Bitcoinjs-message NPM

bitcoinjs-message

Examples (Note about Electrum support at the bottom)

var bitcoin = require('bitcoinjs-lib') // v4.x.x
var bitcoinMessage = require('bitcoinjs-message')

sign(message, privateKey, compressed, network.messagePrefix, sigOptions)
If you pass the sigOptions arg instead of messagePrefix it will dynamically replace.
sigOptions contains two attributes
segwitType should be one of 'p2sh(p2wpkh)' or 'p2wpkh'
extraEntropy will be used to create non-deterministic signatures using the RFC6979 extra entropy parameter. R value reuse is not an issue.

Sign a Bitcoin message

var keyPair = bitcoin.ECPair.fromWIF('L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1')
var privateKey = keyPair.privateKey
var message = 'This is an example of a signed message.'

var signature = bitcoinMessage.sign(message, privateKey, keyPair.compressed)
console.log(signature.toString('base64'))
// => 'H9L5yLFjti0QTHhPyFrZCT1V/MMnBtXKmoiKDZ78NDBjERki6ZTQZdSMCtkgoNmp17By9ItJr8o7ChX0XxY91nk='

To produce non-deterministic signatures you can pass an extra option to sign()

var { randomBytes } = require('crypto')
var keyPair = bitcoin.ECPair.fromWIF('L4rK1yDtCWekvXuE6oXD9jCYfFNV2cWRpVuPLBcCU2z8TrisoyY1')
var privateKey = keyPair.privateKey
var message = 'This is an example of a signed message.'

var signature = bitcoinMessage.sign(message, privateKey, keyPair.compressed, { extraEntropy: randomBytes(32) })
console.log(signature.toString('base64'))
// => different (but valid) signature each time

Sign a Bitcoin message (with segwit addresses)

// P2SH(P2WPKH) address 'p2sh(p2wpkh)'
var signature = bitcoinMessage.sign(message, privateKey, keyPair.compressed, { segwitType: 'p2sh(p2wpkh)' })
console.log(signature.toString('base64'))
// => 'I9L5yLFjti0QTHhPyFrZCT1V/MMnBtXKmoiKDZ78NDBjERki6ZTQZdSMCtkgoNmp17By9ItJr8o7ChX0XxY91nk='

// P2WPKH address 'p2wpkh'
var signature = bitcoinMessage.sign(message, privateKey, keyPair.compressed, { segwitType: 'p2wpkh' })
console.log(signature.toString('base64'))
// => 'J9L5yLFjti0QTHhPyFrZCT1V/MMnBtXKmoiKDZ78NDBjERki6ZTQZdSMCtkgoNmp17By9ItJr8o7ChX0XxY91nk='

verify(message, address, signature, network.messagePrefix, checkSegwitAlways)

Verify a Bitcoin message

var address = '1F3sAm6ZtwLAUnj7d38pGFxtP3RVEvtsbV'

console.log(bitcoinMessage.verify(message, address, signature))
// => true

About Electrum segwit signature support

For Signing: Use the non-segwit compressed signing parameters for both segwit types (p2sh-p2wpkh and p2wpkh)
For Verifying: Pass the checkSegwitAlways argument as true. (messagePrefix should be set to null to default to Bitcoin messagePrefix)