code: private String decryptInternal(SecretKeySpec key, byte[] encryptedBytes) {
          try {
              Cipher cipher = Cipher.getInstance(ENCRYPTION_ALGORITHM + ENCRYPTION_ALGORITHM_MODIFIER);
              cipher.init(Cipher.DECRYPT_MODE, key);
              byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
              return new String(decryptedBytes, ENCODING);
          } catch (GeneralSecurityException e) {
              throw new RuntimeException("Exception during decryptInternal: " + e, e);
          } catch (UnsupportedEncodingException e) {
              throw new RuntimeException("Exception during encryptInternal: " + e, e);
          }
      }
docs: Internal decryption method.
  
  @param key            - the SecretKeySpec used to decrypt
  @param encryptedBytes - the byte[] to decrypt
  @return the decrypted plaintext String.