code: public String getDigestAlgorithm() {
          String dea = getAlgorithm(digestEncryptionAlgorithm);
          if (dea == null)
              dea = digestEncryptionAlgorithm;
          
          return getHashAlgorithm() + "with" + dea;
      }
docs: Get the algorithm used to calculate the message digest
  @return the algorithm used to calculate the message digest