work in node, and have more helpful error message

Author: dominictarr

rng.js

@@ -1,10 +1,27 @@
 (function() {
+  var g = ('undefined' === typeof window ? global : window) || {}
+  var foolBrowserify = require
+  _crypto = (
+    g.crypto || g.msCrypto || foolBrowserify('crypto')
+  )
   module.exports = function(size) {
-    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;
+    // 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
+      return bytes;
+    }
+    else if (_crypto.randomBytes) {
+      return _crypto.randomBytes(size)
+    }
+    else
+      throw new Error(
+        'secure random number generation not supported by this browser\n'+
+        'use chrome, FireFox or Internet Explorer 11'
+      )
   }
 }())