public static function readinvoicepdf()
 {
     Komfortkasse_Order::getInvoicePdfPrepare();
     if (!Komfortkasse_Config::getConfig(Komfortkasse_Config::activate_export)) {
         return;
     }
     if (Komfortkasse::check() === false) {
         return;
     }
     $invoiceNumber = Komfortkasse_Config::getRequestParameter('o');
     $invoiceNumber = Komfortkasse::kkdecrypt($invoiceNumber);
     $orderNumber = Komfortkasse_Config::getRequestParameter('order_id');
     $orderNumber = Komfortkasse::kkdecrypt($orderNumber);
     return Komfortkasse_Order::getInvoicePdf($invoiceNumber, $orderNumber);
 }