private function validateClaims(array $claims)
    {
        if (!isset($claims['iss']) || (strcmp(rtrim($claims['iss'], '/'), rtrim($this->issuerUrl, '/')) !== 0)) {
            throw new HttpException(400, 'Invalid "iss"');
        }
        if (!isset($claims['aud']) || (strcmp($claims['aud'], $this->clientId) !== 0)) {
            throw new HttpException(400, 'Invalid "aud"');
        }
    }