Bitcoin: After signing a message, how to verify the signature with JavaScript/TypeScript?

Verifying signatures on Bitcoin nodes using JavaScript/TypeScript

To verify the signature of a user’s message on a Bitcoin node, we need to make sure that the signature is correct and comes from the same private key. In this article, we’ll discuss how to achieve this using JavaScript/TypeScript.

Setting the environment

Before starting, make sure that Node.js is installed on your system. We will also use the crypto module to generate a SHA-256 hash of the user’s message.

const crypto = require('crypto');

Signing a message using Bitcoin-JS

Bitcoin-JS is a JavaScript library that allows us to interact with Bitcoin nodes. We can sign our message using this library:

async function signMessage(node, message) {
const privateKey = await node.getPrivateKey();
const signature = await privateKey.sign(message);
return signature;
}

Signature verification on a Bitcoin node

After we have signed the message with Bitcoin-JS, we need to verify it on the Bitcoin node. For this purpose, we will use the bitcoinjs-lib library.

const bitcoinjsLib = require('bitcoinjs-lib');
async function verifySignature(node, signature, message) {
const publicKey = await node.getPublicKey();
const isValid = await bitcoinjsLib.verifySignature(signature, publicKey, message);
return isValid;
}

Usage example

Here is an example of using these functions:

const bitcoinNode = '
const privateKey = await bitcoinNode.getPrivateKey();
// Sign the message using Bitcoin-JS
signMessage(bitcoinNode, Sign this message to prove that you are the owner of this wallet', (err, signature) => {
if (err) console.error(err);
else {
const publicKey = await bitcoinNode.getPublicKey();
const isValid = verifySignature(bitcoinNode, signature,Sign this message to prove that you are the owner of this wallet');
console.log(isValid); // Must be true
}
});

Error handling

When using Bitcoin-JS, it is important to correctly handle errors. This can be done by catching any exceptions that may occur.

signMessage(bitcoinNode, `Sign this message to prove that you are the owner of this wallet', (err) => {
if (err) console.error(err);
});

Following these steps and examples, we can verify the signature of a user’s message on a Bitcoin node using JavaScript/TypeScript.