How do you sign data with a private key? [javascript]

Question

Using BlockCypher’s signing tool (link), I can sign the following data:

05de69f5d37f41340eed3230f03d2394dde5e497738a76f027b7d962a0cbdf39

with the private key:

2fd7cab0970c692b4151d77a6aeebcae2a3284556cbfc6f182c571eccfc2424f

to get the result:

30440220352f6d47bc33e2596600c6a297a0e3e84079a9b2f16d10cb9396993370365976022062a30c63adfeef315bcfc690e254dd3b6d4f14fe9919317e14ebb15c29325326

However, I'm am not able to replicate this using javascript using the bitcoinjs-lib module. My attempt is shown below:

var bitcoin = require('bitcoinjs-lib')
var wif = require('wif')

var dataToSign = '05de69f5d37f41340eed3230f03d2394dde5e497738a76f027b7d962a0cbdf39'

var wifObj = wif.decode('KxpiD4T1QHFahGVyg9onfLXjbwBSf5Dyh3BPYY899uXQHn6gfnbz')
var keys = bitcoin.ECPair.fromPrivateKey(wifObj.privateKey)

var signed = keys.sign(Buffer.from(dataToSign, 'hex'))
var signedHex = signed.toString('hex')

Answer 1

You could try using eccrypto

index.js:

var crypto = require("crypto");
var eccrypto = require("eccrypto");

// A new random 32-byte private key.
var privateKey = Buffer.from('2fd7cab0970c692b4151d77a6aeebcae2a3284556cbfc6f182c571eccfc2424f', 'hex')
// Corresponding uncompressed (65-byte) public key.
var publicKey = eccrypto.getPublic(privateKey);

var buf = Buffer.from('05de69f5d37f41340eed3230f03d2394dde5e497738a76f027b7d962a0cbdf39', 'hex')
// Always hash you message to sign!
var msg = crypto.createHash("sha256").update(buf).digest();

eccrypto.sign(privateKey, buf).then(function(sig) {
  console.log("Signature in DER format (hex):", sig.toString('hex'))
  eccrypto.verify(publicKey, buf, sig).then(function() {
    console.log("Signature is OK");
  }).catch(function() {
    console.log("Signature is BAD");
  });
});

console output:

$ node index.js
Signature in DER format (hex): 30440220352f6d47bc33e2596600c6a297a0e3e84079a9b2f16d10cb9396993370365976022062a30c63adfeef315bcfc690e254dd3b6d4f14fe9919317e14ebb15c29325326
Signature is OK