code: public function generateSignCode(array $params, $secret)
      {
          ksort($params);
  
          if (isset($params[self::SIGN_NAMESPACE])) {
              unset($params[self::SIGN_NAMESPACE]);
          }
  
          return md5(implode('', $params) . $secret);
      }
docs: Generate sample secret code for sign any request, etc..
  
  @param array $params
  @param string $secret
  @return string