code: protected function createCipher($key)
      {
          $cipher = mcrypt_module_open(MCRYPT_BLOWFISH, '', MCRYPT_MODE_CBC, '');
  
          if ($cipher === false || $cipher < 0) {
              throw new InternalServerError(
                  T('mcrypt_module_open with {cipher}', ['cipher' => $cipher])
              );
          }
  
          mcrypt_generic_init($cipher, $this->formatKey($key), $this->iv);
  
          return $cipher;
      }
docs: 创建cipher
  
  @param string $key 私钥
  @throws InternalServerError
  @return resource