ROT 13 Verschlüsselung

<!-- präsentiert von kostenlose-javascripts.de -->
<script type='text/javascript'>
<!--
function rot_13()
{
    var keycode = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    var text    = document.getElementById('rot13Text').value;
    var textrot = new String();

    for(var i = 0; i < text.length; i++)
    {
        var codechar = text.substring(i, i + 1);
        var pos = keycode.indexOf(codechar.toUpperCase());

        if(pos >= 0)
        {
            pos = (pos + keycode.length / 2) % keycode.length;
            codechar = (codechar == codechar.toUpperCase()) ? keycode.substring(pos, pos + 1) : keycode.substring(pos, pos + 1).toLowerCase();
        }
        textrot = textrot + codechar;
    }
    document.getElementById('rot13Text').value = textrot;
}

function initRot13() {
    document.write('<textarea name="rot13Text" id="rot13Text" rows="5" cols="60">Dieser Text kann mittels ROT13 verschlüsselt werden.'); } //-->