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noble-secp256k1

secp256k1, an elliptic curve that could be used for assymetric encryption and ECDSA signature scheme.

This library belongs to noble crypto

noble-crypto — high-security, easily auditable set of contained cryptographic libraries and tools.

  • No dependencies, one small file
  • Easily auditable TypeScript/JS code
  • Uses es2019 bigint. Supported in Chrome, Firefox, node 10+
  • All releases are signed and trusted
  • Check out all libraries: secp256k1, ed25519, ripemd160

Usage

npm install noble-secp256k1

import * as secp256k1 from "noble-secp256k1";

// You can also pass BigInt:
// const PRIVATE_KEY = 0xa665a45920422f9d417e4867efn;
const PRIVATE_KEY = Uint8Array.from([
  0xa6, 0x65, 0xa4, 0x59, 0x20, 0x42, 0x2f,
  0x9d, 0x41, 0x7e, 0x48, 0x67, 0xef
]);
const MESSAGE_HASH = "9c1185a5c5e9fc54612808977ee8f548b2258d31";

const publicKey = secp256k1.getPublicKey(PRIVATE_KEY);
const signature = secp256k1.sign(MESSAGE_HASH, PRIVATE_KEY);
const isMessageSigned = secp256k1.verify(signature, MESSAGE_HASH, publicKey);

API

function getPublicKey(privateKey: Uint8Array, isCompressed?: false): Uint8Array;
function getPublicKey(privateKey: string, isCompressed?: false): string;
function getPublicKey(privateKey: bigint): Point;

privateKey will be used to generate public key. Public key is generated by doing scalar multiplication of a base Point(x, y) by a fixed integer. The result is another Point(x, y) which we will by default encode to hex Uint8Array. isCompressed (default is false) determines whether the output should contain y coordinate of the point.

function sign(hash: Uint8Array, privateKey: Uint8Array | bigint, k?: bigint): Uint8Array;
function sign(hash: string, privateKey: string | bigint, k?: bigint): string;
  • hash: Uint8Array | string - message hash which would be signed
  • privateKey: Uint8Array | string | bigint - private key which will sign the hash
  • k?: bigint - optional random seed. Default is one from crypto.getRandomValues(). Must be cryptographically secure, which means Math.random() won’t work.
  • Returns DER encoded ECDSA signature, as hex uint8a / string.
function verify(signature: Uint8Array | string | SignResult, hash: Uint8Array | string): boolean
  • signature: Uint8Array - object returned by the sign function
  • hash: string | Uint8Array - message hash that needs to be verified
  • publicKey: string | Point - e.g. that was generated from privateKey by getPublicKey
  • Returns boolean: true if signature == hash; otherwise false

The library also exports helpers:

// 𝔽p
secp256k1.P // 2 ^ 256 - 2 ^ 32 - 977

// Prime order
secp256k1.PRIME_ORDER // 2 ^ 256 - 432420386565659656852420866394968145599

// Base point
secp256k1.BASE_POINT // new secp256k1.Point(x, y) where
// x = 55066263022277343669578718895168534326250603453777594175500187360389116729240n
// y = 32670510020758816978083085130507043184471273380659243275938904335757337482424n;

// Elliptic curve point
secp256k1.Point {
  constructor(x: bigint, y: bigint);
  // Compressed elliptic curve point representation
  static fromHex(hex: Uint8Array | string);
  static fromCompressedHex(hex: string);
  toHex(): string;
  toCompressedHex(): string;
}
secp256k1.SignResult {
  constructor(r: bigint, s: bigint);
  // DER encoded ECDSA signature
  static fromHex(hex: Uint8Array | string);
  toHex()
}

Security

Noble is production-ready & secure. Our goal is to have it audited by a good security expert.

We’re using built-in JS BigInt, which is “unsuitable for use in cryptography” as per official spec. This means that the lib is vulnerable to timing attacks. But:

  1. JIT-compiler and Garbage Collector make “constant time” extremely hard to achieve in a scripting language.
  2. Which means any other JS library doesn’t use constant-time bigints. Including bn.js or anything else. Even statically typed Rust, a language without GC, makes it harder to achieve constant-time for some cases.
  3. Overall they are quite rare; for our particular usage they’re unimportant. If your goal is absolute security, don’t use any JS lib — including bindings to native ones. Try LibreSSL & similar low-level libraries & languages.
  4. We however consider infrastructure attacks like rogue NPM modules very important; that’s why it’s crucial to minimize the amount of 3rd-party dependencies & native bindings. If your app uses 500 dependencies, any dep could get hacked and you’ll be downloading rootkits with every npm install. Our goal is to minimize this attack vector.

License

MIT (c) Paul Miller (https://paulmillr.com), see LICENSE file.