diff --git a/addKey.php b/addKey.php
index 24c0bcd..7e68090 100644
--- a/addKey.php
+++ b/addKey.php
@@ -16,7 +16,8 @@ if($settings == "valid")
 	if(!@mysqli_select_db($dbconn,$mysql_db))
 		$err = error("Datenbank nicht gefunden!! ($mysql_db)");
 }
-if($_SESSION["login"] == "valid" && isset($_GET["id"])){
+// Wie sites/userkeys.php: nur Superadmins dürfen Passkeys vergeben
+if($_SESSION["login"] == "valid" && isset($_GET["id"]) && ((int)substr($_SESSION["rights"], RIGHTS_SUPERADMIN, 1) & RIGHTS_CHANGE)){
     if(!mysqli_query($dbconn,"DELETE FROM addKey WHERE datetime < DATE_SUB(NOW(), INTERVAL 1 MINUTE);")){
         echo mysqli_error($dbconn);
     }
@@ -25,8 +26,8 @@ if($_SESSION["login"] == "valid" && isset($_GET["id"])){
         if(!mysqli_query($dbconn,"INSERT INTO addKey SET accesskey=".$accessKey.", datetime=NOW();")){
             echo mysqli_error($dbconn);
         }
-        header('Location: https://wm.el-wa.org/kunden?action=userkeys&id='.$_GET["id"].'&addKey='.$accessKey);
-        echo 'https://wm.el-wa.org/kunden?action=userkeys&id='.$_GET["id"].'&addKey='.$accessKey;
+        header('Location: https://wm.el-wa.org/kunden?action=userkeys&id='.(int)$_GET["id"].'&addKey='.$accessKey);
+        echo 'https://wm.el-wa.org/kunden?action=userkeys&id='.(int)$_GET["id"].'&addKey='.$accessKey;
     }else{
         echo "Keine Berechtigung.";
     }
diff --git a/authServer.php b/authServer.php
index 7bf3b01..377eeaa 100644
--- a/authServer.php
+++ b/authServer.php
@@ -107,6 +107,24 @@ try {
     // request for create arguments
     // ------------------------------------
 
+    // Passkeys anlegen darf nur ein angemeldeter Superadmin, der vorher in
+    // sites/userkeys.php eine gültige Einmal-Freigabe (addKey) eingelöst hat.
+    // Die Freigabe liegt in der Session und legt fest, für welchen Benutzer
+    // der Schlüssel gilt - die id aus der URL zählt nicht.
+    $passkeyFreigabe = null;
+    if (isset($_SESSION["passkey_freigabe"]) && $_SESSION["passkey_freigabe"]["bis"] >= time()
+        && ($_SESSION["login"] ?? "") == "valid"
+        && ((int)substr($_SESSION["rights"] ?? "", RIGHTS_SUPERADMIN, 1) & RIGHTS_CHANGE)) {
+        $passkeyFreigabe = $_SESSION["passkey_freigabe"];
+    }
+    if (($fn === 'getCreateArgs' || $fn === 'processCreate') && $passkeyFreigabe === null) {
+        throw new Exception('Keine Berechtigung, Passkeys anzulegen.');
+    }
+    if ($fn === 'queryFidoMetaDataService'
+        && !(($_SESSION["login"] ?? "") == "valid" && ((int)substr($_SESSION["rights"] ?? "", RIGHTS_SUPERADMIN, 1) & RIGHTS_CHANGE))) {
+        throw new Exception('Keine Berechtigung.');
+    }
+
     if ($fn === 'getCreateArgs') {
         $createArgs = $WebAuthn->getCreateArgs(\hex2bin($userId), $userName, $userDisplayName, 60*4, $requireResidentKey, $userVerification, $crossPlatformAttachment);
 
@@ -181,10 +199,12 @@ try {
         if (!isset($_SESSION['registrations']) || !array_key_exists('registrations', $_SESSION) || !is_array($_SESSION['registrations'])) {
             $_SESSION['registrations'] = [];
         }*/
-    	if(!mysqli_query($dbconn,"INSERT INTO passkeys SET credentialId = '".base64_encode($data->credentialId)."', credentialPublicKey = '".base64_encode($data->credentialPublicKey)."', signatureCounter = '".base64_encode($data->signatureCounter)."', name = '".mysqli_real_escape_string($mysql,filter_input(INPUT_GET, 'name'))."', userId = '".mysqli_real_escape_string($mysql,filter_input(INPUT_GET, 'id'))."';")){
+    	if(!mysqli_query($dbconn,"INSERT INTO passkeys SET credentialId = '".base64_encode($data->credentialId)."', credentialPublicKey = '".base64_encode($data->credentialPublicKey)."', signatureCounter = '".base64_encode($data->signatureCounter)."', name = '".mysqli_real_escape_string($mysql,filter_input(INPUT_GET, 'name'))."', userId = '".(int)$passkeyFreigabe["user"]."';")){
 			$msg = "Error:<br>".mysqli_error($dbconn)."<br />";
 		}
 		else{
+			// Freigabe gilt für genau einen Schlüssel
+			unset($_SESSION["passkey_freigabe"]);
         	if ($data->rootValid === false) {
 	            $msg = 'registration ok, but certificate does not match any of the selected root ca. NO PROBLEM FOR THIS APP';
 	        }
@@ -253,10 +273,16 @@ try {
 
         $authKey = strval(random_int(0,99999999));
         $result = mysqli_query($dbconn,"UPDATE passkeys SET authKey=".$authKey.", lastAuth=NOW()  WHERE credentialId = '".base64_encode($id)."';");
-        $qry= mysqli_query($dbconn, "SELECT * FROM user WHERE id = '".mysqli_real_escape_string($dbconn,$userId)."'");
-		if(mysqli_num_rows($qry) == 1)
+        // Gesperrte Benutzer bleiben gesperrt, auch mit gültigem Passkey
+        $qry= mysqli_query($dbconn, "SELECT * FROM user WHERE id = '".mysqli_real_escape_string($dbconn,$userId)."' AND blocked = 0");
+		if(!$qry || mysqli_num_rows($qry) != 1)
+		{
+			throw new Exception('Benutzer nicht gefunden oder gesperrt.');
+		}
+		else
 		{
 			$udata = mysqli_fetch_assoc($qry);
+			session_regenerate_id(true);
 			$_SESSION["login"] = "valid";
 			$_SESSION["logedout"] = $udata["logedout"];
 			$_SESSION["user"] = $udata["id"];
diff --git a/sites/start.php b/sites/start.php
index afd3d03..eb43930 100644
--- a/sites/start.php
+++ b/sites/start.php
@@ -20,6 +20,8 @@ if(isset($_GET["formsent"]) && $_SESSION["login"] != "valid" && isLocal())
 		if(mysqli_num_rows($qry) == 1)
 		{
 			$udata = mysqli_fetch_assoc($qry);
+			// neue Session-ID nach dem Login, sonst ist Session-Fixation möglich
+			session_regenerate_id(true);
 			$_SESSION["login"] = "valid";
 			$_SESSION["logedout"] = $udata["logedout"];
 			$_SESSION["user"] = $udata["id"];
diff --git a/sites/userkeys.php b/sites/userkeys.php
index 64f3e94..fe0a60f 100644
--- a/sites/userkeys.php
+++ b/sites/userkeys.php
@@ -2,7 +2,12 @@
 
 
 if(isset($_GET["id"]) && isset($_GET["addKey"])){
-	if (checkAdduser($_GET["addUser"])) {
+	if (checkAdduser()) {
+		// Freigabe einlösen: gilt 5 Minuten, nur für diesen Benutzer und nur
+		// in dieser Session (geprüft in authServer.php). Der addKey ist damit
+		// verbraucht.
+		$_SESSION["passkey_freigabe"] = array("user" => (int)$_GET["id"], "bis" => time() + 300);
+		mysqli_query($mysql, "DELETE FROM addKey WHERE accesskey = '".mysqli_real_escape_string($mysql, $_GET["addKey"])."'");
         echo <<<ENDE
         <html>
         <head></head>
@@ -73,11 +78,11 @@ if(isset($_GET["id"]) && isset($_GET["addKey"])){
 $smarty->assign("heading","Passkeys für externen Zugang verwalten"); 
 $smarty->display("heading.tpl");
 								
-$qry = mysqli_query($_SESSION["dbconn"],"SELECT id, vname, nname FROM user WHERE blocked = 0 AND user.id = ".mysqli_real_escape_string($_SESSION["dbconn"],$_GET["id"])) or die("Datenbank fehler: ".mysqli_error($_SESSION["dbconn"]));
+$qry = mysqli_query($_SESSION["dbconn"],"SELECT id, vname, nname FROM user WHERE blocked = 0 AND user.id = ".(int)$_GET["id"]) or die("Datenbank fehler: ".mysqli_error($_SESSION["dbconn"]));
 $row=mysqli_fetch_array($qry);
 $smarty->assign("user",$row);
 
-$qry = mysqli_query($_SESSION["dbconn"],"SELECT passkeys.id , passkeys.name FROM user JOIN passkeys ON user.id = passkeys.userId WHERE blocked = 0 AND user.id = ".mysqli_real_escape_string($_SESSION["dbconn"],$_GET["id"])) or die("Datenbank fehler: ".mysqli_error($_SESSION["dbconn"]));
+$qry = mysqli_query($_SESSION["dbconn"],"SELECT passkeys.id , passkeys.name FROM user JOIN passkeys ON user.id = passkeys.userId WHERE blocked = 0 AND user.id = ".(int)$_GET["id"]) or die("Datenbank fehler: ".mysqli_error($_SESSION["dbconn"]));
 $keys = array();
 while($row=mysqli_fetch_array($qry)){
 	$keys[] = $row;