code: public static String decipher(String key,
                                    String cipherText,
                                    String cipherType) {
          if (key == null || key == "") {
              return cipherText;
          }
  
          if (cipherText == null) {
              return null;
          }
  
          if (cipherType == null || cipherType == "") {
              return cipherText;
          } else if ("1".equalsIgnoreCase(cipherType)) {
              byte[] keyBytes = convertKeyToByteArray(key);
              byte[] cipherBytes = Base64.decode(cipherText);
              sanityCheckOnCipherBytes(cipherText, cipherBytes);
              byte[] clearTextBytes = applyCipher(keyBytes, cipherBytes);
              return convertByteArrayToClearText(clearTextBytes);
          } else {
              throw new IllegalArgumentException("Unrecognized cipher type: '"
                      + cipherType + "'");
          }
      }
docs: Use the key to produce a clear text String from the cipherText. If no key
  is provided, or if no type is specified, just return the text as is.