secp256k1

What is secp256k1?

The secp256k1 npm package provides an implementation of the elliptic curve secp256k1, which is widely used in cryptographic applications, particularly in blockchain technologies like Bitcoin and Ethereum. This package allows for key generation, signing, and verification of messages using the secp256k1 curve.

What are secp256k1's main functionalities?

Key Generation

This feature allows you to generate a private key and derive the corresponding public key using the secp256k1 curve.

const secp256k1 = require('secp256k1');
const crypto = require('crypto');

// Generate a private key
let privateKey;
do {
  privateKey = crypto.randomBytes(32);
} while (!secp256k1.privateKeyVerify(privateKey));

// Generate the public key
const publicKey = secp256k1.publicKeyCreate(privateKey);

console.log('Private Key:', privateKey.toString('hex'));
console.log('Public Key:', publicKey.toString('hex'));

Message Signing

This feature allows you to sign a message hash using a private key, producing a signature and a recovery ID.

const secp256k1 = require('secp256k1');
const crypto = require('crypto');

// Generate a private key
let privateKey;
do {
  privateKey = crypto.randomBytes(32);
} while (!secp256k1.privateKeyVerify(privateKey));

// Create a message hash
const message = 'Hello, world!';
const msgHash = crypto.createHash('sha256').update(message).digest();

// Sign the message hash
const sigObj = secp256k1.ecdsaSign(msgHash, privateKey);

console.log('Signature:', sigObj.signature.toString('hex'));
console.log('Recovery ID:', sigObj.recid);

Signature Verification

This feature allows you to verify a signature against a message hash and a public key, ensuring the authenticity of the message.

const secp256k1 = require('secp256k1');
const crypto = require('crypto');

// Generate a private key
let privateKey;
do {
  privateKey = crypto.randomBytes(32);
} while (!secp256k1.privateKeyVerify(privateKey));

// Generate the public key
const publicKey = secp256k1.publicKeyCreate(privateKey);

// Create a message hash
const message = 'Hello, world!';
const msgHash = crypto.createHash('sha256').update(message).digest();

// Sign the message hash
const sigObj = secp256k1.ecdsaSign(msgHash, privateKey);

// Verify the signature
const isValid = secp256k1.ecdsaVerify(sigObj.signature, msgHash, publicKey);

console.log('Signature is valid:', isValid);

Other packages similar to secp256k1

elliptic

The elliptic package is a general-purpose elliptic curve library that supports multiple curves, including secp256k1. It provides similar functionalities for key generation, signing, and verification but also supports other curves like ed25519 and p256. It is more versatile but may be more complex to use for secp256k1-specific applications.

bitcoinjs-lib

The bitcoinjs-lib package is a comprehensive library for Bitcoin-related operations, including key generation, signing, and verification using secp256k1. While it offers similar functionalities, it is more specialized for Bitcoin and includes additional features like transaction creation and parsing.

noble-secp256k1

The noble-secp256k1 package is a modern, fast, and secure implementation of the secp256k1 elliptic curve. It focuses on performance and security, providing similar functionalities for key generation, signing, and verification. It is a good alternative if performance and security are critical.

README

secp256k1-node

This module provides native bindings to bitcoin-core/secp256k1. In browser elliptic will be used as fallback.

Works on node version 10.0.0 or greater, because use N-API.

Installation

from npm

npm install secp256k1

from git

git clone [e-mail]:cryptocoinjs/secp256k1-node.git
cd secp256k1-node
git submodule update --init
npm install

Windows

The easiest way to build the package on windows is to install windows-build-tools.

Or install the following software:

• Git: https://git-scm.com/download/win
• nvm: https://github.com/coreybutler/nvm-windows
• Python 2.7: https://www.python.org/downloads/release/python-2712/
• Visual C++ Build Tools: http://landinghub.visualstudio.com/visual-cpp-build-tools (Custom Install, and select both Windows 8.1 and Windows 10 SDKs)

And run commands:

npm config set msvs_version 2015 --global
npm install npm@next -g

Based on:

• https://github.com/nodejs/node-gyp/issues/629#issuecomment-153196245
• https://github.com/nodejs/node-gyp/issues/972

Usage

• API Reference (v4.x) (current version)
• API Reference (v3.x)
• API Reference (v2.x)

Private Key generation, Public Key creation, signature creation, signature verification

const { randomBytes } = require('crypto')
const secp256k1 = require('secp256k1')
// or require('secp256k1/elliptic')
//   if you want to use pure js implementation in node

// generate message to sign
// message should have 32-byte length, if you have some other length you can hash message
// for example `msg = sha256(rawMessage)`
const msg = randomBytes(32)

// generate privKey
let privKey
do {
  privKey = randomBytes(32)
} while (!secp256k1.privateKeyVerify(privKey))

// get the public key in a compressed format
const pubKey = secp256k1.publicKeyCreate(privKey)

// sign the message
const sigObj = secp256k1.ecdsaSign(msg, privKey)

// verify the signature
console.log(secp256k1.ecdsaVerify(sigObj.signature, msg, pubKey))
// => true

* .verify return false for high signatures

Get X point of ECDH

const { randomBytes } = require('crypto')
// const secp256k1 = require('./elliptic')
const secp256k1 = require('./')

// generate privKey
function getPrivateKey () {
  while (true) {
    const privKey = randomBytes(32)
    if (secp256k1.privateKeyVerify(privKey)) return privKey
  }
}

// generate private and public keys
const privKey = getPrivateKey()
const pubKey = secp256k1.publicKeyCreate(getPrivateKey())

// compressed public key from X and Y
function hashfn (x, y) {
  const pubKey = new Uint8Array(33)
  pubKey[0] = (y[31] & 1) === 0 ? 0x02 : 0x03
  pubKey.set(x, 1)
  return pubKey
}

// get X point of ecdh
const ecdhPointX = secp256k1.ecdh(pubKey, privKey, { hashfn }, Buffer.alloc(33))
console.log(ecdhPointX.toString('hex'))

LICENSE

This library is free and open-source software released under the MIT license.