convert lowBits to unsigned in hash.js

Author: kiran13kumar13

hash.js

@@ -61,7 +61,7 @@ Hash.prototype.digest = function (enc) {
 
   // uint64
   } else {
-    var lowBits = bits & 0xffffffff
+    var lowBits = (bits & 0xffffffff) >>> 0
     var highBits = (bits - lowBits) / 0x100000000
 
     this._block.writeUInt32BE(highBits, this._blockSize - 8)