fix(core): enforce explicit tag length and validation in file keychain by luisfelipe-alt · Pull Request #28523 · google-gemini/gemini-cli

luisfelipe-alt · 2026-07-23T22:54:18Z

Summary

This Pull Request configures explicit authentication tag length and validation
for the file-based credential storage in Gemini CLI. It ensures that the
application strictly enforces standard 128-bit (16-byte) tag lengths across all
supported Node.js runtimes and handles malformed or truncated tags gracefully.

Details

The file-based credential storage in packages/core/src/services/fileKeychain.ts
previously relied on Node.js's default behavior for AES-GCM tag length
enforcement. To improve robustness and prevent potential issues on legacy
runtimes (where short tags could be accepted without explicit configuration),
this PR applies the following changes:

Explicitly configures { authTagLength: 16 } in both crypto.createCipheriv
and crypto.createDecipheriv.
Adds an explicit validation check to ensure the parsed authTag buffer is
exactly 16 bytes before passing it to decipher.setAuthTag().
Updates loadData() to catch any tag length validation errors and wrap them
gracefully in a user-friendly "Corrupted credentials file detected" error.

Related Issues

How to Validate

To validate these changes, run the newly created regression test suite:

Run the following command from the root directory:

npx vitest run packages/core/src/services/gcmTruncationReproduction.test.ts

Verify that both test cases pass successfully:
- should use a secure 128-bit (16-byte) AES-GCM authentication tag
- should reject decryption of a credentials file with a truncated tag

Pre-Merge Checklist

github-actions · 2026-07-23T22:54:32Z

📊 PR Size: size/L

Lines changed: 251
Additions: +233
Deletions: -18
Files changed: 2

gemini-code-assist · 2026-07-23T22:57:00Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request strengthens the security of the file-based credential storage by enforcing a standard 128-bit authentication tag for AES-GCM encryption. By explicitly configuring tag lengths and adding validation checks, the changes prevent potential vulnerabilities related to tag truncation and ensure that the application handles corrupted credential files more gracefully.

Highlights

Explicit AES-GCM Configuration: Configured an explicit 16-byte (128-bit) authentication tag length in both encryption and decryption processes to ensure consistent security across Node.js runtimes.
Enhanced Validation: Added a strict check to verify that the authentication tag is exactly 16 bytes before processing, preventing the use of malformed or truncated tags.
Improved Error Handling: Updated the error handling logic to catch tag length validation failures and provide a clear 'Corrupted credentials file detected' message.
Regression Testing: Introduced a new test suite to verify correct tag length enforcement and ensure that truncated tags are rejected as expected.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize the Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counterproductive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

gemini-code-assist

Code Review

This pull request enhances security in 'FileKeychain' by explicitly setting and validating a 16-byte AES-GCM authentication tag length, and adds corresponding unit tests. The review feedback recommends two valuable improvements: defensively validating the IV length to ensure it is exactly 16 bytes, and refactoring the error handling in 'loadData' to avoid relying on fragile, implementation-specific OpenSSL error message strings.

luisfelipe-alt · 2026-07-23T23:21:18Z

/gemini review

gemini-code-assist

Code Review

This pull request enhances the security of the FileKeychain service by explicitly setting the AES-GCM authentication tag length to 16 bytes and validating the lengths of the IV and authentication tag during decryption. It also refactors error handling during data loading and adds comprehensive unit tests to verify tag length enforcement. The review feedback suggests supporting both 12-byte and 16-byte IVs during decryption to align with standard AES-GCM specifications while maintaining backward compatibility, and logging detailed errors when decryption or parsing fails to facilitate debugging.

luisfelipe-alt · 2026-07-23T23:39:54Z

/gemini review

gemini-code-assist

Code Review

This pull request updates the FileKeychain service to use a standard 12-byte IV and a secure 16-byte (128-bit) authentication tag for AES-256-GCM encryption, while maintaining backward compatibility for legacy 16-byte IVs. It also introduces strict validation checks for both IV and authentication tag lengths during decryption, refactors error handling in loadData to isolate file reading from decryption/parsing, and adds a comprehensive test suite to verify these changes and prevent truncation vulnerabilities. I have no feedback to provide.

DavidAPierce · 2026-07-24T19:52:31Z

Looks like this just needs a few linter issues fixed:

Required code changes

Apply these code modifications to resolve the static analysis failures.

1. Remove console error in file keychain

Remove the console logging statement from
packages/core/src/services/fileKeychain.ts.

Note

Deleting this log prevents stack traces from cluttering the terminal. The UI
layer handles the thrown error gracefully.

Change the try-catch block starting at line 91:

    try {
      const decrypted = this.decrypt(data);
      // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
      return JSON.parse(decrypted) as Record<string, Record<string, string>>;
    } catch (error: unknown) {
      throw new Error(
        `Corrupted credentials file detected at: ${this.tokenFilePath}\n` +
          `Please delete or rename this file to resolve the issue.`,
      );
    }

2. Remove unused variable in reproduction test

Remove encryptedHex from the variable extraction in
packages/core/src/services/gcmTruncationReproduction.test.ts on line 48:

    const ivHex = parts[0];
    const authTagHex = parts[1];

3. Replace any cast in reproduction test

Avoid using the any type in
packages/core/src/services/gcmTruncationReproduction.test.ts on line 87. Use
a cast through unknown to keep the codebase type-safe:

    const encryptionKey = (keychain as unknown as { encryptionKey: Buffer }).encryptionKey;

otherwise, LGTM.

luisfelipe-alt · 2026-07-26T21:21:09Z

/gemini review

gemini-code-assist

Code Review

This pull request updates the FileKeychain service to use a standard 12-byte IV for AES-256-GCM encryption (down from 16 bytes) and explicitly configures a 16-byte authentication tag length. It also adds validation checks during decryption to reject truncated IVs or authentication tags, and refactors the file loading logic to provide clearer error messages when a corrupted credentials file is detected. A comprehensive test suite has been added to verify these security improvements and ensure backward compatibility with legacy 16-byte IVs. Additionally, helper scripts (test-check.bat and test-check.sh) have been introduced to automate local verification steps. I have no further feedback to provide as the changes are well-implemented and thoroughly tested.

luisfelipe-alt · 2026-07-26T21:53:08Z

/gemini review

gemini-code-assist

Code Review

This pull request updates the FileKeychain service to use a standard 12-byte IV (down from 16 bytes) and explicitly configures a 16-byte authentication tag length for AES-256-GCM encryption. It also adds validation checks for IV and authentication tag lengths during decryption, refactors error handling in loadData to catch and report corrupted credential files more cleanly, and introduces a comprehensive test suite to verify these security and backward-compatibility behaviors. I have no additional feedback to provide as there are no review comments.

DavidAPierce

Thanks for addressing my comment.
LGTM!

luisfelipe-alt requested a review from a team as a code owner July 23, 2026 22:54

github-actions Bot added the size/m A medium sized PR label Jul 23, 2026

gemini-code-assist Bot reviewed Jul 23, 2026

View reviewed changes

Comment thread packages/core/src/services/fileKeychain.ts

Comment thread packages/core/src/services/fileKeychain.ts Outdated

luisfelipe-alt force-pushed the bugfix/WT-engineer_472960680 branch from acccd26 to 5846c45 Compare July 23, 2026 23:17

github-actions Bot mentioned this pull request Jul 23, 2026

📊 AI CLI 工具社区动态日报 2026-07-24 junlinzhao327-oss/big_model_radar#140

Open

gemini-code-assist Bot reviewed Jul 23, 2026

View reviewed changes

Comment thread packages/core/src/services/fileKeychain.ts Outdated

Comment thread packages/core/src/services/fileKeychain.ts Outdated

gemini-cli Bot added the status/need-issue Pull requests that need to have an associated issue. label Jul 23, 2026

luisfelipe-alt force-pushed the bugfix/WT-engineer_472960680 branch from e34f5d8 to ec94ba1 Compare July 23, 2026 23:36

gemini-code-assist Bot reviewed Jul 23, 2026

View reviewed changes

This was referenced Jul 24, 2026

📊 AI CLI 工具社区动态日报 2026-07-24 zx0828/big_model_radar#293

Open

📊 AI CLI 工具社区动态日报 2026-07-24 96loveslife/big_model_radar#208

Open

luisfelipe-alt force-pushed the bugfix/WT-engineer_472960680 branch from c5d7093 to 76d0a51 Compare July 26, 2026 17:55

github-actions Bot added the size/l A large sized PR label Jul 26, 2026

github-actions Bot mentioned this pull request Jul 26, 2026

📊 AI CLI 工具社区动态日报 2026-07-27 litang9/big_model_radar#271

Open

gemini-code-assist Bot reviewed Jul 26, 2026

View reviewed changes

luisfelipe-alt added 2 commits July 26, 2026 21:48

fix(core): enforce explicit tag length and validation in file keychain

be3cf7e

Merge commit '3818efbbf' into bugfix/WT-engineer_472960680

7f5d8d7

luisfelipe-alt force-pushed the bugfix/WT-engineer_472960680 branch from 7a45bea to 7f5d8d7 Compare July 26, 2026 21:52

gemini-code-assist Bot reviewed Jul 26, 2026

View reviewed changes

github-actions Bot mentioned this pull request Jul 26, 2026

📊 AI CLI 工具社区动态日报 2026-07-27 junlinzhao327-oss/big_model_radar#165

Open

This was referenced Jul 26, 2026

📊 AI CLI 工具社区动态日报 2026-07-27 junlinzhao327-oss/big_model_radar#170

Open

📊 AI CLI 工具社区动态日报 2026-07-27 96loveslife/big_model_radar#223

Open

DavidAPierce approved these changes Jul 27, 2026

View reviewed changes

DavidAPierce added this pull request to the merge queue Jul 27, 2026

Merged via the queue into google-gemini:main with commit bef6119 Jul 27, 2026
33 checks passed

This was referenced Aug 6, 2026

Tool release: Gemini CLI v0.54.0 (was v0.53.1) agent-sh/agnix#1326

Closed

Tool release: Gemini CLI v0.49.0 (was v0.45.1) oopsoplm/agnix#15

Open

Tool release: Gemini CLI v0.55.1 (was v0.54.4) agent-sh/agnix#1352

Closed

github-actions Bot mentioned this pull request Aug 15, 2026

[ca] CLI/Docker version check: 6 CLI updates, 3 Docker image bumps (2026-08-15) github/gh-aw#52853

Open

4 tasks

Copilot AI mentioned this pull request Aug 15, 2026

Bump CLI, MCP SDK, and scanner image defaults github/gh-aw#52855

Draft

Uh oh!

Conversation

luisfelipe-alt commented Jul 23, 2026

Summary

Details

Related Issues

How to Validate

Pre-Merge Checklist

Uh oh!

github-actions Bot commented Jul 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

gemini-code-assist Bot commented Jul 23, 2026

Summary of Changes

Highlights

Footnotes

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

luisfelipe-alt commented Jul 23, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

Uh oh!

Uh oh!

luisfelipe-alt commented Jul 23, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

DavidAPierce commented Jul 24, 2026

Required code changes

1. Remove console error in file keychain

2. Remove unused variable in reproduction test

3. Replace any cast in reproduction test

Uh oh!

luisfelipe-alt commented Jul 26, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

luisfelipe-alt commented Jul 26, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

DavidAPierce left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

github-actions Bot commented Jul 23, 2026 •

edited

Loading