function getPGTIouFilename($pgt_iou)
    {
        phpCAS::traceBegin();
        $filename = $this->getPath()."phpcas-".hash("sha256", $pgt_iou);
//        $filename = $this->getPath().$pgt_iou.'.plain';
        phpCAS::trace("Sha256 filename:" . $filename);
        phpCAS::traceEnd();
        return $filename;
    }