Sign-verify messages using bitcoinjs

Published in

Singapore Blockchain-Dapps

2 min readMar 17, 2019

Objective — You will be able to digitally sign messages with Bitcoin’s public-private key pair and verify signed message with Bitcoin’s address.

Code

Pre-setup

At the time of writing, 17 March 2019,

mkdir projectDir
cd projectDir
npm init                          // creates packages.json file
npm install bitcoinjs-lib --save
npm install bitcoinjs-message --save

I am also assuming you have your public and private key pair with you. Please let me know in the comments if I should make changes to the script to show how to generate public-private keys.

Code

var bitcoin = require('bitcoinjs-lib') 
var bitcoinMessage = require('bitcoinjs-message')// Sign a message
// For Bitcoin network do not specify any network, its default
var keyPair = bitcoin.ECPair.fromWIF('KyatKtdVaboeVJ8nE1g5VvQpU23R5pezeVvK9bvZxPLSwUh9SJ5J')//var privateKey = keyPair.d.toBuffer(32) // v3.x.x
var privateKey = keyPair.privateKey // v4.x.xvar message = 'Hey I am Kenneth Hu'
var signature = bitcoinMessage.sign(message, privateKey, keyPair.compressed)console.log(signature.toString('base64'))
// => 'H2W5ToC4QVri8f95yeywh+V1G4ds76RXTGHrxRZ2+oJIXEs95phNU4lH5QhHO1UgJFjXgaBGTcnsRKB8e2CT2Jc='
// Verify a message
var address = '1PYxHnYb9yjKAy7tjc4W8N9JwU6hZp65L4'
var signature = signature.toString('base64');
var message = 'Hey I am Kenneth Hu'
console.log("\nResult : ", bitcoinMessage.verify(message, address, signature))var ErrorMessage = 'Hey I am Kenneth'
console.log("\n\nResult : ", bitcoinMessage.verify(ErrorMessage, address, signature))