sign-solana-message

Sign Solana Message with MetaMask

When to use

Use this skill when:

• Signing an arbitrary message on Solana with MetaMask Connect
• Implementing sign-in-with-Solana or message verification flows
• Using useWallet().signMessage in a React app
• Using the solana:signMessage wallet-standard feature in a vanilla browser app

Workflow

Step 1: Encode the message

Solana message signing requires a Uint8Array. Use TextEncoder to convert a string:

const message = new TextEncoder().encode('Sign this message to verify your identity');

Step 2a: Sign with React wallet-adapter (useWallet)

Prerequisites: createSolanaClient has been awaited before rendering, WalletProvider is configured with wallets={[]}, and the user is connected. See the setup-solana-react-app skill.

import { useWallet } from '@solana/wallet-adapter-react';

function SignMessageButton() {
  const { signMessage, publicKey, connected } = useWallet();

  const handleSign = async () => {
    if (!signMessage || !publicKey) {
      console.error('Wallet does not support signMessage or is not connected');
      return;
    }

    try {
      const message = new TextEncoder().encode('Hello from MetaMask on Solana!');
      const signature = await signMessage(message);
      console.log('Signature (bytes):', signature);
      console.log('Signature (hex):', Buffer.from(signature).toString('hex'));
      console.log('Signer:', publicKey.toBase58());
    } catch (err: any) {
      if (err.code === 4001) {
        console.log('User rejected the signature request');
        return;
      }
      console.error('signMessage failed:', err);
    }
  };

  return (
    <button onClick={handleSign} disabled={!connected || !signMessage}>
      Sign Message
    </button>
  );
}

Step 2b: Sign with vanilla browser (wallet-standard feature)

Prerequisites: createSolanaClient has been called and the wallet is connected via standard:connect. See the setup-solana-browser-app skill.