[Kayvan-Zahiri]

Problem

verify_signature() promises a boolean but hmac.compare_digest() only accepts ASCII strings. A malformed non-ASCII received signature (for example "é") raises TypeError instead of returning False. A webhook consumer that branches on the boolean can therefore raise unexpectedly on this invalid input.

Change

Return False for non-ASCII signature strings. A valid SHA-256 hex digest is always ASCII, and valid/invalid ASCII comparisons continue to use the existing constant-time hmac.compare_digest() unchanged.

Add regressions for Latin-1, emoji, a digest-length malformed value and a lone surrogate, with both text and bytes request bodies.

Validation

• Before: all 8 new cases fail with TypeError; 3 existing tests pass.
• After: full pytest tests -q suite: 144 passed.
• Full SDK/test Black and isort checks, Flake8, MyPy (18 source files), and git diff --check pass.

Python 3.12, local editable SDK with declared dependency constraints. Formatter/linter versions match the repository hook pins. No hosted Flagsmith API requests or webhook deployment were used. No public signature or valid-signature behavior change.

[coderabbitai]

Important

Draft PR not reviewed

Draft PRs are not automatically reviewed by default.

• Trigger a manual review

To automatically review draft PRs, update your CodeRabbit configuration:

reviews:
  auto_review:
    drafts: true

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}