return sig len on ksafe sign der

[klever-patrick]

Summary by CodeRabbit

• Bug Fixes
  • Enhanced cryptographic signature handling with improved validation and error detection for signing operations.
  • Signatures now return only the actual signature data rather than fixed-size buffers, improving efficiency.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Review profile: CHILL

Plan: Pro

Run ID: f7f13144-a8f9-4b69-8cf0-1039ca9f03dd

📥 Commits

Reviewing files that changed from the base of the PR and between bfe36c1 and 3d47910.

📒 Files selected for processing (1)

• packages/kos/src/crypto/secp256k1.rs

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📝 Walkthrough

Walkthrough

Updated the secp256k1 signature function to properly return and validate the actual signature length instead of always returning a fixed 72-byte buffer. Added error handling for invalid signature lengths in the sign_der method and extended the error enum accordingly.

Changes

Cohort / File(s)	Summary
Secp256k1 Signature Validation packages/kos/src/crypto/secp256k1.rs	Added SignError variant to Secp256Err enum with Display formatting. Updated FFI binding c_ecdsa_secp256k1_sign_der to return u32 (signature length). Modified sign_der method to capture returned length, validate it (len != 0 and len <= 72), reject invalid lengths, and return only the actual signature bytes instead of the full 72-byte buffer.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~15 minutes

Poem

🐰 A signature once padded and plump,
Now trimmed to its actual length—
No wasted bytes in our crypto leap,
Each hop more lean, each proof more deep! 🔐

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: returning signature length from the ksafe sign_der function, which is the primary modification across the changeset.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/xrp-ksafe

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