Implement pseudoRandomBytes.

Provide the same interface as rng, but fallback to pseudoRandomBytes on node.

Author: plediii

index.js

@@ -1,5 +1,6 @@
 'use strict';
-var rng = require('./rng')
+var rng = exports.rng = require('./rng')
+var prng = exports.prng = require('./prng');
 
 function error () {
   var m = [].slice.call(arguments).join(' ')
@@ -23,6 +24,15 @@ exports.randomBytes = function(size, callback) {
     return new Buffer(rng(size))
   }
 }
+exports.pseudoRandomBytes = function(size, callback) {
+  if (callback && callback.call) {
+    try {
+      callback.call(this, undefined, new Buffer(prng(size)))
+    } catch (err) { callback(err) }
+  } else {
+    return new Buffer(prng(size))
+  }
+}
 
 function each(a, f) {
   for(var i in a)

prng.js

@@ -0,0 +1,27 @@
+'use strict';
+(function() {
+  var g = ('undefined' === typeof window ? global : window) || {}
+  var _crypto = (
+    g.crypto || g.msCrypto || require('crypto')
+  )
+  module.exports = function(size) {
+    // Modern Browsers
+    if(_crypto.getRandomValues) {
+      var bytes = new Buffer(size); //in browserify, this is an extended Uint8Array
+      /* This will not work in older browsers.
+       * See https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues
+       */
+
+      _crypto.getRandomValues(bytes);
+      return bytes;
+    }
+    else if (_crypto.pseudoRandomBytes) {
+      return _crypto.pseudoRandomBytes(size)
+    }
+    else
+      throw new Error(
+        'pseudo random number generation not yet implemented for this browser\n'+
+        'use chrome, FireFox or Internet Explorer 11'
+      )
+  }
+}())