crypto.html
télécharger ou tester sur place (bouton précédent du navigateur pour revenir)
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>César</title>
<link rel="stylesheet" type="text/css" href="style.css" />
<link rel="stylesheet" type="text/css" media="screen" href="screen.css">
<link rel="stylesheet" type="text/css" media="print" href="print.css">
</head>
<body>
<h1>Codage/Décodage de César</h1>
<p><em>Message</em> : <span id="txt"></span>.</p>
<p id="indice"><a href="""?msg=hello&dec=1">Cliquer ici pour un indice</a>
(puis observer l’adresse de la page).<p>
<script>
message_match = window.location.search.match(/[?&]msg=([^&]+)/);
if (!message_match) {
message = "pas de message";
} else {
message = String(message_match[1]);
}
decalage_match = window.location.search.match(/[?&]dec=(\d+)/);
if (!decalage_match) {
decalage = 0;
} else {
decalage = parseInt(decalage_match[1]);
}
texte = "";
for (i=0; i < message.length; i++) {
lettre = message.charAt(i);
code = message.charCodeAt(i) - 96;
texte += String.fromCharCode(code + 96 + decalage);
}
document.getElementById("txt").innerHTML = texte;
if (message && decalage) {
document.getElementById("indice").innerHTML = "";
}
</script>
</body>
</html>