[WeChall] Are you serial

We are serialsly trying to build a secure website.
This time, we have it secure and extensible, and of course you can see all the sourcecode again:

code.php
insecure.inc.php
SERIAL_LoginForm.php
SERIAL_LogoutForm.php
SERIAL_Solution.php
SERIAL_User.php

As always, code you see is code in use.

GeSHi`ed PHP code for SERIAL_LoginForm.php

<?php
final class SERIAL_LoginForm
{
        public function serial_formz()
        {                $data = array();
                $data['username'] = array(GWF_Form::STRING, '', 'Username');
                $data['login'] = array(GWF_Form::SUBMIT, 'Login');
                return new GWF_Form($this, $data);
        }        
        public function execute($username)
        {
                $password = 'testtest'; #random
                                $user = new SERIAL_User($username, $password);
                
                $serial = serialize($user);
                
                $_COOKIE['serial_user'] = $serial;                
                setcookie('serial_user', $serial, time()+31536000, GWF_WEB_ROOT_NO_LANG, GWF_DOMAIN, false, true);
        }
}
?>