/** * @return string the secret key used for cookie validation. If it was not set previously, * a random key will be generated and used. */ public function getCookieValidationKey() { if ($this->_cookieValidationKey === null) { $this->_cookieValidationKey = Security::getSecretKey(__CLASS__ . '/' . Yii::$app->id); } return $this->_cookieValidationKey; }