docs: public static String passwordDecode(String encoded_string) {
          /*
           * check input:
           * 
           * -- encoded_string: any string, any length, cannot be null,
           * may start with valid (supported) crypto algorithm tag
           */
  
          if (encoded_string == null) {
              // don't accept null password
              return null;
          }
  
          String crypto_algorithm = getCryptoAlgorithm(encoded_string);
  
          if (crypto_algorithm == null) {
              // password not encoded
              return encoded_string;
          }
  
          // valid input ... decode password
          return decode_password(removeCryptoAlgorithmTag(encoded_string), crypto_algorithm);
      }