$url = "https://www.polytechnique.org/auth-groupex/utf8";
$url .= "?session=" . session_id();
$url .= "&challenge=" . $_SESSION["auth-x-challenge"];
$url .= "&pass=" . md5($_SESSION["auth-x-challenge"] . XORG_AUTH_KEY);
$url = "https://www.polytechnique.org/auth-groupex/utf8";
$url .= "?session=" . session_id();
$url .= "&challenge=" . $_SESSION["auth-x-challenge"];
$url .= "&pass=" . md5($_SESSION["auth-x-challenge"] . XORG_AUTH_KEY);