diff --git a/plugins/kolab_2fa/config.inc.php.dist b/plugins/kolab_2fa/config.inc.php.dist
--- a/plugins/kolab_2fa/config.inc.php.dist
+++ b/plugins/kolab_2fa/config.inc.php.dist
@@ -121,4 +121,5 @@
     'clientid' => '123456',
     'apikey' => '<your-server-api-key>',
     // 'hosts'  => array('api.myhost1.com','api2.myhost.com'),
+    'use_https' => true,  // connect via https if set to true
 );
\ No newline at end of file
diff --git a/plugins/kolab_2fa/kolab_2fa.php b/plugins/kolab_2fa/kolab_2fa.php
--- a/plugins/kolab_2fa/kolab_2fa.php
+++ b/plugins/kolab_2fa/kolab_2fa.php
@@ -280,14 +280,19 @@
     }
 
     /**
-     * Load driver class for the given method
+     * Load driver class for the given authentication factor
+     *
+     * @param string $factor Factor identifier (<method>:<id>)
+     * @return Kolab2FA\Driver\Base
      */
-    public function get_driver($method)
+    public function get_driver($factor)
     {
+        list($method) = explode(':', $factor, 2);
+
         $rcmail = rcmail::get_instance();
 
-        if ($this->drivers[$method]) {
-            return $this->drivers[$method];
+        if ($this->drivers[$factor]) {
+            return $this->drivers[$factor];
         }
 
         $config = $rcmail->config->get('kolab_2fa_' . $method, array());
@@ -300,7 +305,7 @@
         try {
             // TODO: use external auth service if configured
 
-            $driver = \Kolab2FA\Driver\Base::factory($method, $config);
+            $driver = \Kolab2FA\Driver\Base::factory($factor, $config);
 
             // attach storage
             $driver->storage = $this->get_storage();
@@ -309,7 +314,7 @@
                 $driver->username  = $rcmail->get_user_name();
             }
 
-            $this->drivers[$method] = $driver;
+            $this->drivers[$factor] = $driver;
             return $driver;
         }
         catch (Exception $e) {
diff --git a/plugins/kolab_2fa/lib/Kolab2FA/Driver/Yubikey.php b/plugins/kolab_2fa/lib/Kolab2FA/Driver/Yubikey.php
--- a/plugins/kolab_2fa/lib/Kolab2FA/Driver/Yubikey.php
+++ b/plugins/kolab_2fa/lib/Kolab2FA/Driver/Yubikey.php
@@ -27,12 +27,6 @@
 {
     public $method = 'yubikey';
 
-    protected $config = array(
-        'clientid' => '42',
-        'apikey'   => 'FOOBAR=',
-        'hosts'    => null,
-    );
-
     protected $backend;
 
     /**
@@ -57,6 +51,10 @@
         if (!empty($this->config['hosts'])) {
             $this->backend->setHosts((array)$this->config['hosts']);
         }
+
+        if (isset($this->config['use_https'])) {
+            $this->backend->setUseSecure((bool)$this->config['use_https']);
+        }
     }
 
     /**
@@ -84,7 +82,7 @@
             }
         }
 
-        // rcube::console('VERIFY TOTP', $this->username, $keyid, $code, $pass);
+        // rcube::console('VERIFY Yubikey', $this->username, $keyid, $code, $pass);
         return $pass;
     }