code: public synchronized String decrypt(String encryptedText) {
          assertArgumentNotNull("encryptedText", encryptedText);
          if (decryptingCipher == null) {
              initialize();
          }
          try {
              return new String(doDecrypt(encryptedText), encoding);
          } catch (UnsupportedEncodingException e) {
              throw new CipherFailureException("Failed by unsupported encoding: " + encoding, e);
          }
      }
docs: Decrypt the encrypted text (back to plain text). <br>
  @param encryptedText The encrypted text to be decrypted. (NotNull, EmptyAllowed)
  @return The plain text from the encrypted text. (NotNull, EmptyAllowed: if secret key is empty)
  @throws CipherFailureException When the cipher fails.