code: public static String genAuthCode (User user)
      {
          // concatenate a bunch of secret stuff together
          StringBuilder buf = new StringBuilder();
          buf.append(user.password);
          buf.append(System.currentTimeMillis());
          buf.append(Math.random());
  
          // and MD5 hash it
          return StringUtil.md5hex(buf.toString());
      }
docs: Generates a new random session identifier for the supplied user.