Verify offchain message in golang

Question

I'm trying to verify the offchain message signed by solana cli in golang. but it doesn't work.

Step i did:

• base58 decode the address to get the public key
• base58 decode the signature to get the signature
• append the message with \xffsolana offchain
• call ad25519.verify,

Am I missing something?

my code:

const SOLANA_MESSAGE_HEADER = "\xffsolana offchain"

func verifySolana(address, message, signature string) (bool, error) {

    publicKeyBytes := base58.Decode(address)

    if len(publicKeyBytes) != ed25519.PublicKeySize {
        return false, errors.New("invalid public key")
    }

    signatureBytes := base58.Decode(signature)
    messageWithHeader := fmt.Sprintf("%s%s", SOLANA_MESSAGE_HEADER, message)

    if len(signatureBytes) != ed25519.SignatureSize {
        return false, errors.New("invalid signature")
    }

    isValid := ed25519.Verify(
        publicKeyBytes,
        []byte(messageWithHeader),
        signatureBytes,
    )

    return isValid, nil
}

Answer 1

So the problem is that I need to form the message in the offchain message format:

- \xffsolana offchain (16 bytes)
- 0 (header version - 1 byte)
- 0 (format - 1 byte)
- len(message) (message length - 2 bytes)
- message body

Then it works fine