public function set_auth()
    {
        $date = date("Y-m-d\TH:i:s.000O");
        $this->arrHeaders['X-cXense-Authentication'] = sprintf(
            'username=%s date=%s hmac-sha256-hex=%s',
            WpCxense::instance()->settings->getApiUser(),
            $date,
            hash_hmac("sha256", $date, WpCxense::instance()->settings->getApiKey())
        );

        return $this;
    }