made proper synchronous random bytes generator

index.js

@@ -2,22 +2,37 @@ if (typeof Buffer === 'undefined') {
   global.Buffer = require('buffer').Buffer
 }
 
-var deasync = require('deasync');
+var sjcl = require('sjcl');
+var sjclRandom = new sjcl.prng(10);
 
-var {
-RNRandomBytes
-} = require('react-native').NativeModules;
+var RNRandomBytes = require('react-native').NativeModules.RNRandomBytes;
+
+module.exports.randomBytes = function(length, cb) {
 
-export default function randomBytes(length, cb) {
   if (!cb) {
-    // throw new Error('synchronous API not supported')
-    var exec = deasync(RNRandomBytes.randomBytes);
-    var base64String = exec(length);
-    return new Buffer(base64String, 'base64');
+    var size = length;
+    var wordCount = Math.ceil(size * 0.25);
+    sjclRandom.isReady(3);
+    var randomBytes = sjclRandom.randomWords(wordCount);
+    var hexString = sjcl.codec.hex.fromBits(randomBytes);
+    hexString = hexString.substr(0, size * 2);
+
+    return new Buffer(hexString, 'hex');
   }
 
   RNRandomBytes.randomBytes(length, function(err, base64String) {
-    if (err) cb(err)
-    else cb(null, new Buffer(base64String, 'base64'))
-  })
-}
+    if (err) {
+      cb(err)
+    }
+
+    else {
+      cb(null, new Buffer(base64String, 'base64'))
+    }
+  });
+
+};
+
+module.exports.randomBytes(4096, function(err, base64String){
+  var hexString = base64String.toString('hex');
+  sjclRandom.addEntropy(hexString);
+});

package.json

@@ -15,7 +15,7 @@
   ],
   "dependencies": {
     "buffer": "^3.5.2",
-    "deasync": "^0.1.4"
+    "sjcl": "^1.0.3"
   },
   "author": "Mark Vayngrib <mark.vayngrib@lablz.com> (http://github.com/mvayngrib)",
   "license": "ISC"