Krybtering!!!!!!!!!

Hjææælp!!! Hvorfor f... virker det her modficerede script ikke???

<html>

<head>
<title>(De)kryptering</title>
</head>

<body>
<script language="JavaScript">


var str_in;
var str_out = "";
var num_in;
var num_out = "";
var e = "Skriv noget tekst!";

function str_to_num(form) {
num_out = "";
if(form.input.value == "") alert(e);
else {
str_in = escape(form.input.value);
for(i = 0; i < str_in.length; i++) {
num_out += str_in.charCodeAt(i) - (form.key1.value);
}
form.output.value = num_out;
form.input.value = "";
  }
}

function num_to_str(form) {
str_out = "";
if(form.output.value == "") alert(e)
else {
num_out = form.output.value; 
for(i = 0; i < num_out.length; i += 2) {
num_in = parseInt(num_out.substr(i,[2])) + (form.key2.value);
num_in = unescape('%' + num_in.toString(16));
str_out += num_in;
}
form.input.value = unescape(str_out);
form.output.value = "";
  }
}
//  End -->
</script>

<form name="encryptform">
    <div align="center"><center><table border="1" cellpadding="0"
    cellspacing="0" bgcolor="#C0C0C0" bordercolor="#FFFFFF">
        <tr>
            <td width="35"><font size="2" face="Arial">n&oslash;gle</font></td>
            <td><font size="2" face="Arial">Original tekst</font></td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td><input type="text" size="3" name="key1" value="25"></td>
            <td><input type="text" size="50" name="input"
            value="ikke krypteret"></td>
            <td><input type="button" value="T-&gt;5"
            onclick="java script:str_to_num(this.form)"></td>
        </tr>
        <tr>
            <td><font size="2" face="Arial">n&oslash;gle</font></td>
            <td><font size="2" face="Arial">Krypteret kode</font></td>
            <td>&nbsp;</td>
        </tr>
        <tr>
            <td><input type="text" size="3" name="key2" value="25"></td>
            <td><input type="text" size="50" name="output"></td>
            <td><input type="button" value="5-&gt;T"
            onclick="java script:num_to_str(this.form)"></td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
            <td>&nbsp;</td>
        </tr>
    </table>
    </center></div>
</form>
</body>
</html>