@csquare/random-bytes-seed/dist/esm/random-bytes-seed.js

Zero-dep package to generate random bytes using a seed.

import { Buffer } from 'buffer';
import { createHash, randomBytes } from 'crypto';
/**
 * The default options.
 */
export const options = {
    algorithm: 'sha256',
    seed: 'random-bytes-seed',
};
/**
 * Generate random bytes and allow the final user to pass a seed for repeatability.
 * @param {number} length The random bytes desired length.
 * @param {Buffer | string} seed The seed. If not seed is provided, fallbacks to native {@link randomBytes}.
 * @return {Buffer} A pseudo random bytes buffer.
 */
export function randomBytesSeed(length, seed) {
    // Validate the inputs
    if (typeof length !== 'number' || !Number.isInteger(length) || length < 1) {
        throw new TypeError('`length` argument must be a valid strictly positive integer.');
    }
    if (!seed) {
        // No seed: fallback to native randomBytes
        return randomBytes(length);
    }
    /**
     * The round buffer, which is updated until the output buffer is long enough.
     */
    let round = createHash('sha256').update(options.seed).update(seed).digest();
    /**
     * The output buffer, which size is increased after each round.
     */
    let output = Buffer.alloc(0);
    while (output.length < length) {
        round = createHash('sha256').update(round).digest();
        output = Buffer.concat([output, round]);
    }
    return output.slice(0, length);
}
export default randomBytesSeed;