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