code: @Deprecated
      byte[] createSignatureFor(String algorithm, byte[] secretBytes, byte[] contentBytes) throws NoSuchAlgorithmException, InvalidKeyException {
          final Mac mac = Mac.getInstance(algorithm);
          mac.init(new SecretKeySpec(secretBytes, algorithm));
          return mac.doFinal(contentBytes);
      }
docs: Create signature.
  
  @param algorithm algorithm name.
  @param secretBytes algorithm secret.
  @param contentBytes the content to be signed.
  @return the signature bytes.
  @throws NoSuchAlgorithmException if the algorithm is not supported.
  @throws InvalidKeyException if the given key is inappropriate for initializing the specified algorithm.
  @deprecated rather use corresponding method which takes header and payload as separate inputs