class Model_Auth_User extends ORM {
// ...

  /**
   * Filters to run when data is set in this model. The password filter
   * automatically hashes the password when it's set in the model.
   *
   * @return array Filters
   */
  public function filters()
  {
    return array(
      TRUE => array(
        array('trim'),
      ),
      'password' => array(
        array(array(Auth::instance(), 'hash'))
      ),
      'username' => array(
        array('strtolower'),
      ),
      'login_count' => array(
        array('intval'),
      ),
    );
  }

// ...
}