Cloaking email addresses - very cool

I stumbled across a site that has a very cool way to cloak email addresses against spiders and bots. Check it out at:

http://omt.net/contact.html

This is the script:

<!-- Email-->
<SCRIPT LANGUAGE='JAVASCRIPT'>

function sendto(c,n,d) {
c += ' ';
var length = c.length;
var number = 0;
var bar = 0;
var answer = '';
for(var i = 0; i < length; i++) {
number = 0;
bar = 0;
while(c.charCodeAt(i) != 32) {
number = number * 10;
number = number + c.charCodeAt(i)-48;
i++;
}
answer += String.fromCharCode(decrypt(number,n,d));
}
// Updated security feature
parent.location = 'm'+'a'+'i'+'l'+'t'+'o'+':'+answer;
}

function showText(c,n,d) {
c += ' ';
var length = c.length;
var number = 0;
var bar = 0;
var answer = '';
for(var i = 0; i < length; i++) {
number = 0;
bar = 0;
while(c.charCodeAt(i) != 32) {
number = number * 10;
number = number + c.charCodeAt(i)-48;
i++;
}
document.write('&');
document.write('#');
document.write(decrypt(number,n,d));
}
}

function decrypt(c,n,d) {
// Split exponents up
if (d % 2== 0) {
bar = 1;
for(var i = 1; i <= d/2; i++) {
foo = (c*c) % n;
bar = (foo*bar) % n;
}
} else {
bar = c;
for(var i = 1; i <= d/2; i++) {
foo = (c*c) % n;
bar = (foo*bar) % n;
}
}
return bar;
}
// Stop hiding the script -->
</SCRIPT>

The only problem with that one is that it won't display the actual address for those using a web-based email client. They can't see the actual address. Here's a much simpler one:

<SCRIPT type="text/javascript" language="javascript">
<!-- Begin
a="me";
b="mydomain.com";
document.write('<a href=\"mailto:'+a+'@'+b+'\">');
document.write(a+'@'+b+'<\/a>');
// End -->
</SCRIPT>

I put that in an asp page and just use an include wherever I want it, which I find much simpler that putting the code in everytime. The only problem with either of these would be a site browser that has javascript disabled on their browser. Those are few and far between though.

Too bad there is not a way to do it in ASP though...

For server side protection you just need to use a form and do the email from the server. Another way is just to put the email address in a graphic. .NET let's you do that on the fly. Some ASP components do as well.

As for entering an email address in the script, you don't. You just call the function and pass a string. It decrypts it and pops up a MAILTO:. So you need to reverseengineer the encryption (cipher, whatever) for it. Shouldn't be to hard. I haven't tried yet because it just looked cool. I'm far to lazy at the moment... (Still busy with Flash and .NET).