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noble-secp256k1 Node CI code style: prettier

Fastest JS implementation of secp256k1, an elliptic curve that could be used for asymmetric encryption, ECDH key agreement protocol and signature schemes. Supports deterministic ECDSA from RFC6979 and Schnorr signatures from BIP0340.

Audited with crowdfunding by an independent security firm. Tested against thousands of test vectors from a different library. Check out the online demo and blog post: Learning fast elliptic-curve cryptography in JS

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
  • Supported in all major browsers and stable node.js versions
  • All releases are signed with PGP keys
  • Check out all libraries: secp256k1, ed25519, bls12-381, hashes

Usage

Use NPM in node.js / browser, or include single file from GitHub's releases page:

npm install noble-secp256k1

import * as secp from "noble-secp256k1";
// if you're using single file, use global variable nobleSecp256k1 instead

(async () => {
  // You pass either a hex string, or Uint8Array
  const privateKey = "6b911fd37cdf5c81d4c0adb1ab7fa822ed253ab0ad9aa18d77257c88b29b718e";
  const messageHash = "a33321f98e4ff1c283c76998f14f57447545d339b3db534c6d886decb4209f28";
  const publicKey = secp.getPublicKey(privateKey);
  const signature = await secp.sign(messageHash, privateKey);
  const isSigned = secp.verify(signature, messageHash, publicKey);

  // Supports Schnorr signatures
  const rpub = secp.schnorr.getPublicKey(privateKey);
  const rsignature = await secp.schnorr.sign(messageHash, privateKey);
  const risSigned = await secp.schnorr.verify(rsignature, messageHash, rpub);
})();

Deno:

import * as secp from "https://deno.land/x/secp256k1/mod.ts";
const publicKey = secp.getPublicKey("6b911fd37cdf5c81d4c0adb1ab7fa822ed253ab0ad9aa18d77257c88b29b718e");

API

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

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.

To get Point instance, use Point.fromPrivateKey(privateKey).

getSharedSecret(privateKeyA, publicKeyB)
function getSharedSecret(privateKeyA: Uint8Array, publicKeyB: Uint8Array): Uint8Array;
function getSharedSecret(privateKeyA: string, publicKeyB: string): string;
function getSharedSecret(privateKeyA: bigint, publicKeyB: Point): Uint8Array;

Computes ECDH (Elliptic Curve Diffie-Hellman) shared secret between a private key and a different public key.

To get Point instance, use Point.fromHex(publicKeyB).multiply(privateKeyA).

To speed-up the function massively by precomputing EC multiplications, use getSharedSecret(privateKeyA, secp.utils.precompute(8, publicKeyB))

sign(hash, privateKey)
function sign(msgHash: Uint8Array, privateKey: Uint8Array, opts?: Options): Promise<Uint8Array>;
function sign(msgHash: string, privateKey: string, opts?: Options): Promise<string>;
function sign(msgHash: Uint8Array, privateKey: Uint8Array, opts?: Options): Promise<[Uint8Array | string, number]>;

Generates deterministic ECDSA signature as per RFC6979.

  • msgHash: Uint8Array | string - message hash which would be signed
  • privateKey: Uint8Array | string | bigint - private key which will sign the hash
  • options?: Options - optional object related to signature value and format
  • options?.recovered: boolean = false - whether the recovered bit should be included in the result. In this case, the result would be an array of two items.
  • options?.canonical: boolean = false - whether a signature s should be no more than 1/2 prime order
  • options?.der: boolean = true - whether the returned signature should be in DER format. If false, it would be in Compact format (32-byte r + 32-byte s)

The function is asynchronous because we're utilizing built-in HMAC API to not rely on dependencies.

signSync counterpart could also be used, you need to set utils.hmacSha256Sync to a function with signature key: Uint8Array, ...messages: Uint8Array[]) => Uint8Array. Example with noble-hashes package:

const { hmac } = require('noble-hashes/lib/hmac');
const { sha256 } = require('noble-hashes/lib/sha256');
secp256k1.utils.hmacSha256Sync = (key: Uint8Array, ...msgs: Uint8Array[]) => {
  const h = hmac.create(sha256, key);
  msgs.forEach(msg => h.update(msg));
  return h.digest();
};

// Can be used now
secp256k1.signSync(msgHash, privateKey)
verify(signature, hash, publicKey)
function verify(signature: Uint8Array, msgHash: Uint8Array, publicKey: Uint8Array): boolean
function verify(signature: string, msgHash: string, publicKey: string): boolean
  • signature: Uint8Array | string | { r: bigint, s: bigint } - object returned by the sign function
  • msgHash: Uint8Array | string - message hash that needs to be verified
  • publicKey: Uint8Array | string | Point - e.g. that was generated from privateKey by getPublicKey
  • Returns boolean: true if signature == hash; otherwise false
recoverPublicKey(hash, signature, recovery)
function recoverPublicKey(msgHash: Uint8Array, signature: Uint8Array, recovery: number): Uint8Array | undefined;
function recoverPublicKey(msgHash: string, signature: string, recovery: number): string | undefined;
  • msgHash: Uint8Array | string - message hash which would be signed
  • signature: Uint8Array | string | { r: bigint, s: bigint } - object returned by the sign function
  • recovery: number - recovery bit returned by sign with recovered option 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. If signature is invalid - function will return undefined as result.

To get Point instance, use Point.fromSignature(hash, signature, recovery).

schnorr.getPublicKey(privateKey)
function schnorrGetPublicKey(privateKey: Uint8Array): Uint8Array;
function schnorrGetPublicKey(privateKey: string): string;

Returns 32-byte public key. Warning: it is incompatible with non-schnorr pubkey.

Specifically, its y coordinate may be flipped. See BIP0340 for clarification.

schnorr.sign(hash, privateKey)
function schnorrSign(msgHash: Uint8Array, privateKey: Uint8Array, auxilaryRandom?: Uint8Array): Promise<Uint8Array>;
function schnorrSign(msgHash: string, privateKey: string, auxilaryRandom?: string): Promise<string>;

Generates Schnorr signature as per BIP0340. Asynchronous, so use await.

  • msgHash: Uint8Array | string - message hash which would be signed
  • privateKey: Uint8Array | string | bigint - private key which will sign the hash
  • auxilaryRandom?: Uint8Array — optional 32 random bytes. By default, the method gathers cryptogarphically secure random.
  • Returns Schnorr signature in Hex format.
schnorr.verify(signature, hash, publicKey)
function schnorrVerify(signature: Uint8Array | string, msgHash: Uint8Array | string, publicKey: Uint8Array | string): boolean
  • signature: Uint8Array | string | { r: bigint, s: bigint } - object returned by the sign function
  • msgHash: Uint8Array | string - message hash that needs to be verified
  • publicKey: Uint8Array | string | Point - e.g. that was generated from privateKey by getPublicKey
  • Returns boolean: true if signature == hash; otherwise false

Point methods

Helpers
utils.randomPrivateKey(): Uint8Array

Returns Uint8Array of 32 cryptographically secure random bytes that can be used as private key. The signature is:

(key: Uint8Array, ...msgs: Uint8Array[]): Uint8Array;
utils.hmacSha256Sync

The function is not defined by default, but could be used to implement signSync method (see above).

utils.precompute(W = 8, point = BASE_POINT): Point

Returns cached point which you can use to pass to getSharedSecret or to #multiply by it.

This is done by default, no need to run it unless you want to disable precomputation or change window size.

We're doing scalar multiplication (used in getPublicKey etc) with precomputed BASE_POINT values.

This slows down first getPublicKey() by milliseconds (see Speed section), but allows to speed-up subsequent getPublicKey() calls up to 20x.

You may want to precompute values for your own point.

secp256k1.CURVE.P // Field, 2 ** 256 - 2 ** 32 - 977
secp256k1.CURVE.n // Order, 2 ** 256 - 432420386565659656852420866394968145599
secp256k1.Point.BASE // new secp256k1.Point(Gx, Gy) where
// Gx = 55066263022277343669578718895168534326250603453777594175500187360389116729240n
// Gy = 32670510020758816978083085130507043184471273380659243275938904335757337482424n;

// Elliptic curve point in Affine (x, y) coordinates.
secp256k1.Point {
  constructor(x: bigint, y: bigint);
  // Supports compressed and non-compressed hex
  static fromHex(hex: Uint8Array | string);
  static fromPrivateKey(privateKey: Uint8Array | string | number | bigint);
  static fromSignature(
    msgHash: Hex,
    signature: Signature,
    recovery: number | bigint
  ): Point | undefined {
  toRawBytes(isCompressed = false): Uint8Array;
  toHex(isCompressed = false): string;
  equals(other: Point): boolean;
  negate(): Point;
  add(other: Point): Point;
  subtract(other: Point): Point;
  // Constant-time scalar multiplication.
  multiply(scalar: bigint | Uint8Array): Point;
}
secp256k1.Signature {
  constructor(r: bigint, s: bigint);
  // DER encoded ECDSA signature
  static fromDER(hex: Uint8Array | string);
  // R, S 32-byte each
  static fromCompact(hex: Uint8Array | string);
  toDERRawBytes(): Uint8Array;
  toDERHex(): string;
  toCompactRawBytes(): Uint8Array;
  toCompactHex(): string;
}

Security

Noble is production-ready.

  1. The library has been audited by an independent security firm cure53: PDF. The audit has been crowdfunded by community with help of Umbra.cash.
  2. The library has also been fuzzed by Guido Vranken's cryptofuzz. You can run the fuzzer by yourself to check it.

We're using built-in JS BigInt, which is "unsuitable for use in cryptography" as per official spec. This means that the lib is potentially vulnerable to timing attacks. But, JIT-compiler and Garbage Collector make "constant time" extremely hard to achieve in a scripting language. 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. If your goal is absolute security, don't use any JS lib — including bindings to native ones. Use low-level libraries & languages. Nonetheless we've hardened implementation of koblitz curve multiplication to be algorithmically constant time.

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.

Speed

Benchmarks measured with Apple M1.

getPublicKey(utils.randomPrivateKey()) x 6,121 ops/sec @ 163μs/op
sign x 4,468 ops/sec @ 223μs/op
verify x 923 ops/sec @ 1ms/op
recoverPublicKey x 491 ops/sec @ 2ms/op
getSharedSecret aka ecdh x 534 ops/sec @ 1ms/op
getSharedSecret (precomputed) x 7,105 ops/sec @ 140μs/op
Point.fromHex (decompression) x 12,171 ops/sec @ 82μs/op
schnorr.sign x 409 ops/sec @ 2ms/op
schnorr.verify x 504 ops/sec @ 1ms/op

Compare to other libraries (openssl uses native bindings, not JS):

elliptic#getPublicKey x 1,940 ops/sec
sjcl#getPublicKey x 211 ops/sec

elliptic#sign x 1,808 ops/sec
sjcl#sign x 199 ops/sec
openssl#sign x 4,243 ops/sec
ecdsa#sign x 116 ops/sec
bip-schnorr#sign x 60 ops/sec

elliptic#verify x 812 ops/sec
sjcl#verify x 166 ops/sec
openssl#verify x 4,452 ops/sec
ecdsa#verify x 80 ops/sec
bip-schnorr#verify x 56 ops/sec

elliptic#ecdh x 971 ops/sec

Contributing

Check out a blog post about this library: Learning fast elliptic-curve cryptography in JS.

  1. Clone the repository.
  2. npm install to install build dependencies like TypeScript
  3. npm run compile to compile TypeScript code
  4. npm run test to run jest on test/index.ts

Special thanks to Roman Koblov, who have helped to improve scalar multiplication speed.

License

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