feat: v4 signature

[zhouxl]

Related Issue

Summary of Changes

Need Regression Testing

• Yes
• No

Risk Assessment

• Low
• Medium
• High

Additional Notes

Screenshots (if applicable)

[github-actions]

PR Summary

Updated the EVM signature generation process to use a V4 signature approach. The changes modify how the EVM signature is created by using Keccak256 hashing on the JWT data and signing with the Ethereum key directly, rather than using the previous ethSign method. Added error handling with HUD error displays and a new signFailed error case.

Changes

File	Summary
FRW/Foundation/Bridge/RNBridgeError.swift	Added a new signFailed case to the RNBridgeError enum to handle signature failure scenarios.
FRW/Foundation/Bridge/TurboModule+Onboard.swift	Refactored EVM signature generation to use Keccak256 hashing on JWT data and sign with the Ethereum key directly via getKeyForCoin. Added HUD error displays for invalidMnemonic, invalidSignData, and signFailed errors. The evmSignature is now formatted with hex prefix instead of using hexString.

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[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 91af1db: feat: v4 signature

Files Processed (2)

• FRW/Foundation/Bridge/RNBridgeError.swift (1 hunk)
• FRW/Foundation/Bridge/TurboModule+Onboard.swift (1 hunk)

Actionable Comments (0)

Skipped Comments (2)

• FRW/Foundation/Bridge/TurboModule+Onboard.swift [170-170]

  possible bug: "Potential inconsistent hex formatting between signatures."

• FRW/Foundation/Bridge/RNBridgeError.swift [20-20]

  maintainability: "New error case is defined but not used in the PR."

[github-actions]

🚨 Pull request needs attention.

Review Summary

Commits Considered (1)

• bcdce96: feat: update sign for eoa

Files Processed (1)

• FRW/Foundation/Bridge/TurboModule+Onboard.swift (1 hunk)

Actionable Comments (1)

• FRW/Foundation/Bridge/TurboModule+Onboard.swift [172-172]

  possible issue: "Potential signature format issue for Ethereum V4 signatures."

Skipped Comments (1)

• FRW/Foundation/Bridge/TurboModule+Onboard.swift [166-166]

  enhancement: "Missing HUD error display for ethAddress failure."

[github-actions]

The code signs the raw Keccak256 hash of the JWT data directly. For Ethereum V4 (EIP-712) typed data signatures, the standard requires a specific prefix (\x19Ethereum Signed Message:\n + message length) to be prepended before hashing, or proper EIP-712 domain separator handling. Signing raw hashes without proper prefixing can lead to signature replay attacks or incompatibility with standard Ethereum signature verification.