传递敏感参数时，php中的URL加密（joomla + codeigniter）

I'm using codeigniter inside joomla by using iframe. Some pages i need to get the user group if admin or user So i find a way to send values to iframe by using url with the following code:

<?php
//add user id
$user_id = JFactory::getUser()->id;
?>

<iframe <?php echo $this->wrapper->load; ?>
   id="blockrandom"
   name="iframe"
   src="<?php echo $this->escape($this->wrapper->url) . "?user=" . $user_id; ?>"

The problem is the type of the user will apear in url so is their any way to encrype the url and decrypt it in the other page?