public function validateLogin($username, $password) {
                return (
                        (!empty($username) || $this->invalidate('username', 'notempty')) && // username cannot be empty. throw an error if it is.
                        (!empty($password) || $this->invalidate('password', 'notempty')) && // password cannot be empty. throw an error if it is.
                        ($u = $this->findByUsername($username, 'password')) && // lookup the user by username
                        isset($u['User']['password']) && // make sure the lookup was successful
                        ($hash = $this->generateHash($username, $password)) && // generate the hash for the given username/password
                        $u['User']['password'] == $hash // compare the hashes
                );
        }