|  | 'use strict' | 
|  |  | 
|  | // limit of Crypto.getRandomValues() | 
|  | // https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues | 
|  | var MAX_BYTES = 65536 | 
|  |  | 
|  | // Node supports requesting up to this number of bytes | 
|  | // https://github.com/nodejs/node/blob/master/lib/internal/crypto/random.js#L48 | 
|  | var MAX_UINT32 = 4294967295 | 
|  |  | 
|  | function oldBrowser () { | 
|  | throw new Error('Secure random number generation is not supported by this browser.\nUse Chrome, Firefox or Internet Explorer 11') | 
|  | } | 
|  |  | 
|  | var Buffer = require('safe-buffer').Buffer | 
|  | var crypto = global.crypto || global.msCrypto | 
|  |  | 
|  | if (crypto && crypto.getRandomValues) { | 
|  | module.exports = randomBytes | 
|  | } else { | 
|  | module.exports = oldBrowser | 
|  | } | 
|  |  | 
|  | function randomBytes (size, cb) { | 
|  | // phantomjs needs to throw | 
|  | if (size > MAX_UINT32) throw new RangeError('requested too many random bytes') | 
|  |  | 
|  | var bytes = Buffer.allocUnsafe(size) | 
|  |  | 
|  | if (size > 0) {  // getRandomValues fails on IE if size == 0 | 
|  | if (size > MAX_BYTES) { // this is the max bytes crypto.getRandomValues | 
|  | // can do at once see https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues | 
|  | for (var generated = 0; generated < size; generated += MAX_BYTES) { | 
|  | // buffer.slice automatically checks if the end is past the end of | 
|  | // the buffer so we don't have to here | 
|  | crypto.getRandomValues(bytes.slice(generated, generated + MAX_BYTES)) | 
|  | } | 
|  | } else { | 
|  | crypto.getRandomValues(bytes) | 
|  | } | 
|  | } | 
|  |  | 
|  | if (typeof cb === 'function') { | 
|  | return process.nextTick(function () { | 
|  | cb(null, bytes) | 
|  | }) | 
|  | } | 
|  |  | 
|  | return bytes | 
|  | } |