ripple-keypairs
Version:
Cryptographic key pairs for the XRP Ledger
72 lines • 3.41 kB
JavaScript
;
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.accountPublicFromPublicGenerator = exports.derivePrivateKey = void 0;
const secp256k1_1 = require("@noble/curves/secp256k1");
const Sha512_1 = __importDefault(require("../../utils/Sha512"));
const ZERO = BigInt(0);
function deriveScalar(bytes, discrim) {
const order = secp256k1_1.secp256k1.CURVE.n;
for (let i = 0; i <= 4294967295; i++) {
// We hash the bytes to find a 256-bit number, looping until we are sure it
// is less than the order of the curve.
const hasher = new Sha512_1.default().add(bytes);
// If the optional discriminator index was passed in, update the hash.
if (discrim !== undefined) {
hasher.addU32(discrim);
}
hasher.addU32(i);
const key = hasher.first256BigInt();
/* istanbul ignore else */
if (key > ZERO && key < order) {
return key;
}
}
// This error is practically impossible to reach.
// The order of the curve describes the (finite) amount of points on the curve
// https://github.com/indutny/elliptic/blob/master/lib/elliptic/curves.js#L182
// How often will an (essentially) random number generated by Sha512 be larger than that?
// There's 2^32 chances (the for loop) to get a number smaller than the order,
// and it's rare that you'll even get past the first loop iteration.
// Note that in TypeScript we actually need the throw, otherwise the function signature would be bigint | undefined
//
/* istanbul ignore next */
throw new Error('impossible unicorn ;)');
}
/**
* @param seed - Bytes.
* @param [opts] - Object.
* @param [opts.accountIndex=0] - The account number to generate.
* @param [opts.validator=false] - Generate root key-pair,
* as used by validators.
* @returns {bigint} 256 bit scalar value.
*
*/
function derivePrivateKey(seed, opts = {}) {
const root = opts.validator;
const order = secp256k1_1.secp256k1.CURVE.n;
// This private generator represents the `root` private key, and is what's
// used by validators for signing when a keypair is generated from a seed.
const privateGen = deriveScalar(seed);
if (root) {
// As returned by validation_create for a given seed
return privateGen;
}
const publicGen = secp256k1_1.secp256k1.ProjectivePoint.BASE.multiply(privateGen).toRawBytes(true);
// A seed can generate many keypairs as a function of the seed and a uint32.
// Almost everyone just uses the first account, `0`.
const accountIndex = opts.accountIndex || 0;
return (deriveScalar(publicGen, accountIndex) + privateGen) % order;
}
exports.derivePrivateKey = derivePrivateKey;
function accountPublicFromPublicGenerator(publicGenBytes) {
const rootPubPoint = secp256k1_1.secp256k1.ProjectivePoint.fromHex(publicGenBytes);
const scalar = deriveScalar(publicGenBytes, 0);
const point = secp256k1_1.secp256k1.ProjectivePoint.BASE.multiply(scalar);
const offset = rootPubPoint.add(point);
return offset.toRawBytes(true);
}
exports.accountPublicFromPublicGenerator = accountPublicFromPublicGenerator;
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