3 * Copyright(c) 2016 Douglas Christopher Wilson
10 * Module dependencies.
14 var crypto = require('crypto')
21 var generateAttempts = crypto.randomBytes === crypto.pseudoRandomBytes ? 1 : 3
28 module.exports = randomBytes
29 module.exports.sync = randomBytesSync
32 * Generates strong pseudo-random bytes.
34 * @param {number} size
35 * @param {function} [callback]
40 function randomBytes(size, callback) {
41 // validate callback is a function, if provided
42 if (callback !== undefined && typeof callback !== 'function') {
43 throw new TypeError('argument callback must be a function')
46 // require the callback without promises
47 if (!callback && !global.Promise) {
48 throw new TypeError('argument callback is required')
52 // classic callback style
53 return generateRandomBytes(size, generateAttempts, callback)
56 return new Promise(function executor(resolve, reject) {
57 generateRandomBytes(size, generateAttempts, function onRandomBytes(err, str) {
58 if (err) return reject(err)
65 * Generates strong pseudo-random bytes sync.
67 * @param {number} size
72 function randomBytesSync(size) {
75 for (var i = 0; i < generateAttempts; i++) {
77 return crypto.randomBytes(size)
87 * Generates strong pseudo-random bytes.
89 * @param {number} size
90 * @param {number} attempts
91 * @param {function} callback
95 function generateRandomBytes(size, attempts, callback) {
96 crypto.randomBytes(size, function onRandomBytes(err, buf) {
97 if (!err) return callback(null, buf)
98 if (!--attempts) return callback(err)
99 setTimeout(generateRandomBytes.bind(null, size, attempts, callback), 10)