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Overview

This guide shows you how to sign messages with your EVM wallet. Message signing is commonly used for authentication, nonce verification, and data integrity checks.

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Prerequisites

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Basic Message Signing

import { authenticatedEvmClient } from './client';

const evmClient = await authenticatedEvmClient();

const signature = await evmClient.signMessage({
  message: 'Hello, World!',
  accountAddress: '0xYourWalletAddress',
});

console.log('Message signed:', signature);

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Simple Message Signing

Whether you need to provide externalServerKeyShares depends on how you created your wallet: If you created your wallet with backUpToClientShareService: true, you don’t need to provide external key shares: 
// ✅ Simple signing - no externalServerKeyShares needed
const signature = await evmClient.signMessage({
  message: 'Hello, World!',
  accountAddress: '0xYourWalletAddress',
  password: 'your-password', // Only if wallet was created with password
});

console.log('Message signed:', signature);

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With Manual Backup

If you created your wallet with backUpToClientShareService: false, you must provide external key shares: 
// First, retrieve your stored key shares
const keyShares = await retrieveStoredKeyShares('0xYourWalletAddress');

// ❌ Must provide externalServerKeyShares
const signature = await evmClient.signMessage({
  message: 'Hello, World!',
  accountAddress: '0xYourWalletAddress',
  externalServerKeyShares: keyShares, // Required for manual backup!
  password: 'your-password', // Only if wallet was created with password
});

console.log('Message signed:', signature);

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Advanced: Providing External Key Shares

For advanced scenarios or manual backup, you can provide external server key shares: 
// Example with actual key share structure
const signature = await evmClient.signMessage({
  message: 'Hello, World!',
  accountAddress: '0xYourWalletAddress',
  externalServerKeyShares: [
    {
      pubkey: {
        pubkey: {
          0: 43, 1: 36, 2: 191, 3: 69, 4: 124, 5: 68, 6: 247, 7: 127,
          8: 7, 9: 179, 10: 160, 11: 224, 12: 205, 13: 194, 14: 132, 15: 159,
          // ... continues for 64 bytes total
        }
      },
      secretShare: "020000009ca5a66e79a2ddf631838d5cc5ba6a0cedb15a372e4176e479e0e63abff8cc3d..."
    }
  ],
  password: 'your-password', // Only if wallet was created with password
});

console.log('Message signed:', signature);
Password Handling Notes:
  • If your wallet was created without a password, omit the password parameter
  • If your wallet was created with a password, you must provide it for all operations
  • The password parameter is always optional in the API, but required if the wallet is password-protected

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Common Use Cases

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Authentication

const nonce = Date.now().toString();
const message = `Sign this message to authenticate: ${nonce}`;
const signature = await evmClient.signMessage({
  message,
  accountAddress: '0xYourWalletAddress',
});

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Data Integrity

const data = { userId: 123, action: 'transfer', amount: '100' };
const message = JSON.stringify(data);
const signature = await evmClient.signMessage({
  message,
  accountAddress: '0xYourWalletAddress',
});

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Next Steps