Horde::signQueryString PHP Method

    public static function signQueryString($queryString, $now = null)
    {
        if (!isset($GLOBALS['conf']['secret_key'])) {
            return $queryString;
        }
        if (is_null($now)) {
            $now = time();
        }
        if ($queryString instanceof Horde_Url) {
            $queryString->setRaw(true)->add(array('_t' => $now, '_h' => ''));
            $parse_url = parse_url($queryString);
            $queryString->add('_h', Horde_Url::uriB64Encode(hash_hmac('sha1', $parse_url['query'] . '=', $GLOBALS['conf']['secret_key'], true)));
            return $queryString;
        }
        $queryString .= '&_t=' . $now . '&_h=';
        return $queryString . Horde_Url::uriB64Encode(hash_hmac('sha1', $queryString, $GLOBALS['conf']['secret_key'], true));
    }

 /**
  */
 public function display(Horde_Core_Prefs_Ui $ui)
 {
     global $injector, $notification, $page_output, $prefs, $registry;
     try {
         $facebook = $injector->getInstance('Horde_Service_Facebook');
     } catch (Horde_Exception $e) {
         return $e->getMessage();
     }
     $page_output->addThemeStylesheet('facebook.css');
     $view = new Horde_View(array('templatePath' => HORDE_TEMPLATES . '/prefs'));
     $view->app_name = $registry->get('name', 'horde');
     // Ensure we have authorized horde.
     try {
         $session_uid = $facebook->auth->getLoggedInUser();
         $fbp = unserialize($prefs->getValue('facebook'));
         $uid = $fbp['uid'];
         // Verify the userid matches the one we expect for the session
         if ($fbp['uid'] != $session_uid) {
             $haveSession = false;
         } else {
             $haveSession = true;
         }
     } catch (Horde_Service_Facebook_Exception $e) {
         Horde::log($e->getMessage(), 'ERR');
         $haveSession = false;
         $prefs->setValue('facebook', serialize(array('uid' => '', 'sid' => 0)));
     }
     // Get a token generator
     $token = $injector->getInstance('Horde_Token');
     // We have a session, build the template.
     if (!empty($haveSession)) {
         try {
             $perms = $facebook->users->getAppPermissions();
             $view->have_publish = !empty($perms[Horde_Service_Facebook_Auth::EXTEND_PERMS_PUBLISHSTREAM]);
             $view->have_read = !empty($perms[Horde_Service_Facebook_Auth::EXTEND_PERMS_READSTREAM]);
             $view->have_friends = !empty($perms[Horde_Service_Facebook_Auth::EXTEND_PERMS_FRIENDS_ABOUT]);
         } catch (Horde_Service_Facebook_Exception $e) {
             $notification->push($e->getMessage(), 'horde.error');
         }
         // Get user info. FB recommends using the FB photo and styling.
         $fql = 'SELECT first_name, last_name, status, pic_with_logo, current_location FROM user WHERE uid IN (' . $uid . ')';
         try {
             $user_info = $facebook->fql->run($fql);
         } catch (Horde_Service_Facebook_Exception $e) {
             $notification->push(_("Temporarily unable to connect with Facebook, Please try again."), 'horde.alert');
         }
         // Get a state token.
         $state = $token->get();
         // FB Perms links
         $cburl = Horde::url('services/facebook', true);
         $view->have_session = true;
         $view->user_pic_url = $user_info[0]['pic_with_logo'];
         $view->user_name = $user_info[0]['first_name'] . ' ' . $user_info[0]['last_name'];
         $url = $facebook->auth->getOAuthUrl($cburl, array(Horde_Service_Facebook_Auth::EXTEND_PERMS_PUBLISHSTREAM));
         $view->publish_url = $url;
         // User read perms
         $url = $facebook->auth->getOAuthUrl($cburl, array(Horde_Service_Facebook_Auth::EXTEND_PERMS_READSTREAM, Horde_Service_Facebook_Auth::EXTEND_PERMS_USER_ABOUT, Horde_Service_Facebook_Auth::EXTEND_PERMS_USER_BIRTHDAY, Horde_Service_Facebook_Auth::EXTEND_PERMS_USER_EVENTS, Horde_Service_Facebook_Auth::EXTEND_PERMS_USER_HOMETOWN, Horde_Service_Facebook_Auth::EXTEND_PERMS_USER_LOCATION, Horde_Service_Facebook_Auth::EXTEND_PERMS_USER_PHOTOS), $state);
         $view->read_url = Horde::signQueryString($url);
         // Friend read perms
         $url = $facebook->auth->getOAuthUrl($cburl, array(Horde_Service_Facebook_Auth::EXTEND_PERMS_FRIENDS_ABOUT, Horde_Service_Facebook_Auth::EXTEND_PERMS_FRIENDS_BIRTHDAY, Horde_Service_Facebook_Auth::EXTEND_PERMS_FRIENDS_HOMETOWN, Horde_Service_Facebook_Auth::EXTEND_PERMS_FRIENDS_LOCATION, Horde_Service_Facebook_Auth::EXTEND_PERMS_FRIENDS_PHOTOS), $state);
         $view->friends_url = Horde::signQueryString($url);
     } else {
         /* No existing session */
         $state = $token->get();
         $view->authUrl = $facebook->auth->getOAuthUrl(Horde::url('services/facebook', true), array(), $state);
     }
     return $view->render('facebook');
 }