/application/bootstrap.php

Kohana::modules(array(
    'auth'       => MODPATH.'auth',       // Basic authentication
    // 'codebench'  => MODPATH.'codebench',  // Benchmarking tool
    'database'   => MODPATH.'database',   // Database access
    // 'image'      => MODPATH.'image',      // Image manipulation
    'orm'        => MODPATH.'orm',        // Object Relationship Mapping
    // 'pagination' => MODPATH.'pagination', // Paging of results
    // 'userguide'  => MODPATH.'userguide',  // User guide and API documentation
    ));

application/config/auth.php

<?php defined('SYSPATH') OR die('No direct access allowed.');

return array
(
    'driver' => 'ORM',
    'hash_method' => 'sha1',
    'salt_pattern' => '1, 3, 5, 9, 14, 15, 20, 21, 28, 30',
    'lifetime' => 1209600, //2 weeks
    'session_key' => 'auth_user',
    'users' => array
    (
        // 'admin' => 'b3154acf3a344170077d11bdb5fff31532f679a1919e716a02',
    ),
);


application/classes/controller/register.php

<?php defined('SYSPATH') OR die('No direct access allowed.');

class Controller_Register extends Controller_Common
{
    public function action_index()
    {
        $user = ORM::factory('user');

        $post = Validate::factory($_POST)

            ->filter(TRUE, 'trim')
            ->filter('username', 'strtolower')

            ->rule('username', 'not_empty')
            ->rule('username', 'regex', array('/^[a-z_.0-9]++$/iD'))
            ->callback('username', array($user, 'username_available'))

            ->rule('password', 'not_empty')

            ->rule('confirm', 'not_empty')
            ->rule('confirm', 'matches', array('password'))

            ->rule('email', 'not_empty')
            ->rule('email', 'email')
            ->callback('email', array($user, 'email_available'));

        if ($post->check())
        {
            // Create a new user record in the database
            $user = Model_Auth_User::factory('user');
            $user->username = $_POST['username'];
            $user->email = $_POST['email'];
            $user->password = $_POST['email'];
            $user->save();

            $login_role = new Model_Role(array('name' =>'login'));
            $user->add('roles',$login_role);

            $this->request->redirect('/?msg='.urldecode('please log in now. sorry!'));
        }

        // Validation failed, collect the errors
        $errors = $post->errors('user');

        // Display the registration form
        $this->template
            ->bind('post', $post)
            ->bind('errors', $errors);
    }
}


application/classes/controller/default.php

<?php defined('SYSPATH') OR die('No direct access allowed.');

class Controller_Default extends Controller_Common
{
    public function action_index()
    {
        $msg = '';
        $auth = Auth::instance();

        if ($auth->logged_in()) {
            $this->request->redirect('/chat');
        }

        $post = Validate::factory($_POST)
            ->filter(TRUE, 'trim')
            ->filter('username', 'strtolower')

            ->rule('username', 'not_empty')

            ->rule('password', 'not_empty');

        if ($post->check()) {
            $login = $auth->login($_POST['username'], $_POST['password'], true);

            if ($login) {
                $this->request->redirect('/chat');
            } else {
                $msg = 'wrong password.';
            }
        }

        $msg = !empty($_REQUEST['msg']) ? $_REQUEST['msg'] : $msg;

        $this->template->post = $post;
        $this->template->errors = $post->errors('user');
        $this->template->msg = $msg;

    }
}


/application/classes/controller/common.php (simple extension that sets up my templates based on the requested path)
<?php defined('SYSPATH') or die('No direct script access.');

class Controller_Common extends Controller_Template {
    public function __construct(Kohana_Request $request)
    {
        parent::__construct($request);
        $this->template = $request->controller . '/' . $request->action;
    }
}