(boolean enabled)
+    {
+        this.cimdAllowlistEnabled = enabled;
+
+        return this;
+    }
+
+
+    /**
+     * Get the allowlist for client IDs in the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> context.
+     *
+     * <p>
+     * When the allowlist feature is enabled (see {@link #isCimdAllowlistEnabled()}),
+     * the allowlist specified by this property is consulted to determine
+     * whether the client ID in a request is valid in the CIMD context.
+     * In this case, the client ID must match at least one entry in the
+     * allowlist.
+     * </p>
+     *
+     * <p>
+     * Each entry in the allowlist must be a valid URI. The comparison between
+     * an allowlist entry and a client ID is performed as follows:
+     * </p>
+     *
+     * <ol>
+     * <li>[scheme] Simple string comparison.
+     * <li>[authority] Simple string comparison.
+     * <li>[path] The client ID's path must contain all path segments of
+     *     the allowlist entry in the same order.
+     * <li>[query] Simple string comparison, but only if the allowlist
+     *     entry has a query component.
+     * </ol>
+     *
+     * <p>
+     * For example, if the allowlist contains "{@code https://example.com/a/b}",
+     * then "{@code https://example.com/a/b/c}" is considered valid, but
+     * "{@code https://example.com/a}" is not.
+     * </p>
+     *
+     * @return
+     *         The allowlist for client IDs in the CIMD context.
+     *
+     * @since 4.31
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public String[] getCimdAllowlist()
+    {
+        return cimdAllowlist;
+    }
+
+
+    /**
+     * Set the allowlist for client IDs in the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> context.
+     *
+     * <p>
+     * When the allowlist feature is enabled (see {@link #isCimdAllowlistEnabled()}),
+     * the allowlist specified by this property is consulted to determine
+     * whether the client ID in a request is valid in the CIMD context.
+     * In this case, the client ID must match at least one entry in the
+     * allowlist.
+     * </p>
+     *
+     * <p>
+     * Each entry in the allowlist must be a valid URI. The comparison between
+     * an allowlist entry and a client ID is performed as follows:
+     * </p>
+     *
+     * <ol>
+     * <li>[scheme] Simple string comparison.
+     * <li>[authority] Simple string comparison.
+     * <li>[path] The client ID's path must contain all path segments of
+     *     the allowlist entry in the same order.
+     * <li>[query] Simple string comparison, but only if the allowlist
+     *     entry has a query component.
+     * </ol>
+     *
+     * <p>
+     * For example, if the allowlist contains "{@code https://example.com/a/b}",
+     * then "{@code https://example.com/a/b/c}" is considered valid, but
+     * "{@code https://example.com/a}" is not.
+     * </p>
+     *
+     * @param allowlist
+     *         The allowlist for client IDs in the CIMD context.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.31
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setCimdAllowlist(String[] allowlist)
+    {
+        this.cimdAllowlist = allowlist;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether Authlete should always fetch the
+     * client metadata from the location specified by the client ID (when
+     * <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> applies), regardless of whether a cached copy already exists
+     * and has not yet expired.
+     *
+     * <p>
+     * Under normal circumstances, client metadata retrieved from the location
+     * referenced by the client ID is stored in the database with an expiration
+     * time calculated using HTTP caching mechanisms (see <a href=
+     * "https://www.rfc-editor.org/rfc/rfc9111.html">RFC 9111 HTTP Caching</a>).
+     * Until that expiration time is reached, Authlete does not attempt to
+     * retrieve the client metadata again.
+     * </p>
+     *
+     * <p>
+     * When this flag is set to {@code true}, Authlete retrieves the client
+     * metadata regardless of the cache's validity.
+     * </p>
+     *
+     * <p>
+     * Some Authlete APIs accept a {@code cimdOptions.alwaysRetrieved} request
+     * parameter (see {@link CimdOptions}). If the parameter is provided and
+     * its value is {@code true}, it takes precedence over this service
+     * configuration.
+     * </p>
+     *
+     * <p>
+     * This flag is effective only when the service supports CIMD (see {@link
+     * Service#isClientIdMetadataDocumentSupported()}) and CIMD is actually
+     * used to resolve client metadata. For example, if the client ID in a
+     * request does not appear to be a valid URI, CIMD will not be used even
+     * if the service is configured to support it. In such cases, this flag
+     * has no effect.
+     * </p>
+     *
+     * <p>
+     * Client metadata retrieval is performed only in the initiating request
+     * of an authorization flow, and not in any subsequent requests. For
+     * example, in the authorization code flow, metadata may be retrieved
+     * during the authorization request, but not during the subsequent token
+     * request. In contrast, in the client credentials flow, metadata retrieval
+     * may occur because the token request itself is the initiating request
+     * in the flow.
+     * </p>
+     *
+     * @return
+     *         {@code true} if Authlete attempts to retrieve client metadata
+     *         regardless of the cache's validity.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isCimdAlwaysRetrieved()
+    {
+        return cimdAlwaysRetrieved;
+    }
+
+
+    /**
+     * Set the flag that indicates whether Authlete should always fetch the
+     * client metadata from the location specified by the client ID (when
+     * <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> applies), regardless of whether a cached copy already exists
+     * and has not yet expired.
+     *
+     * <p>
+     * Under normal circumstances, client metadata retrieved from the location
+     * referenced by the client ID is stored in the database with an expiration
+     * time calculated using HTTP caching mechanisms (see <a href=
+     * "https://www.rfc-editor.org/rfc/rfc9111.html">RFC 9111 HTTP Caching</a>).
+     * Until that expiration time is reached, Authlete does not attempt to
+     * retrieve the client metadata again.
+     * </p>
+     *
+     * <p>
+     * When this flag is set to {@code true}, Authlete retrieves the client
+     * metadata regardless of the cache's validity.
+     * </p>
+     *
+     * <p>
+     * Some Authlete APIs accept a {@code cimdOptions.alwaysRetrieved} request
+     * parameter (see {@link CimdOptions}). If the parameter is provided and
+     * its value is {@code true}, it takes precedence over this service
+     * configuration.
+     * </p>
+     *
+     * <p>
+     * This flag is effective only when the service supports CIMD (see {@link
+     * Service#isClientIdMetadataDocumentSupported()}) and CIMD is actually
+     * used to resolve client metadata. For example, if the client ID in a
+     * request does not appear to be a valid URI, CIMD will not be used even
+     * if the service is configured to support it. In such cases, this flag
+     * has no effect.
+     * </p>
+     *
+     * <p>
+     * Client metadata retrieval is performed only in the initiating request
+     * of an authorization flow, and not in any subsequent requests. For
+     * example, in the authorization code flow, metadata may be retrieved
+     * during the authorization request, but not during the subsequent token
+     * request. In contrast, in the client credentials flow, metadata retrieval
+     * may occur because the token request itself is the initiating request
+     * in the flow.
+     * </p>
+     *
+     * @param always
+     *         {@code true} to instruct Authlete to retrieve client metadata
+     *         regardless of the cache's validity.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setCimdAlwaysRetrieved(boolean always)
+    {
+        this.cimdAlwaysRetrieved = always;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether the {@code http} scheme in the client
+     * ID is permitted (when <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> applies).
+     *
+     * <p>
+     * The specification requires the {@code https} scheme, but if this flag is
+     * set to {@code true}, Authlete also allows the {@code http} scheme. The
+     * main purpose of this option is to make development easier for developers
+     * who run CIMD-enabled servers and a web server publishing client metadata
+     * on their local machines without TLS.
+     * </p>
+     *
+     * <p>
+     * Given this purpose, it is not recommended to enable this option in
+     * production environments unless an allowlist is used (see {@link
+     * Service#isCimdAllowlistEnabled()}).
+     * </p>
+     *
+     * <p>
+     * Some Authlete APIs accept a {@code cimdOptions.httpPermitted} request
+     * parameter (see {@link CimdOptions}). If the parameter is provided and
+     * its value is {@code true}, it takes precedence over this service
+     * configuration.
+     * </p>
+     *
+     * @return
+     *         {@code true} if the {@code http} scheme in the client ID is
+     *         permitted.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isCimdHttpPermitted()
+    {
+        return cimdHttpPermitted;
+    }
+
+
+    /**
+     * Set the flag that indicates whether the {@code http} scheme in the client
+     * ID is permitted (when <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> applies).
+     *
+     * <p>
+     * The specification requires the {@code https} scheme, but if this flag is
+     * set to {@code true}, Authlete also allows the {@code http} scheme. The
+     * main purpose of this option is to make development easier for developers
+     * who run CIMD-enabled servers and a web server publishing client metadata
+     * on their local machines without TLS.
+     * </p>
+     *
+     * <p>
+     * Given this purpose, it is not recommended to enable this option in
+     * production environments unless an allowlist is used (see {@link
+     * Service#isCimdAllowlistEnabled()}).
+     * </p>
+     *
+     * <p>
+     * Some Authlete APIs accept a {@code cimdOptions.httpPermitted} request
+     * parameter (see {@link CimdOptions}). If the parameter is provided and
+     * its value is {@code true}, it takes precedence over this service
+     * configuration.
+     * </p>
+     *
+     * @param permitted
+     *         {@code true} to permit the {@code http} scheme in the client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setCimdHttpPermitted(boolean permitted)
+    {
+        this.cimdHttpPermitted = permitted;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether a query component in the client ID
+     * is permitted (when <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> applies).
+     *
+     * <p>
+     * Although the specification states that a client ID <i>"SHOULD NOT
+     * include a query string component,"</i> it does technically allow it.
+     * However, query components are prone to misuse. Therefore, Authlete does
+     * not allow them by default. Setting this flag to {@code true} relaxes
+     * that restriction.
+     * </p>
+     *
+     * <p>
+     * Some Authlete APIs accept a {@code cimdOptions.queryPermitted} request
+     * parameter (see {@link CimdOptions}). If the parameter is provided and
+     * its value is {@code true}, it takes precedence over this service
+     * configuration.
+     * </p>
+     *
+     * @return
+     *         {@code true} if a query component in the client ID is permitted.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isCimdQueryPermitted()
+    {
+        return cimdQueryPermitted;
+    }
+
+
+    /**
+     * Set the flag that indicates whether a query component in the client ID
+     * is permitted (when <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> applies).
+     *
+     * <p>
+     * Although the specification states that a client ID <i>"SHOULD NOT
+     * include a query string component,"</i> it does technically allow it.
+     * However, query components are prone to misuse. Therefore, Authlete does
+     * not allow them by default. Setting this flag to {@code true} relaxes
+     * that restriction.
+     * </p>
+     *
+     * <p>
+     * Some Authlete APIs accept a {@code cimdOptions.queryPermitted} request
+     * parameter (see {@link CimdOptions}). If the parameter is provided and
+     * its value is {@code true}, it takes precedence over this service
+     * configuration.
+     * </p>
+     *
+     * @param permitted
+     *         {@code true} to permit a query component in the client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setCimdQueryPermitted(boolean permitted)
+    {
+        this.cimdQueryPermitted = permitted;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether to apply the metadata policy to
+     * client metadata that is obtained through the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> mechanism.
+     *
+     * <p>
+     * If this flag is set to {@code true}, the metadata policy specified by
+     * the {@code cimdMetadataPolicy} property, if available, is applied to
+     * the client metadata that is obtained through the CIMD mechanism.
+     * </p>
+     *
+     * @return
+     *         {@code true} if the metadata policy is applied to client
+     *         metadata that is obtained through the CIMD mechanism.
+     *
+     * @since 4.33
+     * @since Authlete 3.0.23
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isCimdMetadataPolicyEnabled()
+    {
+        return cimdMetadataPolicyEnabled;
+    }
+
+
+    /**
+     * Set the flag that indicates whether to apply the metadata policy to
+     * client metadata that is obtained through the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> mechanism.
+     *
+     * <p>
+     * If this flag is set to {@code true}, the metadata policy specified by
+     * the {@code cimdMetadataPolicy} property, if available, is applied to
+     * the client metadata that is obtained through the CIMD mechanism.
+     * </p>
+     *
+     * @param enabled
+     *         {@code true} to apply the metadata policy to client metadata
+     *         that is obtained through the CIMD mechanism.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.33
+     * @since Authlete 3.0.23
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setCimdMetadataPolicyEnabled(boolean enabled)
+    {
+        this.cimdMetadataPolicyEnabled = enabled;
+
+        return this;
+    }
+
+
+    /**
+     * Get the metadata policy applied to client metadata that is obtained
+     * through the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> mechanism.
+     *
+     * <p>
+     * If the {@code cimdMetadataPolicyEnabled} property is set to {@code true},
+     * the metadata policy specified by this {@code cimdMetadataPolicy} property
+     * is applied to client metadata that is obtained through the CIMD mechanism.
+     * </p>
+     *
+     * <p>
+     * The metadata policy must comply with the grammar defined in <a href=
+     * "https://openid.net/specs/openid-federation-1_0.html#name-metadata-policy"
+     * >6.1. Metadata Policy</a> of the <a href=
+     * "https://openid.net/specs/openid-federation-1_0.html">OpenID Federation
+     * 1.0</a> specification. Below is an example of metadata policy:
+     * </p>
+     *
+     * <pre style="border: 1px solid black; margin: 1em; padding-top: 0.5em; padding-bottom: 0.5em;">
+     * {
+     *   <font color="navy">"grant_types"</font>: {
+     *     <font color="darkgreen">"default"</font>: [
+     *       <font color="brown">"authorization_code"</font>
+     *     ],
+     *     <font color="darkgreen">"subset_of"</font>: [
+     *       <font color="brown">"authorization_code"</font>,
+     *       <font color="brown">"refresh_token"</font>
+     *     ],
+     *     <font color="darkgreen">"superset_of"</font>: [
+     *       <font color="brown">"authorization_code"</font>
+     *     ]
+     *   },
+     *   <font color="navy">"token_endpoint_auth_method"</font>: {
+     *     <font color="darkgreen">"one_of"</font>: [
+     *       <font color="brown">"private_key_jwt"</font>,
+     *       <font color="brown">"self_signed_tls_client_auth"</font>
+     *     ],
+     *     <font color="darkgreen">"essential"</font>: <font color="chocolate">true</font>
+     *   },
+     *   <font color="navy">"token_endpoint_auth_signing_alg"</font> : {
+     *     <font color="darkgreen">"one_of"</font>: [
+     *       <font color="brown">"PS256"</font>,
+     *       <font color="brown">"ES256</font>"
+     *     ]
+     *   }
+     * }</pre>
+     *
+     * @return
+     *         The metadata policy applied to client metadata that is obtained
+     *         through the CIMD mechanism.
+     *
+     * @since 4.33
+     * @since Authlete 3.0.23
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html#name-metadata-policy">
+     *      OpenID Federation 1.0, Section 6.1. Metadata Policy</a>
+     */
+    public String getCimdMetadataPolicy()
+    {
+        return cimdMetadataPolicy;
+    }
+
+
+    /**
+     * Set the metadata policy applied to client metadata that is obtained
+     * through the <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> mechanism.
+     *
+     * <p>
+     * If the {@code cimdMetadataPolicyEnabled} property is set to {@code true},
+     * the metadata policy specified by this {@code cimdMetadataPolicy} property
+     * is applied to client metadata that is obtained through the CIMD mechanism.
+     * </p>
+     *
+     * <p>
+     * The metadata policy must comply with the grammar defined in <a href=
+     * "https://openid.net/specs/openid-federation-1_0.html#name-metadata-policy"
+     * >6.1. Metadata Policy</a> of the <a href=
+     * "https://openid.net/specs/openid-federation-1_0.html">OpenID Federation
+     * 1.0</a> specification. Below is an example of metadata policy:
+     * </p>
+     *
+     * <pre style="border: 1px solid black; margin: 1em; padding-top: 0.5em; padding-bottom: 0.5em;">
+     * {
+     *   <font color="navy">"grant_types"</font>: {
+     *     <font color="darkgreen">"default"</font>: [
+     *       <font color="brown">"authorization_code"</font>
+     *     ],
+     *     <font color="darkgreen">"subset_of"</font>: [
+     *       <font color="brown">"authorization_code"</font>,
+     *       <font color="brown">"refresh_token"</font>
+     *     ],
+     *     <font color="darkgreen">"superset_of"</font>: [
+     *       <font color="brown">"authorization_code"</font>
+     *     ]
+     *   },
+     *   <font color="navy">"token_endpoint_auth_method"</font>: {
+     *     <font color="darkgreen">"one_of"</font>: [
+     *       <font color="brown">"private_key_jwt"</font>,
+     *       <font color="brown">"self_signed_tls_client_auth"</font>
+     *     ],
+     *     <font color="darkgreen">"essential"</font>: <font color="chocolate">true</font>
+     *   },
+     *   <font color="navy">"token_endpoint_auth_signing_alg"</font> : {
+     *     <font color="darkgreen">"one_of"</font>: [
+     *       <font color="brown">"PS256"</font>,
+     *       <font color="brown">"ES256</font>"
+     *     ]
+     *   }
+     * }</pre>
+     *
+     * @param policy
+     *         The metadata policy applied to client metadata that is obtained
+     *         through the CIMD mechanism.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.33
+     * @since Authlete 3.0.23
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html#name-metadata-policy">
+     *      OpenID Federation 1.0, Section 6.1. Metadata Policy</a>
+     */
+    public Service setCimdMetadataPolicy(String policy)
+    {
+        this.cimdMetadataPolicy = policy;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag that indicates whether to prohibit client ID aliases that
+     * start with {@code https://} or {@code http://}.
+     *
+     * <p>
+     * The primary purpose of this flag is to prevent the use of client ID
+     * aliases that may conflict with entity IDs in <a href=
+     * "https://openid.net/specs/openid-federation-1_0.html">OpenID Federation
+     * 1.0</a> or metadata document locations in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a>.
+     * </p>
+     *
+     * <p>
+     * For backward compatibility, the default value of this flag is set to
+     * {@code false}, but it is recommended to set it to {@code true} whenever
+     * possible.
+     * </p>
+     *
+     * @return
+     *         {@code true} if client ID aliases that start with {@code https://}
+     *         or {@code http://} are prohibited.
+     *
+     * @since 4.32
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html">
+     *      OpenID Federation 1.0</a>
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isHttpAliasProhibited()
+    {
+        return httpAliasProhibited;
+    }
+
+
+    /**
+     * Set the flag that indicates whether to prohibit client ID aliases that
+     * start with {@code https://} or {@code http://}.
+     *
+     * <p>
+     * The primary purpose of this flag is to prevent the use of client ID
+     * aliases that may conflict with entity IDs in <a href=
+     * "https://openid.net/specs/openid-federation-1_0.html">OpenID Federation
+     * 1.0</a> or metadata document locations in <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a>.
+     * </p>
+     *
+     * <p>
+     * For backward compatibility, the default value of this flag is set to
+     * {@code false}, but it is recommended to set it to {@code true} whenever
+     * possible.
+     * </p>
+     *
+     * @param prohibited
+     *         {@code true} to prohibit client ID aliases that start with
+     *         {@code https://} or {@code http://}.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.32
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html">
+     *      OpenID Federation 1.0</a>
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public Service setHttpAliasProhibited(boolean prohibited)
+    {
+        this.httpAliasProhibited = prohibited;
+
+        return this;
+    }
+
+
+    /**
+     * Get the URI of the challenge endpoint that is defined in
+     * OAuth 2&#x2E;0 Attestation-Based Client Authentication.
+     *
+     * @return
+     *         The URI of the challenge endpoint.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public URI getChallengeEndpoint()
+    {
+        return challengeEndpoint;
+    }
+
+
+    /**
+     * Set the URI of the challenge endpoint that is defined in
+     * OAuth 2&#x2E;0 Attestation-Based Client Authentication.
+     *
+     * @param endpoint
+     *         The URI of the challenge endpoint.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public Service setChallengeEndpoint(URI endpoint)
+    {
+        this.challengeEndpoint = endpoint;
+
+        return this;
+    }
+
+
+    /**
+     * Get the time window of attestation challenges in seconds.
+     *
+     * <p>
+     * The value of this property is used as the time window of attestation
+     * challenges issued from the challenge endpoint defined in the
+     * OAuth 2.0 Attestation-Based Client Authentication.
+     * </p>
+     *
+     * @return
+     *         The time window of attestation challenges in seconds.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public long getAttestationChallengeTimeWindow()
+    {
+        return attestationChallengeTimeWindow;
+    }
+
+
+    /**
+     * Set the time window of attestation challenges in seconds.
+     *
+     * <p>
+     * The value of this property is used as the time window of attestation
+     * challenges issued from the challenge endpoint defined in the
+     * OAuth 2.0 Attestation-Based Client Authentication.
+     * </p>
+     *
+     * @param timeWindow
+     *         The time window of attestation challenges in seconds.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public Service setAttestationChallengeTimeWindow(long timeWindow)
+    {
+        this.attestationChallengeTimeWindow = timeWindow;
+
+        return this;
+    }
+
+
+    /**
+     * Get the HAIP version to comply with. Valid values for this property are
+     * as follows:
+     *
+     * <ul>
+     * <li>{@code "1.0"}
+     * </ul>
+     *
+     * <p>
+     * If this property is set, requests to this service undergo additional
+     * validation based on the specified version of the <a href=
+     * "https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >HAIP</a> specification.
+     * </p>
+     *
+     * <p>
+     * Note that even if this property is not set, additional validation based
+     * on the HAIP specification is performed if the {@link Client}'s
+     * {@code haipVersion} is set or if a scope with the {@code haip} attribute
+     * is included in the request.
+     * </p>
+     *
+     * @return
+     *         The HAIP version to comply with.
+     *
+     * @since 4.41
+     * @since 3.0.29
+     *
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     */
+    public String getHaipVersion()
+    {
+        return haipVersion;
+    }
+
+
+    /**
+     * Set the HAIP version to comply with. Valid values for this property are
+     * as follows:
+     *
+     * <ul>
+     * <li>{@code "1.0"}
+     * </ul>
+     *
+     * <p>
+     * If this property is set, requests to this service undergo additional
+     * validation based on the specified version of the <a href=
+     * "https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >HAIP</a> specification.
+     * </p>
+     *
+     * <p>
+     * Note that even if this property is not set, additional validation based
+     * on the HAIP specification is performed if the {@link Client}'s
+     * {@code haipVersion} is set or if a scope with the {@code haip} attribute
+     * is included in the request.
+     * </p>
+     *
+     * @param version
+     *         The HAIP version to comply with.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.41
+     * @since 3.0.29
+     *
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     */
+    public Service setHaipVersion(String version)
+    {
+        this.haipVersion = version;
+
+        return this;
+    }
+
+
+    /**
+     * Get the trusted root certificates used to validate the certificate chain
+     * specified in the {@code x5c} header parameter of the Client Attestation
+     * JWT.
+     *
+     * <p>
+     * If the Client Attestation JWT includes the {@code x5c} header parameter,
+     * Authlete validates the specified certificate chain. During validation,
+     * Authlete uses the X.509 certificates specified by this property as
+     * trusted root certificates when the {@code clientAttesterRootsEnabled}
+     * property is set to {@code true}. System-installed root certificates are
+     * also used unless the {@code clientAttesterRootsOnly} property is set to
+     * {@code true}.
+     * </p>
+     *
+     * <p>
+     * Each element in this property represents an X.509 certificate. The value
+     * is a base64-encoded string of the certificate in DER format, with or
+     * without PEM markers. The base64-encoded string may contain newlines and
+     * other whitespace characters.
+     * </p>
+     *
+     * <p>
+     * When Authlete returns this certificate list from its APIs, the certificates
+     * are provided in PEM format with PEM markers.
+     * </p>
+     *
+     * <p>
+     * Note that the <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >OpenID4VC High Assurance Interoperability Profile 1.0</a> specification
+     * requires the Client Attestation JWT to include the {@code x5c} header
+     * parameter.
+     * </p>
+     *
+     * @return
+     *         Trusted root certificates used to validate the certificate chain
+     *         of the Client Attestation JWT.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #isClientAttesterRootsEnabled()
+     * @see #isClientAttesterRootsOnly()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public String[] getClientAttesterRoots()
+    {
+        return clientAttesterRoots;
+    }
+
+
+    /**
+     * Set the trusted root certificates used to validate the certificate chain
+     * specified in the {@code x5c} header parameter of the Client Attestation
+     * JWT.
+     *
+     * <p>
+     * If the Client Attestation JWT includes the {@code x5c} header parameter,
+     * Authlete validates the specified certificate chain. During validation,
+     * Authlete uses the X.509 certificates specified by this property as
+     * trusted root certificates when the {@code clientAttesterRootsEnabled}
+     * property is set to {@code true}. System-installed root certificates are
+     * also used unless the {@code clientAttesterRootsOnly} property is set to
+     * {@code true}.
+     * </p>
+     *
+     * <p>
+     * Each element in this property represents an X.509 certificate. The value
+     * is a base64-encoded string of the certificate in DER format, with or
+     * without PEM markers. The base64-encoded string may contain newlines and
+     * other whitespace characters.
+     * </p>
+     *
+     * <p>
+     * When Authlete returns this certificate list from its APIs, the certificates
+     * are provided in PEM format with PEM markers.
+     * </p>
+     *
+     * <p>
+     * Note that the <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >OpenID4VC High Assurance Interoperability Profile 1.0</a> specification
+     * requires the Client Attestation JWT to include the {@code x5c} header
+     * parameter.
+     * </p>
+     *
+     * @param certificates
+     *         Trusted root certificates used to validate the certificate chain
+     *         of the Client Attestation JWT.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #setClientAttesterRootsEnabled(boolean)
+     * @see #setClientAttesterRootsOnly(boolean)
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public Service setClientAttesterRoots(String[] certificates)
+    {
+        this.clientAttesterRoots = certificates;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether to use the trusted root certificates
+     * specified by the {@code clientAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Client Attestation JWT.
+     *
+     * @return
+     *         {@code true} if the trusted root certificates specified by the
+     *         {@code clientAttesterRoots} property are used to validate the
+     *         certificate chain of the Client Attestation JWT.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #getClientAttesterRoots()
+     * @see #isClientAttesterRootsOnly()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public boolean isClientAttesterRootsEnabled()
+    {
+        return clientAttesterRootsEnabled;
+    }
+
+
+    /**
+     * Set the flag indicating whether to use the trusted root certificates
+     * specified by the {@code clientAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Client Attestation JWT.
+     *
+     * @param enabled
+     *         {@code true} to use the trusted root certificates specified by
+     *         the {@code clientAttesterRoots} property.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #setClientAttesterRoots(String[])
+     * @see #setClientAttesterRootsOnly(boolean)
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public Service setClientAttesterRootsEnabled(boolean enabled)
+    {
+        this.clientAttesterRootsEnabled = enabled;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether to use only the trusted root certificates
+     * specified by the {@code clientAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Client Attestation JWT, without using system-installed root certificates.
+     *
+     * @return
+     *         {@code true} if only the trusted root certificates specified by
+     *         the {@code clientAttesterRoots} property are used.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #getClientAttesterRoots()
+     * @see #isClientAttesterRootsEnabled()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public boolean isClientAttesterRootsOnly()
+    {
+        return clientAttesterRootsOnly;
+    }
+
+
+    /**
+     * Set the flag indicating whether to use only the trusted root certificates
+     * specified by the {@code clientAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Client Attestation JWT, without using system-installed root certificates.
+     *
+     * @param only
+     *         {@code true} to use only the trusted root certificates specified
+     *         by the {@code clientAttesterRoots} property.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #setClientAttesterRoots(String[])
+     * @see #isClientAttesterRootsEnabled()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public Service setClientAttesterRootsOnly(boolean only)
+    {
+        this.clientAttesterRootsOnly = only;
+
+        return this;
+    }
+
+
+    /**
+     * Get the trusted root certificates used to validate the certificate chain
+     * specified in the {@code x5c} header parameter of the Key Attestation JWT.
+     *
+     * <p>
+     * If the Key Attestation JWT includes the {@code x5c} header parameter,
+     * Authlete validates the specified certificate chain. During validation,
+     * Authlete uses the X.509 certificates specified by this property as
+     * trusted root certificates when the {@code keyAttesterRootsEnabled}
+     * property is set to {@code true}. System-installed root certificates are
+     * also used unless the {@code keyAttesterRootsOnly} property is set to
+     * {@code true}.
+     * </p>
+     *
+     * <p>
+     * Each element in this property represents an X.509 certificate. The value
+     * is a base64-encoded string of the certificate in DER format, with or
+     * without PEM markers. The base64-encoded string may contain newlines and
+     * other whitespace characters.
+     * </p>
+     *
+     * <p>
+     * When Authlete returns this certificate list from its APIs, the certificates
+     * are provided in PEM format with PEM markers.
+     * </p>
+     *
+     * <p>
+     * Note that the <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >OpenID4VC High Assurance Interoperability Profile 1.0</a> specification
+     * requires the Key Attestation JWT to include the {@code x5c} header
+     * parameter.
+     * </p>
+     *
+     * @return
+     *         Trusted root certificates used to validate the certificate chain
+     *         of the Key Attestation JWT.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *      OpenID for Verifiable Credential Issuance 1.0</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #isKeyAttesterRootsEnabled()
+     * @see #isKeyAttesterRootsOnly()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public String[] getKeyAttesterRoots()
+    {
+        return keyAttesterRoots;
+    }
+
+
+    /**
+     * Set the trusted root certificates used to validate the certificate chain
+     * specified in the {@code x5c} header parameter of the Key Attestation JWT.
+     *
+     * <p>
+     * If the Key Attestation JWT includes the {@code x5c} header parameter,
+     * Authlete validates the specified certificate chain. During validation,
+     * Authlete uses the X.509 certificates specified by this property as
+     * trusted root certificates when the {@code keyAttesterRootsEnabled}
+     * property is set to {@code true}. System-installed root certificates are
+     * also used unless the {@code keyAttesterRootsOnly} property is set to
+     * {@code true}.
+     * </p>
+     *
+     * <p>
+     * Each element in this property represents an X.509 certificate. The value
+     * is a base64-encoded string of the certificate in DER format, with or
+     * without PEM markers. The base64-encoded string may contain newlines and
+     * other whitespace characters.
+     * </p>
+     *
+     * <p>
+     * When Authlete returns this certificate list from its APIs, the certificates
+     * are provided in PEM format with PEM markers.
+     * </p>
+     *
+     * <p>
+     * Note that the <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html"
+     * >OpenID4VC High Assurance Interoperability Profile 1.0</a> specification
+     * requires the Key Attestation JWT to include the {@code x5c} header
+     * parameter.
+     * </p>
+     *
+     * @param certificates
+     *         Trusted root certificates used to validate the certificate chain
+     *         of the Key Attestation JWT.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *      OpenID for Verifiable Credential Issuance 1.0</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #setKeyAttesterRootsEnabled(boolean)
+     * @see #setKeyAttesterRootsOnly(boolean)
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public Service setKeyAttesterRoots(String[] certificates)
+    {
+        this.keyAttesterRoots = certificates;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether to use the trusted root certificates
+     * specified by the {@code keyAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Key Attestation JWT.
+     *
+     * @return
+     *         {@code true} if the trusted root certificates specified by the
+     *         {@code keyAttesterRoots} property are used to validate the
+     *         certificate chain of the Key Attestation JWT.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *      OpenID for Verifiable Credential Issuance 1.0</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #getKeyAttesterRoots()
+     * @see #isKeyAttesterRootsOnly()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public boolean isKeyAttesterRootsEnabled()
+    {
+        return keyAttesterRootsEnabled;
+    }
+
+
+    /**
+     * Set the flag indicating whether to use the trusted root certificates
+     * specified by the {@code keyAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Key Attestation JWT.
+     *
+     * @param enabled
+     *         {@code true} to use the trusted root certificates specified by
+     *         the {@code keyAttesterRoots} property.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *      OpenID for Verifiable Credential Issuance 1.0</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #setKeyAttesterRoots(String[])
+     * @see #setKeyAttesterRootsOnly(boolean)
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public Service setKeyAttesterRootsEnabled(boolean enabled)
+    {
+        this.keyAttesterRootsEnabled = enabled;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether to use only the trusted root certificates
+     * specified by the {@code keyAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Key Attestation JWT, without using system-installed root certificates.
+     *
+     * @return
+     *         {@code true} if only the trusted root certificates specified by
+     *         the {@code keyAttesterRoots} property are used.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *      OpenID for Verifiable Credential Issuance 1.0</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #getKeyAttesterRoots()
+     * @see #isKeyAttesterRootsEnabled()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public boolean isKeyAttesterRootsOnly()
+    {
+        return keyAttesterRootsOnly;
+    }
+
+
+    /**
+     * Set the flag indicating whether to use only the trusted root certificates
+     * specified by the {@code keyAttesterRoots} property to validate the
+     * certificate chain specified in the {@code x5c} header parameter of the
+     * Key Attestation JWT, without using system-installed root certificates.
+     *
+     * @param only
+     *         {@code true} to use only the trusted root certificates specified
+     *         by the {@code keyAttesterRoots} property.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html">
+     *      OpenID for Verifiable Credential Issuance 1.0</a>
+     * @see <a href="https://openid.net/specs/openid4vc-high-assurance-interoperability-profile-1_0.html">
+     *      OpenID4VC High Assurance Interoperability Profile 1.0</a>
+     * @see #setKeyAttesterRoots(String[])
+     * @see #isKeyAttesterRootsEnabled()
+     *
+     * @since 4.42
+     * @since Authlete 3.0.31
+     */
+    public Service setKeyAttesterRootsOnly(boolean only)
+    {
+        this.keyAttesterRootsOnly = only;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether to support the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1&#x2E;0</a> specification. This property
+     * corresponds to the <code>backchannel_<wbr>logout_<wbr>supported</code>
+     * server metadata parameter defined in the specification.
+     *
+     * <p>
+     * The <code>/api<wbr>/<i>{service-id}</i><wbr>/backchannel<wbr>/logout<wbr>/token</code>
+     * API can be used to generate a <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>. See {@link BackchannelLogoutTokenRequest} and
+     * {@link BackchannelLogoutTokenResponse} for details.
+     * </p>
+     *
+     * @return
+     *         The flag indicating whether to support the <a href=
+     *         "https://openid.net/specs/openid-connect-backchannel-1_0.html"
+     *         >OpenID Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     * @see BackchannelLogoutTokenRequest
+     * @see BackchannelLogoutTokenResponse
+     */
+    public boolean isBackchannelLogoutSupported()
+    {
+        return backchannelLogoutSupported;
+    }
+
+
+    /**
+     * Set the flag indicating whether to support the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1&#x2E;0</a> specification. This property
+     * corresponds to the <code>backchannel_<wbr>logout_<wbr>supported</code>
+     * server metadata parameter defined in the specification.
+     *
+     * <p>
+     * The <code>/api<wbr>/<i>{service-id}</i><wbr>/backchannel<wbr>/logout<wbr>/token</code>
+     * API can be used to generate a <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>. See {@link BackchannelLogoutTokenRequest} and
+     * {@link BackchannelLogoutTokenResponse} for details.
+     * </p>
+     *
+     * @param supported
+     *         {@code true} to indicate that this service supports the <a href=
+     *         "https://openid.net/specs/openid-connect-backchannel-1_0.html"
+     *         >OpenID Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     * @see BackchannelLogoutTokenRequest
+     * @see BackchannelLogoutTokenResponse
+     */
+    public Service setBackchannelLogoutSupported(boolean supported)
+    {
+        this.backchannelLogoutSupported = supported;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag indicating whether to support the {@code sid} claim of
+     * <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>s. This property corresponds to the
+     * <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code> server
+     * metadata parameter defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * <p>
+     * If this property is set to {@code true}, the {@code sessionId} request
+     * parameter for the <code>/auth<wbr>/authorization<wbr>/issue</code> API
+     * (see {@link AuthorizationIssueRequest#getSessionId()}) is recognized,
+     * and the specified value is embedded in ID Tokens as the value of the
+     * {@code sid} claim.
+     * </p>
+     *
+     * <p>
+     * If this property is set to {@code true}, API calls to the
+     * <code>/api/<i>{service-id}</i><wbr>/backchannel<wbr>/logout<wbr>/token</code>
+     * API should include the {@code sessionId} request parameter (see
+     * {@link BackchannelLogoutTokenRequest#getSessionId()}).
+     * </p>
+     *
+     * @return
+     *         The flag indicating whether to support the {@code sid} claim
+     *         of Logout Tokens.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     */
+    public boolean isBackchannelLogoutSessionSupported()
+    {
+        return backchannelLogoutSessionSupported;
+    }
+
+
+    /**
+     * Set the flag indicating whether to support the {@code sid} claim of
+     * <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html#LogoutToken"
+     * >Logout Token</a>s. This property corresponds to the
+     * <code>backchannel_<wbr>logout_<wbr>session_<wbr>supported</code> server
+     * metadata parameter defined in the <a href=
+     * "https://openid.net/specs/openid-connect-backchannel-1_0.html">OpenID
+     * Connect Back-Channel Logout 1.0</a> specification.
+     *
+     * <p>
+     * If this property is set to {@code true}, the {@code sessionId} request
+     * parameter for the <code>/auth<wbr>/authorization<wbr>/issue</code> API
+     * (see {@link AuthorizationIssueRequest#getSessionId()}) is recognized,
+     * and the specified value is embedded in ID Tokens as the value of the
+     * {@code sid} claim.
+     * </p>
+     *
+     * <p>
+     * If this property is set to {@code true}, API calls to the
+     * <code>/api/<i>{service-id}</i><wbr>/backchannel<wbr>/logout<wbr>/token</code>
+     * API should include the {@code sessionId} request parameter (see
+     * {@link BackchannelLogoutTokenRequest#getSessionId()}).
+     * </p>
+     *
+     * @param supported
+     *         {@code true} to indicate that the {@code sid} claim of Logout
+     *         Tokens is supported.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.44
+     * @since Authlete 3.0.32
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-backchannel-1_0.html">
+     *      OpenID Connect Back-Channel Logout 1.0</a>
+     */
+    public Service setBackchannelLogoutSessionSupported(boolean supported)
+    {
+        this.backchannelLogoutSessionSupported = supported;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/TokenCreateRequest.java b/src/main/java/com/authlete/common/dto/TokenCreateRequest.java
index 8006269a39..d1afdca893 100644
--- a/src/main/java/com/authlete/common/dto/TokenCreateRequest.java
+++ b/src/main/java/com/authlete/common/dto/TokenCreateRequest.java
@@ -275,7 +275,7 @@
  */
 public class TokenCreateRequest implements Serializable
 {
-    private static final long serialVersionUID = 15L;
+    private static final long serialVersionUID = 16L;
 
 
     private GrantType grantType;
@@ -287,6 +287,7 @@ public class TokenCreateRequest implements Serializable
     private Property[] properties;
     private boolean clientIdAliasUsed;
     private boolean clientEntityIdUsed;
+    private boolean metadataDocumentUsed;
     private String accessToken;
     private String refreshToken;
     private boolean accessTokenPersistent;
@@ -595,8 +596,8 @@ public TokenCreateRequest setProperties(Property[] properties)
      * </p>
      *
      * <p>
-     * Note that {@code clientIdAliasUsed} and {@code clientEntityIdUsed} are
-     * mutually exclusive.
+     * Note that {@code clientIdAliasUsed}, {@code clientEntityIdUsed}, and
+     * {@code metadataDocumentUsed} are mutually exclusive.
      * </p>
      *
      * @return
@@ -633,8 +634,8 @@ public boolean isClientIdAliasUsed()
      * </p>
      *
      * <p>
-     * Note that {@code clientIdAliasUsed} and {@code clientEntityIdUsed} are
-     * mutually exclusive.
+     * Note that {@code clientIdAliasUsed}, {@code clientEntityIdUsed}, and
+     * {@code metadataDocumentUsed} are mutually exclusive.
      * </p>
      *
      * @param used
@@ -679,8 +680,8 @@ public TokenCreateRequest setClientIdAliasUsed(boolean used)
      * </p>
      *
      * <p>
-     * Note that {@code clientIdAliasUsed} and {@code clientEntityIdUsed} are
-     * mutually exclusive.
+     * Note that {@code clientIdAliasUsed}, {@code clientEntityIdUsed}, and
+     * {@code metadataDocumentUsed} are mutually exclusive.
      * </p>
      *
      * @return
@@ -721,8 +722,8 @@ public boolean isClientEntityIdUsed()
      * </p>
      *
      * <p>
-     * Note that {@code clientIdAliasUsed} and {@code clientEntityIdUsed} are
-     * mutually exclusive.
+     * Note that {@code clientIdAliasUsed}, {@code clientEntityIdUsed}, and
+     * {@code metadataDocumentUsed} are mutually exclusive.
      * </p>
      *
      * @param used
@@ -743,6 +744,77 @@ public TokenCreateRequest setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the flag which indicates whether to emulate that the location of
+     * the client's metadata document is used as a client ID.
+     *
+     * <p>
+     * If the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()}), the
+     * location of the client's metadata document can be used as a client ID.
+     * </p>
+     *
+     * <p>
+     * Note that {@code clientIdAliasUsed}, {@code clientEntityIdUsed}, and
+     * {@code metadataDocumentUsed} are mutually exclusive.
+     * </p>
+     *
+     * @return
+     *         {@code true} to emulate that the location of the client's
+     *         metadata document is used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether to emulate that the location of
+     * the client's metadata document is used as a client ID.
+     *
+     * <p>
+     * If the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()}), the
+     * location of the client's metadata document can be used as a client ID.
+     * </p>
+     *
+     * <p>
+     * Note that {@code clientIdAliasUsed}, {@code clientEntityIdUsed}, and
+     * {@code metadataDocumentUsed} are mutually exclusive.
+     * </p>
+     *
+     * @param used
+     *         {@code true} to emulate that the location of the client's
+     *         metadata document is used as a client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public TokenCreateRequest setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+
+        return this;
+    }
+
+
     /**
      * Get the access token.
      *
diff --git a/src/main/java/com/authlete/common/dto/TokenFailRequest.java b/src/main/java/com/authlete/common/dto/TokenFailRequest.java
index a834f51987..80ffb34a3d 100644
--- a/src/main/java/com/authlete/common/dto/TokenFailRequest.java
+++ b/src/main/java/com/authlete/common/dto/TokenFailRequest.java
@@ -63,37 +63,68 @@ public enum Reason
          * Unknown reason.
          *
          * <p>
-         * Using this reason will result in
-         * {@code "error":"server_error"}.
+         * Using this reason will result in {@code "error":"server_error"}.
          * </p>
          */
         UNKNOWN,
 
         /**
-         * The resource owner's credentials ({@code username} and
-         * {@code password}) contained in the token request whose
-         * flow is <a href="http://tools.ietf.org/html/rfc6749#section-4.3">
-         * "Resource Owner Password Credentials"</a>) are invalid.
+         * The resource owner's credentials ({@code username} and {@code password}) contained in the token request whose flow is <a href="http://tools.ietf.org/html/rfc6749#section-4.3"> "Resource
+         * Owner Password Credentials"</a>) are invalid.
          *
          * <p>
-         * Using this reason will result in
-         * {@code "error":"invalid_request"}.
+         * Using this reason will result in {@code "error":"invalid_request"}.
          * </p>
          */
         INVALID_RESOURCE_OWNER_CREDENTIALS,
 
         /**
-         * The requested resource is invalid, missing, unknown, or malformed.
-         * See <i>"Resource Indicators for OAuth 2.0"</i> for details.
+         * The requested resource is invalid, missing, unknown, or malformed. See <i>"Resource Indicators for OAuth 2.0"</i> for details.
          *
          * <p>
-         * Using this reason will result in
-         * {@code "error":"invalid_target"}.
+         * Using this reason will result in {@code "error":"invalid_target"}.
          * </p>
          *
          * @since 2.62
          */
         INVALID_TARGET,
+
+        /**
+         * Client authentication failed (e.g., unknown client, no client authentication included, or unsupported
+         * authentication method).  The authorization server MAY return an HTTP 401 (Unauthorized) status code to indicate
+         * which HTTP authentication schemes are supported. If the client attempted to authenticate via the "Authorization"
+         * request header field, the authorization server MUST respond with an HTTP 401 (Unauthorized) status code and
+         * include the "WWW-Authenticate" response header field matching the authentication scheme used by the client.
+         *
+         * <p>
+         * Using this reason will result in {@code "error":"invalid_client"}.
+         * </p>
+         *
+         * @since 4.46
+         */
+        INVALID_CLIENT,
+
+        /**
+         * The authenticated client is not authorized to use this authorization grant type.
+         *
+         * <p>
+         * Using this reason will result in {@code "error":"unauthorized_client"}.
+         * </p>
+         *
+         * @since 4.46
+         */
+        UNAUTHORIZED_CLIENT,
+
+        /**
+         * The requested scope is invalid, unknown, malformed, or exceeds the scope granted by the resource owner.
+         *
+         * <p>
+         * Using this reason will result in {@code "error":"invalid_scope"}.
+         * </p>
+         *
+         * @since 4.46
+         */
+        INVALID_SCOPE,
     }
 
 
diff --git a/src/main/java/com/authlete/common/dto/TokenInfo.java b/src/main/java/com/authlete/common/dto/TokenInfo.java
index 20d0621f42..c087f8034a 100644
--- a/src/main/java/com/authlete/common/dto/TokenInfo.java
+++ b/src/main/java/com/authlete/common/dto/TokenInfo.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022-2023 Authlete, Inc.
+ * Copyright (C) 2022-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,7 @@
  */
 public class TokenInfo implements Serializable
 {
-    private static final long serialVersionUID = 2L;
+    private static final long serialVersionUID = 3L;
 
 
     /**
@@ -106,6 +106,25 @@ public class TokenInfo implements Serializable
     private boolean clientEntityIdUsed;
 
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+
+    /**
+     * Flag which indicates whether the location of the client's metadata
+     * document was used when the request for the token was made.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
+
     /**
      * The target resources of the token.
      */
@@ -459,6 +478,110 @@ public TokenInfo setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public TokenInfo setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+
+        return this;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public TokenInfo setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+
+        return this;
+    }
+
+
     /**
      * Get the resources associated with the token.
      *
diff --git a/src/main/java/com/authlete/common/dto/TokenIssueResponse.java b/src/main/java/com/authlete/common/dto/TokenIssueResponse.java
index 823f6376ff..8a7423548e 100644
--- a/src/main/java/com/authlete/common/dto/TokenIssueResponse.java
+++ b/src/main/java/com/authlete/common/dto/TokenIssueResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2023 Authlete, Inc.
+ * Copyright (C) 2014-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -103,7 +103,7 @@
  */
 public class TokenIssueResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 10L;
+    private static final long serialVersionUID = 11L;
 
 
     /**
@@ -202,6 +202,22 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * Whether the client's metadata document was used.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 1.1
      */
@@ -685,6 +701,100 @@ public void setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+    }
+
+
     /**
      * Get the subject (= resource owner's ID) of the access token.
      *
diff --git a/src/main/java/com/authlete/common/dto/TokenRequest.java b/src/main/java/com/authlete/common/dto/TokenRequest.java
index f0be40df27..46a68f24ca 100644
--- a/src/main/java/com/authlete/common/dto/TokenRequest.java
+++ b/src/main/java/com/authlete/common/dto/TokenRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2024 Authlete, Inc.
+ * Copyright (C) 2014-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -212,7 +212,7 @@
  */
 public class TokenRequest implements Serializable
 {
-    private static final long serialVersionUID = 12L;
+    private static final long serialVersionUID = 13L;
 
 
     /**
@@ -346,6 +346,15 @@ public class TokenRequest implements Serializable
     private String oauthClientAttestationPop;
 
 
+    /**
+     * Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     */
+    private CimdOptions cimdOptions;
+
+
     /**
      * Get the value of {@code parameters} which are the request
      * parameters that the OAuth 2.0 token endpoint of the service
@@ -1247,4 +1256,49 @@ public TokenRequest setOauthClientAttestationPop(String jwt)
 
         return this;
     }
+
+
+    /**
+     * Get options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @return
+     *         Options for CIMD processing.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public CimdOptions getCimdOptions()
+    {
+        return cimdOptions;
+    }
+
+
+    /**
+     * Set options for <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >CIMD</a> processing.
+     *
+     * @param options
+     *         Options for CIMD processing.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.30
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public TokenRequest setCimdOptions(CimdOptions options)
+    {
+        this.cimdOptions = options;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/TokenResponse.java b/src/main/java/com/authlete/common/dto/TokenResponse.java
index 7a15841744..16fc38d69b 100644
--- a/src/main/java/com/authlete/common/dto/TokenResponse.java
+++ b/src/main/java/com/authlete/common/dto/TokenResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2025 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -1165,6 +1165,33 @@
  * 2.0 Demonstrating Proof of Possession (DPoP)</a> for details.
  * </p>
  *
+ * <hr>
+ * <h3>Attestation Challenge (Authlete 3.0.28 onwards)</h3>
+ *
+ * <p>
+ * Since version 3.0.28, Authlete recognizes the {@code challenge} claim in
+ * Client Attestation PoP JWTs. If the {@code challenge} claim is required
+ * (= if the service's challenge endpoint is configured), the Authlete API
+ * checks whether the {@code challenge} claim in the presented Client
+ * Attestation PoP JWT is identical to the expected value.
+ * </p>
+ *
+ * <p>
+ * If the {@code attestationChallenge} response parameter from the API is not
+ * null, its value is the expected attestation challenge value for Client
+ * Attestation PoP JWT. The expected value needs to be conveyed to the client
+ * application as the value of the {@code OAuth-Client-Attestation-Challenge}
+ * HTTP header.
+ * </p>
+ *
+ * <pre style="border: solid 1px black; padding: 0.5em;"
+ * >OAuth-Client-Attestation-Challenge: (The value returned from {@link #getAttestationChallenge()})</pre>
+ *
+ * <p>
+ * See <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/"
+ * >OAuth 2.0 Attestation-Based Client Authentication</a> for details.
+ * </p>
+ *
  * @see <a href="https://www.rfc-editor.org/rfc/rfc6749.html"
  *      >RFC 6749 The OAuth 2.0 Authorization Framework</a>
  *
@@ -1184,10 +1211,13 @@
  *
  * @see <a href="https://openid.net/specs/openid-connect-native-sso-1_0.html"
  *      >OpenID Connect Native SSO for Mobile Apps 1.0</a>
+ *
+ * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+ *      OAuth 2.0 Attestation-Based Client Authentication</a>
  */
 public class TokenResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 21L;
+    private static final long serialVersionUID = 23L;
 
 
     /**
@@ -1414,6 +1444,22 @@ public enum Action
      */
     private boolean clientEntityIdUsed;
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+    /**
+     * Whether the client's metadata document was used.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
     /**
      * @since Authlete 1.1.9
      */
@@ -1598,6 +1644,12 @@ public enum Action
      */
     private String sessionId;
 
+    /**
+     * Additional claims that need to be added to the ID token.
+     * This field contains a JSON string with claims like nonce and s_hash.
+     */
+    private String additionalClaims;
+
     /**
      * The device secret.
      *
@@ -1614,6 +1666,16 @@ public enum Action
      */
     private String deviceSecretHash;
 
+    /**
+     * The expected attestation challenge value for Client Attestation PoP JWT,
+     * which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    private String attestationChallenge;
+
 
     /**
      * Get the next action that the service implementation should take.
@@ -2206,6 +2268,100 @@ public void setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+    }
+
+
     /**
      * Get the subject (= resource owner's ID) of the access token.
      *
@@ -3556,6 +3712,44 @@ public void setSessionId(String sessionId)
     }
 
 
+    /**
+     * Get the additional claims that need to be added to the ID token.
+     *
+     * <p>
+     * This field contains a JSON string with claims like nonce and s_hash
+     * that need to be included in the ID token when the action is NATIVE_SSO.
+     * </p>
+     *
+     * @return
+     *         The additional claims as a JSON string.
+     */
+    public String getAdditionalClaims()
+    {
+        return additionalClaims;
+    }
+
+
+    /**
+     * Set the additional claims that need to be added to the ID token.
+     *
+     * <p>
+     * This field should contain a JSON string with claims like nonce and s_hash
+     * that need to be included in the ID token when the action is NATIVE_SSO.
+     * </p>
+     *
+     * @param additionalClaims
+     *         The additional claims as a JSON string.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public TokenResponse setAdditionalClaims(String additionalClaims)
+    {
+        this.additionalClaims = additionalClaims;
+        return this;
+    }
+
+
     /**
      * Get the device secret presented in the token request. This is available
      * only when the authorization server supports the <a href=
@@ -3682,4 +3876,68 @@ public void setDeviceSecretHash(String deviceSecretHash)
     {
         this.deviceSecretHash = deviceSecretHash;
     }
+
+
+    /**
+     * Get the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * token endpoint should add the {@code OAuth-Client-Attestation-Challenge}
+     * HTTP header in the response from the endpoint to the client application,
+     * using the value of this response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @return
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public String getAttestationChallenge()
+    {
+        return attestationChallenge;
+    }
+
+
+    /**
+     * Set the expected attestation challenge value for Client Attestation PoP
+     * JWT, which should be used as the value of the
+     * {@code OAuth-Client-Attestation-Challenge} HTTP header.
+     *
+     * <p>
+     * When this response parameter is not null, the implementation of the
+     * token endpoint should add the {@code OAuth-Client-Attestation-Challenge}
+     * HTTP header in the response from the endpoint to the client application,
+     * using the value of this response parameter as the value of the HTTP header.
+     * </p>
+     *
+     * <pre>
+     * OAuth-Client-Attestation-Challenge: (<i>The value of this {@code attestationChallenge} response parameter</i>)
+     * </pre>
+     *
+     * @param challenge
+     *         The expected attestation challenge value for Client Attestation
+     *         PoP JWT.
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     */
+    public void setAttestationChallenge(String challenge)
+    {
+        this.attestationChallenge = challenge;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/TokenRevokeRequest.java b/src/main/java/com/authlete/common/dto/TokenRevokeRequest.java
index a5ed98fdea..90303484bc 100644
--- a/src/main/java/com/authlete/common/dto/TokenRevokeRequest.java
+++ b/src/main/java/com/authlete/common/dto/TokenRevokeRequest.java
@@ -79,6 +79,14 @@
  * the API returns {@code 400 Bad Request}.
  * </p>
  * </ol>
+ * 
+ * <p>
+ * Bulk revocation with {@code clientIdentifier} only, {@code clientIdentifier} + {@code subject}, 
+ * or {@code subject} only deletes at most <b>20 tokens per request</b>
+ * (the default of {@code token.revoke.count.max} in {@code ServerConfiguration.java}). If the
+ * target has more than 20 tokens, the response {@code count} will be 20 and the remainder 
+ * is left untouched. To fully wipe them, call the endpoint repeatedly until {@code count} returns 0.
+ * </p>
  *
  * @since 3.26
  * @since Authlete 2.2.29
diff --git a/src/main/java/com/authlete/common/dto/TokenRevokeResponse.java b/src/main/java/com/authlete/common/dto/TokenRevokeResponse.java
index 3286520b27..2b16591fba 100644
--- a/src/main/java/com/authlete/common/dto/TokenRevokeResponse.java
+++ b/src/main/java/com/authlete/common/dto/TokenRevokeResponse.java
@@ -26,12 +26,19 @@ public class TokenRevokeResponse extends ApiResponse
 {
     private static final long serialVersionUID = 1L;
 
-
+    /**
+     * The maximum amount of tokens that can be revoked per request is 20.
+     * If 20 is returned then additional token revocation requests should be made until this value 
+     * is 0 to ensure that all tokens are revoked.
+     */
     private int count;
 
 
     /**
      * Get the number of revoked tokens.
+     * The maximum amount of tokens that can be revoked per request is 20.
+     * If 20 is returned then additional token revocation requests should be made until this value 
+     * is 0 to ensure that all tokens are revoked.
      *
      * @return
      *         The number of revoked tokens.
@@ -44,6 +51,9 @@ public int getCount()
 
     /**
      * Set the number of revoked tokens.
+     * The maximum amount of tokens that can be revoked per request is 20.
+     * If 20 is returned then additional token revocation requests should be made until this value 
+     * is 0 to ensure that all tokens are revoked.
      *
      * @param count
      *         The number of revoked tokens.
diff --git a/src/main/java/com/authlete/common/dto/TokenUpdateRequest.java b/src/main/java/com/authlete/common/dto/TokenUpdateRequest.java
index 1435639af2..a9afe91398 100644
--- a/src/main/java/com/authlete/common/dto/TokenUpdateRequest.java
+++ b/src/main/java/com/authlete/common/dto/TokenUpdateRequest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2023 Authlete, Inc.
+ * Copyright (C) 2016-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -90,6 +90,28 @@
  * </p>
  * </dd>
  *
+ * <dt><b><code>refreshToken</code></b></dt>
+ * <dd>
+ * <p>
+ * The refresh token value associated with the access token to update.
+ * </p>
+ * <p>
+ * The value of the {@code accessToken} parameter and the {@code accessTokenHash}
+ * parameter take precedence.
+ * </p>
+ * </dd>
+ *
+ * <dt><b><code>refreshTokenHash</code></b></dt>
+ * <dd>
+ * <p>
+ * The hash of the refresh token value associated with the access token to update.
+ * </p>
+ * <p>
+ * The value of the {@code accessToken} parameter, the {@code accessTokenHash} parameter
+ * and the {@code refreshToken} parameter take precedence.
+ * </p>
+ * </dd>
+ *
  * <dt><b><code>accessTokenValueUpdated</code></b></dt>
  * <dd>
  * <p>
@@ -152,7 +174,7 @@
  */
 public class TokenUpdateRequest implements Serializable
 {
-    private static final long serialVersionUID = 8L;
+    private static final long serialVersionUID = 9L;
 
 
     private String accessToken;
@@ -170,6 +192,8 @@ public class TokenUpdateRequest implements Serializable
     private AuthzDetails authorizationDetails;
     private boolean forExternalAttachment;
     private String tokenId;
+    private String refreshToken;
+    private String refreshTokenHash;
 
 
     /**
@@ -928,4 +952,93 @@ public TokenUpdateRequest setTokenId(String tokenId)
 
         return this;
     }
+
+
+    /**
+     * Get the refresh token associated with the access token to update.
+     *
+     * <p>
+     * The value of the {@code accessToken} parameter and the {@code accessTokenHash}
+     * parameter take precedence.
+     * </p>
+     *
+     * @return
+     *         The refresh token associated with the access token to update.
+     *
+     * @since 4.38
+     */
+    public String getRefreshToken()
+    {
+        return refreshToken;
+    }
+
+
+    /**
+     * Set the refresh token associated with the access token to update.
+     *
+     * <p>
+     * The value of the {@code accessToken} parameter and the {@code accessTokenHash}
+     * parameter take precedence.
+     * </p>
+     *
+     * @param refreshToken
+     *         The refresh token associated with the access token to update.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.38
+     */
+    public TokenUpdateRequest setRefreshToken(String refreshToken)
+    {
+        this.refreshToken = refreshToken;
+
+        return this;
+    }
+
+
+    /**
+     * Get the hash of the refresh token value associated with the access token to update.
+     *
+     * <p>
+     * The value of the {@code accessToken} parameter, the {@code accessTokenHash}
+     * parameter and the {@code refreshToken} parameter take precedence.
+     * </p>
+     *
+     * @return
+     *         The hash of the refresh token value associated with the access token to
+     *         update.
+     *
+     * @since 4.38
+     */
+    public String getRefreshTokenHash()
+    {
+        return refreshTokenHash;
+    }
+
+
+    /**
+     * Set the hash of the refresh token value associated with the access
+     * token to update.
+     *
+     * <p>
+     * The value of the {@code accessToken} parameter, the {@code accessTokenHash}
+     * parameter and the {@code refreshToken} parameter take precedence.
+     * </p>
+     *
+     * @param refreshTokenHash
+     *         The hash of the refresh token value associated with the
+     *         access token to update.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.38
+     */
+    public TokenUpdateRequest setRefreshTokenHash(String refreshTokenHash)
+    {
+        this.refreshTokenHash = refreshTokenHash;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/dto/UserInfoResponse.java b/src/main/java/com/authlete/common/dto/UserInfoResponse.java
index dc15d2efb9..6820f70e16 100644
--- a/src/main/java/com/authlete/common/dto/UserInfoResponse.java
+++ b/src/main/java/com/authlete/common/dto/UserInfoResponse.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015-2023 Authlete, Inc.
+ * Copyright (C) 2015-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -247,7 +247,7 @@
  */
 public class UserInfoResponse extends ApiResponse
 {
-    private static final long serialVersionUID = 7L;
+    private static final long serialVersionUID = 8L;
 
 
     /**
@@ -392,6 +392,25 @@ public enum Action
     private boolean clientEntityIdUsed;
 
 
+    /**
+     * The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private URI metadataDocumentLocation;
+
+
+    /**
+     * Flag which indicates whether the location of the client's metadata
+     * document was used when the request for the access token was made.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     */
+    private boolean metadataDocumentUsed;
+
+
     /**
      * "userinfo" in "claims" of an authorization request.
      * @since Authlete 2.2.1
@@ -801,6 +820,100 @@ public void setClientEntityIdUsed(boolean used)
     }
 
 
+    /**
+     * Get the location of the client's metadata document. This property
+     * holds a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @return
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public URI getMetadataDocumentLocation()
+    {
+        return metadataDocumentLocation;
+    }
+
+
+    /**
+     * Set the location of the client's metadata document. This property
+     * should hold a non-null value only when {@link #isMetadataDocumentUsed()}
+     * returns {@code true}.
+     *
+     * @param location
+     *         The location of the client's metadata document.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentLocation(URI location)
+    {
+        this.metadataDocumentLocation = location;
+    }
+
+
+    /**
+     * Get the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @return
+     *         {@code true} if the location of client's metadata document
+     *         was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentUsed()
+    {
+        return metadataDocumentUsed;
+    }
+
+
+    /**
+     * Set the flag which indicates whether the location of the client's
+     * metadata document was used as a client ID.
+     *
+     * <p>
+     * This can happen when the service supports <a href=
+     * "https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     * (cf. {@link Service#isClientIdMetadataDocumentSupported()})
+     * </p>
+     *
+     * @param used
+     *         {@code true} to indicate that the location of the client's
+     *         metadata document was used as a client ID.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public void setMetadataDocumentUsed(boolean used)
+    {
+        this.metadataDocumentUsed = used;
+    }
+
+
     /**
      * Get the value of the {@code "userinfo"} property in the {@code "claims"}
      * request parameter or in the {@code "claims"} property in an authorization
diff --git a/src/main/java/com/authlete/common/package-info.java b/src/main/java/com/authlete/common/package-info.java
index b50466ba76..ca6e225b94 100644
--- a/src/main/java/com/authlete/common/package-info.java
+++ b/src/main/java/com/authlete/common/package-info.java
@@ -17,11 +17,11 @@
  * <span class="tag">&lt;dependency&gt;
  *     &lt;groupId&gt;</span>com.authlete<span class="tag">&lt;/groupId&gt;
  *     &lt;artifactId&gt;</span>authlete-java-common<span class="tag">&lt;/artifactId&gt;
- *     &lt;version&gt;</span>4.21<span class="tag">&lt;/version&gt;
+ *     &lt;version&gt;</span>4.23<span class="tag">&lt;/version&gt;
  * &lt;/dependency&gt;</span><!--
  * --></pre>
  *
- * @version 4.21
+ * @version 4.23
  */
 package com.authlete.common;
 
diff --git a/src/main/java/com/authlete/common/types/ClientAssertionType.java b/src/main/java/com/authlete/common/types/ClientAssertionType.java
index ce3f877cac..450777d9b5 100644
--- a/src/main/java/com/authlete/common/types/ClientAssertionType.java
+++ b/src/main/java/com/authlete/common/types/ClientAssertionType.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2023-2024 Authlete, Inc.
+ * Copyright (C) 2023-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
@@ -64,6 +64,22 @@ public enum ClientAssertionType
      * @deprecated
      */
     JWT_CLIENT_ATTESTATION((short)2, "urn:ietf:params:oauth:client-assertion-type:jwt-client-attestation"),
+
+
+    /**
+     * {@code "urn:ietf:params:oauth:client-assertion-type:jwt-spiffe"}.
+     *
+     * <p>
+     * The client assertion type used by the OAuth SPIFFE Client Authentication.
+     * </p>
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-spiffe-client-auth/">
+     *      OAuth SPIFFE Client Authentication</a>
+     *
+     * @since 4.37
+     * @since Authlete 3.0.28
+     */
+    JWT_SPIFFE((short)3, "urn:ietf:params:oauth:client-assertion-type:jwt-spiffe"),
     ;
 
 
diff --git a/src/main/java/com/authlete/common/types/ClientAuthMethod.java b/src/main/java/com/authlete/common/types/ClientAuthMethod.java
index 56645e282c..7a192dc9ef 100644
--- a/src/main/java/com/authlete/common/types/ClientAuthMethod.java
+++ b/src/main/java/com/authlete/common/types/ClientAuthMethod.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2024 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -157,6 +157,22 @@ public enum ClientAuthMethod
      *      >OAuth 2.0 Attestation-Based Client Authentication</a>
      */
     ATTEST_JWT_CLIENT_AUTH((short)7, "attest_jwt_client_auth", 0x2),
+
+
+    /**
+     * {@code "spiffe_jwt"} (8).
+     *
+     * <p>
+     * OAuth SPIFFE Client Authentication using JWT-SVID.
+     * </p>
+     *
+     * @since 4.36
+     * @since Authlete 3.0.28
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-spiffe-client-auth/">
+     *      OAuth SPIFFE Client Authentication</a>
+     */
+    SPIFFE_JWT((short)8, "spiffe_jwt", 0x2),
     ;
 
 
diff --git a/src/main/java/com/authlete/common/types/ClientSource.java b/src/main/java/com/authlete/common/types/ClientSource.java
new file mode 100644
index 0000000000..0db40b51a0
--- /dev/null
+++ b/src/main/java/com/authlete/common/types/ClientSource.java
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2025 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.types;
+
+
+/**
+ * The source of a client.
+ *
+ * <blockquote>
+ * <table border="1" cellpadding="5" style="border-collapse: collapse;">
+ *   <tr bgcolor="orange">
+ *     <th>enum value</th>
+ *     <th>description</th>
+ *   </tr>
+ *   <tr>
+ *     <td>{@link #STATIC_REGISTRATION}</td>
+ *     <td>Static registration.</td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@link #DYNAMIC_REGISTRATION}</td>
+ *     <td>
+ *       Dynamic registration defined in
+ *       <a href="https://www.rfc-editor.org/rfc/rfc7591.html">RFC 7591:
+ *       OAuth 2.0 Dynamic Client Registration Protocol</a> or
+ *       <a href="https://openid.net/specs/openid-connect-registration-1_0.html">
+ *       OpenID Connect Dynamic Client Registration 1.0</a>.
+ *     </td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@link #AUTOMATIC_REGISTRATION}</td>
+ *     <td>
+ *       Automatic registration defined in
+ *       <a href="https://openid.net/specs/openid-federation-1_0.html">OpenID
+ *       Federation 1.0</a>.
+ *     </td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@link #EXPLICIT_REGISTRATION}</td>
+ *     <td>
+ *       Explicit registration defined in
+ *       <a href="https://openid.net/specs/openid-federation-1_0.html">OpenID
+ *       Federation 1.0</a>.
+ *     </td>
+ *   </tr>
+ *   <tr>
+ *     <td>{@link #METADATA_DOCUMENT}</td>
+ *     <td>
+ *       Discovery using
+ *       <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+ *       OAuth Client ID Metadata Document</a>.
+ *     </td>
+ *   </tr>
+ * </table>
+ * </blockquote>
+ *
+ * @since 4.29
+ * @since Authlete 3.0.22
+ */
+public enum ClientSource
+{
+    /**
+     * Static registration.
+     */
+    STATIC_REGISTRATION,
+
+
+    /**
+     * Dynamic registration defined in
+     * <a href="https://www.rfc-editor.org/rfc/rfc7591.html">RFC 7591: OAuth
+     * 2&#x2E;0 Dynamic Client Registration Protocol</a> or
+     * <a href="https://openid.net/specs/openid-connect-registration-1_0.html"
+     * >OpenID Connect Dynamic Client Registration 1&#x2E;0</a>.
+     *
+     * @see <a href="https://www.rfc-editor.org/rfc/rfc7591.html">
+     *      RFC 7591: OAuth 2.0 Dynamic Client Registration Protocol</a>
+     *
+     * @see <a href="https://openid.net/specs/openid-connect-registration-1_0.html">
+     *      OpenID Connect Dynamic Client Registration 1.0</a>
+     */
+    DYNAMIC_REGISTRATION,
+
+
+    /**
+     * Automatic registration defined in
+     * <a href="https://openid.net/specs/openid-federation-1_0.html"
+     * >OpenID Federation 1&#x2E;0</a>.
+     *
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html">
+     *      OpenID Federation 1.0</a>
+     */
+    AUTOMATIC_REGISTRATION,
+
+
+    /**
+     * Explicit registration defined in
+     * <a href="https://openid.net/specs/openid-federation-1_0.html"
+     * >OpenID Federation 1&#x2E;0</a>.
+     *
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html">
+     *      OpenID Federation 1.0</a>
+     */
+    EXPLICIT_REGISTRATION,
+
+
+    /**
+     * Discovery using
+     * <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/"
+     * >OAuth Client ID Metadata Document</a>.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    METADATA_DOCUMENT,
+    ;
+}
diff --git a/src/main/java/com/authlete/common/types/ErrorCode.java b/src/main/java/com/authlete/common/types/ErrorCode.java
index 0cb8f13450..76cc10bca8 100644
--- a/src/main/java/com/authlete/common/types/ErrorCode.java
+++ b/src/main/java/com/authlete/common/types/ErrorCode.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014-2023 Authlete, Inc.
+ * Copyright (C) 2014-2026 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,7 +44,11 @@
  * @see <a href="https://www.rfc-editor.org/rfc/rfc7591.html#section-3.2.2"
  *      >RFC 7591, 3.2.2. Client Registration Error Response</a>
  *
- * @author Takahiko Kawasaki
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-credential-request-errors"
+ *      >OpenID for Verifiable Credential Issuance 1.0, 8.3.1.2. Credential Request Errors</a>
+ *
+ * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-notification-error-response"
+ *      >OpenID for Verifiable Credential Issuance 1.0, 11.3. Notification Error Response</a>
  */
 public enum ErrorCode
 {
@@ -620,5 +624,124 @@ public enum ErrorCode
      * @since Authlete 3.0
      */
     use_dpop_nonce,
+
+
+    /**
+     * Requested Credential Configuration is unknown.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-credential-request-errors">
+     *      OpenID for Verifiable Credential Issuance 1.0, 8.3.1.2. Credential Request Errors</a>
+     *
+     * @since 4.28
+     * @since Authlete 3.0.22
+     */
+    unknown_credential_configuration,
+
+
+    /**
+     * Requested Credential identifier is unknown.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-credential-request-errors">
+     *      OpenID for Verifiable Credential Issuance 1.0, 8.3.1.2. Credential Request Errors</a>
+     *
+     * @since 4.28
+     * @since Authlete 3.0.22
+     */
+    unknown_credential_identifier,
+
+
+    /**
+     * The {@code proofs} parameter in the Credential Request uses an invalid
+     * nonce: at least one of the key proofs contains an invalid {@code c_nonce}
+     * value. The wallet should retrieve a new {@code c_nonce value} (refer to
+     * <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-nonce-endpoint"
+     * >Section 7</a>).
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-credential-request-errors">
+     *      OpenID for Verifiable Credential Issuance 1.0, 8.3.1.2. Credential Request Errors</a>
+     *
+     * @since 4.28
+     * @since Authlete 3.0.22
+     */
+    invalid_nonce,
+
+
+    /**
+     * The Credential Request has not been accepted by the Credential Issuer.
+     * The Wallet SHOULD treat this error as unrecoverable, meaning if
+     * received from a Credential Issuer the Credential cannot be issued.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-credential-request-errors">
+     *      OpenID for Verifiable Credential Issuance 1.0, 8.3.1.2. Credential Request Errors</a>
+     *
+     * @since 4.28
+     * @since Authlete 3.0.22
+     */
+    credential_request_denied,
+
+
+    /**
+     * The {@code notification_id} in the Notification Request was invalid.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-notification-error-response">
+     *      OpenID for Verifiable Credential Issuance 1.0, 11.3. Notification Error Response</a>
+     *
+     * @since 4.28
+     * @since Authlete 3.0.22
+     */
+    invalid_notification_id,
+
+
+    /**
+     * The Notification Request is missing a required parameter, includes an
+     * unsupported parameter or parameter value, repeats the same parameter,
+     * or is otherwise malformed.
+     *
+     * @see <a href="https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0.html#name-notification-error-response">
+     *      OpenID for Verifiable Credential Issuance 1.0, 11.3. Notification Error Response</a>
+     *
+     * @since 4.28
+     * @since Authlete 3.0.22
+     */
+    invalid_notification_request,
+
+
+    /**
+     * The Client Attestation PoP JWT is not using an expected server-provided
+     * challenge.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    use_attestation_challenge,
+
+
+    /**
+     * The Client Attestation JWT is deemed to be not fresh enough to be
+     * accepted by the server.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    use_fresh_attestation,
+
+
+    /**
+     * The attestation or its proof of possession could not be successfully
+     * verified.
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-attestation-based-client-auth/">
+     *      OAuth 2.0 Attestation-Based Client Authentication</a>
+     *
+     * @since 4.39
+     * @since Authlete 3.0.28
+     */
+    invalid_client_attestation,
     ;
 }
diff --git a/src/main/java/com/authlete/common/types/JWEZip.java b/src/main/java/com/authlete/common/types/JWEZip.java
new file mode 100644
index 0000000000..512e75407f
--- /dev/null
+++ b/src/main/java/com/authlete/common/types/JWEZip.java
@@ -0,0 +1,189 @@
+/*
+ * Copyright (C) 2025 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.types;
+
+
+import java.util.EnumSet;
+
+
+/**
+ * {@code "zip"} (Compression Algorithm) Header Parameter Values for JWE.
+ *
+ * @see <a href="https://www.rfc-editor.org/rfc/rfc7516.html#section-4.1.3">
+ *      RFC 7516: JSON Web Encryption (JWE),
+ *      Section 4.1.3. "zip" (Compression Algorithm) Header Parameter</a>
+ *
+ * @see <a href="https://www.rfc-editor.org/rfc/rfc7518.html#section-7.3">
+ *      RFC 7518: JSON Web Algorithms (JWA),
+ *      Section 7.3. JSON Web Encryption Compression Algorithms Registry</a>
+ *
+ * @see <a href="https://www.iana.org/assignments/jose/jose.xhtml#web-encryption-compression-algorithms">
+ *      IANA: JSON Object Signing and Encryption (JOSE),
+ *      JSON Web Encryption Compression Algorithms</a>
+ *
+ * @since 4.26
+ */
+public enum JWEZip
+{
+    /**
+     * {@code "DEF"} (1); DEFLATE.
+     */
+    DEF((short)1, "DEF"),
+    ;
+
+
+    private static final JWEZip[] sValues = values();
+    private static final Helper sHelper = new Helper(sValues);
+    private final short mValue;
+    private final String mString;
+
+
+    private JWEZip(short value, String string)
+    {
+        mValue  = value;
+        mString = string;
+    }
+
+
+    /**
+     * Get the name of this algorithm.
+     *
+     * One of the values listed in the table in
+     * <a href="https://www.iana.org/assignments/jose/jose.xhtml#web-encryption-compression-algorithms"
+     * >JSON Web Encryption Compression Algorithms</a>.
+     *
+     * @return
+     *         The name of this algorithm.
+     */
+    public String getName()
+    {
+        return mString;
+    }
+
+
+    /**
+     * Get the integer representation of this enum instance.
+     */
+    public short getValue()
+    {
+        return mValue;
+    }
+
+
+    @Override
+    public String toString()
+    {
+        return mString;
+    }
+
+
+    /**
+     * Find an instance of this enum by a value.
+     *
+     * @param value
+     *         The integer representation of the instance to find.
+     *
+     * @return
+     *         An instance of this enum, or {@code null} if not found.
+     */
+    public static JWEZip getByValue(short value)
+    {
+        if (value < 1 || sValues.length < value)
+        {
+            // Not found.
+            return null;
+        }
+
+        return sValues[value - 1];
+    }
+
+
+    /**
+     * Convert {@code String} to {@code JWEZip}.
+     *
+     * @param alg
+     *         Algorithm name. For example, {@code "DEF"}.
+     *
+     * @return
+     *         {@code JWEZip} instance, or {@code null}.
+     */
+    public static JWEZip parse(String alg)
+    {
+        if (alg == null)
+        {
+            return null;
+        }
+
+        for (JWEZip entry : sValues)
+        {
+            if (entry.mString.equals(alg))
+            {
+                // Found.
+                return entry;
+            }
+        }
+
+        // Not found.
+        return null;
+    }
+
+
+    public static int toBits(EnumSet<JWEZip> set)
+    {
+        return sHelper.toBits(set);
+    }
+
+
+    public static JWEZip[] toArray(int bits)
+    {
+        return sHelper.toArray(bits);
+    }
+
+
+    public static EnumSet<JWEZip> toSet(int bits)
+    {
+        return sHelper.toSet(bits);
+    }
+
+
+    public static EnumSet<JWEZip> toSet(JWEZip[] array)
+    {
+        return sHelper.toSet(array);
+    }
+
+
+    private static class Helper extends EnumHelper<JWEZip>
+    {
+        public Helper(JWEZip[] values)
+        {
+            super(JWEZip.class, values);
+        }
+
+
+        @Override
+        protected short getValue(JWEZip entry)
+        {
+            return entry.getValue();
+        }
+
+
+        @Override
+        protected JWEZip[] newArray(int size)
+        {
+            return new JWEZip[size];
+        }
+    }
+}
diff --git a/src/main/java/com/authlete/common/util/ClientMetadataControl.java b/src/main/java/com/authlete/common/util/ClientMetadataControl.java
index 5d62a51efd..0a76924dcf 100644
--- a/src/main/java/com/authlete/common/util/ClientMetadataControl.java
+++ b/src/main/java/com/authlete/common/util/ClientMetadataControl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2022 Authlete, Inc.
+ * Copyright (C) 2022-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@ public class ClientMetadataControl extends MapControl
     private boolean customIncluded;
     private boolean aliasPreferred;
     private boolean entityIdPreferred;
+    private boolean metadataDocumentLocationPreferred;
 
 
     @Override
@@ -179,6 +180,9 @@ public ClientMetadataControl setAliasPreferred(boolean preferred)
      * @return
      *         {@code true} if the entity ID is used as the value of the
      *         {@code client_id} property when available.
+     *
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html">
+     *      OpenID Federation 1.0</a>
      */
     public boolean isEntityIdPreferred()
     {
@@ -196,6 +200,9 @@ public boolean isEntityIdPreferred()
      *
      * @return
      *         {@code this} object.
+     *
+     * @see <a href="https://openid.net/specs/openid-federation-1_0.html">
+     *      OpenID Federation 1.0</a>
      */
     public ClientMetadataControl setEntityIdPreferred(boolean preferred)
     {
@@ -203,4 +210,53 @@ public ClientMetadataControl setEntityIdPreferred(boolean preferred)
 
         return this;
     }
+
+
+    /**
+     * Get the flag whether to use the location of the client's metadata
+     * document as the value of the {@code client_id} property when
+     * available.
+     *
+     * @return
+     *         {@code true} if the location of the client's metadata
+     *         document is used as the value of the {@code client_id}
+     *         property when available.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public boolean isMetadataDocumentLocationPreferred()
+    {
+        return metadataDocumentLocationPreferred;
+    }
+
+
+    /**
+     * Set the flag whether to use the location of the client's metadata
+     * document as the value of the {@code client_id} property when
+     * available.
+     *
+     * @param preferred
+     *         {@code true} to use the location of the client's metadata
+     *         document as the value of the {@code client_id} property
+     *         when available.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @since 4.29
+     * @since Authlete 3.0.22
+     *
+     * @see <a href="https://datatracker.ietf.org/doc/draft-ietf-oauth-client-id-metadata-document/">
+     *      OAuth Client ID Metadata Document</a>
+     */
+    public ClientMetadataControl setMetadataDocumentLocationPreferred(boolean preferred)
+    {
+        this.metadataDocumentLocationPreferred = preferred;
+
+        return this;
+    }
 }
diff --git a/src/main/java/com/authlete/common/util/digest/Digest.java b/src/main/java/com/authlete/common/util/digest/Digest.java
new file mode 100644
index 0000000000..e9c2de26da
--- /dev/null
+++ b/src/main/java/com/authlete/common/util/digest/Digest.java
@@ -0,0 +1,2444 @@
+package com.authlete.common.util.digest;
+
+
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.nio.ByteBuffer;
+import java.security.DigestException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.Provider;
+import java.util.HashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import org.apache.commons.codec.BinaryEncoder;
+import org.apache.commons.codec.EncoderException;
+
+
+/**
+ * A wrapper class over MessageDigest with many {@code update}
+ * methods in a fluent style, meaning {@code update} methods
+ * can be chained.
+ *
+ * <p>
+ * {@code update} methods are provided for all the primitive types
+ * and {@code String}, and their array types. In addition,
+ * {@link #updateJson(String)} has been available since the version
+ * 1.2 which updates the digest with the content of the given JSON.
+ * Note that {@link #update(String)} and {@link #updateJson(String)}
+ * are different.
+ * </p>
+ *
+ * <p>
+ * <code>getInstance<i>XXX</i></code> methods (where <code><i>XXX</i></code>
+ * is a pre-defined algorithm name with hyphens removed) such as
+ * {@link #getInstanceSHA1()} are provided. They won't throw
+ * {@code NoSuchAlgorithmException}.
+ * </p>
+ *
+ * <pre style="background-color: #EEEEEE; margin-left: 2em; margin-right: 2em; border: 1px solid black;">
+ * <span style="color: darkgreen;">
+ * // Compute SHA-1 of "Hello, world.".
+ * // 'digest' will have "2ae01472317d1935a84797ec1983ae243fc6aa28".</span>
+ * String digest = Digest.{@link #getInstanceSHA1()}
+ *                 .{@link #update(String) update}(<span style="color: #990000">"Hello, world."</span>)
+ *                 .{@link #digestAsString()};
+ *
+ * <span style="color: darkgreen;">// Compute SHA-1 of "Hello, world." and get the result as Base64.
+ * // 'digest' will have "KuAUcjF9GTWoR5fsGYOuJD/Gqig=".</span>
+ * String digest = Digest.{@link #getInstanceSHA1()}
+ *                 .{@link #update(String) update}(<span style="color: #990000">"Hello, world."</span>)
+ *                 .{@link #digestAsString(BinaryEncoder) digestAsString}(new {@link
+ *                 org.apache.commons.codec.binary.Base64#Base64() Base64()});
+ *
+ * <span style="color: darkgreen;">// Compute SHA-1 of two JSONs.
+ * // 'result1' and 'result2' will have the same value.</span>
+ * String json1 = <span style="color: #990000">"{ \"key1\":\"value1\", \"key2\":\"value2\" }"</span>;
+ * String json2 = <span style="color: #990000">"{ \"key2\":\"value2\", \"key1\":\"value1\" }"</span>;
+ * String result1 = Digest.{@link #getInstanceSHA1()}.{@link #updateJson(String)
+ * updateJson}(json1).{@link #digestAsString()};
+ * String result2 = Digest.{@link #getInstanceSHA1()}.{@link #updateJson(String)
+ * updateJson}(json2).{@link #digestAsString()};
+ * </pre>
+ *
+ * @author Takahiko Kawasaki
+ * @since 4.23
+ */
+public class Digest implements Cloneable
+{
+    /**
+     * Features to control behaviors.
+     *
+     */
+    public static enum Feature
+    {
+        /**
+         * Ignore JSON key-value entries whose value is {@code null}.
+         * In other words, JSON key-value entries whose value is
+         * {@code null} are treated as if they did not exist.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":null }
+         * { "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'disabled'.
+         * </p>
+         */
+        IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_NULL,
+
+
+        /**
+         * Ignore JSON key-value entries whose value is {@code false}.
+         * In other words, JSON key-value entries whose value is
+         * {@code false} are treated as if they did not exist.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":false }
+         * { "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'disabled'.
+         * </p>
+         */
+        IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_FALSE,
+
+
+        /**
+         * Ignore JSON key-value entries whose value is zero.
+         * In other words, JSON key-value entries whose value is
+         * zero are treated as if they did not exist.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":0, "key3":0.0 }
+         * { "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'disabled'.
+         * </p>
+         */
+        IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_ZERO,
+
+
+        /**
+         * Ignore JSON key-value entries whose value is an empty string.
+         * In other words, JSON key-value entries whose value is an empty
+         * string are treated as if they did not exist.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":"" }
+         * { "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'disabled'.
+         * </p>
+         */
+        IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_STRING,
+
+
+        /**
+         * Ignore JSON key-value entries whose value is an empty array.
+         * In other words, JSON key-value entries whose value is an empty
+         * array are treated as if they did not exist.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":[] }
+         * { "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'disabled'.
+         * </p>
+         */
+        IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_ARRAY,
+
+
+        /**
+         * Ignore JSON key-value entries whose value is an empty object.
+         * In other words, JSON key-value entries whose value is an empty
+         * object are treated as if they did not exist.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":{} }
+         * { "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'disabled'.
+         * </p>
+         */
+        IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_OBJECT,
+
+
+        /**
+         * Sort keys of JSON key-value entries before updating.
+         *
+         * <p>
+         * If this feature is enabled, two JSONs below generate
+         * the same digest value.
+         * </p>
+         *
+         * <pre>
+         * { "key1":"value1", "key2":"value2" }
+         * { "key2":"value2", "key1":"value1" }
+         * </pre>
+         *
+         * <p>
+         * The default value is 'enabled'.
+         * </p>
+         */
+        SORT_JSON_OBJECT_ENTRY_KEYS
+    }
+
+
+    /**
+     * Characters used to generate a hex string.
+     */
+    private static final char[] mHexArray = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+
+
+    /**
+     * The wrapped messaged digest object.
+     */
+    private MessageDigest mMessageDigest;
+
+
+    /**
+     * Features (configuration).
+     */
+    private HashMap<Feature, Boolean> mFeatures;
+
+
+    /**
+     * Constructor with a {@link MessageDigest} instance.
+     *
+     * @param messageDigest
+     *         A {@link MessageDigest} instance wrapped in this
+     *         {@code Digest} instance.
+     *
+     * @throws IllegalArgumentException
+     *         The given argument is null.
+     */
+    public Digest(MessageDigest messageDigest)
+    {
+        if (messageDigest == null)
+        {
+            throw new IllegalArgumentException("messageDigest is null");
+        }
+
+        mMessageDigest = messageDigest;
+        mFeatures = createFeatureMap();
+    }
+
+
+    /**
+     * Create a feature map with default values.
+     */
+    private HashMap<Feature, Boolean> createFeatureMap()
+    {
+        HashMap<Feature, Boolean> map = new HashMap<Feature, Boolean>();
+
+        map.put(Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_NULL,         Boolean.FALSE);
+        map.put(Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_FALSE,        Boolean.FALSE);
+        map.put(Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_ZERO,         Boolean.FALSE);
+        map.put(Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_STRING, Boolean.FALSE);
+        map.put(Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_ARRAY,  Boolean.FALSE);
+        map.put(Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_OBJECT, Boolean.FALSE);
+        map.put(Feature.SORT_JSON_OBJECT_ENTRY_KEYS, Boolean.TRUE);
+
+        return map;
+    }
+
+
+    /**
+     * Constructor with an algorithm name.
+     *
+     * <p>
+     * This constructor is equivalent to {@link #Digest(MessageDigest) this}{@code
+     * (}{@link MessageDigest#getInstance(String) MessageDigest.getInstance}{@code
+     * (algorithm))}.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @throws NoSuchAlgorithmException
+     *         No provider supports the specified algorithm.
+     */
+    public Digest(String algorithm) throws NoSuchAlgorithmException
+    {
+        this(MessageDigest.getInstance(algorithm));
+    }
+
+
+    /**
+     * Constructor with an algorithm name and a provider.
+     *
+     * <p>
+     * This constructor is equivalent to {@link #Digest(MessageDigest) this}{@code
+     * (}{@link MessageDigest#getInstance(String,String) MessageDigest.getInstance}{@code
+     * (algorithm, provider))}.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @param provider
+     *         Provider name.
+     *
+     * @throws NoSuchAlgorithmException
+     *         The provider does not support the specified algorithm.
+     *
+     * @throws NoSuchProviderException
+     *         The specified provider is not registered in the security provider list.
+     */
+    public Digest(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException
+    {
+        this(MessageDigest.getInstance(algorithm, provider));
+    }
+
+
+    /**
+     * Constructor with an algorithm name and a provider.
+     *
+     * <p>
+     * This constructor is equivalent to {@link #Digest(MessageDigest) this}{@code
+     * (}{@link MessageDigest#getInstance(String,Provider) MessageDigest.getInstance}{@code
+     * (algorithm, provider))}.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @param provider
+     *         Provider.
+     *
+     * @throws NoSuchAlgorithmException
+     *         The provider does not support the specified algorithm.
+     */
+    public Digest(String algorithm, Provider provider) throws NoSuchAlgorithmException
+    {
+        this(MessageDigest.getInstance(algorithm, provider));
+    }
+
+
+    /**
+     * Create a {@code Digest} instance with the specified algorithm.
+     *
+     * <p>
+     * This method creates a {@link MessageDigest} instance by
+     * {@link MessageDigest#getInstance(String)} and wraps it
+     * in a {@code Digest} instance.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @return
+     *         A {@code Digest} instance that implements the specified algorithm.
+     *
+     * @throws NoSuchAlgorithmException
+     *         No provider supports the specified algorithm.
+     */
+    public static Digest getInstance(String algorithm) throws NoSuchAlgorithmException
+    {
+        return new Digest(algorithm);
+    }
+
+
+    /**
+     * Create a {@code Digest} instance with the specified algorithm.
+     *
+     * <p>
+     * This method creates a {@link MessageDigest} instance by
+     * {@link MessageDigest#getInstance(String, String)} and wraps it
+     * in a {@code Digest} instance.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @param provider
+     *         Provider name.
+     *
+     * @return
+     *         A {@code Digest} instance that implements the specified algorithm.
+     *
+     * @throws NoSuchAlgorithmException
+     *         The provider does not support the specified algorithm.
+     *
+     * @throws NoSuchProviderException
+     *         The specified provider is not registered in the security provider list.
+     */
+    public static Digest getInstance(String algorithm, String provider)
+            throws NoSuchAlgorithmException, NoSuchProviderException
+    {
+        return new Digest(algorithm, provider);
+    }
+
+
+    /**
+     * Create a {@code Digest} instance with the specified algorithm.
+     *
+     * <p>
+     * This method creates a {@link MessageDigest} instance by
+     * {@link MessageDigest#getInstance(String, Provider)} and wraps it
+     * in a {@code Digest} instance.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @param provider
+     *         Provider.
+     *
+     * @return
+     *         A {@code Digest} instance that implements the specified algorithm.
+     *
+     * @throws NoSuchAlgorithmException
+     *         The provider does not support the specified algorithm.
+     */
+    public static Digest getInstance(String algorithm, Provider provider) throws NoSuchAlgorithmException
+    {
+        return new Digest(algorithm, provider);
+    }
+
+
+    /**
+     * Create a {@code Digest} instance with the specified algorithm.
+     *
+     * <p>
+     * This method exists just to ignore {@code NoSuchAlgorithmException}.
+     * </p>
+     *
+     * @param algorithm
+     *         Algorithm name such as "MD5" and "SHA-1".
+     *
+     * @return
+     *         A {@code Digest} instance that implements the specified algorithm.
+     */
+    private static Digest getInstancePredefined(String algorithm)
+    {
+        try
+        {
+            return getInstance(algorithm);
+        }
+        catch (NoSuchAlgorithmException e)
+        {
+            // This won't happen.
+            return null;
+        }
+    }
+
+
+    /**
+     * Create a {@code Digest} instance that implements MD2.
+     *
+     * @return
+     *         A {@code Digest} instance that implements MD2.
+     */
+    public static Digest getInstanceMD2()
+    {
+        return getInstancePredefined("MD2");
+    }
+
+
+    /**
+     * Create a {@code Digest} instance that implements MD5.
+     *
+     * @return
+     *         A {@code Digest} instance that implements MD5.
+     */
+    public static Digest getInstanceMD5()
+    {
+        return getInstancePredefined("MD5");
+    }
+
+
+    /**
+     * Create a {@code Digest} instance that implements SHA-1.
+     *
+     * @return
+     *         A {@code Digest} instance that implements SHA-1.
+     */
+    public static Digest getInstanceSHA1()
+    {
+        return getInstancePredefined("SHA-1");
+    }
+
+
+    /**
+     * Create a {@code Digest} instance that implements SHA-256.
+     *
+     * @return
+     *         A {@code Digest} instance that implements SHA-256.
+     */
+    public static Digest getInstanceSHA256()
+    {
+        return getInstancePredefined("SHA-256");
+    }
+
+
+    /**
+     * Create a {@code Digest} instance that implements SHA-384.
+     *
+     * @return
+     *         A {@code Digest} instance that implements SHA-384.
+     */
+    public static Digest getInstanceSHA384()
+    {
+        return getInstancePredefined("SHA-384");
+    }
+
+
+    /**
+     * Create a {@code Digest} instance that implements SHA-512.
+     *
+     * @return
+     *         A {@code Digest} instance that implements SHA-512.
+     */
+    public static Digest getInstanceSHA512()
+    {
+        return getInstancePredefined("SHA-512");
+    }
+
+
+    /**
+     * Get the algorithm name.
+     *
+     * <p>
+     * This method just calls {@link MessageDigest#getAlgorithm()
+     * getAlgorithm()} of the wrapped {@code MessageDigest} instance.
+     * </p>
+     *
+     * @return
+     *         Algorithm name.
+     */
+    public String getAlgorithm()
+    {
+        return mMessageDigest.getAlgorithm();
+    }
+
+
+    /**
+     * Get the length of the digest in bytes.
+     *
+     * <p>
+     * This method just calls {@link MessageDigest#getDigestLength()
+     * getDigestLength()} of the wrapped {@code MessageDigest} instance.
+     * </p>
+     *
+     * @return
+     *         Length of the digest in bytes.
+     */
+    public int getDigestLength()
+    {
+        return mMessageDigest.getDigestLength();
+    }
+
+
+    /**
+     * Get the provider.
+     *
+     * <p>
+     * This method just calls {@link MessageDigest#getProvider()
+     * getProvider()} of the wrapped {@code MessageDigest} instance.
+     * </p>
+     *
+     * @return
+     *         Provider.
+     */
+    public Provider getProvider()
+    {
+        return mMessageDigest.getProvider();
+    }
+
+
+    /**
+     * Get the wrapped {@code MessageDigest} instance.
+     *
+     * @return
+     *         The {@code MessageDigest} instance that has been
+     *         given to the constructor.
+     */
+    public MessageDigest getWrappedMessageDigest()
+    {
+        return mMessageDigest;
+    }
+
+
+    /**
+     * Get a clone of this {@code Digest} instance.
+     *
+     * @return
+     *         A cloned object.
+     *
+     * @throws CloneNotSupportedException
+     *         The implementation does not support {@code clone} operation.
+     */
+    @SuppressWarnings("unchecked")
+    @Override
+    public Object clone() throws CloneNotSupportedException
+    {
+        Digest cloned = (Digest)super.clone();
+
+        cloned.mMessageDigest = (MessageDigest)mMessageDigest.clone();
+        cloned.mFeatures      = (HashMap<Feature, Boolean>)mFeatures.clone();
+
+        return cloned;
+    }
+
+
+    /**
+     * Complete the hash computation. The digest is reset after
+     * this call is made.
+     *
+     * <p>
+     * This method just calls {@link MessageDigest#digest() digest()}
+     * method of the wrapped {@code MessageDigest} instance.
+     * </p>
+     *
+     * @return
+     *         The resulting hash value.
+     */
+    public byte[] digest()
+    {
+        return mMessageDigest.digest();
+    }
+
+
+    /**
+     * Perform the final update with the given byte array, and then
+     * complete the hash computation. The digest is reset after
+     * this call is made.
+     *
+     * <p>
+     * This method just calls {@link MessageDigest#digest(byte[])
+     * digest(byte[])} method of the wrapped {@code MessageDigest}
+     * instance.
+     * </p>
+     *
+     * @param input
+     *         Byte array used for the last update.
+     *
+     * @return
+     *         The resulting hash value.
+     */
+    public byte[] digest(byte[] input)
+    {
+        return mMessageDigest.digest(input);
+    }
+
+
+    /**
+     * Complete the hash computation. The digest is reset after
+     * this call is made.
+     *
+     * <p>
+     * This method just calls {@link MessageDigest#digest(byte[],int,int)
+     * digest(byte[], int, int)} method of the wrapped {@code MessageDigest}
+     * instance.
+     * </p>
+     *
+     * @param output
+     *         Output buffer for the computed digest.
+     *
+     * @param offset
+     *         Offset into the output buffer to begin storing the digest.
+     *
+     * @param length
+     *         Number of bytes within the output buffer allotted for the digest.
+     *
+     * @return
+     *         The resulting hash value.
+     *
+     * @throws DigestException
+     *         The {@code digest} method of the {@link MessageDigest} class
+     *         failed.
+     */
+    public int digest(byte[] output, int offset, int length) throws DigestException
+    {
+        return mMessageDigest.digest(output, offset, length);
+    }
+
+
+    /**
+     * Complete the hash computation and get the resulting hash value
+     * as a hex string. The digest is reset after this call is made.
+     *
+     * <p>
+     * This method calls {@link #digest()} method and converts the result
+     * to a String object.
+     * </p>
+     *
+     * @return
+     *         The result hash value represented in a hex String.
+     */
+    public String digestAsString()
+    {
+        return bytesToHex(digest());
+    }
+
+
+    /**
+     * Perform the final update with the given byte array, and then
+     * complete the hash computation and get the resulting hash value
+     * as a hex string. The digest is reset after this call is made.
+     *
+     * <p>
+     * This method calls {@link #digest(byte[])} method and converts
+     * the result to a String object.
+     * </p>
+     *
+     * @param input
+     *         Byte array used for the last update.
+     *
+     * @return
+     *         The result hash value represented in a hex String.
+     */
+    public String digestAsString(byte[] input)
+    {
+        return bytesToHex(digest(input));
+    }
+
+
+    /**
+     * Complete the hash computation and get the resulting hash value
+     * as a string. The given encoder is used to convert the digest
+     * value to a string.
+     *
+     * <p>
+     * This method is an alias of {@link #digestAsString(byte[],
+     * BinaryEncoder) digestAsString((byte[])null, encoder)}.
+     * </p>
+     *
+     * @param encoder
+     *         Encoder to convert a digest value to a byte array
+     *         whose elements are printable characters. For example,
+     *         {@link org.apache.commons.codec.binary.Base64}.
+     *
+     * @return
+     *         The result hash value encoded by the encoder.
+     *
+     * @throws RuntimeException
+     *         If the encoder throws {@link EncoderException},
+     *         a {@code RuntimeException} wrapping the
+     *         {@code EncoderException} is thrown.
+     */
+    public String digestAsString(BinaryEncoder encoder)
+    {
+        return digestAsString((byte[])null, encoder);
+    }
+
+
+    /**
+     * Perform the final update with the given byte array, and then
+     * complete the hash computation and get the resulting hash value
+     * as a string. The given encoder is used to convert the digest
+     * value to a string.
+     *
+     * @param input
+     *         Byte array used for the last update. If {@code null}
+     *         is given, it is just ignored.
+     *
+     * @param encoder
+     *         Encoder to convert a digest value to a byte array
+     *         whose elements are printable characters. For example,
+     *         {@link org.apache.commons.codec.binary.Base64}.
+     *
+     * @return
+     *         The result hash value encoded by the encoder.
+     *
+     * @throws IllegalArgumentException
+     *         {@code encoder} is {@code null}.
+     *
+     * @throws RuntimeException
+     *         If the encoder throws {@link EncoderException},
+     *         a {@code RuntimeException} wrapping the
+     *         {@code EncoderException} is thrown.
+     */
+    public String digestAsString(byte[] input, BinaryEncoder encoder)
+    {
+        if (encoder == null)
+        {
+            throw new IllegalArgumentException("encoder is null.");
+        }
+
+        // Compute the digest value.
+        byte[] digest = (input != null) ? digest(input) : digest();
+
+        // Encoded value.
+        byte[] encoded = null;
+
+        try
+        {
+            // Encode the digest value.
+            encoded = encoder.encode(digest);
+        }
+        catch (EncoderException e)
+        {
+            // Failed to encode the digest value.
+            throw new RuntimeException("Failed to encode the digest value.", e);
+        }
+
+        try
+        {
+            // Convert the byte array into a string.
+            return new String(encoded, "UTF-8");
+        }
+        catch (UnsupportedEncodingException e)
+        {
+            // This won't happen.
+            return null;
+        }
+    }
+
+
+    /**
+     * Reset the wrapped {@code MessageDigest} instance.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest reset()
+    {
+        mMessageDigest.reset();
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link MessageDigest#update(byte) update(byte)}
+     * method of the wrapped {@code MessageDigest} instance.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(byte input)
+    {
+        mMessageDigest.update(input);
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link MessageDigest#update(byte[]) update(byte[])}
+     * method of the wrapped {@code MessageDigest} instance.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(byte[] input)
+    {
+        mMessageDigest.update(input);
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link MessageDigest#update(byte[],int,int)
+     * update(byte[], int, int)} method of the wrapped
+     * {@code MessageDigest} instance.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(byte[] input, int offset, int length)
+    {
+        mMessageDigest.update(input, offset, length);
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link MessageDigest#update(ByteBuffer)
+     * update(ByteBuffer)} method of the wrapped {@code MessageDigest}
+     * instance.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(ByteBuffer input)
+    {
+        mMessageDigest.update(input);
+
+        return this;
+    }
+
+
+    /**
+     * Check the validity of the combination of the given parameters.
+     *
+     * @param size
+     *         Size of an array.
+     *
+     * @param offset
+     *         Offset in the array.
+     *
+     * @param length
+     *         Length of data to use.
+     *
+     * @throws IllegalArgumentException
+     * <ul>
+     * <li>{@code offset < 0}
+     * <li>{@code size <= offset}
+     * <li>{@code length < 0}
+     * <li>{@code size < (offset + length)}
+     * </ul>
+     */
+    private void checkRange(int size, int offset, int length)
+    {
+        String message = null;
+
+        if (offset < 0)
+        {
+            message = "The offset is less than 0.";
+        }
+        else if (size <= offset)
+        {
+            message = "The offset is equal to or greater than the size.";
+        }
+        else if (length < 0)
+        {
+            message = "The length is less than 0.";
+        }
+        else if (size < (offset + length))
+        {
+            message = "The sum of the offset and the length is greater than the size.";
+        }
+
+        if (message != null)
+        {
+            throw new IllegalArgumentException(message);
+        }
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(boolean)
+     * update}{@code (input.booleanValue())}.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Boolean input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input.booleanValue());
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(Boolean[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Boolean[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(Boolean)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(Boolean[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * @param input
+     *         Input data. {@code true} results in {@link #update(byte)
+     *         update}{@code ((byte)1)} and {@code false} results in
+     *         {@link #update(byte) update}{@code ((byte)0)}.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(boolean input)
+    {
+        return update((byte)(input ? 1 : 0));
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(boolean[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(boolean[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(boolean)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(boolean[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(char)
+     * update}{@code (input.charValue())}.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Character input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input.charValue());
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(Character[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Character[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(Character)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(Character[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(byte) update}{@code
+     * ((byte)((input >> 8) & 0xff))} and {@link #update(byte)
+     * update}({@code ((byte)(input >> 0) & 0xff)}.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(char input)
+    {
+        update((byte)((input >> 8) & 0xff));
+        update((byte)((input >> 0) & 0xff));
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(char[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(char[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(char)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(char[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(byte) update}{@code
+     * ((byte)((input >> 8) & 0xff))} and {@link #update(byte)
+     * update}({@code ((byte)(input >> 0) & 0xff)}.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(short input)
+    {
+        update((byte)((input >> 8) & 0xff));
+        update((byte)((input >> 0) & 0xff));
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(short[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(short[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(short)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(short[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(byte)} for each byte of the
+     * 4 bytes from MSB to LSB (from {@code ((input >> 24) & 0xff)}
+     * to {@code ((input >> 0) & 0xff)}).
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(int input)
+    {
+        update((byte)((input >> 24) & 0xff));
+        update((byte)((input >> 16) & 0xff));
+        update((byte)((input >>  8) & 0xff));
+        update((byte)((input >>  0) & 0xff));
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(int[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(int[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(int)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(int[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(byte)} for each byte of the
+     * 8 bytes from MSB to LSB (from {@code ((input >> 54) & 0xff)}
+     * to {@code ((input >> 0) & 0xff)}).
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(long input)
+    {
+        update((byte)((input >> 54) & 0xff));
+        update((byte)((input >> 48) & 0xff));
+        update((byte)((input >> 40) & 0xff));
+        update((byte)((input >> 32) & 0xff));
+        update((byte)((input >> 24) & 0xff));
+        update((byte)((input >> 16) & 0xff));
+        update((byte)((input >>  8) & 0xff));
+        update((byte)((input >>  0) & 0xff));
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(long[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(long[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(long)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(long[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method converts the given {@code float} value to a
+     * {@code int} by {@link Float#floatToRawIntBits(float)}
+     * and then passes it to {@link #update(int)}.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(float input)
+    {
+        return update(Float.floatToRawIntBits(input));
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(float[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(float[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(float)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(float[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method converts the given {@code double} value to a
+     * {@code long} by {@link Double#doubleToRawLongBits(double)}
+     * and then passes it to {@link #update(long)}.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(double input)
+    {
+        return update(Double.doubleToRawLongBits(input));
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(double[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(double[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(double)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(double[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method checks the class of the given instance and
+     * calls a corresponding {@code update} method.
+     * </p>
+     *
+     * <table border="1" style="margin: 1em; border-collapse: collapse; padding: 5px;">
+     *   <caption></caption>
+     *   <tr style="background-color: orange;">
+     *     <th>Class</th>
+     *     <th>Executed code</th>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code Byte}</td>
+     *     <td>{@link #update(byte) update}{@code (((Byte)number).byteValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code Short}</td>
+     *     <td>{@link #update(short) update}{@code (((Short)number).shortValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code Integer}</td>
+     *     <td>{@link #update(int) update}{@code (((Integer)number).intValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code Long}</td>
+     *     <td>{@link #update(long) update}{@code (((Long)number).longValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code Float}</td>
+     *     <td>{@link #update(float) update}{@code (((Float)number).floatValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code Double}</td>
+     *     <td>{@link #update(double) update}{@code (((Double)number).doubleValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code BigInteger}</td>
+     *     <td>{@link #update(byte[]) update}{@code (((BigInteger)number).toByteArray())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code BigDecimal}</td>
+     *     <td>{@link #update(String) update}{@code (((BigDecimal)number).toString())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code AtomicInteger}</td>
+     *     <td>{@link #update(int) update}{@code (((AtomicInteger)number).intValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>{@code AtomicLong}</td>
+     *     <td>{@link #update(long) update}{@code (((AtomicLong)number).longValue())}</td>
+     *   </tr>
+     *   <tr>
+     *     <td>Others</td>
+     *     <td>Ignored.</td>
+     *   </tr>
+     * </table>
+     *
+     * @param number
+     *         Input data. If null or none of the above, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Number number)
+    {
+        if (number == null)
+        {
+            return this;
+        }
+
+        // Byte
+        if (number instanceof Byte)
+        {
+            update(((Byte)number).byteValue());
+        }
+        // Short
+        else if (number instanceof Short)
+        {
+            update(((Short)number).shortValue());
+        }
+        // Integer
+        else if (number instanceof Integer)
+        {
+            update(((Integer)number).intValue());
+        }
+        // Long
+        else if (number instanceof Long)
+        {
+            update(((Long)number).longValue());
+        }
+        // Float
+        else if (number instanceof Float)
+        {
+            update(((Float)number).floatValue());
+        }
+        // Double
+        else if (number instanceof Double)
+        {
+            update(((Double)number).doubleValue());
+        }
+        // BigInteger
+        else if (number instanceof BigInteger)
+        {
+            update(((BigInteger)number).toByteArray());
+        }
+        // BigDecimal
+        else if (number instanceof BigDecimal)
+        {
+            update(((BigDecimal)number).toString());
+        }
+        // AtomicInteger
+        else if (number instanceof AtomicInteger)
+        {
+            update(((AtomicInteger)number).intValue());
+        }
+        // AtomicLong
+        else if (number instanceof AtomicLong)
+        {
+            update(((AtomicLong)number).longValue());
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(Number[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param <TNumber>
+     *         The subclass of the {@link Number} class.
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public <TNumber extends Number> Digest update(TNumber[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(Number)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param <TNumber>
+     *         The subclass of the {@link Number} class.
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public <TNumber extends Number> Digest update(TNumber[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method converts the given string into bytes with the
+     * character set of UTF-8 and then passes the byte array to
+     * {@link #update(byte[])}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(String input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        try
+        {
+            return update(input.getBytes("UTF-8"));
+        }
+        catch (UnsupportedEncodingException e)
+        {
+            // This won't happen.
+            return this;
+        }
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method is an alias of {@link #update(String[], int, int)
+     * update}{@code (input, 0, input.length)}.
+     * </p>
+     *
+     * @param input
+     *         Input data. If null is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(String[] input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        return update(input, 0, input.length);
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(String)} for each
+     * array element which is in the specified range.
+     * </p>
+     *
+     * @param input
+     *         Input data.
+     *
+     * @param offset
+     *         The offset to start from in the array.
+     *
+     * @param length
+     *         The number of elements to use, starting at offset.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         The range specified by the parameters is invalid.
+     */
+    public Digest update(String[] input, int offset, int length)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        checkRange(input.length, offset, length);
+
+        for (int i = 0; i < length; ++i)
+        {
+            update(input[i + offset]);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(Object)} for each element.
+     * </p>
+     *
+     * @param input
+     *         Input data. If {@code null} is given, update is not performed.
+     *         {@code null} elements are ignored. Elements of unsupported
+     *         classes are ignored, too.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Iterable<?> input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        for (Object element : input)
+        {
+            if (element == null)
+            {
+                continue;
+            }
+
+            update(element);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method calls {@link #update(Object)} for each element.
+     * </p>
+     *
+     * @param input
+     *         Input data. If {@code null} is given, update is not performed.
+     *         {@code null} elements are ignored. Elements of unsupported
+     *         classes are ignored, too.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Object... input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        for (Object element : input)
+        {
+            if (element == null)
+            {
+                continue;
+            }
+
+            update(element);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given input data.
+     *
+     * <p>
+     * This method checks the class of the given object and calls
+     * a corresponding {@code update} method.
+     * </p>
+     *
+     * @param input
+     *         Input data. If {@code null} is given, update is not performed.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest update(Object input)
+    {
+        if (input == null)
+        {
+            return this;
+        }
+
+        if (input instanceof String)
+        {
+            update((String)input);
+        }
+        else if (input instanceof String[])
+        {
+            update((String[])input);
+        }
+        else if (input instanceof Character)
+        {
+            update((Character)input);
+        }
+        else if (input instanceof Character[])
+        {
+            update((Character[])input);
+        }
+        else if (input instanceof Boolean)
+        {
+            update((Boolean)input);
+        }
+        else if (input instanceof boolean[])
+        {
+            update((boolean[])input);
+        }
+        else if (input instanceof Boolean[])
+        {
+            update((Boolean[])input);
+        }
+        else if (input instanceof Number)
+        {
+            update((Number)input);
+        }
+        else if (input instanceof byte[])
+        {
+            update((byte[])input);
+        }
+        else if (input instanceof Byte[])
+        {
+            update((Byte[])input);
+        }
+        else if (input instanceof ByteBuffer)
+        {
+            update((ByteBuffer)input);
+        }
+        else if (input instanceof char[])
+        {
+            update((char[])input);
+        }
+        else if (input instanceof double[])
+        {
+            update((double[])input);
+        }
+        else if (input instanceof Double[])
+        {
+            update((Double[])input);
+        }
+        else if (input instanceof float[])
+        {
+            update((float[])input);
+        }
+        else if (input instanceof Float[])
+        {
+            update((Float[])input);
+        }
+        else if (input instanceof int[])
+        {
+            update((int[])input);
+        }
+        else if (input instanceof Integer[])
+        {
+            update((Integer[])input);
+        }
+        else if (input instanceof long[])
+        {
+            update((long[])input);
+        }
+        else if (input instanceof Long[])
+        {
+            update((Long[])input);
+        }
+        else if (input instanceof short[])
+        {
+            update((short[])input);
+        }
+        else if (input instanceof Short[])
+        {
+            update((Short[])input);
+        }
+        else if (input instanceof Iterable<?>)
+        {
+            update((Iterable<?>)input);
+        }
+
+        return this;
+    }
+
+
+    /**
+     * Update the wrapped {@code MessageDigest} object with the
+     * given JSON. This method updates the digest based on the
+     * content of the given JSON, and in the respect, this method
+     * is different from {@link #update(String)}.
+     *
+     * <p>
+     * JSONs with the same content, for example, two JSONs below,
+     * generate the same digest.
+     * </p>
+     *
+     * <pre>
+     * { "key1":"value1", "key2":"value2" }
+     * { "key1" : "value1" , "key2" : "value2" }
+     * </pre>
+     *
+     * <p>
+     * If {@link Feature#IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_NULL}
+     * is enabled (it is disabled by default), key-value entries
+     * with value 'null' are treated as if they did not exist.
+     * Therefore, two JSONs below generate the same digest value.
+     * </p>
+     *
+     * <pre>
+     * { "key1":"value1", "key2":null }
+     * { "key1":"value1" }
+     * </pre>
+     *
+     * <p>
+     * If {@link Feature#SORT_JSON_OBJECT_ENTRY_KEYS} is enabled
+     * (it is enabled by default), orders of JSON object keys do
+     * not matter. Therefore, two JSONs below generate the same
+     * digest value.
+     * </p>
+     *
+     * <pre>
+     * { "key1":"value1", "key2":"value2" }
+     * { "key2":"value2", "key1":"value1" }
+     * </pre>
+     *
+     * @param json
+     *         JSON.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IOException
+     *         Failed to parse the given JSON.
+     */
+    public Digest updateJson(String json) throws IOException
+    {
+        return new JsonDigestUpdater().update(this, json);
+    }
+
+
+    /**
+     * Check if the specified feature is enabled.
+     *
+     * @param feature
+     *         Feature to check.
+     *
+     * @return
+     *         {@code true} if the feature is enabled. Otherwise, {@code false}.
+     */
+    public boolean isEnabled(Feature feature)
+    {
+        return mFeatures.get(feature).booleanValue();
+    }
+
+
+    /**
+     * Enable or disable the specified feature.
+     *
+     * @param feature
+     *         {@link Feature} to enable or disable.
+     *
+     * @param enabled
+     *         {@code true} to enable the feature.
+     *         {@code false} to disable the feature.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public Digest setEnabled(Feature feature, boolean enabled)
+    {
+        mFeatures.put(feature, Boolean.valueOf(enabled));
+
+        return this;
+    }
+
+
+    /**
+     * Convert the given byte array to a hex string.
+     *
+     * @param bytes
+     *         A byte array to convert.
+     *
+     * @return
+     *         A hex string with 0-9 and a-f.
+     */
+    public static String bytesToHex(byte[] bytes)
+    {
+        // http://stackoverflow.com/a/9855338/1174054
+        char[] hexChars = new char[bytes.length * 2];
+        int v;
+
+        for (int j = 0; j < bytes.length; ++j)
+        {
+            v = bytes[j] & 0xFF;
+            hexChars[j * 2] = mHexArray[v >>> 4];
+            hexChars[j * 2 + 1] = mHexArray[v & 0x0F];
+        }
+
+        return new String(hexChars);
+    }
+}
diff --git a/src/main/java/com/authlete/common/util/digest/JsonDigestUpdater.java b/src/main/java/com/authlete/common/util/digest/JsonDigestUpdater.java
new file mode 100644
index 0000000000..5026a2e54e
--- /dev/null
+++ b/src/main/java/com/authlete/common/util/digest/JsonDigestUpdater.java
@@ -0,0 +1,398 @@
+package com.authlete.common.util.digest;
+
+
+import static com.authlete.common.util.digest.Digest.Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_ARRAY;
+import static com.authlete.common.util.digest.Digest.Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_OBJECT;
+import static com.authlete.common.util.digest.Digest.Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_STRING;
+import static com.authlete.common.util.digest.Digest.Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_FALSE;
+import static com.authlete.common.util.digest.Digest.Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_NULL;
+import static com.authlete.common.util.digest.Digest.Feature.IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_ZERO;
+import static com.authlete.common.util.digest.Digest.Feature.SORT_JSON_OBJECT_ENTRY_KEYS;
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+
+/**
+ * Implementation of {@link Digest#updateJson(String)}.
+ *
+ * @author Takahiko Kawasaki
+ *
+ * @since 4.23
+ */
+class JsonDigestUpdater
+{
+    private Digest digest;
+    private StringBuilder path;
+    private boolean ignoreNull;
+    private boolean ignoreFalse;
+    private boolean ignoreZero;
+    private boolean ignoreEmptyString;
+    private boolean ignoreEmptyArray;
+    private boolean ignoreEmptyObject;
+    private boolean sortKeys;
+
+
+    public Digest update(Digest digest, String json) throws IOException
+    {
+        // Set the digest to update.
+        this.digest = digest;
+
+        // Initialize the path.
+        this.path = new StringBuilder();
+
+        // Copy configuration.
+        this.ignoreNull        = digest.isEnabled(IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_NULL);
+        this.ignoreFalse       = digest.isEnabled(IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_FALSE);
+        this.ignoreZero        = digest.isEnabled(IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_ZERO);
+        this.ignoreEmptyString = digest.isEnabled(IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_STRING);
+        this.ignoreEmptyArray  = digest.isEnabled(IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_ARRAY);
+        this.ignoreEmptyObject = digest.isEnabled(IGNORE_JSON_OBJECT_ENTRY_WITH_VALUE_EMPTY_OBJECT);
+        this.sortKeys          = digest.isEnabled(SORT_JSON_OBJECT_ENTRY_KEYS);
+
+        // Convert JSON to a node tree.
+        JsonNode root = createTree(json);
+
+        // Path start
+        mark("P");
+
+        // Traverse the node tree.
+        update(root);
+
+        // Path end
+        mark("p");
+
+        // Finally, update the digest with 'path' in order to prevent
+        // different JSONs from generating the same digest accidentally.
+        digest.update(path.toString());
+
+        return digest;
+    }
+
+
+    private JsonNode createTree(String json) throws IOException
+    {
+        return createObjectMapper().readTree(json);
+    }
+
+
+    private ObjectMapper createObjectMapper()
+    {
+        ObjectMapper mapper = new ObjectMapper();
+
+        mapper.configure(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS, true);
+
+        return mapper;
+    }
+
+
+    private void mark(String mark)
+    {
+        path.append(mark);
+    }
+
+
+    private void update(JsonNode node)
+    {
+        if (node.isArray())
+        {
+            updateArray(node);
+        }
+        else if (node.isObject())
+        {
+            updateObject(node);
+        }
+        else if (node.isBoolean())
+        {
+            updateBoolean(node);
+        }
+        else if (node.isNumber())
+        {
+            updateNumber(node);
+        }
+        else if (node.isTextual())
+        {
+            updateText(node);
+        }
+        else if (node.isNull())
+        {
+            updateNull(node);
+        }
+        else if (node.isBinary())
+        {
+            // Probably, this won't happen.
+            updateBinary(node);
+        }
+    }
+
+
+    private void updateArray(JsonNode node)
+    {
+        // Array start.
+        mark("A");
+
+        // For each element.
+        for (JsonNode element : node)
+        {
+            // Array element start.
+            mark("E");
+
+            // Update the digest with the element.
+            update(element);
+
+            // Array element end.
+            mark("e");
+        }
+
+        // Array end.
+        mark("a");
+    }
+
+
+    private void updateObject(JsonNode node)
+    {
+        // Object start.
+        mark("O");
+
+        // Field names.
+        List<String> names = getFieldNames(node);
+
+        // For each field name.
+        for (String name : names)
+        {
+            // Get the value of the field.
+            JsonNode value = node.findValue(name);
+
+            // Update the digest with the pair of name and value.
+            updateObjectEntry(name, value);
+        }
+
+        // Object end.
+        mark("o");
+    }
+
+
+    private void updateObjectEntry(String name, JsonNode value)
+    {
+        if (shouldIgnore(value))
+        {
+            // Ignore this entry.
+            return;
+        }
+
+        // Key start.
+        mark("K");
+
+        // Update the digest with the name.
+        digest.update(name);
+
+        // Key end and Value start.
+        mark("kV");
+
+        // Update the digest with the value.
+        update(value);
+
+        // Value end.
+        mark("v");
+    }
+
+
+    private boolean shouldIgnore(JsonNode value)
+    {
+        if (ignoreNull && value.isNull())
+        {
+            // The value of the field is null. Ignore this entry.
+            return true;
+        }
+
+        if (ignoreFalse && value.isBoolean())
+        {
+            // Ignore this entry if its value is false.
+            return value.asBoolean() == false;
+        }
+
+        if (ignoreZero && value.isNumber())
+        {
+            // Ignore this entry if its value is zero.
+            return isZero(value);
+        }
+
+        if (ignoreEmptyString && value.isTextual())
+        {
+            // Ignore this entry if its value is an empty string.
+            return value.textValue().length() == 0;
+        }
+
+        if (ignoreEmptyArray && value.isArray())
+        {
+            // Ignore this entry if its value is an empty array.
+            return value.size() == 0;
+        }
+
+        if (ignoreEmptyObject && value.isObject())
+        {
+            // Ignore this entry if its value is an empty object.
+            return value.size() == 0;
+        }
+
+        // Should not ignore.
+        return false;
+    }
+
+
+    private boolean isZero(JsonNode value)
+    {
+        // int
+        if (value.isInt() && value.intValue() == 0)
+        {
+            return true;
+        }
+
+        // long
+        if (value.isLong() && value.longValue() == 0)
+        {
+            return true;
+        }
+
+        // short
+        if (value.isShort() && value.shortValue() == 0)
+        {
+            return true;
+        }
+
+        // float
+        if (value.isFloat() && value.floatValue() == 0.0F)
+        {
+            return true;
+        }
+
+        // double
+        if (value.isDouble() && value.doubleValue() == 0.0)
+        {
+            return true;
+        }
+
+        // BigInteger
+        if (value.isBigInteger() && value.bigIntegerValue().equals(BigInteger.ZERO))
+        {
+            return true;
+        }
+
+        // BigDecimal
+        if (value.isBigDecimal() && value.decimalValue().equals(BigDecimal.ZERO))
+        {
+            return true;
+        }
+
+        return false;
+    }
+
+
+    private List<String> getFieldNames(JsonNode node)
+    {
+        // Generate a list of field names.
+        List<String> list = iteratorToList(node.fieldNames());
+
+        if (sortKeys)
+        {
+            // Sort on field names.
+            Collections.sort(list);
+        }
+
+        return list;
+    }
+
+
+    private <TElement> List<TElement> iteratorToList(Iterator<TElement> iterator)
+    {
+        List<TElement> list = new ArrayList<TElement>();
+
+        while (iterator.hasNext())
+        {
+            list.add(iterator.next());
+        }
+
+        return list;
+    }
+
+
+    private void updateBoolean(JsonNode node)
+    {
+        // Boolean start.
+        mark("B");
+
+        digest.update(node.asBoolean());
+
+        // "Boolean end.
+        mark("b");
+    }
+
+
+    private void updateNumber(JsonNode node)
+    {
+        // Number start.
+        mark("N");
+
+        // Numbers contribute to the digest as String to make it
+        // easy to implement JsonDigestUpdater equivalent for other
+        // non-Java platforms.
+        //
+        // Note that BigDecimal.toString() is used for floating point
+        // numbers because USE_BIG_DECIMAL_FOR_FLOATS is enabled.
+        digest.update(node.toString());
+
+        // Number end.
+        mark("n");
+    }
+
+
+    private void updateText(JsonNode node)
+    {
+        // Text start.
+        mark("T");
+
+        digest.update(node.asText());
+
+        // Text end.
+        mark("t");
+    }
+
+
+    private void updateNull(JsonNode node)
+    {
+        // Null start.
+        mark("<");
+
+        digest.update("NULL");
+
+        // Null end.
+        mark(">");
+    }
+
+
+    private void updateBinary(JsonNode node)
+    {
+        // Binary start.
+        mark("[");
+
+        try
+        {
+            digest.update(node.binaryValue());
+        }
+        catch (IOException e)
+        {
+            // This won't happen because updateBinary(JsonNode)
+            // is called only when node.isBinary() returns true.
+        }
+
+        // Binary end.
+        mark("]");
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/authlete/common/util/security/AESCipher.java b/src/main/java/com/authlete/common/util/security/AESCipher.java
new file mode 100644
index 0000000000..9e770a70a2
--- /dev/null
+++ b/src/main/java/com/authlete/common/util/security/AESCipher.java
@@ -0,0 +1,554 @@
+package com.authlete.common.util.security;
+
+
+import static com.authlete.common.util.security.StandardCipherTransformations.AES_CBC_PKCS5PADDING;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.IvParameterSpec;
+import org.apache.commons.codec.BinaryDecoder;
+import org.apache.commons.codec.BinaryEncoder;
+import org.apache.commons.codec.binary.Base64;
+
+
+/**
+ * Cipher using {@code "AES/CBC/PKCS5Padding"}.
+ *
+ * <pre style="background-color: #EEEEEE; margin: 2em; border: 1px solid black; padding: 0.5em;">
+ * <span style="color: darkgreen;">// Create a cipher with a secret key.</span>
+ * AESCipher cipher = new {@link #AESCipher()}.{@link #setKey(String, String) setKey}(<span style="color: darkred;">"secret key"</span>, <span style="color: darkred;">"initial vector"</span>);
+ *
+ * <span style="color: darkgreen;">// Encryption &amp; decryption.
+ * // 'plaintext' and 'decrypted' have the same value.</span>
+ * String plaintext = <span style="color: darkred;">"plain text"</span>;
+ * String encrypted = cipher.{@link #encrypt(String) encrypt(plaintext)};
+ * String decrypted = cipher.{@link #decrypt(String) decrypt(encrypted)};
+ *
+ * <span style="color: darkgreen;">// In the above example, 'encrypted' is encoded by Base64 (default).
+ * // If you want to change the format, use {@code setCoder} method.
+ * // For example, to change the format to hexadecimal:</span>
+ * Hex hex = new org.apache.commons.codec.binary.Hex();
+ * cipher.setCoder(hex);
+ *
+ * <span style="color: darkgreen;">// Binary representation (only "0"s and "1"s) also can be used.</span>
+ * BinaryCodec binary = new org.apache.commons.codec.BinaryCodec();
+ * cipher.setCoder(binary);
+ *
+ * <span style="color: darkgreen;">// Coder can be specified as a constructor parameter.</span>
+ * cipher = new AESCipher(hex);
+ *
+ * <span style="color: darkgreen;">// If you want, an encoder and a decoder can be set separately.</span>
+ * cipher.{@link #setEncoder(BinaryEncoder) setEncoder(hex)};
+ * cipher.{@link #setDecoder(BinaryDecoder) setDecoder(hex)};
+ * </pre>
+ *
+ * <pre style="background-color: #EEEEEE; margin: 2em; border: 1px solid black; padding: 0.5em;">
+ * <span style="color: darkgreen;">// Another example which performs encryption without initial vector.</span>
+ * String secretkey = <span style="color: darkred;">"secret key"</span>;
+ * String plaintext = <span style="color: darkred;">"plain text"</span>;
+ *
+ * <span style="color: darkgreen;">// Create and set up without initial vector.</span>
+ * AESCipher cipher = new AESCipher().setKey(secretkey);
+ *
+ * <span style="color: darkgreen;">// Encrypt.</span>
+ * String encrypted = cipher.encrypt(plaintext);
+ *
+ * <span style="color: darkgreen;">// Get the auto-generated initial vector.</span>
+ * byte[] iv = cipher.getCipher().getIV();
+ *
+ * <span style="color: darkgreen;">// Decryption requires initial vector.</span>
+ * cipher.setKey(secretkey, iv);
+ *
+ * <span style="color: darkgreen;">// Decrypt.</span>
+ * String decrypted = cipher.decrypt(encrypted);
+ * </pre>
+ *
+ * @author Takahiko Kawasaki
+ * @since 4.23
+ */
+public class AESCipher extends CodecCipher
+{
+    /**
+     * The default key size. The value is 16, meaning 128 bits.
+     */
+    public static final int DEFAULT_KEY_SIZE = 16;
+
+
+    /**
+     * The default transformation. The value is "AES/CBC/PKCS5Padding".
+     */
+    public static final String DEFAULT_TRANSFORMATION = AES_CBC_PKCS5PADDING;
+
+
+    /**
+     * The initial vector. The size of initial vectors for AES is always 16.
+     */
+    private static final int INITIAL_VECTOR_SIZE = 16;
+
+
+    /**
+     * Constructor.
+     *
+     * <p>
+     * This constructor just performs {@link CodecCipher#CodecCipher(String)
+     * super("AES/CBC/PKCS5Padding")}.
+     * </p>
+     */
+    public AESCipher()
+    {
+        super(DEFAULT_TRANSFORMATION);
+    }
+
+
+    /**
+     * Constructor.
+     *
+     * <p>
+     * This constructor just performs {@link CodecCipher#CodecCipher(String)
+     * super(transformation)}.
+     * </p>
+     */
+    public AESCipher(String transformation)
+    {
+        super(transformation);
+    }
+
+
+    /**
+     * Constructor with an encoder and a decoder.
+     *
+     * <p>
+     * This constructor just performs {@link CodecCipher#CodecCipher(String,
+     * BinaryEncoder, BinaryDecoder) super("AES/CBC/PKCS5Padding", encoder, decoder)}.
+     * </p>
+     *
+     * @param encoder
+     *         An encoder used in {@link #encrypt(String) encrypt(String)} and
+     *         {@link #encrypt(byte[]) encrypt(byte[])} to encode an encrypted byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         encoder.
+     *
+     * @param decoder
+     *         A decoder used in {@link #decrypt(String) decrypt(String)} and
+     *         {@link #decrypt(byte[]) decrypt(byte[])} to decode an encoded input byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         decoder.
+     */
+    public AESCipher(BinaryEncoder encoder, BinaryDecoder decoder)
+    {
+        super(DEFAULT_TRANSFORMATION, encoder, decoder);
+    }
+
+
+    /**
+     * Constructor with a transformation, an encoder and a decoder.
+     *
+     * <p>
+     * This constructor just performs {@link CodecCipher#CodecCipher(String,
+     * BinaryEncoder, BinaryDecoder) super(transformation, encoder, decoder)}.
+     * </p>
+     *
+     * @param encoder
+     *         An encoder used in {@link #encrypt(String) encrypt(String)} and
+     *         {@link #encrypt(byte[]) encrypt(byte[])} to encode an encrypted byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         encoder.
+     *
+     * @param decoder
+     *         A decoder used in {@link #decrypt(String) decrypt(String)} and
+     *         {@link #decrypt(byte[]) decrypt(byte[])} to decode an encoded input byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         decoder.
+     */
+    public AESCipher(String transformation, BinaryEncoder encoder, BinaryDecoder decoder)
+    {
+        super(transformation, encoder, decoder);
+    }
+
+
+    /**
+     * Constructor with a coder.
+     *
+     * <p>
+     * This constructor just performs {@code super("AES/CBC/PKCS5Padding", coder)}.
+     * </p>
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> AESCipher(TCoder coder)
+    {
+        super(DEFAULT_TRANSFORMATION, coder);
+    }
+
+
+    /**
+     * Constructor with a transformation and a coder.
+     *
+     * <p>
+     * This constructor just performs {@code super(transformation, coder)}.
+     * </p>
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> AESCipher(String transformation, TCoder coder)
+    {
+        super(transformation, coder);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setInit(java.security.Key,
+     * java.security.spec.AlgorithmParameterSpec) setInit(key, iv)}.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param iv
+     *         Initial vector.
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public AESCipher setKey(SecretKey key, IvParameterSpec iv)
+    {
+        return (AESCipher)setInit(key, iv);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], byte[], int)
+     * setKey}<code>(key, iv, {@link #DEFAULT_KEY_SIZE})</code>.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param iv
+     *         Initial vector.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(byte[] key, byte[] iv)
+    {
+        return setKey(key, iv, DEFAULT_KEY_SIZE);
+    }
+
+
+    /**
+     * Set cipher initialization parameters. Other {@code setKey}
+     * method variants except {@link #setKey(SecretKey, IvParameterSpec)}
+     * eventually call this method.
+     *
+     * <p>
+     * This method constructs a {@link SecretKey} instance and an
+     * {@link IvParameterSpec} instance from the arguments,
+     * and then calls {@link #setKey(SecretKey, IvParameterSpec)}.
+     * </p>
+     *
+     * @param key
+     *         Secret key. If {@code null} is given, {@code new byte[16]}
+     *         is used. If not {@code null} and the length is less than 16,
+     *         a byte array of size 16 is allocated and the content of
+     *         {@code key} is copied to the newly allocated byte array,
+     *         and the resultant byte array is used.
+     *
+     * @param iv
+     *         Initial vector. If {@code null} is given, {@code null}
+     *         is used, meaning that {@code IvParameterSepc} argument
+     *         passed to {@link #setKey(SecretKey, IvParameterSpec)} is
+     *         {@code null}. In that case, you will want to obtain the
+     *         auto-generated initial vector by calling {@link #getCipher()
+     *         getCipher()}{@code .}{@link javax.crypto.Cipher#getIV()
+     *         getIV()} in order to decrypt the encrypted data.
+     *
+     *         <p>
+     *         If {@code iv} is not {@code null} and the length is less
+     *         than 16, a byte array of size 16 is allocated and the content
+     *         of {@code iv} is copied to the newly allocated byte array,
+     *         and the resultant byte array is used. Even if the length is
+     *         greater than 16, only the first 16 bytes are used to construct
+     *         an {@code IvParameterSpec} instance.
+     *         </p>
+     *
+     * @param keySize
+     *         The size of the secret key in bytes.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(byte[] key, byte[] iv, int keySize)
+    {
+        SecretKey secretKey  = Utils.createSecretKeySpec(key, getAlgorithm(), keySize);
+        IvParameterSpec spec = null;
+
+        if (iv != null)
+        {
+            spec = Utils.createIvParameterSpec(iv, INITIAL_VECTOR_SIZE);
+        }
+
+        return setKey(secretKey, spec);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(String, byte[], int)
+     * setKey}<code>(key, iv, {@link #DEFAULT_KEY_SIZE})</code>.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param iv
+     *         Initial vector.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(String key, byte[] iv)
+    {
+        return setKey(key, iv, DEFAULT_KEY_SIZE);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], byte[], int)}.
+     * </p>
+     *
+     * @param key
+     *         Secret key. The value is converted to a byte array
+     *         by {@code key.getBytes("UTF-8")} and used as the
+     *         first argument of {@link #setKey(byte[], byte[], int)}.
+     *
+     * @param iv
+     *         Initial vector.
+     *
+     * @param keySize
+     *         The size of the secret key in bytes.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(String key, byte[] iv, int keySize)
+    {
+        byte[] key2 = Utils.getBytesUTF8(key);
+
+        return setKey(key2, iv, keySize);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(String, String, int)
+     * setKey}<code>(key, iv, {@link #DEFAULT_KEY_SIZE})</code>.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param iv
+     *         Initial vector.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(String key, String iv)
+    {
+        return setKey(key, iv, DEFAULT_KEY_SIZE);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], byte[], int)}.
+     * </p>
+     *
+     * @param key
+     *         Secret key. The value is converted to a byte array
+     *         by {@code key.getBytes("UTF-8")} and used as the
+     *         first argument of {@link #setKey(byte[], byte[], int)}.
+     *
+     * @param iv
+     *         Initial vector. The value is converted to a byte array
+     *         by {@code iv.getBytes("UTF-8")} and used as the
+     *         second argument of {@link #setKey(byte[], byte[], int)}.
+     *
+     * @param keySize
+     *         The size of the secret key in bytes.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(String key, String iv, int keySize)
+    {
+        byte[] key2 = Utils.getBytesUTF8(key);
+        byte[] iv2  = Utils.getBytesUTF8(iv);
+
+        return setKey(key2, iv2, keySize);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(String, int)
+     * setKey}<code>(key, {@link #DEFAULT_KEY_SIZE})</code>
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(String key)
+    {
+        return setKey(key, DEFAULT_KEY_SIZE);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], byte[], int)}.
+     * </p>
+     *
+     * @param key
+     *         Secret key. The value is converted to a byte array
+     *         by {@code key.getBytes("UTF-8")} and used as the
+     *         first argument of {@link #setKey(byte[], byte[], int)}.
+     *
+     * @param keySize
+     *         The size of the secret key in bytes.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(String key, int keySize)
+    {
+        byte[] key2 = Utils.getBytesUTF8(key);
+
+        return setKey(key2, (byte[])null, keySize);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], String, int)
+     * setKey}<code>(key, iv, {@link #DEFAULT_KEY_SIZE})</code>.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param iv
+     *         Initial vector.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(byte[] key, String iv)
+    {
+        return setKey(key, iv, DEFAULT_KEY_SIZE);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], byte[], int)}.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param iv
+     *         Initial vector. The value is converted to a byte array
+     *         by {@code iv.getBytes("UTF-8")} and used as the
+     *         second argument of {@link #setKey(byte[], byte[], int)}.
+     *
+     * @param keySize
+     *         The size of the secret key in bytes.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(byte[] key, String iv, int keySize)
+    {
+        byte[] iv2 = Utils.getBytesUTF8(iv);
+
+        return setKey(key, iv2, keySize);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], int)
+     * setKey}<code>(key, {@link #DEFAULT_KEY_SIZE})</code>.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(byte[] key)
+    {
+        return setKey(key, DEFAULT_KEY_SIZE);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * This method is an alias of {@link #setKey(byte[], byte[], int)
+     * setKey}<code>(key, (byte[])null, keySize)</code>.
+     * </p>
+     *
+     * @param key
+     *         Secret key.
+     *
+     * @param keySize
+     *         The size of the secret key in bytes.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public AESCipher setKey(byte[] key, int keySize)
+    {
+        return setKey(key, (byte[])null, keySize);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/authlete/common/util/security/CodecCipher.java b/src/main/java/com/authlete/common/util/security/CodecCipher.java
new file mode 100644
index 0000000000..06739d7582
--- /dev/null
+++ b/src/main/java/com/authlete/common/util/security/CodecCipher.java
@@ -0,0 +1,1209 @@
+package com.authlete.common.util.security;
+
+
+import java.security.AlgorithmParameters;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.Key;
+import java.security.Provider;
+import java.security.SecureRandom;
+import java.security.cert.Certificate;
+import java.security.spec.AlgorithmParameterSpec;
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import org.apache.commons.codec.BinaryDecoder;
+import org.apache.commons.codec.BinaryEncoder;
+import org.apache.commons.codec.DecoderException;
+import org.apache.commons.codec.EncoderException;
+import org.apache.commons.codec.binary.Base64;
+
+
+/**
+ * Cipher with encoder and decoder.
+ *
+ * <pre style="background-color: #EEEEEE; margin-left: 2em; margin-right: 2em; border: 1px solid black; padding: 0.5em;">
+ * <span style="color: darkgreen;">// This example shows encryption/decryption using "AES/CBC/PKCS5Padding",
+ * // but {@link AESCipher <span style="color: darkgreen;">AESCipher</span>} is much easier to use for "AES/CBC/PKCS5Padding".
+ *
+ * // Prepare cipher initialization parameters.</span>
+ * Key key
+ *     = new SecretKeySpec(<span style="color: darkred;">"1234567890123456"</span>.getBytes(<span style="color: darkred;">"UTF-8"</span>), <span style="color: darkred;">"AES"</span>);
+ * AlgorithmParameterSpec spec
+ *     = new IvParameterSpec(<span style="color: darkred;">"abcdefghijklmnop"</span>.getBytes(<span style="color: darkred;">"UTF-8"</span>));
+ *
+ * <span style="color: darkgreen;">// Create a cipher using "AES/CBC/PKCS5Padding".</span>
+ * String transformation = {@link StandardCipherTransformations}.{@link StandardCipherTransformations#AES_CBC_PKCS5PADDING AES_CBC_PKCS5PADDING};
+ * CodecCipher cipher = new {@link #CodecCipher(String) CodecCipher(transformation)};
+ *
+ * <span style="color: darkgreen;">// Set initialization parameters.</span>
+ * cipher.{@link #setInit(Key, AlgorithmParameterSpec) setInit(key, spec)};
+ *
+ * <span style="color: darkgreen;">// Encryption &amp; decryption.
+ * // 'plaintext' and 'decrypted' have the same value.</span>
+ * String plaintext = <span style="color: darkred;">"plain text"</span>;
+ * String encrypted = cipher.{@link #encrypt(String) encrypt(plaintext)};
+ * String decrypted = cipher.{@link #decrypt(String) decrypt(encrypted)};
+ *
+ * <span style="color: darkgreen;">// In the above example, 'encrypted' is encoded by Base64 (default).
+ * // If you want to change the format, use {@code setCoder} method.
+ * // For example, to change the format to hexadecimal:</span>
+ * Hex hex = new org.apache.commons.codec.binary.Hex();
+ * cipher.setCoder(hex);
+ *
+ * <span style="color: darkgreen;">// Binary representation (only "0"s and "1"s) also can be used.</span>
+ * BinaryCodec binary = new org.apache.commons.codec.BinaryCodec();
+ * cipher.setCoder(binary);
+ *
+ * <span style="color: darkgreen;">// Coder can be specified as a parameter of some constructors.</span>
+ * cipher = new CodecCipher(<span style="color: darkred;">"AES/CBC/PKCS5Padding"</span>, hex);
+ *
+ * <span style="color: darkgreen;">// If you want, an encoder and a decoder can be set separately.</span>
+ * cipher.{@link #setEncoder(BinaryEncoder) setEncoder(hex)};
+ * cipher.{@link #setDecoder(BinaryDecoder) setDecoder(hex)};
+ * </pre>
+ *
+ * @see <a href="http://docs.oracle.com/javase/7/docs/api/javax/crypto/Cipher.html"
+ *      >javax.crypto.Cipher</a>
+ *
+ * @author Takahiko Kawasaki
+ * @since 4.23
+ */
+public class CodecCipher
+{
+    private static final Base64 DEFAULT_CODER = new Base64();
+
+    private Cipher cipher;
+    private BinaryEncoder encoder;
+    private BinaryDecoder decoder;
+    private Key key;
+    private AlgorithmParameters params;
+    private AlgorithmParameterSpec spec;
+    private Certificate certificate;
+    private SecureRandom random;
+
+
+    /**
+     * The default constructor.
+     */
+    public CodecCipher()
+    {
+    }
+
+
+    /**
+     * Constructor with a cipher, an encoder and a decoder.
+     *
+     * @param cipher
+     *         A cipher. If {@code null} is given, {@link #setCipher(Cipher)}
+     *         must be called later with a valid cipher.
+     *
+     * @param encoder
+     *         An encoder used in {@link #encrypt(String)} and
+     *         {@link #encrypt(byte[])} to encode an encrypted byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         encoder.
+     *
+     * @param decoder
+     *         A decoder used in {@link #decrypt(String)} and
+     *         {@link #decrypt(byte[])} to decode an encoded input byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         decoder.
+     */
+    public CodecCipher(Cipher cipher, BinaryEncoder encoder, BinaryDecoder decoder)
+    {
+        this.cipher  = cipher;
+        this.encoder = encoder;
+        this.decoder = decoder;
+    }
+
+
+    /**
+     * Constructor with a cipher and a coder.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(Cipher, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(cipher, coder, coder)}.
+     * </p>
+     *
+     * @param cipher
+     *         A cipher. If {@code null} is given, {@link #setCipher(Cipher)}
+     *         must be called later with a valid cipher.
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> CodecCipher(Cipher cipher, TCoder coder)
+    {
+        this(cipher, coder, coder);
+    }
+
+
+    /**
+     * Constructor with a cipher.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(Cipher, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(cipher, (BinaryEncoder)null, (BinaryDecoder)null)}.
+     * </p>
+     *
+     * @param cipher
+     *         A cipher. If {@code null} is given, {@link #setCipher(Cipher)}
+     *         must be called later with a valid cipher.
+     */
+    public CodecCipher(Cipher cipher)
+    {
+        this(cipher, (BinaryEncoder)null, (BinaryDecoder)null);
+    }
+
+
+    /**
+     * Constructor with a transformation, an encoder and a decoder.
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param encoder
+     *         An encoder used in {@link #encrypt(String)} and
+     *         {@link #encrypt(byte[])} to encode an encrypted byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         encoder.
+     *
+     * @param decoder
+     *         A decoder used in {@link #decrypt(String)} and
+     *         {@link #decrypt(byte[])} to decode an encoded input byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         decoder.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException} and {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public CodecCipher(String transformation, BinaryEncoder encoder, BinaryDecoder decoder) throws IllegalArgumentException
+    {
+        this(getCipherInstance(transformation), encoder, decoder);
+    }
+
+
+    /**
+     * Constructor with a transformation and a coder.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(String, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(transformation, coder, coder)}.
+     * </p>
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException} and {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> CodecCipher(String transformation, TCoder coder) throws IllegalArgumentException
+    {
+        this(transformation, coder, coder);
+    }
+
+
+    /**
+     * Constructor with a transformation.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(String, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(transformation, (BinaryEncoder)null, (BinaryDecoder)null)}.
+     * </p>
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException} and {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> CodecCipher(String transformation) throws IllegalArgumentException
+    {
+        this(transformation, (BinaryEncoder)null, (BinaryDecoder)null);
+    }
+
+
+    /**
+     * Constructor with a transformation, a provider, an encoder and a decoder.
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param provider
+     *         A name of provider which provides the implementation of the
+     *         transformation.
+     *
+     * @param encoder
+     *         An encoder used in {@link #encrypt(String)} and
+     *         {@link #encrypt(byte[])} to encode an encrypted byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         encoder.
+     *
+     * @param decoder
+     *         A decoder used in {@link #decrypt(String)} and
+     *         {@link #decrypt(byte[])} to decode an encoded input byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         decoder.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException}, {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException} and {@link java.security.NoSuchProviderException
+     *         NoSuchProviderException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public CodecCipher(String transformation, String provider, BinaryEncoder encoder, BinaryDecoder decoder) throws IllegalArgumentException
+    {
+        this(getCipherInstance(transformation, provider), encoder, decoder);
+    }
+
+
+    /**
+     * Constructor with a transformation, a provider and a coder.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(String, String, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(transformation, provider, coder, coder)}.
+     * </p>
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param provider
+     *         A name of provider which provides the implementation of the
+     *         transformation.
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException}, {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException} and {@link java.security.NoSuchProviderException
+     *         NoSuchProviderException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> CodecCipher(String transformation, String provider, TCoder coder) throws IllegalArgumentException
+    {
+        this(transformation, provider, coder, coder);
+    }
+
+
+    /**
+     * Constructor with a transformation and a provider.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(String, String, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(transformation, provider, (BinaryEncoder)null, (BinaryDecoder)null)}.
+     * </p>
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param provider
+     *         A name of provider which provides the implementation of the
+     *         transformation.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException}, {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException} and {@link java.security.NoSuchProviderException
+     *         NoSuchProviderException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public CodecCipher(String transformation, String provider) throws IllegalArgumentException
+    {
+        this(transformation, provider, (BinaryEncoder)null, (BinaryDecoder)null);
+    }
+
+
+    /**
+     * Constructor with a transformation, a provider, an encoder and a decoder.
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param provider
+     *         A provider which provides the implementation of the transformation.
+     *
+     * @param encoder
+     *         An encoder used in {@link #encrypt(String)} and
+     *         {@link #encrypt(byte[])} to encode an encrypted byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         encoder.
+     *
+     * @param decoder
+     *         A decoder used in {@link #decrypt(String)} and
+     *         {@link #decrypt(byte[])} to decode an encoded input byte array.
+     *         If {@code null} is given, {@link Base64} is used as the default
+     *         decoder.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException} and {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public CodecCipher(String transformation, Provider provider, BinaryEncoder encoder, BinaryDecoder decoder) throws IllegalArgumentException
+    {
+        this(getCipherInstance(transformation, provider), encoder, decoder);
+    }
+
+
+    /**
+     * Constructor with a transformation, a provider and a coder.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(String, Provider, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(transformation, provider, coder, coder)}.
+     * </p>
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param provider
+     *         A provider which provides the implementation of the transformation.
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException} and {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> CodecCipher(String transformation, Provider provider, TCoder coder) throws IllegalArgumentException
+    {
+        this(transformation, provider, coder, coder);
+    }
+
+
+    /**
+     * Constructor with a transformation and a provider.
+     *
+     * <p>
+     * This constructor is an alias of {@link #CodecCipher(String, Provider, BinaryEncoder, BinaryDecoder)
+     * CodecCipher(transformation, provider, (BinaryEncoder)null, (BinaryDecoder)null)}.
+     * </p>
+     *
+     * @param transformation
+     *         A transformation in the form of either <code>"<i>algorithm/mode/padding</i>"</code>
+     *         or <code>"<i>algorithm</i>"</code>. For example, <code>"AES/CBC/PKCS5Padding"</code>.
+     *
+     * @param provider
+     *         A provider which provides the implementation of the transformation.
+     *
+     * @throws IllegalArgumentException
+     *         The given transformation is not supported. This exception wraps
+     *         the original exception (such as {@link java.security.NoSuchAlgorithmException
+     *         NoSuchAlgorithmException} and {@link javax.crypto.NoSuchPaddingException
+     *         NoSuchPaddingException}) as the cause.
+     *
+     * @see <a href="http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Cipher"
+     *      >Cipher (Encryption) Algorithms</a>
+     *
+     * @see StandardCipherTransformations
+     */
+    public CodecCipher(String transformation, Provider provider) throws IllegalArgumentException
+    {
+        this(transformation, provider, (BinaryEncoder)null, (BinaryDecoder)null);
+    }
+
+
+    /**
+     * Create a {@link Cipher} instance by {@link Cipher#getInstance(String)
+     * Cipher.getInstance(transformation)}.
+     */
+    private static Cipher getCipherInstance(String transformation) throws IllegalArgumentException
+    {
+        try
+        {
+            return Cipher.getInstance(transformation);
+        }
+        catch (Exception e)
+        {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+
+    /**
+     * Create a {@link Cipher} instance by {@link Cipher#getInstance(String, String)
+     * Cipher.getInstance(transformation, provider)}.
+     */
+    private static Cipher getCipherInstance(String transformation, String provider)
+    {
+        try
+        {
+            return Cipher.getInstance(transformation, provider);
+        }
+        catch (Exception e)
+        {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+
+    /**
+     * Create a {@link Cipher} instance by {@link Cipher#getInstance(String, Provider)
+     * Cipher.getInstance(transformation, provider)}.
+     */
+    private static Cipher getCipherInstance(String transformation, Provider provider)
+    {
+        try
+        {
+            return Cipher.getInstance(transformation, provider);
+        }
+        catch (Exception e)
+        {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+
+    /**
+     * Get the cipher which this instance internally holds.
+     *
+     * @return
+     *         The {@link Cipher} instance.
+     */
+    public Cipher getCipher()
+    {
+        return cipher;
+    }
+
+
+    /**
+     * Set a cipher instance.
+     *
+     * @param cipher
+     *         A cipher instance.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CodecCipher setCipher(Cipher cipher)
+    {
+        if (cipher == null)
+        {
+            throw new IllegalArgumentException("cipher is null.");
+        }
+
+        this.cipher = cipher;
+
+        return this;
+    }
+
+
+    /**
+     * Get the cipher algorithm name.
+     *
+     * <p>
+     * If the internal cipher is {@code null}, {@code null} is returned.
+     * Otherwise, the algorithm part of the cipher's transformation is
+     * returned.
+     * </p>
+     *
+     * @return
+     *         The cipher algorithm name.
+     */
+    public String getAlgorithm()
+    {
+        if (cipher == null)
+        {
+            return null;
+        }
+
+        String transformation = cipher.getAlgorithm();
+
+        if (transformation == null)
+        {
+            return null;
+        }
+
+        // Separator position.
+        int pos = transformation.indexOf('/');
+
+        if (pos < 0)
+        {
+            return transformation;
+        }
+
+        return transformation.substring(0, pos);
+    }
+
+
+    /**
+     * Get the encoder which this instance internally holds.
+     *
+     * @return
+     *         The internal encoder. This may be {@code null}, and
+     *         in such a case, {@link #encrypt(String)} and
+     *         {@link #encrypt(byte[])} use {@link Base64}.
+     */
+    public BinaryEncoder getEncoder()
+    {
+        return encoder;
+    }
+
+
+    /**
+     * Set an encoder.
+     *
+     * @param encoder
+     *         An encoder used by {@link #encrypt(String)} and
+     *         {@link #encrypt(byte[])}.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CodecCipher setEncoder(BinaryEncoder encoder)
+    {
+        this.encoder = encoder;
+
+        return this;
+    }
+
+
+    /**
+     * Get the decoder which this instance internally holds.
+     *
+     * @return
+     *         The internal decoder. This may be {@code null}, and
+     *         in such a case, {@link #decrypt(String)} and
+     *         {@link #decrypt(byte[])} use {@link Base64}.
+     */
+    public BinaryDecoder getDecoder()
+    {
+        return decoder;
+    }
+
+
+    /**
+     * Set a decoder.
+     *
+     * @param decoder
+     *         A decoder used by {@link #decrypt(String)} and
+     *         {@link #decrypt(byte[])}.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public CodecCipher setDecoder(BinaryDecoder decoder)
+    {
+        this.decoder = decoder;
+
+        return this;
+    }
+
+
+    /**
+     * Set a coder.
+     *
+     * @param coder
+     *         A coder which works as both an encoder and a decoder.
+     *         If {@code null} is given, {@link Base64} is used as the
+     *         default coder.
+     *
+     * @return
+     *         {@code this} object.
+     */
+    public <TCoder extends BinaryEncoder & BinaryDecoder> CodecCipher setCoder(TCoder coder)
+    {
+        this.encoder = coder;
+        this.decoder = coder;
+
+        return this;
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Key) Cipher.init(mode, (Key)key)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param key
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public CodecCipher setInit(Key key) throws IllegalArgumentException
+    {
+        return setInit(key, null, null, null);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Key, SecureRandom)
+     * Cipher.init(mode, (Key)key, (SecureRandom)random)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param key
+     *
+     * @param random
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public CodecCipher setInit(Key key, SecureRandom random) throws IllegalArgumentException
+    {
+        return setInit(key, null, null, random);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Key, AlgorithmParameters)
+     * Cipher.init(mode, (Key)key, (AlgorithmParameters)params)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param key
+     *
+     * @param params
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public CodecCipher setInit(Key key, AlgorithmParameters params) throws IllegalArgumentException
+    {
+        return setInit(key, params, null, null);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Key, AlgorithmParameters, SecureRandom)
+     * Cipher.init(mode, (Key)key, (AlgorithmParameters)params, (SecureRandom)random)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param key
+     *
+     * @param params
+     *
+     * @param random
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public CodecCipher setInit(Key key, AlgorithmParameters params, SecureRandom random) throws IllegalArgumentException
+    {
+        return setInit(key, params, null, random);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Key, AlgorithmParameterSpec)
+     * Cipher.init(mode, (Key)key, (AlgorithmParameterSpec)spec)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param key
+     *
+     * @param spec
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public CodecCipher setInit(Key key, AlgorithmParameterSpec spec) throws IllegalArgumentException
+    {
+        return setInit(key, null, spec, null);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Key, AlgorithmParameterSpec, SecureRandom)
+     * Cipher.init(mode, (Key)key, (AlgorithmParameterSpec)spec, (SecureRandom)random)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param key
+     *
+     * @param spec
+     *
+     * @param random
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code key} is {@code null}.
+     */
+    public CodecCipher setInit(Key key, AlgorithmParameterSpec spec, SecureRandom random) throws IllegalArgumentException
+    {
+        return setInit(key, null, spec, random);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Certificate)
+     * Cipher.init(mode, (Certificate)certificate)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param certificate
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code certificate} is {@code null}.
+     */
+    public CodecCipher setInit(Certificate certificate) throws IllegalArgumentException
+    {
+        return setInit(certificate, null);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     *
+     * <p>
+     * If this method is used to set initialization parameters,
+     * {@link Cipher#init(int, Certificate, SecureRandom)
+     * Cipher.init(mode, (Certificate)certificate, (SecureRandom)random)}
+     * is called later from within {@code encrypt}/{@code decrypt} methods.
+     * </p>
+     *
+     * @param certificate
+     *
+     * @param random
+     *
+     * @return
+     *         {@code this} object.
+     *
+     * @throws IllegalArgumentException
+     *         {@code certificate} is {@code null}.
+     */
+    public CodecCipher setInit(Certificate certificate, SecureRandom random) throws IllegalArgumentException
+    {
+        if (certificate == null)
+        {
+            throw new IllegalArgumentException("certificate is null.");
+        }
+
+        return setInit(null, null, null, certificate, random);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     */
+    private CodecCipher setInit(Key key, AlgorithmParameters params, AlgorithmParameterSpec spec, SecureRandom random)
+    {
+        if (key == null)
+        {
+            throw new IllegalArgumentException("key is null.");
+        }
+
+        return setInit(key, params, spec, null, random);
+    }
+
+
+    /**
+     * Set cipher initialization parameters.
+     */
+    private CodecCipher setInit(Key key, AlgorithmParameters params, AlgorithmParameterSpec spec, Certificate certificate, SecureRandom random)
+    {
+        this.key         = key;
+        this.params      = params;
+        this.spec        = spec;
+        this.certificate = certificate;
+        this.random      = random;
+
+        return this;
+    }
+
+
+    /**
+     * Encrypt the given string.
+     *
+     * @param input
+     *         Plain text before encryption.
+     *
+     * @return
+     *         Encrypted string encoded by the encoder.
+     *         If {@code input} is {@code null}, {@code null} is returned.
+     *
+     * @throws IllegalStateException
+     *         Failed to encrypt the input. The {@code IllegalStateException}
+     *         wraps the original exception (such as {@link InvalidKeyException}
+     *         and {@link EncoderException}) as the cause, if any.
+     *         <ul>
+     *         <li>A cipher instance has not been set.
+     *         <li>{@code setInit} method has not been called.
+     *         <li>The cipher failed to encrypt the input (probably initialization
+     *             parameters set by {@code setInit} method are wrong).
+     *         <li>The encoder failed to encode the encrypted byte array.
+     *         </ul>
+     */
+    public String encrypt(String input) throws IllegalStateException
+    {
+        return cipher(input, Cipher.ENCRYPT_MODE);
+    }
+
+
+    /**
+     * Decrypt the given string.
+     *
+     * @param input
+     *         Encrypted string encoded by an encoder.
+     *
+     * @return
+     *         Decrypted plain text.
+     *         If {@code input} is {@code null}, {@code null} is returned.
+     *
+     * @throws IllegalStateException
+     *         Failed to decrypt the input. The {@code IllegalStateException}
+     *         wraps the original exception (such as {@link InvalidKeyException}
+     *         and {@link DecoderException}) as the cause, if any.
+     *         <ul>
+     *         <li>A cipher instance has not been set.
+     *         <li>{@code setInit} method has not been called.
+     *         <li>The decoder failed to decode the input.
+     *         <li>The cipher failed to decrypt the byte array (probably initialization
+     *             parameters set by {@code setInit} method are wrong).
+     *         </ul>
+     */
+    public String decrypt(String input) throws IllegalStateException
+    {
+        return cipher(input, Cipher.DECRYPT_MODE);
+    }
+
+
+    /**
+     * Encrypt the given byte array.
+     *
+     * @param input
+     *         Plain byte array before encryption.
+     *
+     * @return
+     *         Encrypted byte array encoded by the encoder.
+     *         If {@code input} is {@code null}, {@code null} is returned.
+     *
+     * @throws IllegalStateException
+     *         Failed to encrypt the input. The {@code IllegalStateException}
+     *         wraps the original exception (such as {@link InvalidKeyException}
+     *         and {@link EncoderException}) as the cause, if any.
+     *         <ul>
+     *         <li>A cipher instance has not been set.
+     *         <li>{@code setInit} method has not been called.
+     *         <li>The cipher failed to encrypt the input (probably initialization
+     *             parameters set by {@code setInit} method are wrong).
+     *         <li>The encoder failed to encode the encrypted byte array.
+     *         </ul>
+     */
+    public byte[] encrypt(byte[] input) throws IllegalStateException
+    {
+        return cipher(input, Cipher.ENCRYPT_MODE);
+    }
+
+
+    /**
+     * Decrypt the given byte array.
+     *
+     * @param input
+     *         Encrypted byte array encoded by an encoder.
+     *
+     * @return
+     *         Decrypted plain byte array.
+     *         If {@code input} is {@code null}, {@code null} is returned.
+     *
+     * @throws IllegalStateException
+     *         Failed to decrypt the input. The {@code IllegalStateException}
+     *         wraps the original exception (such as {@link InvalidKeyException}
+     *         and {@link DecoderException}) as the cause, if any.
+     *         <ul>
+     *         <li>A cipher instance has not been set.
+     *         <li>{@code setInit} method has not been called.
+     *         <li>The decoder failed to decode the input.
+     *         <li>The cipher failed to decrypt the byte array (probably initialization
+     *             parameters set by {@code setInit} method are wrong).
+     *         </ul>
+     */
+    public byte[] decrypt(byte[] input) throws IllegalStateException
+    {
+        return cipher(input, Cipher.DECRYPT_MODE);
+    }
+
+
+    /**
+     * Encrypt or decrypt.
+     */
+    private String cipher(String input, int mode)
+    {
+        if (input == null)
+        {
+            return null;
+        }
+
+        // Convert the input string into a byte array.
+        byte[] inputBytes = Utils.getBytesUTF8(input);
+
+        // Encrypt or decrypt.
+        byte[] outputBytes = cipher(inputBytes, mode);
+
+        // Build a string from the byte array.
+        return Utils.toStringUTF8(outputBytes);
+    }
+
+
+    /**
+     * Encrypt or decrypt.
+     */
+    private byte[] cipher(byte[] input, int mode)
+    {
+        try
+        {
+            return doCipher(input, mode);
+        }
+        catch (Exception e)
+        {
+            throw new IllegalStateException(e);
+        }
+    }
+
+
+    /**
+     * Encrypt or decrypt.
+     */
+    private byte[] doCipher(byte[] input, int mode) throws
+            DecoderException, InvalidKeyException, InvalidAlgorithmParameterException,
+            IllegalBlockSizeException, BadPaddingException, EncoderException
+    {
+        if (input == null)
+        {
+            return null;
+        }
+
+        if (cipher == null)
+        {
+            throw new IllegalStateException("setCipher() has not been called.");
+        }
+
+        if (key == null && certificate == null)
+        {
+            throw new IllegalStateException("setInit() has not been called.");
+        }
+
+        if (mode == Cipher.DECRYPT_MODE)
+        {
+            input = decode(input);
+        }
+
+        initCipher(mode);
+
+        byte[] output = cipher.doFinal(input);
+
+        if (mode == Cipher.ENCRYPT_MODE)
+        {
+            output = encode(output);
+        }
+
+        return output;
+    }
+
+
+    /**
+     * Initialize {@link cipher} by calling one of {@code Cipher.init} methods
+     * using {@code mode} and one or some of {@link #key}, {@link #params},
+     * {@link #spec}, {@link #certificate} and {@link #random}.
+     */
+    private void initCipher(int mode) throws InvalidKeyException, InvalidAlgorithmParameterException
+    {
+        if (key != null)
+        {
+            if (params != null)
+            {
+                if (random != null)
+                {
+                    cipher.init(mode, key, params, random);
+                }
+                else
+                {
+                    cipher.init(mode, key, params);
+                }
+            }
+            else if (spec != null)
+            {
+                if (random != null)
+                {
+                    cipher.init(mode, key, spec, random);
+                }
+                else
+                {
+                    cipher.init(mode, key, spec);
+                }
+            }
+            else
+            {
+                if (random != null)
+                {
+                    cipher.init(mode, key, random);
+                }
+                else
+                {
+                    cipher.init(mode, key);
+                }
+            }
+        }
+        else
+        {
+            if (random != null)
+            {
+                cipher.init(mode, certificate, random);
+            }
+            else
+            {
+                cipher.init(mode, certificate);
+            }
+        }
+    }
+
+
+    /**
+     * Encode the byte array using {@link #encoder}, or using
+     * {@link #DEFAULT_CODER} if {@code encoder} is {@code null}.
+     */
+    private byte[] encode(byte[] input) throws EncoderException
+    {
+        if (encoder != null)
+        {
+            return encoder.encode(input);
+        }
+        else
+        {
+            return DEFAULT_CODER.encode(input);
+        }
+    }
+
+
+    /**
+     * Decode the byte array using {@link #decoder}, or using
+     * {@link #DEFAULT_CODER} if {@code decoder} is {@code null}.
+     */
+    private byte[] decode(byte[] input) throws DecoderException
+    {
+        if (decoder != null)
+        {
+            return decoder.decode(input);
+        }
+        else
+        {
+            return DEFAULT_CODER.decode(input);
+        }
+    }
+}
diff --git a/src/main/java/com/authlete/common/util/security/StandardCipherTransformations.java b/src/main/java/com/authlete/common/util/security/StandardCipherTransformations.java
new file mode 100644
index 0000000000..1489f5ae09
--- /dev/null
+++ b/src/main/java/com/authlete/common/util/security/StandardCipherTransformations.java
@@ -0,0 +1,114 @@
+package com.authlete.common.util.security;
+
+
+/**
+ * List of standard cipher transformations which are valid as
+ * arguments for {@link javax.crypto.Cipher#getInstance(String)}.
+ *
+ * <p>
+ * The list here is a copy from Java SE 7 JavaDoc. Therefore,
+ * they may not be supported in older Java SE environments.
+ * </p>
+ *
+ * @see <a href="http://docs.oracle.com/javase/7/docs/api/javax/crypto/Cipher.html"
+ *      >javax.crypto.Cipher</a>
+ *
+ * @author Takahiko Kawasaki
+ * @since 4.23
+ */
+public class StandardCipherTransformations
+{
+    /**
+     * AES/CBC/NoPadding (128)
+     */
+    public static final String AES_CBC_NOPADDING = "AES/CBC/NoPadding";
+
+
+    /**
+     * AES/CBC/PKCS5Padding (128)
+     */
+    public static final String AES_CBC_PKCS5PADDING = "AES/CBC/PKCS5Padding";
+
+
+    /**
+     * AES/ECB/NoPadding (128)
+     */
+    public static final String AES_ECB_NOPADDING = "AES/ECB/NoPadding";
+
+
+    /**
+     * AES/ECB/PKCS5Padding (128)
+     */
+    public static final String AES_ECB_PKCS5PADDING = "AES/ECB/PKCS5Padding";
+
+
+    /**
+     * DES/CBC/NoPadding (56)
+     */
+    public static final String DES_CBC_NOPADDING = "DES/CBC/NoPadding";
+
+
+    /**
+     * DES/CBC/PKCS5Padding (56)
+     */
+    public static final String DES_CBC_PKCS5PADDING = "DES/CBC/PKCS5Padding";
+
+
+    /**
+     * DES/ECB/NoPadding (56)
+     */
+    public static final String DES_ECB_NOPADDING = "DES/ECB/NoPadding";
+
+
+    /**
+     * DES/ECB/PKCS5Padding (56)
+     */
+    public static final String DES_ECB_PKCS5PADDING = "DES/ECB/PKCS5Padding";
+
+
+    /**
+     * DESede/CBC/NoPadding (168)
+     */
+    public static final String DESEDE_CBC_NOPADDING = "DESede/CBC/NoPadding";
+
+
+    /**
+     * DESede/CBC/PKCS5Padding (168)
+     */
+    public static final String DESEDE_CBC_PKCS5PADDING = "DESede/CBC/PKCS5Padding";
+
+
+    /**
+     * DESede/ECB/NoPadding (168)
+     */
+    public static final String DESEDE_ECB_NOPADDING = "DESede/ECB/NoPadding";
+
+
+    /**
+     * DESede/ECB/PKCS5Padding (168)
+     */
+    public static final String DESEDE_ECB_PKCS5PADDING = "DESede/ECB/PKCS5Padding";
+
+
+    /**
+     * RSA/ECB/PKCS1Padding (1024, 2048)
+     */
+    public static final String RSA_ECB_PKCS1PADDING = "RSA/ECB/PKCS1Padding";
+
+
+    /**
+     * RSA/ECB/OAEPWithSHA-1AndMGF1Padding (1024, 2048)
+     */
+    public static final String RSA_ECB_OAEPWITHSHA1ANDMGF1PADDING = "RSA/ECB/OAEPWithSHA-1AndMGF1Padding";
+
+
+    /**
+     * RSA/ECB/OAEPWithSHA-256AndMGF1Padding (1024, 2048)
+     */
+    public static final String RSA_ECB_OAEPWITHSHA256ANDMGF1PADDING = "RSA/ECB/OAEPWithSHA-256AndMGF1Padding";
+
+
+    private StandardCipherTransformations()
+    {
+    }
+}
diff --git a/src/main/java/com/authlete/common/util/security/Utils.java b/src/main/java/com/authlete/common/util/security/Utils.java
new file mode 100644
index 0000000000..9977d45a92
--- /dev/null
+++ b/src/main/java/com/authlete/common/util/security/Utils.java
@@ -0,0 +1,113 @@
+package com.authlete.common.util.security;
+
+
+import java.io.UnsupportedEncodingException;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+
+/**
+ * Utility methods for internal implementation.
+ *
+ * @author Takahiko Kawasaki
+ * @since 4.23
+ */
+class Utils
+{
+    private Utils()
+    {
+    }
+
+
+    /**
+     * Get bytes by {@code input.getBytes("UTF-8")}.
+     */
+    public static byte[] getBytesUTF8(String string)
+    {
+        if (string == null)
+        {
+            return null;
+        }
+
+        try
+        {
+            // Convert the string to a byte array encoded in UTF-8.
+            return string.getBytes("UTF-8");
+        }
+        catch (UnsupportedEncodingException e)
+        {
+            // This won't happen.
+            return null;
+        }
+    }
+
+
+    /**
+     * Build a {@code String} instance by {@code new String(input, "UTF-8")}.
+     */
+    public static String toStringUTF8(byte[] input)
+    {
+        if (input == null)
+        {
+            return null;
+        }
+
+        try
+        {
+            return new String(input, "UTF-8");
+        }
+        catch (UnsupportedEncodingException e)
+        {
+            // This won't happen.
+            return null;
+        }
+    }
+
+
+    public static byte[] ensureSize(byte[] data, int size)
+    {
+        if (data == null)
+        {
+            return new byte[size];
+        }
+
+        if (size <= data.length)
+        {
+            return data;
+        }
+
+        byte[] data2 = new byte[size];
+
+        System.arraycopy(data, 0, data2, 0, data.length);
+
+        return data2;
+    }
+
+
+    public static SecretKeySpec createSecretKeySpec(String key, String algorithm, int size)
+    {
+        return createSecretKeySpec(getBytesUTF8(key), algorithm, size);
+    }
+
+
+    public static SecretKeySpec createSecretKeySpec(byte[] key, String algorithm, int size)
+    {
+        key = ensureSize(key, size);
+
+        return new SecretKeySpec(key, 0, size, algorithm);
+    }
+
+
+    public static IvParameterSpec createIvParameterSpec(String iv, int size)
+    {
+        return createIvParameterSpec(getBytesUTF8(iv), size);
+    }
+
+
+    public static IvParameterSpec createIvParameterSpec(byte[] iv, int size)
+    {
+        iv = ensureSize(iv, size);
+
+        return new IvParameterSpec(iv, 0, size);
+    }
+}
diff --git a/src/test/java/com/authlete/common/api/AccessRightTest.java b/src/test/java/com/authlete/common/api/AccessRightTest.java
new file mode 100644
index 0000000000..5ef8a6161a
--- /dev/null
+++ b/src/test/java/com/authlete/common/api/AccessRightTest.java
@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2026 Authlete, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.authlete.common.api;
+
+
+import static com.authlete.common.api.AccessRight.*;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import org.junit.Test;
+
+
+public class AccessRightTest
+{
+    private static final long SERVICE_ID = 1L;
+    private static final long CLIENT_ID = 2L;
+    private static final long NONE = 0L;
+
+
+    // --- canDo: identity ---
+
+    @Test
+    public void testCanDoSelf()
+    {
+        assertTrue(USE_INTROSPECTION.canDo(NONE, SERVICE_ID, USE_INTROSPECTION));
+        assertTrue(USE_SERVICE.canDo(NONE, SERVICE_ID, USE_SERVICE));
+        assertTrue(MODIFY_SERVICE.canDo(NONE, SERVICE_ID, MODIFY_SERVICE));
+        assertTrue(CREATE_CLIENT.canDo(NONE, SERVICE_ID, CREATE_CLIENT));
+        assertTrue(ADMIN.canDo(NONE, NONE, ADMIN));
+    }
+
+
+    // --- canDo: USE_INTROSPECTION subsumption ---
+
+    @Test
+    public void testUseServiceIncludesUseIntrospection()
+    {
+        assertTrue(USE_SERVICE.canDo(NONE, SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testModifyServiceIncludesUseIntrospection()
+    {
+        assertTrue(MODIFY_SERVICE.canDo(NONE, SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testCreateClientIncludesUseIntrospection()
+    {
+        assertTrue(CREATE_CLIENT.canDo(NONE, SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testAdminIncludesUseIntrospection()
+    {
+        assertTrue(ADMIN.canDo(NONE, SERVICE_ID, USE_INTROSPECTION));
+    }
+
+
+    // --- canDo: VIEW_SERVICE subsumption ---
+
+    @Test
+    public void testUseServiceIncludesViewService()
+    {
+        assertTrue(USE_SERVICE.canDo(NONE, SERVICE_ID, VIEW_SERVICE));
+    }
+
+    @Test
+    public void testModifyServiceIncludesViewService()
+    {
+        assertTrue(MODIFY_SERVICE.canDo(NONE, SERVICE_ID, VIEW_SERVICE));
+    }
+
+    @Test
+    public void testCreateClientIncludesViewService()
+    {
+        assertTrue(CREATE_CLIENT.canDo(NONE, SERVICE_ID, VIEW_SERVICE));
+    }
+
+
+    // --- canDo: missing service/client IDs ---
+
+    @Test
+    public void testServiceSpecificRequiresServiceId()
+    {
+        assertFalse(USE_INTROSPECTION.canDo(NONE, NONE, USE_INTROSPECTION));
+        assertFalse(USE_SERVICE.canDo(NONE, NONE, USE_SERVICE));
+        assertFalse(MODIFY_SERVICE.canDo(NONE, NONE, MODIFY_SERVICE));
+    }
+
+    @Test
+    public void testClientSpecificRequiresBoth()
+    {
+        assertFalse(VIEW_CLIENT.canDo(NONE, SERVICE_ID, VIEW_CLIENT));
+        assertFalse(VIEW_CLIENT.canDo(CLIENT_ID, NONE, VIEW_CLIENT));
+        assertTrue(VIEW_CLIENT.canDo(CLIENT_ID, SERVICE_ID, VIEW_CLIENT));
+    }
+
+
+    // --- canDo: no upward escalation ---
+
+    @Test
+    public void testUseIntrospectionDoesNotIncludeUseService()
+    {
+        assertFalse(USE_INTROSPECTION.canDo(NONE, SERVICE_ID, USE_SERVICE));
+    }
+
+    @Test
+    public void testViewServiceDoesNotIncludeModifyService()
+    {
+        assertFalse(VIEW_SERVICE.canDo(NONE, SERVICE_ID, MODIFY_SERVICE));
+    }
+
+    @Test
+    public void testUseServiceDoesNotIncludeModifyService()
+    {
+        assertFalse(USE_SERVICE.canDo(NONE, SERVICE_ID, MODIFY_SERVICE));
+    }
+
+
+    // --- canDoAny: USE_INTROSPECTION ---
+
+    @Test
+    public void testCanDoAnyUseServiceIncludesUseIntrospection()
+    {
+        assertTrue(USE_SERVICE.canDoAny(SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testCanDoAnyModifyServiceIncludesUseIntrospection()
+    {
+        assertTrue(MODIFY_SERVICE.canDoAny(SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testCanDoAnyCreateClientIncludesUseIntrospection()
+    {
+        assertTrue(CREATE_CLIENT.canDoAny(SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testCanDoAnyAdminIncludesUseIntrospection()
+    {
+        assertTrue(ADMIN.canDoAny(SERVICE_ID, USE_INTROSPECTION));
+    }
+
+    @Test
+    public void testCanDoAnyClientSpecificRequiresServiceId()
+    {
+        // VIEW_CLIENT is clientSpecific — canDoAny requires a serviceId in that case
+        assertFalse(VIEW_CLIENT.canDoAny(NONE, VIEW_CLIENT));
+        assertTrue(VIEW_CLIENT.canDoAny(SERVICE_ID, VIEW_CLIENT));
+    }
+}
diff --git a/src/test/java/com/authlete/common/assurance/VerifiedClaimsTest.java b/src/test/java/com/authlete/common/assurance/VerifiedClaimsTest.java
index 6cdd7dedbb..1d5defac96 100644
--- a/src/test/java/com/authlete/common/assurance/VerifiedClaimsTest.java
+++ b/src/test/java/com/authlete/common/assurance/VerifiedClaimsTest.java
@@ -21,9 +21,9 @@
 import java.io.IOException;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import com.authlete.common.util.digest.Digest;
 import org.junit.Test;
 import com.google.gson.Gson;
-import com.neovisionaries.security.Digest;
 
 
 public class VerifiedClaimsTest
diff --git a/src/test/java/com/authlete/common/assurance/constraint/VerifiedClaimsContainerConstraintTest.java b/src/test/java/com/authlete/common/assurance/constraint/VerifiedClaimsContainerConstraintTest.java
index a4f1263f7c..bd271178e6 100644
--- a/src/test/java/com/authlete/common/assurance/constraint/VerifiedClaimsContainerConstraintTest.java
+++ b/src/test/java/com/authlete/common/assurance/constraint/VerifiedClaimsContainerConstraintTest.java
@@ -19,19 +19,8 @@
 
 import static org.junit.Assert.*;
 import java.io.IOException;
+import com.authlete.common.util.digest.Digest;
 import org.junit.Test;
-import com.authlete.common.assurance.constraint.ClaimsConstraint;
-import com.authlete.common.assurance.constraint.EvidenceArrayConstraint;
-import com.authlete.common.assurance.constraint.EvidenceConstraint;
-import com.authlete.common.assurance.constraint.IDDocumentConstraint;
-import com.authlete.common.assurance.constraint.LeafConstraint;
-import com.authlete.common.assurance.constraint.QESConstraint;
-import com.authlete.common.assurance.constraint.TimeConstraint;
-import com.authlete.common.assurance.constraint.UtilityBillConstraint;
-import com.authlete.common.assurance.constraint.VerificationConstraint;
-import com.authlete.common.assurance.constraint.VerifiedClaimsConstraint;
-import com.authlete.common.assurance.constraint.VerifiedClaimsContainerConstraint;
-import com.neovisionaries.security.Digest;
 
 
 public class VerifiedClaimsContainerConstraintTest
diff --git a/src/test/java/com/authlete/common/dto/AuthzDetailsElementTest.java b/src/test/java/com/authlete/common/dto/AuthzDetailsElementTest.java
index 3210ed2af9..0db0d215a9 100644
--- a/src/test/java/com/authlete/common/dto/AuthzDetailsElementTest.java
+++ b/src/test/java/com/authlete/common/dto/AuthzDetailsElementTest.java
@@ -16,10 +16,10 @@
 package com.authlete.common.dto;
 
 
+import com.authlete.common.util.digest.Digest;
 import org.junit.Test;
 import com.google.gson.Gson;
 import com.google.gson.JsonParseException;
-import com.neovisionaries.security.Digest;
 import static org.junit.Assert.*;
 import java.io.IOException;
 import java.util.ArrayList;
diff --git a/src/test/java/com/authlete/common/dto/CredentialIssuerMetadataTest.java b/src/test/java/com/authlete/common/dto/CredentialIssuerMetadataTest.java
index 39b755295a..fc5eaf1f20 100644
--- a/src/test/java/com/authlete/common/dto/CredentialIssuerMetadataTest.java
+++ b/src/test/java/com/authlete/common/dto/CredentialIssuerMetadataTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2024 Authlete, Inc.
+ * Copyright (C) 2024-2025 Authlete, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,8 +19,11 @@
 import org.junit.Test;
 import com.authlete.common.types.JWEAlg;
 import com.authlete.common.types.JWEEnc;
+import com.authlete.common.types.JWEZip;
+import com.nimbusds.jose.jwk.JWK;
+import com.nimbusds.jose.jwk.JWKSet;
 import static org.junit.Assert.*;
-import java.net.URI;
+import java.text.ParseException;
 import java.util.List;
 import java.util.Map;
 
@@ -29,31 +32,87 @@ public class CredentialIssuerMetadataTest
 {
     @SuppressWarnings("unchecked")
     @Test
-    public void test_toMap()
+    public void test_toMap_request_encryption() throws ParseException
     {
-        URI      issuer = URI.create("https://example.com");
-        JWEAlg[] algs   = new JWEAlg[] { JWEAlg.ECDH_ES };
-        JWEEnc[] encs   = new JWEEnc[] { JWEEnc.A128CBC_HS256 };
+        String jwks =
+                "{\n"
+                + "  \"keys\": [\n"
+                + "    {\n"
+                + "      \"kty\": \"EC\",\n"
+                + "      \"crv\": \"P-256\",\n"
+                + "      \"x\": \"8fpkqvB9-NjASgqR4KnM9s1gjyaDZpYYp9E65c7glns\",\n"
+                + "      \"y\": \"SdbSFS314C2N415VQ7IaXkxHRH34aA32csKOs_JipSg\",\n"
+                + "      \"d\": \"gTVIUWvmYAW2WT_lOMiQGBK2BbRHOhew-sO5JBTCkp4\",\n"
+                + "      \"kid\": \"TxNdpxeiLUxuPXh_INadmBVkOqk77pmYLL7BthTpZsA\"\n"
+                + "    }\n"
+                + "  ]\n"
+                + "}\n"
+                + "";
+        JWEEnc[] encs = new JWEEnc[] { JWEEnc.A128CBC_HS256 };
+        JWEZip[] zips = new JWEZip[] { JWEZip.DEF };
+
+        CredentialIssuerMetadata metadata = new CredentialIssuerMetadata()
+                .setCredentialRequestEncryptionJwks(jwks)
+                .setCredentialRequestEncryptionEncValuesSupported(encs)
+                .setCredentialRequestEncryptionZipValuesSupported(zips)
+                .setRequireCredentialRequestEncryption(true)
+                ;
+
+        Map<String, Object> map = metadata.toMap();
+
+        // credential_request_encryption
+        Map<String, Object> encryption = (Map<String, Object>)map.get("credential_request_encryption");
+        assertNotNull(encryption);
+
+        // credential_request_encryption.jwks
+        Map<String, Object> publicJwks = (Map<String, Object>)encryption.get("jwks");
+
+        List<JWK> publicKeys = JWKSet.parse(publicJwks).getKeys();
+        assertEquals(1, publicKeys.size());
+
+        for (JWK key : publicKeys)
+        {
+            assertFalse("Keys in 'jwks' must not be private keys.", key.isPrivate());
+        }
+
+        // credential_request_encryption.enc_values_supported
+        List<String> encValues = (List<String>)encryption.get("enc_values_supported");
+        assertNotNull(encValues);
+        assertEquals(1, encValues.size());
+        assertEquals("A128CBC-HS256", encValues.get(0));
+
+        // credential_request_encryption.zip_values_supported
+        List<String> zipValues = (List<String>)encryption.get("zip_values_supported");
+        assertNotNull(zipValues);
+        assertEquals(1, zipValues.size());
+        assertEquals("DEF", zipValues.get(0));
+
+        // credential_request_encryption.encrypition_required
+        assertEquals(Boolean.TRUE, encryption.get("encryption_required"));
+    }
+
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void test_toMap_response_encryption()
+    {
+        JWEAlg[] algs = new JWEAlg[] { JWEAlg.ECDH_ES };
+        JWEEnc[] encs = new JWEEnc[] { JWEEnc.A128CBC_HS256 };
+        JWEZip[] zips = new JWEZip[] { JWEZip.DEF };
 
         CredentialIssuerMetadata metadata = new CredentialIssuerMetadata()
-                .setRequireCredentialResponseEncryption(true)
-                .setCredentialIssuer(issuer)
                 .setCredentialResponseEncryptionAlgValuesSupported(algs)
                 .setCredentialResponseEncryptionEncValuesSupported(encs)
+                .setCredentialResponseEncryptionZipValuesSupported(zips)
+                .setRequireCredentialResponseEncryption(true)
                 ;
 
         Map<String, Object> map = metadata.toMap();
 
-        // credential_issuer
-        assertEquals("https://example.com", map.get("credential_issuer"));
-
         // credential_response_encryption
         Map<String, Object> encryption = (Map<String, Object>)map.get("credential_response_encryption");
         assertNotNull(encryption);
 
-        // credential_response_encryption.encrypition_required
-        assertEquals(Boolean.TRUE, encryption.get("encryption_required"));
-
         // credential_response_encryption.alg_values_supported
         List<String> algValues = (List<String>)encryption.get("alg_values_supported");
         assertNotNull(algValues);
@@ -65,5 +124,92 @@ public void test_toMap()
         assertNotNull(encValues);
         assertEquals(1, encValues.size());
         assertEquals("A128CBC-HS256", encValues.get(0));
+
+        // credential_response_encryption.zip_values_supported
+        List<String> zipValues = (List<String>)encryption.get("zip_values_supported");
+        assertNotNull(zipValues);
+        assertEquals(1, zipValues.size());
+        assertEquals("DEF", zipValues.get(0));
+
+        // credential_response_encryption.encrypition_required
+        assertEquals(Boolean.TRUE, encryption.get("encryption_required"));
+    }
+
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void test_toMap_batch_size_1()
+    {
+        CredentialIssuerMetadata metadata = new CredentialIssuerMetadata()
+                .setBatchSize(1)
+                ;
+
+        Map<String, Object> map = metadata.toMap();
+
+        // batch_credential_issuance
+        Map<String, Object> bci = (Map<String, Object>)map.get("batch_credential_issuance");
+        assertNull(bci);
+    }
+
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void test_toMap_batch_size_2()
+    {
+        CredentialIssuerMetadata metadata = new CredentialIssuerMetadata()
+                .setBatchSize(2)
+                ;
+
+        Map<String, Object> map = metadata.toMap();
+
+        // batch_credential_issuance
+        Map<String, Object> bci = (Map<String, Object>)map.get("batch_credential_issuance");
+        assertNotNull(bci);
+
+        // batch_credential_issuance.batch_size
+        Number bs = (Number)bci.get("batch_size");
+        assertNotNull(bs);
+        assertEquals(2, bs.intValue());
+    }
+
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void test_toMap_display()
+    {
+        String display =
+                "[\n"
+                + "  {\n"
+                + "    \"name\": \"Example University\",\n"
+                + "    \"locale\": \"en-US\",\n"
+                + "    \"logo\": {\n"
+                + "      \"uri\": \"https://university.example.edu/public/logo.png\",\n"
+                + "      \"alt_text\":\"a square logo of a university\"\n"
+                + "    }\n"
+                + "  },\n"
+                + "  {\n"
+                + "    \"name\": \"Example Université\",\n"
+                + "    \"locale\": \"fr-FR\",\n"
+                + "    \"logo\": {\n"
+                + "      \"uri\": \"https://university.example.edu/public/logo.png\",\n"
+                + "      \"alt_text\":\"Un logo universitaire carré\"\n"
+                + "    }\n"
+                + "  }\n"
+                + "]";
+
+        CredentialIssuerMetadata metadata = new CredentialIssuerMetadata()
+                .setDisplay(display)
+                ;
+
+        Map<String, Object> map = metadata.toMap();
+
+        // display
+        Object displayObject = map.get("display");
+        assertNotNull(displayObject);
+
+        assertTrue("The value of 'display' should be a list", displayObject instanceof List);
+        List<Object> displayList = (List<Object>)displayObject;
+
+        assertEquals(2, displayList.size());
     }
 }
diff --git a/src/test/java/com/authlete/common/ida/DatasetExtractorTest.java b/src/test/java/com/authlete/common/ida/DatasetExtractorTest.java
index 6416a46d84..0a33c00de1 100644
--- a/src/test/java/com/authlete/common/ida/DatasetExtractorTest.java
+++ b/src/test/java/com/authlete/common/ida/DatasetExtractorTest.java
@@ -16,11 +16,11 @@
 package com.authlete.common.ida;
 
 
+import com.authlete.common.util.digest.Digest;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import com.google.gson.Gson;
-import com.neovisionaries.security.Digest;
 import static org.junit.Assert.*;
 import java.io.IOException;
 import java.io.InputStreamReader;