code: private byte[] encrypt(final byte[] bytes) throws IOException {
          try (Formatter formatter = new Formatter()) {
              for (final byte byt : this.create().doFinal(bytes)) {
                  formatter.format("%02x", byt);
              }
              return formatter.toString().getBytes(Charset.defaultCharset());
          }
      }
docs: Encrypt the given bytes using HMAC.
  
  @param bytes
  Bytes to encrypt
  @return Encrypted bytes
  @throws IOException
  for all unexpected exceptions