server/submission.php

<?php

function show($file)
{
    if (file_exists($file))
        print file_get_contents($file);
    else
        header("HTTP/1.1 403 Forbidden");
}

$filename = intval($_GET["team"])."-".intval($_GET["theme"])."-".urlencode($_GET["exercice"]);
$file = __DIR__."/submission/".$filename;


if (file_exists($file))
    show(__DIR__."/teams/".intval($_GET["team"])."/".urlencode($_GET["theme"])."/".urlencode($_GET["exercice"])."/submission/serr/index.html");

else if (!empty($_POST["solution"]) && !empty($_GET["team"]) && !empty($_GET["theme"]) && !empty($_GET["exercice"]))
{
    $algos = array("md5", "sha1", "sha256", "sha384", "sha512", "whirlpool");
    $content = "";
    foreach($algos as $algo)
      $content .= mcrypt_encrypt(MCRYPT_SERPENT_256, hash($algo, $_POST["solution"]), hash($algo, $filename), MCRYPT_MODE_ECB)."\n";

    file_put_contents($file, $content, LOCK_EX);

    show(__DIR__."/teams/".intval($_GET["team"])."/".urlencode($_GET["theme"])."/".urlencode($_GET["exercice"])."/submission/index.html");
}

else
    show(__DIR__."/teams/".intval($_GET["team"])."/".urlencode($_GET["theme"])."/".urlencode($_GET["exercice"])."/submission/gerr/index.html");