sign-evm-message

Sign EVM Messages with MetaMask Connect

When to use

Use this skill when:

• Signing a plaintext message with personal_sign for authentication or verification
• Signing structured EIP-712 typed data with eth_signTypedData_v4 for permits, orders, or typed messages
• Using the connectAndSign shortcut to connect and sign in a single user approval
• Handling signature errors and user rejections

Workflow

Step 1: Get the provider and connected account

Ensure the client is connected before requesting a signature:

import { createEVMClient, getInfuraRpcUrls } from '@metamask/connect-evm';

const client = await createEVMClient({
  dapp: { name: 'My DApp', url: window.location.href },
  api: {
    supportedNetworks: {
      ...getInfuraRpcUrls({ infuraApiKey: 'YOUR_INFURA_KEY', chainIds: ['0x1'] }),
    },
  },
});

const { accounts } = await client.connect({ chainIds: ['0x1'] });
const provider = client.getProvider();
const account = accounts[0]; // Address (0x-prefixed hex)

Step 2: Sign with personal_sign

personal_sign signs a UTF-8 message. The params order is [message, account] where message is a hex-encoded string:

// Convert message to hex
const message = 'Hello, MetaMask!';
const hexMessage = '0x' + Array.from(new TextEncoder().encode(message))
  .map((b) => b.toString(16).padStart(2, '0'))
  .join('');

try {
  const signature = await provider.request({
    method: 'personal_sign',
    params: [hexMessage, account],
  });

  console.log('Signature:', signature);
  // signature is a Hex string: 0x...
} catch (err: any) {
  if (err.code === 4001) {
    console.log('User rejected the signature request');
    return;
  }
  throw err;
}

MetaMask also accepts a raw UTF-8 string for the message parameter, but hex encoding is the canonical format per EIP-191.

Step 3: Sign EIP-712 typed data with eth_signTypedData_v4

Build the full EIP-712 typed data structure with types, primaryType, domain, and message, then pass it as a JSON string: