secure-random/lib/secure-random.js

Normalize the creation of cryptographically strong random values.

!function(globals){
'use strict'

//*** UMD BEGIN
if (typeof define !== 'undefined' && define.amd) { //require.js / AMD
  define([], function() {
    return secureRandom
  })
} else if (typeof module !== 'undefined' && module.exports) { //CommonJS
  module.exports = secureRandom
} else { //script / browser
  globals.secureRandom = secureRandom
}
//*** UMD END

//options.type is the only valid option
function secureRandom(count, options) {
  options = options || {type: 'Array'}
  //we check for process.pid to prevent browserify from tricking us
  if (
    typeof process != 'undefined'
    && typeof process.pid == 'number'
    && process.versions
    && process.versions.node
  ) {
    return nodeRandom(count, options)
  } else {
    var crypto = window.crypto || window.msCrypto
    if (!crypto) throw new Error("Your browser does not support window.crypto.")
    return browserRandom(count, options)
  }
}

function nodeRandom(count, options) {
  var crypto = require('crypto')
  var buf = crypto.randomBytes(count)

  switch (options.type) {
    case 'Array':
      return [].slice.call(buf)
    case 'Buffer':
      return buf
    case 'Uint8Array':
      var arr = new Uint8Array(count)
      for (var i = 0; i < count; ++i) { arr[i] = buf.readUInt8(i) }
      return arr
    default:
      throw new Error(options.type + " is unsupported.")
  }
}

function browserRandom(count, options) {
  var nativeArr = new Uint8Array(count)
  var crypto = window.crypto || window.msCrypto
  crypto.getRandomValues(nativeArr)

  switch (options.type) {
    case 'Array':
      return [].slice.call(nativeArr)
    case 'Buffer':
      try { var b = new Buffer(1) } catch(e) { throw new Error('Buffer not supported in this environment. Use Node.js or Browserify for browser support.')}
      return new Buffer(nativeArr)
    case 'Uint8Array':
      return nativeArr
    default:
      throw new Error(options.type + " is unsupported.")
  }
}

secureRandom.randomArray = function(byteCount) {
  return secureRandom(byteCount, {type: 'Array'})
}

secureRandom.randomUint8Array = function(byteCount) {
  return secureRandom(byteCount, {type: 'Uint8Array'})
}

secureRandom.randomBuffer = function(byteCount) {
  return secureRandom(byteCount, {type: 'Buffer'})
}


}(this);