var key = 'foobarbaz';

function encrypt(data, key, rev){

 var output = '';
 data = data.toLowerCase();

 // make key at least as long as data
 while(key.length < data.length){
  key += key;
 }

 // process char by char
 for(var i = 0; i<data.length; i++){

  var a = data.charCodeAt(i);
  var b = key.charCodeAt(i);

  if (a >= 97 && a <= 122 ){

   if (rev){
    b = -b;
   }

   a = ((((a - 97) + b) + 260) % 26) + 97;
  }

  output += String.fromCharCode(a);
 }

 return output;
}

window.onload = function()
{
	if (document.getElementsByTagName)
	{
		var allLinks = document.getElementsByTagName('a');

		for (var i = 0; i < allLinks.length; i++)
		{
			if (allLinks[i].getAttribute('href').indexOf('mailto')>=0)
			{
				oldHref = allLinks[i].getAttribute('href').replace('mailto:', '');
				decryptedHref = encrypt(oldHref, key, 0);
				allLinks[i].setAttribute('href','mailto:'+decryptedHref);
				allLinks[i].setAttribute('title',decryptedHref);
			}
		}
	}
};