@scure/bip32
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Secure, audited & minimal implementation of BIP32 hierarchical deterministic (HD) wallets over secp256k1
313 lines • 11.9 kB
JavaScript
/**
* BIP32 hierarchical deterministic (HD) wallets over secp256k1.
* @module
* @example
* ```js
* import { HDKey } from "@scure/bip32";
* import { sha256 } from '@noble/hashes/sha2.js';
* import { randomBytes } from '@noble/hashes/utils.js';
* const seed = randomBytes(32);
* const root = HDKey.fromMasterSeed(seed);
* const base58key = root.privateExtendedKey;
* const restored = HDKey.fromExtendedKey(base58key);
* const fromJson = HDKey.fromJSON({ xpriv: base58key });
* const child = fromJson.derive("m/0/2147483647'/1");
* const msgHash = sha256(new TextEncoder().encode('hello scure-bip32'));
*
* // props
* [root.depth, root.index, root.chainCode];
* [restored.privateKey, restored.publicKey];
* const sig = child.sign(msgHash);
* child.verify(msgHash, sig);
* ```
*/
/*! scure-bip32 - MIT License (c) 2022 Patricio Palladino, Paul Miller (paulmillr.com) */
import { secp256k1 as secp } from '@noble/curves/secp256k1.js';
import { hmac } from '@noble/hashes/hmac.js';
import { ripemd160 } from '@noble/hashes/legacy.js';
import { sha256, sha512 } from '@noble/hashes/sha2.js';
import { abytes, concatBytes, createView } from '@noble/hashes/utils.js';
import { createBase58check } from '@scure/base';
const Point = /* @__PURE__ */ (() => secp.Point)();
const Fn = /* @__PURE__ */ (() => Point.Fn)();
const base58check = /* @__PURE__ */ createBase58check(sha256);
const MASTER_SECRET = /* @__PURE__ */ (() => {
return Uint8Array.from('Bitcoin seed'.split(''), (char) => char.charCodeAt(0));
})();
const BITCOIN_VERSIONS = { private: 0x0488ade4, public: 0x0488b21e };
/** Hardened child index offset from BIP32. */
export const HARDENED_OFFSET = 0x80000000;
const hash160 = (data) => ripemd160(sha256(data));
const fromU32 = (data) => createView(data).getUint32(0, false);
const toU32 = (n) => {
if (typeof n !== 'number')
throw new TypeError('invalid number, should be from 0 to 2**32-1, got ' + n);
if (!Number.isSafeInteger(n) || n < 0 || n > 2 ** 32 - 1)
throw new RangeError('invalid number, should be from 0 to 2**32-1, got ' + n);
const buf = new Uint8Array(4);
createView(buf).setUint32(0, n, false);
return buf;
};
/**
* HDKey from BIP32
* @param opt - Node fields used to construct one HDKey instance.
* @example
* ```js
* import { HDKey } from '@scure/bip32';
* import { randomBytes } from '@noble/hashes/utils.js';
*
* const seed = randomBytes(32);
* const root = HDKey.fromMasterSeed(seed);
* const account0 = root.derive("m/0/1'");
* account0.publicKey;
* ```
*/
export class HDKey {
get fingerprint() {
if (!this.pubHash) {
throw new Error('No publicKey set!');
}
return fromU32(this.pubHash);
}
get identifier() {
return this.pubHash;
}
get pubKeyHash() {
return this.pubHash;
}
// Returns the live private key buffer for this instance.
// Copy it first if you need an immutable snapshot.
get privateKey() {
return this._privateKey || null;
}
get publicKey() {
return this._publicKey || null;
}
get privateExtendedKey() {
const priv = this._privateKey;
if (!priv) {
throw new Error('No private key');
}
return base58check.encode(this.serialize(this.versions.private, concatBytes(Uint8Array.of(0), priv)));
}
get publicExtendedKey() {
if (!this._publicKey) {
throw new Error('No public key');
}
return base58check.encode(this.serialize(this.versions.public, this._publicKey));
}
static fromMasterSeed(seed, versions = BITCOIN_VERSIONS) {
abytes(seed);
if (8 * seed.length < 128 || 8 * seed.length > 512) {
throw new RangeError('HDKey: seed length must be between 128 and 512 bits; 256 bits is advised, got ' +
seed.length);
}
const I = hmac(sha512, MASTER_SECRET, seed);
const privateKey = I.slice(0, 32);
const chainCode = I.slice(32);
return new HDKey({ versions, chainCode, privateKey });
}
static fromExtendedKey(base58key, versions = BITCOIN_VERSIONS) {
// => version(4) || depth(1) || fingerprint(4) || index(4) || chain(32) || key(33)
const keyBuffer = base58check.decode(base58key);
const keyView = createView(keyBuffer);
const version = keyView.getUint32(0, false);
const opt = {
versions,
depth: keyBuffer[4],
parentFingerprint: keyView.getUint32(5, false),
index: keyView.getUint32(9, false),
chainCode: keyBuffer.slice(13, 45),
};
const key = keyBuffer.slice(45);
const isPriv = key[0] === 0;
if (version !== versions[isPriv ? 'private' : 'public']) {
throw new Error('Version mismatch');
}
if (isPriv) {
return new HDKey({ ...opt, privateKey: key.slice(1) });
}
else {
return new HDKey({ ...opt, publicKey: key });
}
}
static fromJSON(json) {
return HDKey.fromExtendedKey(json.xpriv);
}
versions;
depth = 0;
index = 0;
chainCode = null;
parentFingerprint = 0;
_privateKey;
_publicKey;
pubHash;
constructor(opt) {
if (!opt || typeof opt !== 'object') {
throw new Error('HDKey.constructor must not be called directly');
}
this.versions = opt.versions || BITCOIN_VERSIONS;
this.depth = opt.depth || 0;
this.chainCode = opt.chainCode ? Uint8Array.from(opt.chainCode) : null;
this.index = opt.index || 0;
this.parentFingerprint = opt.parentFingerprint || 0;
if (!this.depth) {
if (this.parentFingerprint || this.index) {
throw new Error('HDKey: zero depth with non-zero index/parent fingerprint');
}
}
if (this.depth > 255) {
throw new Error('HDKey: depth exceeds the serializable value 255');
}
if (opt.publicKey && opt.privateKey) {
throw new Error('HDKey: publicKey and privateKey at same time.');
}
if (opt.privateKey) {
if (!secp.utils.isValidSecretKey(opt.privateKey))
throw new Error('Invalid private key');
// Don't alias caller-owned secret buffers.
this._privateKey = Uint8Array.from(opt.privateKey);
this._publicKey = secp.getPublicKey(this._privateKey, true);
}
else if (opt.publicKey) {
this._publicKey = Point.fromBytes(opt.publicKey).toBytes(true); // force compressed point
}
else {
throw new Error('HDKey: no public or private key provided');
}
this.pubHash = hash160(this._publicKey);
}
derive(path) {
if (!/^[mM]'?/.test(path)) {
throw new Error('Path must start with "m" or "M"');
}
if (/^[mM]'?$/.test(path)) {
return this;
}
const parts = path.replace(/^[mM]'?\//, '').split('/');
// tslint:disable-next-line
let child = this;
for (const c of parts) {
const m = /^(\d+)('?)$/.exec(c);
const m1 = m && m[1];
if (!m || m.length !== 3 || typeof m1 !== 'string')
throw new Error('invalid child index: ' + c);
let idx = +m1;
if (!Number.isSafeInteger(idx) || idx >= HARDENED_OFFSET) {
throw new Error('Invalid index');
}
// hardened key
if (m[2] === "'") {
idx += HARDENED_OFFSET;
}
child = child.deriveChild(idx);
}
return child;
}
/**
* @param _I - Test-only override for the 64-byte HMAC-SHA512 output; normal callers must omit it.
*/
deriveChild(index, _I) {
if (!this._publicKey || !this.chainCode) {
throw new Error('No publicKey or chainCode set');
}
let data = toU32(index);
if (index >= HARDENED_OFFSET) {
// Hardened
const priv = this._privateKey;
if (!priv) {
throw new Error('Could not derive hardened child key');
}
// Hardened child: 0x00 || ser256(kpar) || ser32(index)
data = concatBytes(Uint8Array.of(0), priv, data);
}
else {
// Normal child: serP(point(kpar)) || ser32(index)
data = concatBytes(this._publicKey, data);
}
const out = _I || hmac(sha512, this.chainCode, data);
abytes(out, 64);
const childTweak = out.slice(0, 32);
const chainCode = out.slice(32);
const opt = {
versions: this.versions,
chainCode,
depth: this.depth + 1,
parentFingerprint: this.fingerprint,
index,
};
// Fail early instead of re-trying different index
if (opt.depth > 255) {
throw new Error('HDKey: depth exceeds the serializable value 255');
}
try {
const ctweak = Fn.fromBytes(childTweak);
// BIP-32 private derivation retries only when parse256(I_L) >= n or k_i = 0.
// BIP-32 public derivation retries only when parse256(I_L) >= n or K_i is infinity.
// So I_L = 0 is valid here; Fn.fromBytes still rejects parse256(I_L) >= n.
if (this._privateKey) {
const added = Fn.create(Fn.fromBytes(this._privateKey) + ctweak);
if (!Fn.isValidNot0(added)) {
throw new Error('The tweak was out of range or the resulted private key is invalid');
}
opt.privateKey = Fn.toBytes(added);
}
else {
const point = Point.fromBytes(this._publicKey);
const added = ctweak === 0n ? point : point.add(Point.BASE.multiply(ctweak));
// Cryptographically impossible: hmac-sha512 preimage would need to be found
if (added.equals(Point.ZERO)) {
throw new Error('The tweak was equal to negative P, which made the result key invalid');
}
opt.publicKey = added.toBytes(true);
}
return new HDKey(opt);
}
catch (err) {
return this.deriveChild(index + 1);
}
}
sign(hash) {
if (!this._privateKey) {
throw new Error('No privateKey set!');
}
abytes(hash, 32);
return secp.sign(hash, this._privateKey, { prehash: false });
}
verify(hash, signature) {
abytes(hash, 32);
abytes(signature, 64);
if (!this._publicKey) {
throw new Error('No publicKey set!');
}
return secp.verify(signature, hash, this._publicKey, { prehash: false });
}
wipePrivateData() {
if (this._privateKey) {
this._privateKey.fill(0);
this._privateKey = undefined;
}
return this;
}
toJSON() {
return {
xpriv: this.privateExtendedKey,
xpub: this.publicExtendedKey,
};
}
serialize(version, key) {
if (!this.chainCode) {
throw new Error('No chainCode set');
}
abytes(key, 33);
// version(4) || depth(1) || fingerprint(4) || index(4) || chain(32) || key(33)
return concatBytes(toU32(version), new Uint8Array([this.depth]), toU32(this.parentFingerprint), toU32(this.index), this.chainCode, key);
}
}
export const __TESTS = /* @__PURE__ */ Object.freeze({
deriveChildWithI(key, index, I) {
// Bytes wrappers widen the exported test seam, but deriveChild still needs concrete inputs.
return key.deriveChild(index, I);
},
});
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