Bitcoin Message Signing Verification Issues

[iamonuwa]

Description

When using AppKit's Bitcoin message signing functionality, the signature verification is failing with various errors including:

• "Point is not on curve: Cannot find square root"
• "recovery id 2 or 3 invalid"

Despite attempts to normalize the signature format, the verification process consistently fails.

Current Implementation

We've attempted to normalize the signature by:

1. Ensuring 65-byte signature length
2. Restricting recovery IDs to 0 or 1
3. Adding proper compression flags
4. Following Bitcoin message signing standards

Steps to Reproduce

1. Connect to a Bitcoin wallet using AppKit
2. Attempt to sign a message using provider.signMessage()
3. Try to verify the signature using standard Bitcoin message verification

Current Workarounds Attempted

const signature = await provider.signMessage({
address,
message
});
// Attempted to normalize signature format
let sigBytes = Buffer.from(signature, 'base64');
let recoveryId = sigBytes[0] & 1; // Force recovery ID to 0 or 1
const finalSigBytes = new Uint8Array(65);
finalSigBytes[0] = recoveryId + 27 + 4; // Set proper flag byte
finalSigBytes.set(compactSig, 1);

Expected Behavior

The signature should be returned in a format compatible with Bitcoin message verification:

• First byte: 27 + recoveryId (0/1) + 4 (compressed flag)
• Following 64 bytes: signature data (r,s values)

Actual Behavior

The signature returned by AppKit's Bitcoin provider is not in a format that can be properly verified, leading to cryptographic verification failures.

Questions

1. What is the expected format of signatures returned by AppKit's Bitcoin provider?
2. Is there documentation on the exact signature format being used?
3. Are there any specific requirements or transformations needed for Bitcoin message signatures?

Environment

• AppKit Version: 1.6.5
• Bitcoin Adapter Version: 1.6.8

Additional Context

This is blocking the implementation of Bitcoin signature verification in our application. Any guidance on the correct way to handle Bitcoin message signatures with AppKit would be greatly appreciated.