gistfile1.txt

    private function __get_id($qr_code) {
        if (empty($qr_code)) {
            return false;
        }
        $arrBarCode = explode(',', $qr_code);
        if (empty($arrBarCode[1])) {
            return false;
        }
        $beginning = substr($arrBarCode[1], 0, 16);
        $end = substr($arrBarCode[1], -16);
        $id = str_replace(array($beginning, $end), '', $arrBarCode[1]);
        if (empty($id) || !is_numeric($id)) {
            return false;
        }

        $qrOptions = Configure::read('Campaign.QR');
        $md5 = md5(urlencode(trim($arrBarCode[0])) . ',' . $id . ',' . $qrOptions['secret']);
        if ($beginning . $end !== $md5) {
            return false;
        }
        return $id;
    }