diff --git a/config.sample.php b/config.sample.php
index 4fce912..9e43883 100644
--- a/config.sample.php
+++ b/config.sample.php
@@ -19,6 +19,10 @@ $config = [
     // - local (recommended; using a table in the database to store credentials;
     //   synapse has to be configured to use that)
     "operationMode" => "local",
+
+    // This setting is only required for operationMode = synapse
+    "registration_shared_secret" => "SOME_SECRET_KEY_FROM_HOMESERVER_CONFIG"
+
     // When you want to collect the password on registration set this to true
     // only evaluated when operationMode = local
     "getPasswordOnRegistration" => false,
diff --git a/language.php b/language.php
index 145215e..14fe117 100644
--- a/language.php
+++ b/language.php
@@ -28,4 +28,4 @@ if (!file_exists($lang_file)) {
 $lang_file = dirname(__FILE__) . "/lang/lang." . $lang . ".php";
 require_once($lang_file);
 unset($lang_file);
-?>
\ No newline at end of file
+?>
diff --git a/public/verify_admin.php b/public/verify_admin.php
index 554c23e..9e98375 100644
--- a/public/verify_admin.php
+++ b/public/verify_admin.php
@@ -70,8 +70,25 @@ try {
         require_once("../MatrixConnection.php");
         $mxConn = new MatrixConnection($config["homeserver"], $config["access_token"]);
 
-        // generate a password with 8 characters
-        $password = $mx_db->addUser($first_name, $last_name, $username, $email);
+        $password = NULL;
+        switch ($config["operationMode"]) {
+            case "synapse":
+                // register with registration_shared_secret
+                // generate a password with 10 characters
+                $password = bin2hex(openssl_random_pseudo_bytes(5));
+                $res = $mxConn->register($username, $password, $config["registration_shared_secret"]);
+                if (!$res) {
+                    // something went wrong while registering
+                    $password = NULL;
+                }
+                break;
+            case "local":
+                // register by adding a user to the local database
+                $password = $mx_db->addUser($first_name, $last_name, $username, $email);
+                break;
+            default:
+                throw new Exception("Unknown operationMode");
+        }
         if ($password != NULL) {
             // send registration_success
             $res = send_mail_registration_success(