diff --git a/calendar.php b/calendar.php
index 65cc153..691dca7 100644
--- a/calendar.php
+++ b/calendar.php
@@ -928,6 +928,18 @@ $("#rcmfd_new_category").keypress(function(event) {
         }
 
         switch ($action) {
+        case "new-source": //we "misuse" create_calendar() to stay compatible with other drivers
+            $cal['new-source'] = true;
+            $success = $this->driver->create_calendar($cal);
+            $reload  = true;
+            break;
+        case "delete-source": //we "misuse" delete_calendar() to stay compatible with other drivers
+            $cal['delete-source'] = true;
+            $success = $this->driver->delete_calendar($cal);
+            $reload  = true;
+            break;
+        case "form-source-new": //we "misuse" calendar_editform() to stay compatible with other drivers
+        case "form-source-delete": //we "misuse" calendar_editform() to stay compatible with other drivers
         case "form-new":
         case "form-edit":
             echo $this->ui->calendar_editform($action, $cal);
diff --git a/calendar_ui.js b/calendar_ui.js
index 571c153..50c1126 100644
--- a/calendar_ui.js
+++ b/calendar_ui.js
@@ -2884,6 +2884,64 @@ function rcube_calendar_ui(settings)
       return update_event_confirm('remove', event, { id:event.id, calendar:event.calendar, attendees:event.attendees });
     };
 
+    //opens a dialog to add caldav sources
+    this.calendar_new_source = function() {
+        var title = rcmail.gettext('addsources', 'calendar'),
+            params = {action: 'form-source-new', _framed: 1},
+            $dialog = $('<iframe>').attr('src', rcmail.url('calendar', params)),
+            save_func = function() {
+                var data,
+                    form = $dialog.contents().find('#calendarpropform');
+    
+                // form is not loaded
+                if (!form || !form.length)
+                    return false;
+    
+                // post data to server
+                data = form.serializeJSON();
+                if (data.color)
+                    data.color = data.color.replace(/^#/, '');
+                if (calendar.id)
+                    data.id = calendar.id;
+    
+                me.saving_lock = rcmail.set_busy(true, 'calendar.savingdata');
+                rcmail.http_post('calendar', { action:'new-source', c:data });
+                $dialog.dialog("close");
+            };
+    
+        rcmail.simple_dialog($dialog, title, save_func, {
+            width: 600,
+            height: 400
+        });
+    };
+    
+    //opens a dialog to delete caldav sources
+    this.calendar_delete_sources = function() {
+        var title = rcmail.gettext('deletesources', 'calendar'),
+            params = {action: 'form-source-delete', _framed: 1},
+            $dialog = $('<iframe>').attr('src', rcmail.url('calendar', params)),
+            save_func = function() {
+                var data,
+                    form = $dialog.contents().find('#calendarpropform');
+    
+                // form is not loaded
+                if (!form || !form.length)
+                    return false;
+    
+                // post data to server
+                data = form.serializeJSON();
+    
+                me.saving_lock = rcmail.set_busy(true, 'calendar.savingdata');
+                rcmail.http_post('calendar', { action:'delete-source', c:data });
+                $dialog.dialog("close");
+            };
+    
+        rcmail.simple_dialog($dialog, title, save_func, {
+            width: 600,
+            height: 400
+        });
+    };
+    
     // opens a jquery UI dialog with event properties (or empty for creating a new calendar)
     this.calendar_edit_dialog = function(calendar)
     {
@@ -4168,6 +4226,8 @@ window.rcmail && rcmail.addEventListener('init', function(evt) {
   rcmail.register_command('print', function(){ cal.print_calendars(); }, true);
 
   // configure list operations
+  rcmail.register_command('calendar-sources-add', cal.calendar_new_source, true);
+  rcmail.register_command('calendar-sources-delete', cal.calendar_delete_sources, true);
   rcmail.register_command('calendar-create', function(){ cal.calendar_edit_dialog(null); }, true);
   rcmail.register_command('calendar-edit', function(){ cal.calendar_edit_dialog(cal.calendars[cal.selected_calendar]); }, false);
   rcmail.register_command('calendar-remove', function(){ cal.calendar_remove(cal.calendars[cal.selected_calendar]); }, false);
diff --git a/composer.json b/composer.json
index e5accdc..0bd024a 100644
--- a/composer.json
+++ b/composer.json
@@ -21,13 +21,18 @@
         {
             "type": "composer",
             "url": "https://plugins.roundcube.net"
+        },
+        {
+            "type": "vcs",
+            "url": "https://github.com/JodliDev/libcalendaring"
         }
     ],
     "require": {
-        "php": ">=5.4.0",
+        "php": ">=5.5",
         "roundcube/plugin-installer": ">=0.1.3",
-        "kolab/libcalendaring": ">=3.4.0",
-        "kolab/libkolab": ">=3.4.0"
+        "jodlidev/libcalendaring": ">=3.4.0",
+        "kolab/libkolab": ">=3.4.0",
+        "sabre/dav": ">=4.1.5"
     },
      "extra": {
         "roundcube": {
diff --git a/config.inc.php.dist b/config.inc.php.dist
index 970feb7..ca6ff09 100644
--- a/config.inc.php.dist
+++ b/config.inc.php.dist
@@ -25,8 +25,12 @@
  +-------------------------------------------------------------------------+
 */
 
-// backend type (database, kolab)
-$config['calendar_driver'] = "database";
+// backend type (database, kolab, caldav)
+$config['calendar_driver'] = "caldav";
+
+// Enable debugging output for iCAL/CalDAV drivers
+$config['calendar_caldav_debug'] = false;
+$config['calendar_ical_debug'] = false;
 
 // default calendar view (agendaDay, agendaWeek, month)
 $config['calendar_default_view'] = "agendaWeek";
diff --git a/drivers/caldav/SQL/mysql.initial.sql b/drivers/caldav/SQL/mysql.initial.sql
index d60d482..1c0c2cf 100644
--- a/drivers/caldav/SQL/mysql.initial.sql
+++ b/drivers/caldav/SQL/mysql.initial.sql
@@ -3,6 +3,7 @@
  *
  * @version @package_version@
  * @author Daniel Morlock <daniel.morlock@awesome-it.de>
+ * @author JodliDev <jodlidev@gmail.com>
  *
  * Copyright (C) Awesome IT GbR <info@awesome-it.de>
  *
@@ -20,23 +21,37 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
+CREATE TABLE IF NOT EXISTS `caldav_sources` (
+  `source_id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
+  `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+
+  `caldav_url` varchar(255) NOT NULL,
+  `caldav_user` varchar(255) DEFAULT NULL,
+  `caldav_pass` varchar(1024) DEFAULT NULL,
+
+  PRIMARY KEY(`source_id`),
+  CONSTRAINT `fk_caldav_sources_user_id` FOREIGN KEY (`user_id`)
+  REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE
+) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
+
 CREATE TABLE IF NOT EXISTS `caldav_calendars` (
   `calendar_id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
   `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+  `source_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
   `name` varchar(255) NOT NULL,
   `color` varchar(8) NOT NULL,
   `showalarms` tinyint(1) NOT NULL DEFAULT '1',
 
-  `caldav_url` varchar(255) NOT NULL,
   `caldav_tag` varchar(255) DEFAULT NULL,
-  `caldav_user` varchar(255) DEFAULT NULL,
-  `caldav_pass` varchar(1024) DEFAULT NULL,
+  `caldav_url` varchar(255) NOT NULL,
   `caldav_last_change` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
 
   PRIMARY KEY(`calendar_id`),
   INDEX `caldav_user_name_idx` (`user_id`, `name`),
   CONSTRAINT `fk_caldav_calendars_user_id` FOREIGN KEY (`user_id`)
-  REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE
+  REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE,
+  CONSTRAINT `fk_caldav_calendars_sources` FOREIGN KEY (`source_id`)
+  REFERENCES `caldav_sources`(`source_id`) ON DELETE CASCADE ON UPDATE CASCADE
 ) /*!40000 ENGINE=INNODB */ /*!40101 CHARACTER SET utf8 COLLATE utf8_general_ci */;
 
 CREATE TABLE IF NOT EXISTS `caldav_events` (
diff --git a/drivers/caldav/caldav_client.php b/drivers/caldav/caldav_client.php
new file mode 100644
index 0000000..712a0b7
--- /dev/null
+++ b/drivers/caldav/caldav_client.php
@@ -0,0 +1,398 @@
+<?php
+
+/**
+ * CalDAV Client
+ *
+ * @version @package_version@
+ * @author Daniel Morlock <daniel.morlock@awesome-it.de>
+ * @author JodliDev <jodlidev@gmail.com>
+ *
+ * Copyright (C) Awesome IT GbR <info@awesome-it.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+class caldav_client extends Sabre\DAV\Client
+{
+    const CLARK_GETCTAG = '{http://calendarserver.org/ns/}getctag';
+    const CLARK_GETETAG = '{DAV:}getetag';
+    const CLARK_CALDATA = '{urn:ietf:params:xml:ns:caldav}calendar-data';
+
+    private $base_uri;
+    private $path;
+    private $libvcal;
+
+    /**
+     *  Default constructor for CalDAV client.
+     *
+     * @param string Caldav URI to appropriate calendar.
+     * @param string Username for HTTP basic auth.
+     * @param string Password for HTTP basic auth.
+     */
+    public function __construct($uri, $user = null, $pass = null)
+    {
+
+        // Include libvcalendar on demand ...
+        if(!class_exists("libvcalendar"))
+            require_once __DIR__ .'/../../../libcalendaring/libvcalendar.php';
+    
+    
+        $this->libvcal = new libvcalendar();
+
+        $tokens = parse_url($uri);
+        $this->base_uri = $tokens['scheme']."://".$tokens['host'].($tokens['port'] ? ":".$tokens['port'] : null);
+        $this->path = $tokens['path'].($tokens['query'] ? "?".$tokens['query'] : null);
+
+        $settings = array(
+            'baseUri' => $this->base_uri,
+            'authType' => Sabre\DAV\Client::AUTH_BASIC
+        );
+
+        $this->rc = rcmail::get_instance();
+
+        if ($user) $settings['userName'] = $user;
+        if ($pass) $settings['password'] = $pass;
+
+        parent::__construct($settings);
+    }
+
+    /**
+     * Fetches calendar ctag.
+     *
+     * @see http://code.google.com/p/sabredav/wiki/BuildingACalDAVClient#Retrieving_calendar_information
+     * @return Calendar ctag or null on error.
+     */
+    public function get_ctag()
+    {
+        try
+        {
+            $arr = $this->propFind($this->path, array(self::CLARK_GETCTAG));
+
+            if (isset($arr[self::CLARK_GETCTAG]))
+                return $arr[self::CLARK_GETCTAG];
+        }
+        catch(Sabre\DAV\Exception $err)
+        {
+            rcube::raise_error(array(
+                'code' => $err->getHTTPCode(),
+                'type' => 'DAV',
+                'file' => $err->getFile(),
+                'line' => $err->getLine(),
+                'message' => $err->getMessage()
+            ), true, false);
+        }
+
+        return null;
+    }
+
+    /**
+     * Fetches event etags and urls.
+     *
+     * @see http://code.google.com/p/sabredav/wiki/BuildingACalDAVClient#Finding_out_if_anything_changed
+     *
+     * @param array Optional list of relative event URL's to retrieve specific etags. If not specified, all etags of the current calendar are returned.
+     * @return array List of etag properties with keys:
+     *    url: Event ical path relative to the calendar URL.
+     *   etag: Current event etag.
+     */
+    public function get_etags(array $event_urls = array())
+    {
+        $etags = array();
+
+        try
+        {
+            $arr = $this->prop_report($this->path, array(self::CLARK_GETETAG), $event_urls);
+            foreach ($arr as $path => $data)
+            {
+                // Some caldav server return an empty calendar as event where etag is missing. Skip this!
+                if($data[self::CLARK_GETETAG])
+                {
+                    array_push($etags, array(
+                       "url" => $path,
+                       "etag" => str_replace('"', null, $data[self::CLARK_GETETAG])
+                    ));
+                }
+            }
+        }
+        catch(Sabre\DAV\Exception $err)
+        {
+            rcube::raise_error(array(
+                'code' => $err->getHTTPCode(),
+                'type' => 'DAV',
+                'file' => $err->getFile(),
+                'line' => $err->getLine(),
+                'message' => $err->getMessage()
+            ), true, false);
+        }
+
+        return $etags;
+    }
+
+    /**
+     * Fetches calendar events.
+     *
+     * @see http://code.google.com/p/sabredav/wiki/BuildingACalDAVClient#Downloading_objects
+     * @param array $urls = array() Optional list of event URL's to fetch. If non is specified, all
+     *        events from the appropriate calendar will be fetched.
+     * @return Array hash list that maps the events URL to the appropriate event properties.
+     */
+    public function get_events($urls = array())
+    {
+        $events = array();
+
+        try
+        {
+            $vcals = $this->prop_report($this->path, array(
+                self::CLARK_GETETAG,
+                self::CLARK_CALDATA
+            ), $urls);
+
+            foreach ($vcals as $path => $response)
+            {
+                $vcal = $response[self::CLARK_CALDATA];
+                foreach ($this->libvcal->import($vcal) as $event) {
+                    $events[$path] = $event;
+                }
+            }
+        }
+        catch(Sabre\DAV\Exception $err)
+        {
+            rcube::raise_error(array(
+                'code' => $err->getHTTPCode(),
+                'type' => 'DAV',
+                'file' => $err->getFile(),
+                'line' => $err->getLine(),
+                'message' => $err->getMessage()
+            ), true, false);
+        }
+        return $events;
+    }
+
+    /**
+     * Does a REPORT request
+     *
+     * @param string $url
+     * @param array $properties List of requested properties must be specified as an array, in clark
+     *        notation.
+     * @param array $event_urls If specified, a multiget report request will be initiated with the
+     *        specified event urls.
+     * @param int $depth = 1 Depth should be either 0 or 1. A depth of 1 will cause a request to be
+     *        made to the server to also return all child resources.
+     * @return array Hash with ics event path as key and a hash array with properties and appropriate values.
+     */
+    public function prop_report($url, array $properties, array $event_urls = array(), $depth = 1)
+    {
+        $parent_tag = sizeof($event_urls) > 0 ? "c:calendar-multiget" : "d:propfind";
+        $method = sizeof($event_urls) > 0 ? 'REPORT' : 'PROPFIND';
+
+        $body = '<?xml version="1.0"?>'."\n".'<'.$parent_tag.' xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">'."\n";
+
+        $body .= '  <d:prop>'."\n";
+        foreach ($properties as $property)
+        {
+
+            list($namespace, $elementName) = Sabre\Xml\Service::parseClarkNotation($property);
+
+            if ($namespace === 'DAV:')
+            {
+                $body .= '    <d:'.$elementName.' />'."\n";
+            }
+            else
+            {
+                $body .= '    <x:'.$elementName.' xmlns:x="'.$namespace.'"/>'."\n";
+            }
+        }
+        $body .= '  </d:prop>'."\n";
+
+        // http://tools.ietf.org/html/rfc4791#page-90
+        // http://www.bedework.org/trac/bedework/wiki/Bedework/DevDocs/Filters
+        /*
+         if($start && $end)
+         {
+         $body.= '  <c:filter>'."\n".
+         '    <c:comp-filter name="VCALENDAR">'."\n".
+         '      <c:comp-filter name="VEVENT">'."\n".
+         '        <c:time-range start="'.$start.'" end="'.$end.'" />'."\n".
+         '      </c:comp-filter>'."\n".
+         '    </c:comp-filter>'."\n".
+         '  </c:filter>' . "\n";
+         }
+         */
+
+        foreach ($event_urls as $event_url)
+        {
+            $body .= '<d:href>'.$event_url.'</d:href>'."\n";
+        }
+
+        $body .= '</'.$parent_tag.'>';
+
+        $response = $this->request($method, $url, $body, array(
+            'Depth' => $depth,
+            'Content-Type' => 'application/xml'
+        ));
+
+        $result = $this->parseMultiStatus($response['body']);
+
+        // If depth was 0, we only return the top item
+        if ($depth === 0)
+        {
+            reset($result);
+            $result = current($result);
+            return isset($result[200]) ? $result[200] : array();
+        }
+
+        $new_result = array();
+        foreach ($result as $href => $status_list)
+        {
+            $new_result[$href] = isset($status_list[200]) ? $status_list[200] : array();
+        }
+
+        return $new_result;
+    }
+
+    /**
+     * Updates or creates a calendar event.
+     *
+     * @see http://code.google.com/p/sabredav/wiki/BuildingACalDAVClient#Updating_a_calendar_object
+     * @param string Event ics path for the event.
+     * @param array Hash array with event properties.
+     * @param string Current event etag to match against server data. Pass null for new events.
+     * @return True on success, -1 if precondition failed i.e. local etag is not up to date, false on error.
+     */
+    public function put_event($path, $event, $etag = null)
+    {
+        try
+        {
+            $headers = array("Content-Type" => "text/calendar; charset=utf-8");
+            if ($etag) $headers["If-Match"] = '"'.$etag.'"';
+
+            // Temporarily disable error reporting since libvcal seems not checking array key properly.
+            // TODO: Remove this todo if we could ensure that those errors come not from incomplete event properties.
+            $err_rep = error_reporting(E_ERROR);
+            $vcal = $this->libvcal->export(array($event));
+            if (is_array($vcal))
+                $vcal = array_shift($vcal);
+            error_reporting($err_rep);
+
+            $response = $this->request('PUT', $path, $vcal, $headers);
+
+            // Following http://code.google.com/p/sabredav/wiki/BuildingACalDAVClient#Creating_a_calendar_object, the
+            // caldav server must not always return the new etag.
+
+            return $response["statusCode"] == 201 || // 201 (created, successfully created)
+                   $response["statusCode"] == 204;   // 204 (no content, successfully updated)
+        }
+        catch(Sabre\DAV\Exception\PreconditionFailed $err)
+        {
+            // Event tag not up to date, must be updated first ...
+            return -1;
+        }
+        catch(Sabre\DAV\Exception $err)
+        {
+            rcube::raise_error(array(
+                'code' => $err->getHTTPCode(),
+                'type' => 'DAV',
+                'file' => $err->getFile(),
+                'line' => $err->getLine(),
+                'message' => $err->getMessage()
+            ), true, false);
+        }
+        return false;
+    }
+
+    /**
+     * Removes event of given URL.
+     *
+     * @see http://code.google.com/p/sabredav/wiki/BuildingACalDAVClient#Deleting_a_calendar_object
+     * @param string Event ics path for the event.
+     * @param string Current event etag to match against server data. Pass null to force removing the event.
+     * @return True on success, -1 if precondition failed i.e. local etag is not up to date, false on error.
+     **/
+    public function remove_event($path, $etag = null)
+    {
+        try
+        {
+            $headers = array("Content-Type" => "text/calendar; charset=utf-8");
+            if ($etag) $headers["If-Match"] = '"'.$etag.'"';
+
+            $response = $this->request('DELETE', $path, null, $headers);
+            return $response["statusCode"] == 204 ||    // 204 (no content, successfully deleted)
+                   $response["statusCode"] == 200;      // 200 (OK, successfully deleted)
+        }
+        catch(Sabre\DAV\Exception\PreconditionFailed $err)
+        {
+            // Event tag not up to date, must be updated first ...
+            return -1;
+        }
+        catch(Sabre\DAV\Exception $err)
+        {
+            rcube::raise_error(array(
+                'code' => $err->getHTTPCode(),
+                'type' => 'DAV',
+                'file' => $err->getFile(),
+                'line' => $err->getLine(),
+                'message' => $err->getMessage()
+            ), true, false);
+        }
+        return false;
+    }
+
+    /**
+     * Make a propFind query to caldav server
+     * @param string $path absolute or relative URL to Resource
+     * @param array $props list of properties to use for the query. Properties must have clark-notation.
+     * @param int $depth 0 means no recurse while 1 means recurse
+     * @return array
+     */
+    public function prop_find($path, $props, $depth)
+    {
+        try {
+            $response = $this->propFind($path, $props, $depth);
+        }
+        catch(Sabre\DAV\Exception $err)
+        {
+            rcube::raise_error(array(
+                'code' => $err->getHTTPCode(),
+                'type' => 'DAV',
+                'file' => $err->getFile(),
+                'line' => $err->getLine(),
+                'message' => $err->getMessage()
+            ), true, false);
+        }
+        return $response;
+    }
+
+    public function create_calendar($path, $name, $color) {
+        $headers = array("Content-Type" => "application/xml; charset=utf-8");
+        $body = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>
+<C:mkcalendar xmlns:D=\"DAV:\" xmlns:C=\"urn:ietf:params:xml:ns:caldav\" xmlns:ical=\"http://apple.com/ns/ical/\">
+<D:set>
+    <D:prop>
+        <D:displayname>$name</D:displayname>
+        <ical:calendar-color>#$color</ical:calendar-color>
+    </D:prop>
+</D:set>
+</C:mkcalendar>";
+
+        $response = $this->request('MKCALENDAR', $path, $body, $headers);
+        return $response["statusCode"] === 201;
+    }
+
+    public function delete_calendar() {
+        $response = $this->request('DELETE', $this->base_uri .$this->path);
+        return $response["statusCode"] === 204 ||    // 204 (no content, successfully deleted)
+            $response["statusCode"] === 200;      // 200 (OK, successfully deleted)
+    }
+};
+?>
diff --git a/drivers/caldav/caldav_driver.php b/drivers/caldav/caldav_driver.php
index b39aeff..87f4763 100644
--- a/drivers/caldav/caldav_driver.php
+++ b/drivers/caldav/caldav_driver.php
@@ -4,6 +4,7 @@
  * CalDAV driver for the Calendar plugin
  *
  * @author Daniel Morlock <daniel.morlock@awesome-it.de>
+ * @author JodliDev <jodlidev@gmail.com>
  *
  * Copyright (C) Awesome IT GbR <info@awesome-it.de>
  *
@@ -21,8 +22,8 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-require_once (dirname(__FILE__).'/caldav_sync.php');
-require_once (dirname(__FILE__).'/../../lib/encryption.php');
+require_once 'caldav_sync.php';
+require_once 'encryption.php';
 
 
 class caldav_driver extends calendar_driver
@@ -47,13 +48,11 @@ class caldav_driver extends calendar_driver
     private $sensitivity_map = array('public' => 0, 'private' => 1, 'confidential' => 2);
     private $server_timezone;
 
-    private $db_events = 'caldav_events';
+    private $db_sources = 'caldav_sources';
     private $db_calendars = 'caldav_calendars';
+    private $db_events = 'caldav_events';
     private $db_attachments = 'caldav_attachments';
 
-    // Crypt key for CalDAV auth
-    private $crypt_key;
-
     // Holds CalDAV sync clients
     private $sync_clients = array();
 
@@ -92,10 +91,10 @@ class caldav_driver extends calendar_driver
 
         // read database config
         $db = $this->rc->get_dbh();
-        $this->db_events = $this->rc->config->get('db_table_caldav_events', $db->table_name($this->db_events));
+        $this->db_sources = $this->rc->config->get('db_table_caldav_sources', $db->table_name($this->db_sources));
         $this->db_calendars = $this->rc->config->get('db_table_caldav_calendars', $db->table_name($this->db_calendars));
+        $this->db_events = $this->rc->config->get('db_table_caldav_events', $db->table_name($this->db_events));
         $this->db_attachments = $this->rc->config->get('db_table_caldav_attachments', $db->table_name($this->db_attachments));
-        $this->crypt_key = $this->rc->config->get("calendar_crypt_key", "%E`c{2;<J2F^4_&._BxfQ<5Pf3qv!m{e");
 
         // Set debug state
         if(self::$debug === null)
@@ -113,10 +112,22 @@ class caldav_driver extends calendar_driver
 
         if (!empty($this->rc->user->ID)) {
             $calendar_ids = array();
-            $result = $this->rc->db->query("SELECT *, calendar_id AS id
-                FROM " . $this->db_calendars . "
-                WHERE user_id=?
-                ORDER BY name",
+            $result = $this->rc->db->query('SELECT 
+                   cal.calendar_id AS `calendar_id`, 
+                   cal.source_id AS `source_id`, 
+                   cal.name AS `name`, 
+                   cal.color AS `color`, 
+                   cal.showalarms AS `showalarms`,
+                   cal.caldav_tag AS `caldav_tag`, 
+                   cal.caldav_url AS `caldav_url`,
+                   s.caldav_user AS `caldav_user`,
+                   s.caldav_pass AS `caldav_pass`,
+                   cal.caldav_last_change AS `caldav_last_change`,
+                   cal.calendar_id AS `id`
+                FROM ' . $this->db_calendars . ' AS cal
+                LEFT JOIN ' .$this->db_sources .' AS s ON (cal.source_id = s.source_id)
+                WHERE cal.user_id=?
+                ORDER BY name',
                 $this->rc->user->ID
             );
             while ($result && ($arr = $this->rc->db->fetch_assoc($result))) {
@@ -132,6 +143,7 @@ class caldav_driver extends calendar_driver
 
                 // Init sync client
                 $cal_id = $arr['calendar_id'];
+
                 $this->sync_clients[$cal_id] = new caldav_sync($arr);
             }
             $this->calendar_ids = join(',', $calendar_ids);
@@ -160,23 +172,73 @@ class caldav_driver extends calendar_driver
 
         // 'personal' is unsupported in this driver
 
+        // append the virtual birthdays calendar
+        if ($this->rc->config->get('calendar_contact_birthdays', false)) {
+            $prefs  = $this->rc->config->get('birthday_calendar', array('color' => '87CEFA'));
+            $hidden = array_filter(explode(',', $this->rc->config->get('hidden_calendars', '')));
+            $id     = self::BIRTHDAY_CALENDAR_ID;
+
+            if (empty($active) || !in_array($id, $hidden)) {
+                $calendars[$id] = array(
+                    'id'         => $id,
+                    'name'       => $this->cal->gettext('birthdays'),
+                    'listname'   => $this->cal->gettext('birthdays'),
+                    'color'      => $prefs['color'],
+                    'showalarms' => (bool)$this->rc->config->get('calendar_birthdays_alarm_type'),
+                    'active'     => !in_array($id, $hidden),
+                    'group'      => 'x-birthdays',
+                    'editable'  => false,
+                    'default'    => false,
+                    'children'   => false,
+                );
+            }
+        }
+
         return $calendars;
     }
 
     /**
-     * Extracts CalDAV calendar.
+     * Creates CalDAV calendar or call create_source()
+     * (we use the same function for both calendar and source to stay compatible with other drivers)
      *
      * @see database_driver::create_calendar()
      */
     public function create_calendar($cal)
     {
-        $result = false;
-        $cal['caldav_url'] = self::_encode_url($cal["caldav_url"]);
-        if(!isset($cal['color'])) $cal['color'] = 'cc0000';
+        if(isset($cal['new-source'])) {
+            return $this->create_source($cal);
+        }
+        else {
+            $result = $this->rc->db->query('SELECT source_id, caldav_url, caldav_user, caldav_pass
+                FROM ' . $this->db_sources . '
+                WHERE user_id=? AND source_id=?',
+                $this->rc->user->ID,
+                $cal['source_id']
+            );
+            if(!$result || !($source = $this->rc->db->fetch_assoc($result))) {
+                return false;
+            }
 
-        $calendars = $this->_autodiscover_calendars($this->_expand_pass($cal));
+
+
+            $server_url = self::_encode_url($source['caldav_url']);
+            $server_path = parse_url($server_url, PHP_URL_PATH);
+            $calId = $this->cal->generate_uid();
+            $path = "/calendars/$source[caldav_user]/$calId";
+
+            self::debug_log("Creating new calendar \"$cal[name]\" with path $path at: " . $server_url);
+            $client = new caldav_client($server_url, $source["caldav_user"], $source["caldav_pass"]);
+
+            if($client->create_calendar($server_path . $path, $cal['name'], isset($cal['color']) ? $cal['color'] : 'cc0000')) {
+                $calendars = $this->_autodiscover_calendars($source);
+                return $this->_add_calendars($calendars, $source);
+            }
+        }
+    }
+    private function _add_calendars($calendars, $source) {
         $cal_ids = array();
 
+        $result = false;
         if($calendars)
         {
             $result = true;
@@ -186,13 +248,13 @@ class caldav_driver extends calendar_driver
                 $result = $this->rc->db->query("SELECT * FROM ".$this->db_calendars." WHERE user_id=? and caldav_url LIKE ?", $this->rc->user->ID, $calendar['href']);
                 if($this->rc->db->affected_rows($result)) continue;
 
-                $cal['caldav_url'] = self::_encode_url($calendar['href']);
+                $cal = array(
+                    'caldav_url' => self::_encode_url($calendar['href']),
+                    'name' => $calendar['name'],
+                    'color' => $calendar['color']
+                );
 
-                // Respect $props['name'] if only a single calendar was found e.g. no auto-discovery.
-                if(sizeof($calendars) > 1 || !isset($cal['name'])  || $cal['name'] == "")
-                    $cal['name'] = $calendar['name'];
-
-                if (($obj_id = $this->_db_create_calendar($cal)) !== false) {
+                if (($obj_id = $this->_db_create_calendar($cal, $source)) !== false) {
                     array_push($cal_ids, $obj_id);
                 } else $result = false;
             }
@@ -213,6 +275,48 @@ class caldav_driver extends calendar_driver
         return $result;
     }
 
+    /**
+     * Adds CalDAV source and loads adds all calendars from that source
+     *
+     * @see database_driver::create_calendar()
+     */
+    public function create_source($source)
+    {
+        $source['caldav_url'] = self::_encode_url($source['caldav_url']);
+
+        try {
+            $calendars = $this->_autodiscover_calendars($source);
+        }
+        catch(Exception $e) {
+            self::debug_log("Could not add source: $source");
+        }
+        if($calendars) {
+            $pass = isset($source['caldav_pass']) ? $this->_encrypt_pass($source['caldav_pass']) : null;
+            $db_source_result = $this->rc->db->query(
+                "INSERT INTO " . $this->db_sources . "
+                   (user_id, caldav_url, caldav_user, caldav_pass)
+                   VALUES (?, ?, ?, ?)",
+                $this->rc->user->ID,
+                $source['caldav_url'],
+                isset($source['caldav_user']) ? $source['caldav_user'] : null,
+                $pass
+            );
+
+            if($db_source_result)
+                $source['source_id'] = $this->rc->db->insert_id($this->db_sources);
+            else {
+                self::debug_log("Could not save source $source[caldav_url] to db");
+                return false;
+            }
+
+            return $this->_add_calendars($calendars, $source);
+        }
+        else {
+            self::debug_log("Did not find any calendars at $source[caldav_url]. Aborting");
+            return false;
+        }
+    }
+
     /**
      * Create a new calendar assigned to the current user
      *
@@ -226,20 +330,19 @@ class caldav_driver extends calendar_driver
      *
      * @return mixed ID of the calendar on success, False on error
      */
-    private function _db_create_calendar($prop)
+    private function _db_create_calendar($prop, $source)
     {
         $result = $this->rc->db->query(
             "INSERT INTO " . $this->db_calendars . "
-       (user_id, name, color, showalarms, caldav_url, caldav_tag, caldav_user, caldav_pass)
-       VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+       (user_id, source_id, name, color, showalarms, caldav_url, caldav_tag)
+       VALUES (?, ?, ?, ?, ?, ?, ?)",
             $this->rc->user->ID,
+            $source['source_id'],
             $prop['name'],
             $prop['color'],
             $prop['showalarms']?1:0,
             $prop['caldav_url'],
-            isset($prop["caldav_tag"]) ? $prop["caldav_tag"] : null,
-            isset($prop["caldav_user"]) ? $prop["caldav_user"] : null,
-            isset($prop["caldav_pass"]) ? $this->_encrypt_pass($prop["caldav_pass"]) : null
+            isset($prop["caldav_tag"]) ? $prop["caldav_tag"] : null
         );
 
         if ($result)
@@ -256,31 +359,16 @@ class caldav_driver extends calendar_driver
     public function edit_calendar($cal)
     {
         $query = $this->rc->db->query("UPDATE " . $this->db_calendars . "
-            SET   name=?, color=?, showalarms=?, caldav_url=?, caldav_tag=?, caldav_user=?
+            SET   name=?, color=?, showalarms=?
             WHERE calendar_id=?
             AND   user_id=?",
             $cal['name'],
             $cal['color'],
             $cal['showalarms']?1:0,
-            $cal['caldav_url'],
-            isset($cal["caldav_tag"]) ? $cal["caldav_tag"] : null,
-            isset($cal["caldav_user"]) ? $cal["caldav_user"] : null,
             $cal['id'],
             $this->rc->user->ID
         );
 
-        // Change password if specified
-        if (isset($cal["caldav_pass"])) {
-            $query = $this->rc->db->query("UPDATE " . $this->db_calendars . "
-            SET   caldav_pass=?
-            WHERE calendar_id=?
-            AND   user_id=?",
-                $this->_encrypt_pass($cal['caldav_pass']),
-                $cal['id'],
-                $this->rc->user->ID
-            );
-        }
-
         return $this->rc->db->affected_rows($query);
     }
 
@@ -303,23 +391,41 @@ class caldav_driver extends calendar_driver
     }
 
     /**
-     * Delete the given calendar with all its contents
+     * Delete the given calendar or source with all its contents
+     * (we use the same function for both calendar and source to stay compatible with other drivers)
      *
      * @see calendar_driver::delete_calendar()
      */
     public function delete_calendar($prop)
     {
-        if (!$this->calendars[$prop['id']])
-            return false;
-
         // events and attachments will be deleted by foreign key cascade
 
-        $query = $this->rc->db->query(
-            "DELETE FROM " . $this->db_calendars . " WHERE calendar_id=?",
-            $prop['id']
-        );
+        if(isset($prop['delete-source'])) {
+            unset($prop['delete-source']);
+            $count = 0;
+            foreach($prop as $url) {
+                self::debug_log("Deleting source id $url");
+                $query = $this->rc->db->query("DELETE FROM " . $this->db_sources . " WHERE source_id=?", $url);
+                $count += $this->rc->db->affected_rows($query);
+            }
+            self::debug_log("Deleted $count entries");
+            return $count;
+        }
+        else {
+            if(!$this->calendars[$prop['id']])
+                return false;
 
-        return $this->rc->db->affected_rows($query);
+            if(!$this->sync_clients[$prop['id']]->delete_calendar())
+                return false;
+
+            $query = $this->rc->db->query(
+                "DELETE FROM " . $this->db_calendars . " WHERE calendar_id=?",
+                $prop['id']
+            );
+
+            return $this->rc->db->affected_rows($query);
+
+        }
     }
 
     /**
@@ -349,8 +455,10 @@ class caldav_driver extends calendar_driver
         if (!empty($this->calendars)) {
             if ($event['calendar'] && !$this->calendars[$event['calendar']])
                 return false;
-            if (!$event['calendar'])
-                $event['calendar'] = reset(array_keys($this->calendars));
+            if (!$event['calendar']) {
+                $keys = array_keys($this->calendars);
+                $event['calendar'] = reset($keys);
+            }
 
             if($event = $this->_save_preprocess($event)) {
 
@@ -605,7 +713,7 @@ class caldav_driver extends calendar_driver
                             $recurrence_id_format = libcalendaring::recurrence_id_format($event);
                             foreach ($exceptions as $exception) {
                                 $recurrence_id = rcube_utils::anytodatetime($exception['_instance'], $old['start']->getTimezone());
-                                if (is_a($recurrence_id, 'DateTime')) {
+                                if (is_a($recurrence_id, 'DateTime') || is_a($recurrence_id, 'DateTimeImmutable')) {
                                     $recurrence_id->add($date_shift);
                                     $exception['_instance'] = $recurrence_id->format($recurrence_id_format);
                                     $this->_update_event($exception, false);
@@ -696,7 +804,7 @@ class caldav_driver extends calendar_driver
         foreach (self::$scheduling_properties as $prop) {
             $a = $old[$prop];
             $b = $event[$prop];
-            if ($event['allday'] && ($prop == 'start' || $prop == 'end') && $a instanceof DateTime && $b instanceof DateTime) {
+            if ($event['allday'] && ($prop == 'start' || $prop == 'end') && ($a instanceof DateTime || $a instanceof DateTimeImmutable) && ($b instanceof DateTime || $b instanceof DateTimeImmutable)) {
                 $a = $a->format('Y-m-d');
                 $b = $b->format('Y-m-d');
             }
@@ -811,7 +919,7 @@ class caldav_driver extends calendar_driver
         $sql_set = array();
         $set_cols = array('start', 'end', 'all_day', 'recurrence_id', 'isexception', 'sequence', 'title', 'description', 'location', 'categories', 'url', 'free_busy', 'priority', 'sensitivity', 'status', 'attendees', 'alarms', 'notifyat', 'caldav_url', 'caldav_tag');
         foreach ($set_cols as $col) {
-            if (is_object($event[$col]) && is_a($event[$col], 'DateTime'))
+            if (is_object($event[$col]) && (is_a($event[$col], 'DateTime') || is_a($event[$col], 'DateTimeImmutable')))
                 $sql_set[] = $this->rc->db->quote_identifier($col) . '=' . $this->rc->db->quote($event[$col]->format(self::DB_DATE_FORMAT));
             else if (is_array($event[$col]))
                 $sql_set[] = $this->rc->db->quote_identifier($col) . '=' . $this->rc->db->quote(join(',', $event[$col]));
@@ -1209,12 +1317,25 @@ class caldav_driver extends calendar_driver
         $calendar_ids = array_intersect($calendars, array_keys($this->calendars));
 
         // Make sure that the calendars are in sync.
-        foreach ($calendar_ids as $cal_id) {
-            if (!$this->_is_synced($cal_id))
-                $this->_sync_calendar($cal_id);
+        try {
+            foreach($calendar_ids as $cal_id) {
+                if(!$this->_is_synced($cal_id))
+                    $this->_sync_calendar($cal_id);
+            }
+        }
+        catch(Exception $err) {
+            self::debug_log("Could not sync calendars: $err");
+            return [];
         }
 
-        return $this->_db_load_events($start, $end, $query, $calendars, $virtual, $modifiedsince);
+        $events = $this->_db_load_events($start, $end, $query, $calendars, $virtual, $modifiedsince);
+
+        // add events from the address books birthday calendar
+        if (in_array(self::BIRTHDAY_CALENDAR_ID, $calendars) && empty($query)) {
+            $events = array_merge($events, $this->load_birthday_events($start, $end, null, $modifiedsince));
+        }
+
+        return $events;
     }
 
     /**
@@ -1582,7 +1703,7 @@ class caldav_driver extends calendar_driver
     private function serialize_alarms($valarms)
     {
         foreach ((array)$valarms as $i => $alarm) {
-            if ($alarm['trigger'] instanceof DateTime) {
+            if ($alarm['trigger'] instanceof DateTime || $alarm['trigger'] instanceof DateTimeImmutable) {
                 $valarms[$i]['trigger'] = '@' . $alarm['trigger']->format('c');
             }
         }
@@ -1632,7 +1753,7 @@ class caldav_driver extends calendar_driver
             $attendees = json_decode($s_attendees, true);
         } // decode the old serialization format
         else {
-            foreach (explode("\n", $event['attendees']) as $line) {
+            foreach (explode("\n", $s_attendees) as $line) {
                 $att = array();
                 foreach (rcube_utils::explode_quoted_string(';', $line) as $prop) {
                     list($key, $value) = explode("=", $prop);
@@ -1670,13 +1791,15 @@ class caldav_driver extends calendar_driver
             }
         }
 
-        foreach (array($this->db_calendars, 'itipinvitations') as $table) {
+        foreach (array($this->db_sources, $this->db_calendars, 'itipinvitations') as $table) {
             $db->query("DELETE FROM $table WHERE user_id=?", $user->ID);
         }
     }
 
     /**
      * Callback function to produce driver-specific calendar create/edit form
+     * We are misusing calendar_form() for sources to stay compatible with the other drivers
+     * and not having to change too much of the original code
      *
      * @param string Request action 'form-edit|form-new'
      * @param array  Calendar properties (e.g. id, color)
@@ -1686,44 +1809,66 @@ class caldav_driver extends calendar_driver
      */
     public function calendar_form($action, $calendar, $formfields)
     {
-        // Make sure we have current attributes
-        $calendar = $this->calendars[$calendar["id"]];
+        switch($action) {
+        case "form-source-new":
+            array_splice($formfields, 0);
 
-        $input_caldav_url = new html_inputfield( array(
-            "name" => "caldav_url",
-            "id" => "caldav_url",
-            "size" => 20
-        ));
+            $input_caldav_url = new html_inputfield( array(
+                "name" => "caldav_url",
+                "id" => "caldav_url",
+                "size" => 20
+            ));
+            $formfields["caldav_url"] = array(
+                "label" => $this->cal->gettext("url"),
+                "value" => $input_caldav_url->show(null),
+                "id" => "caldav_url",
+            );
 
-        $formfields["caldav_url"] = array(
-            "label" => $this->cal->gettext("caldavurl"),
-            "value" => $input_caldav_url->show($calendar["caldav_url"]),
-            "id" => "caldav_url",
-        );
 
-        $input_caldav_user = new html_inputfield( array(
-            "name" => "caldav_user",
-            "id" => "caldav_user",
-            "size" => 20
-        ));
+            $input_caldav_user = new html_inputfield( array(
+                "name" => "caldav_user",
+                "id" => "caldav_user",
+                "size" => 20
+            ));
+            $formfields["caldav_user"] = array(
+                "label" => $this->cal->gettext("username"),
+                "value" => $input_caldav_user->show(null),
+                "id" => "caldav_user",
+            );
 
-        $formfields["caldav_user"] = array(
-            "label" => $this->cal->gettext("username"),
-            "value" => $input_caldav_user->show($calendar["caldav_user"]),
-            "id" => "caldav_user",
-        );
 
-        $input_caldav_pass = new html_passwordfield( array(
-            "name" => "caldav_pass",
-            "id" => "caldav_pass",
-            "size" => 20
-        ));
+            $input_caldav_pass = new html_passwordfield( array(
+                "name" => "caldav_pass",
+                "id" => "caldav_pass",
+                "size" => 20
+            ));
+            $formfields["caldav_pass"] = array(
+                "label" => $this->cal->gettext("password"),
+                "value" => $input_caldav_pass->show(null),
+                "id" => "caldav_pass",
+            );
+            break;
+        case "form-source-delete":
+            array_splice($formfields, 0);
+
+            $result = $this->rc->db->query("SELECT source_id, caldav_url FROM ".$this->db_sources);
+            if($this->rc->db->num_rows($result)) {
+                for($i=0; $source = $this->rc->db->fetch_assoc($result); ++$i) {
+                    $checkbox = new html_checkbox( array(
+                        "name" => "delete$i",
+                        "value" => $source['source_id']
+                    ));
+
+                    $formfields[$source['source_id']] = array(
+                        "label" => $source['caldav_url'],
+                        "value" => $checkbox->show(null),
+                        "id" => "caldav_url",
+                    );
+                }
+            }
+            break;
+        }
 
-        $formfields["caldav_pass"] = array(
-            "label" => $this->cal->gettext("password"),
-            "value" => $input_caldav_pass->show(null), // Don't send plain text password to GUI
-            "id" => "caldav_pass",
-        );
 
         return parent::calendar_form($action, $calendar, $formfields);
     }
@@ -1747,22 +1892,6 @@ class caldav_driver extends calendar_driver
         else return $url;
     }
 
-    /**
-     * Expand all "%p" occurrences in 'caldav_pass' element of calendar object
-     * properties array with RC (imap) password.
-     * Other elements are left untouched.
-     *
-     * @param array List of properties
-     * @return array List of properties, with expanded 'caldav_pass' attribute
-     *
-     */
-    private function _expand_pass($props)
-    {
-        if (isset($props['caldav_pass']))
-            $props['caldav_pass'] = str_replace('%p', $this->rc->get_user_password(), $props['caldav_pass']);
-
-        return $props;
-    }
 
     /**
      * Auto discover calenders available to the user on the caldav server
@@ -1779,9 +1908,9 @@ class caldav_driver extends calendar_driver
         $calendars = array();
         $current_user_principal = array('{DAV:}current-user-principal');
         $calendar_home_set = array('{urn:ietf:params:xml:ns:caldav}calendar-home-set');
-        $cal_attribs = array('{DAV:}resourcetype', '{DAV:}displayname');
+        $cal_attribs = array('{DAV:}resourcetype', '{DAV:}displayname', '{http://apple.com/ns/ical/}calendar-color');
 
-        require_once ($this->cal->home.'/lib/caldav-client.php');
+        require_once 'caldav_client.php';
         $caldav = new caldav_client($props["caldav_url"], $props["caldav_user"], $props["caldav_pass"]);
 
         $tokens = parse_url($props["caldav_url"]);
@@ -1793,7 +1922,7 @@ class caldav_driver extends calendar_driver
             return false;
         }
         else if (array_key_exists ('{DAV:}resourcetype', $response) &&
-            $response['{DAV:}resourcetype'] instanceof OldSabre\DAV\Property\ResourceType &&
+            $response['{DAV:}resourcetype'] instanceof Sabre\DAV\Xml\Property\ResourceType &&
             in_array('{urn:ietf:params:xml:ns:caldav}calendar',
                 $response['{DAV:}resourcetype']->getValue())) {
 
@@ -1810,22 +1939,25 @@ class caldav_driver extends calendar_driver
             // directly return given url as it is a calendar
         }
         // probe further for principal url and user home set
-        $caldav_url = $base_uri . $response[$current_user_principal[0]];
+//        $caldav_url = $base_uri . $response[$current_user_principal[0]]; //### I guess this was the format that "OldSabre" in the original library used
+        $caldav_url = $base_uri . $response[$current_user_principal[0]][0]['value'];
         $response = $caldav->prop_find($caldav_url, $calendar_home_set, 0);
         if (!$response) {
             $this->_raise_error("Resource \"$caldav_url\" contains no calendars.");
             return false;
         }
-        $caldav_url = $base_uri . $response[$calendar_home_set[0]];
+//        $caldav_url = $base_uri . $response[$calendar_home_set[0]]; //### I guess this was the format that "OldSabre" in the original library used
+        $caldav_url = $base_uri . $response[$calendar_home_set[0]][0]['value'];
         $response = $caldav->prop_find($caldav_url, $cal_attribs, 1);
         foreach($response as $collection => $attribs)
         {
             $found = false;
             $name = '';
+            $color = null;
             foreach($attribs as $key => $value)
             {
                 if ($key == '{DAV:}resourcetype' && is_object($value)) {
-                    if ($value instanceof OldSabre\DAV\Property\ResourceType) {
+                    if ($value instanceof Sabre\DAV\Xml\Property\ResourceType) {
                         $values = $value->getValue();
                         if (in_array('{urn:ietf:params:xml:ns:caldav}calendar', $values))
                             $found = true;
@@ -1834,11 +1966,28 @@ class caldav_driver extends calendar_driver
                 else if ($key == '{DAV:}displayname') {
                     $name = $value;
                 }
+                else if ($key == '{http://apple.com/ns/ical/}calendar-color') {
+                    //Thanks to https://github.com/agendav/agendav/blob/10397b6c04a52acd6cb9528683f9e167d516cdb5/web/src/CalDAV/Resource/Calendar.php#L264
+                    if (strlen($value) === 7) {
+                        return $value . 'ff';
+                    }
+
+                    if (strlen($value) === 4) {
+                        preg_match('/#(.)(.)(.)/', $value, $matches);
+                        return '#' .
+                            $matches[1] .$matches[1] .
+                            $matches[2] .$matches[2] .
+                            $matches[3] .$matches[3] .
+                            'ff';
+                    }
+
+                }
             }
             if ($found) {
                 array_push($calendars, array(
                     'name' => $name,
                     'href' => $base_uri.$collection,
+                    'color' => $color ?: 'cc0000'
                 ));
             }
         }
@@ -2024,13 +2173,13 @@ class caldav_driver extends calendar_driver
 
     private function _decrypt_pass($pass) {
         $p = base64_decode($pass);
-        $e = new Encryption(MCRYPT_BlOWFISH, MCRYPT_MODE_CBC);
-        return $e->decrypt($p, $this->crypt_key);
+        $e = new Encryption();
+        return $e->decrypt($p);
     }
 
     private function _encrypt_pass($pass) {
-        $e = new Encryption(MCRYPT_BlOWFISH, MCRYPT_MODE_CBC);
-        $p = $e->encrypt($pass, $this->crypt_key);
+        $e = new Encryption();
+        $p = $e->encrypt($pass);
         return base64_encode($p);
     }
 }
diff --git a/drivers/caldav/caldav_sync.php b/drivers/caldav/caldav_sync.php
index efe92c2..3c483a4 100644
--- a/drivers/caldav/caldav_sync.php
+++ b/drivers/caldav/caldav_sync.php
@@ -21,14 +21,10 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-require_once (dirname(__FILE__).'/../../lib/caldav-client.php');
+require_once 'caldav_client.php';
 
 class caldav_sync
 {
-    const ACTION_NONE = 1;
-    const ACTION_UPDATE = 2;
-    const ACTION_CREATE = 4;
-
     private $cal_id = null;
     private $ctag = null;
     private $username = null;
diff --git a/drivers/caldav/encryption.php b/drivers/caldav/encryption.php
new file mode 100644
index 0000000..39519c6
--- /dev/null
+++ b/drivers/caldav/encryption.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * Encryption class
+ * (Copied by JodliDev from https://github.com/mstilkerich/rcmcarddav/blob/master/carddav.php)
+ *
+ * @author Jorge López Pérez <jorge@adobo.org> (original author)
+ * @author JodliDev <jodlidev@gmail.com>
+ *
+ *
+ */
+
+class Encryption {
+    private function getDesKey()
+    {
+        $rcube = rcube::get_instance();
+        $imap_password = $rcube->decrypt((string) $_SESSION['password']);
+        
+        if ($imap_password === false || strlen($imap_password) == 0) {
+            throw new \Exception('No password available to use for encryption');
+        }
+        
+        while (strlen($imap_password) < 24) {
+            $imap_password .= $imap_password;
+        }
+        return substr($imap_password, 0, 24);
+    }
+    
+    /**
+     * Converts a password to storage format according to the password storage scheme setting.
+     *
+     * @param string $clear The password in clear text.
+     * @return string The password in storage format (e.g. encrypted with user password as key)
+     * @throws Exception
+     */
+    public function encrypt($clear) {
+        // encrypted with IMAP password
+        $rcube = rcube::get_instance();
+    
+        $imap_password = $this->getDesKey();
+        $rcube->config->set('carddav_des_key', $imap_password);
+    
+        $crypted = $rcube->encrypt($clear, 'carddav_des_key');
+    
+        // there seems to be no way to unset a preference
+        $rcube->config->set('carddav_des_key', '');
+    
+        if ($crypted === false) {
+            throw new \Exception('Password encryption with user password failed');
+        }
+    
+        return $crypted;
+    }
+    
+    public function decrypt($crypt) {
+        try {
+            $rcube = rcube::get_instance();
+        
+            $imap_password = $this->getDesKey();
+            $rcube->config->set('carddav_des_key', $imap_password);
+            $clear = $rcube->decrypt($crypt, 'carddav_des_key');
+            // there seems to be no way to unset a preference
+            $rcube->config->set('carddav_des_key', '');
+            if ($clear === false) {
+                $clear = '';
+            }
+        
+            return $clear;
+        } catch (\Exception $e) {
+            return "";
+        }
+    }
+}
+?>
diff --git a/drivers/calendar_driver.php b/drivers/calendar_driver.php
index 2c0fc6c..23392d4 100644
--- a/drivers/calendar_driver.php
+++ b/drivers/calendar_driver.php
@@ -362,11 +362,11 @@ abstract class calendar_driver
     {
         $valid = true;
 
-        if (empty($event['start']) || !is_object($event['start']) || !is_a($event['start'], 'DateTime')) {
+        if (empty($event['start']) || !is_object($event['start']) || (!is_a($event['start'], 'DateTime') && !is_a($event['start'], 'DateTimeImmutable'))) {
             $valid = false;
         }
 
-        if (empty($event['end']) || !is_object($event['end']) || !is_a($event['end'], 'DateTime')) {
+        if (empty($event['end']) || !is_object($event['end']) || (!is_a($event['end'], 'DateTime') && !is_a($event['end'], 'DateTimeImmutable'))) {
             $valid = false;
         }
 
diff --git a/localization/de.inc b/localization/de.inc
index 9f3321f..2f8ee88 100644
--- a/localization/de.inc
+++ b/localization/de.inc
@@ -6,6 +6,8 @@
  *
  * For translation see https://www.transifex.com/projects/p/kolab/resource/calendar/
  */
+$labels['addsources'] = 'Externe Quellen hinzufügen ';
+$labels['deletesources'] = 'Externe Quellen löschen ';
 $labels['default_view'] = 'Standardansicht';
 $labels['time_format'] = 'Zeitformatierung';
 $labels['timeslots'] = 'Zeitfenster pro Stunde';
diff --git a/localization/de_CH.inc b/localization/de_CH.inc
index bd77a8b..a58c061 100644
--- a/localization/de_CH.inc
+++ b/localization/de_CH.inc
@@ -6,6 +6,8 @@
  *
  * For translation see https://www.transifex.com/projects/p/kolab/resource/calendar/
  */
+$labels['addsources'] = 'Externe Quellen hinzufügen ';
+$labels['deletesources'] = 'Externe Quellen löschen ';
 $labels['default_view'] = 'Standardansicht';
 $labels['time_format'] = 'Zeitformatierung';
 $labels['timeslots'] = 'Abschnitte pro Stunde';
diff --git a/localization/de_DE.inc b/localization/de_DE.inc
index a62975c..640b414 100644
--- a/localization/de_DE.inc
+++ b/localization/de_DE.inc
@@ -6,6 +6,8 @@
  *
  * For translation see https://www.transifex.com/projects/p/kolab/resource/calendar/
  */
+$labels['addsources'] = 'Externe Quellen hinzufügen ';
+$labels['deletesources'] = 'Externe Quellen löschen ';
 $labels['default_view'] = 'Standardansicht';
 $labels['time_format'] = 'Zeitformatierung';
 $labels['timeslots'] = 'Zeitfenster pro Stunde';
diff --git a/localization/en_US.inc b/localization/en_US.inc
index 0f97d56..fd794b1 100644
--- a/localization/en_US.inc
+++ b/localization/en_US.inc
@@ -10,6 +10,10 @@
 
 $labels = array();
 
+//caldav driver
+$labels['addsources'] = 'Add external sources ';
+$labels['deletesources'] = 'Delete external sources ';
+
 // preferences
 $labels['default_view'] = 'Default view';
 $labels['time_format'] = 'Time format';
diff --git a/skins/elastic/templates/calendar.html b/skins/elastic/templates/calendar.html
index 9a9f891..2a1dcc8 100644
--- a/skins/elastic/templates/calendar.html
+++ b/skins/elastic/templates/calendar.html
@@ -141,6 +141,10 @@
 <div id="calendaractions-menu" class="popupmenu">
 	<h3 id="aria-label-calendaroptions" class="voice"><roundcube:label name="calendar.calendaractions" /></h3>
 	<ul class="menu listing" role="menu" aria-labelledby="aria-label-calendaroptions">
+		<roundcube:if condition="env:calendar_driver == 'caldav'" />
+			<roundcube:button type="link-menuitem" command="calendar-sources-new" label="calendar.addsources" class="create" />
+			<roundcube:button type="link-menuitem" command="calendar-sources-delete" label="calendar.deletesources" class="delete" />
+		<roundcube:endif />
 		<roundcube:button type="link-menuitem" command="calendar-create" label="calendar.addcalendar" class="create disabled" classAct="create active" />
 		<roundcube:button type="link-menuitem" command="calendar-edit" label="calendar.editcalendar" class="edit disabled" classAct="edit active" />
 		<roundcube:button type="link-menuitem" command="calendar-delete" label="calendar.deletecalendar" class="delete disabled" classAct="delete active" />
diff --git a/skins/larry/templates/calendar.html b/skins/larry/templates/calendar.html
index d59c299..1fa348b 100644
--- a/skins/larry/templates/calendar.html
+++ b/skins/larry/templates/calendar.html
@@ -68,6 +68,10 @@
 <div id="calendaroptionsmenu" class="popupmenu" aria-hidden="true">
 	<h3 id="aria-label-calendaroptions" class="voice"><roundcube:label name="calendar.calendaractions" /></h3>
 	<ul id="calendaroptionsmenu-menu" class="toolbarmenu" role="menu" aria-labelledby="aria-label-calendaroptions">
+		<roundcube:if condition="env:calendar_driver == 'caldav'" />
+			<li role="menuitem"><roundcube:button type="link" command="calendar-sources-new" label="calendar.addsources" class="active" /></li>
+			<li role="menuitem"><roundcube:button type="link" command="calendar-sources-delete" label="calendar.deletesources" class="active" /></li>
+		<roundcube:endif />
 		<li role="menuitem"><roundcube:button type="link" command="calendar-edit" label="calendar.edit" classAct="active" /></li>
 		<li role="menuitem"><roundcube:button type="link" command="calendar-delete" label="delete" classAct="active" /></li>
 		<roundcube:if condition="env:calendar_driver == 'kolab'" />