Sign BTC Messages

Learn how to sign messages using Dynamic’s Node SDK for Bitcoin

Overview

This guide shows you how to sign messages with your Bitcoin wallet. Message signing uses the BIP-322 standard, which provides a unified way to sign messages across all Bitcoin address types. The signature is returned as a base64 string.

Prerequisites

• Created a Bitcoin wallet

Basic Message Signing

import { authenticatedBtcClient } from './client';
import { BitcoinNetwork } from '@dynamic-labs-wallet/core';

const btcClient = await authenticatedBtcClient();

const signature = await btcClient.signMessage({
  message: 'Hello, Bitcoin!',
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
});

console.log('Message signed (base64):', signature);

Simple Message Signing

Whether you need to provide externalServerKeyShares depends on how you created your wallet:

With Automatic Backup (Recommended)

If you created your wallet with backUpToDynamic: true, you don’t need to provide external key shares:

import { BitcoinNetwork } from '@dynamic-labs-wallet/core';

// Simple signing - no externalServerKeyShares needed
const signature = await btcClient.signMessage({
  message: 'Hello, Bitcoin!',
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
});

console.log('Message signed (base64):', signature);

With Manual Backup

If you created your wallet with backUpToDynamic: false, you must provide external key shares:

// First, retrieve your stored key shares
const keyShares = await retrieveStoredKeyShares('bc1q...your-wallet-address');

// Must provide externalServerKeyShares
const signature = await btcClient.signMessage({
  message: 'Hello, Bitcoin!',
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
  externalServerKeyShares: keyShares, // Required for manual backup!
  password: 'your-password', // Only if wallet was created with password
});

console.log('Message signed (base64):', 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

BIP-322 Message Signing

The SDK automatically uses BIP-322 for message signing, which works with both Native SegWit and Taproot addresses:

Native SegWit (P2WPKH)

// Native SegWit wallet — walletMetadata.addressType is 'native_segwit'
const signature = await btcClient.signMessage({
  message: 'Verify my ownership',
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
});
// Returns BIP-322 signature in base64 format

Taproot (P2TR)

// Taproot wallet — walletMetadata.addressType is 'taproot'
const signature = await btcClient.signMessage({
  message: 'Verify my ownership',
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
});
// Returns BIP-322 signature with Schnorr (BIP-340) in base64 format

Common Use Cases

Authentication

const nonce = Date.now().toString();
const message = `Sign this message to authenticate: ${nonce}`;
const signature = await btcClient.signMessage({
  message,
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
});
// signature is a BIP-322 encoded signature in base64

Data Integrity

const data = { userId: 123, action: 'transfer', amount: '100000' };
const message = JSON.stringify(data);
const signature = await btcClient.signMessage({
  message,
  walletMetadata,
  network: BitcoinNetwork.MAINNET,
});

Proof of Ownership

const proofMessage = `I own this Bitcoin address: ${walletAddress}`;
const signature = await btcClient.signMessage({
  message: proofMessage,
  accountAddress: walletAddress,
  network: BitcoinNetwork.MAINNET,
});

Understanding BIP-322

BIP-322 (Generic Signed Message Format) provides a standardized way to sign and verify messages for all Bitcoin address types:

• Native SegWit (P2WPKH): Uses ECDSA signatures
• Taproot (P2TR): Uses Schnorr signatures (BIP-340)

The signature format encodes the signed message in a way that can be verified by any BIP-322 compatible verifier.

Error Handling

try {
  const signature = await btcClient.signMessage({
    message: 'Test message',
    accountAddress: walletAddress,
    network: BitcoinNetwork.MAINNET,
  });
  console.log('Signature:', signature);
} catch (error) {
  console.error('Message signing failed:', error.message);
}

Next Steps

• Sign Bitcoin transactions