code: public static String sum(byte[] bytes) {
      String result = "";
      for (byte b : bytes) {
        result += Integer.toString((b & 0xff) + 0x100, 16).substring(1);
      }
      return result;
    }
docs: Return the MD5 HEX sum of a hashed MD5 byte array.
  
  @param bytes the hashed MD5 byte array
  @return HEX version of the byte array