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

This module provides native bindings to ecdsa secp256k1 functions

Install

npm install secp256k1

Usage

var ecdsa = require('secp256k1'),
  sr = require('secure-random'); 

var privateKey = sr.randomBuffer(32);

//a random message to sign
var msg = sr.randomBuffer(32);

//get the public key in a compressed format
var pubKey = ecdsa.createPublicKey(privateKey, true);

//sign the message
var sig = ecdsa.sign(privateKey, msg);

//verify the signature
if(ecdsa.verify(pubKey, msg, sig)){
  console.log("valid signature");
}

Test

run npm test

API

secp256k1.verifySecretKey(secretKey)

Verify an ECDSA secret key.

Parameters

secretKey: Buffer, the secret Key to verify

Returns: Boolean, true if secret key is valid, false secret key is invalid

secp256k1.verifyPublicKey(publicKey)

Verify an ECDSA public key.

Parameters

publicKey: Buffer, the public Key to verify

Returns: Boolean, true if public key is valid, false secret key is invalid

secp256k1.sign(secretkey, msg, cb)

Create an ECDSA signature.

Parameters

secretkey: Buffer, a 32-byte secret key (assumed to be valid)

msg: Buffer, he message being signed

cb: function, the callback given. The callback is given the signature

Returns: Buffer, if no callback is given a 72-byte signature is returned

secp256k1.signCompact(secretKey, msg, cb)

Create a compact ECDSA signature (64 byte + recovery id). Runs asynchronously if given a callback

Parameters

secretKey: Buffer, a 32-byte secret key (assumed to be valid)

msg: Buffer, the message being signed

cb: function, the callback which is give err, sig the

• param {Buffer} sig a 64-byte buffer repersenting the signature
• param {Number} recid an int which is the recovery id.

Returns: result only returned if no callback is given

• result.signature
• result.r
• result.s
• result.recoveryId

secp256k1.verify(pubKey, mgs, sig)

Verify an ECDSA signature. Runs asynchronously if given a callback

Parameters

pubKey: Buffer, the public key

mgs: Buffer, the message

sig: Buffer, the signature

Returns: Integer,

• 1: correct signature
• 0: incorrect signature
• -1: invalid public key
• -2: invalid signature

secp256k1.recoverCompact(msg, sig, recid, compressed, cb)

Recover an ECDSA public key from a compact signature in the process also verifing it. Runs asynchronously if given a callback

Parameters

msg: Buffer, the message assumed to be signed

sig: Buffer, the signature as 64 byte buffer

recid: Integer, the recovery id (as returned by ecdsa_sign_compact)

compressed: Boolean, whether to recover a compressed or uncompressed pubkey

cb: function, Recover an ECDSA public key from a compact signature. In the process also verifing it.

Returns: Buffer, the pubkey, a 33 or 65 byte buffer

secp256k1.createPubKey(secKey, compressed)

Compute the public key for a secret key.

Parameters

secKey: Buffer, a 32-byte private key.

compressed: Boolean, whether the computed public key should be compressed

Returns: Buffer, a 33-byte (if compressed) or 65-byte (if uncompressed) area to store the public key.

secp256k1.exportPrivateKey(secertKey, compressed)

Parameters

secertKey: Buffer

compressed: Boolean

Returns: Buffer, privateKey

secp256k1.importPrivateKey(privateKey)

Parameters

privateKey: Buffer, This module provides native bindings to ecdsa secp256k1 functions

Returns: Buffer, secertKey

secp256k1.decompressPublickey(secretKey)

Parameters

secretKey: Buffer, This module provides native bindings to ecdsa secp256k1 functions

Returns: Buffer, This module provides native bindings to ecdsa secp256k1 functions

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NOTES

This will not work on node version 11 yet. Arrays need to have isolates for this.