A simple jQuery plugin to encrypt form data client-side and pass it (with an obfuscated key) to the processor via the POST method.

Demo:

View the jqCrypt Demo

Implementation:

<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="jquery.jqcrypt.js"></script>
<script type="text/javascript">
 $(function(){
 $('#form_id').jqcrypt({
 keyname: 'jqckval',
 randomkey: false,
 key: 'some_key_value',
 callback: function(form){ 
 form.submit(); 
 }
 });
 });
</script>

Implementation of the jqCrypt plugin consists simply of including the jQuery core, the plugin file, and associating the function with the id of the form to be encrypted.

Parameters:

keyname: The name of the key, this is the name of the form field containing the key value (Default: 'jqckval')

randomkey: Tells the system wether or not to use a random key or one of your choosing (Default: true)

key: If 'randomkey' parameter is set to 'false' this is the key that will be used instead (Default: '123456')

callback: function to be fired after fields have been encrypted (Default: submit form)

Decrypting (PHP):

The following PHP function can be used to decrypt the values using PHP:

function c2sdecrypt($s,$k){
 $k = base64_decode(urldecode($k));
 $s = urldecode($s);
 $k = str_split(str_pad('', strlen($s), $k));
 $sa = str_split($s);
 foreach($sa as $i=>$v){
 $t = ord($v)-ord($k[$i]);
 $sa[$i] = chr( $t < 0 ?($t+256):$t);
 }
 return urldecode(join('', $sa));
 }

Download:

Download the jquery.jqcrypt.js plugin (with example)