$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 7200;
$config['sess_expire_on_close'] = TRUE;
$config['sess_encrypt_cookie'] = TRUE;
$config['sess_use_database'] = TRUE;
$config['sess_table_name'] = 'ci_sessions';
$config['sess_match_ip'] = TRUE;
$config['sess_match_useragent'] = TRUE;
$config['sess_time_to_update'] = 300;

function logout(){
        $this->session->sess_destroy();
        $this->load->helper('url');
        redirect("/topic");
    }

function authentication(){
        $this->load->model('user_model');
        $user = $this->user_model->getByEmail(array('email'=>$this->input->post('email')));
        if(!function_exists('password_hash')){
            $this->load->helper('password');
        }
        if(
            $this->input->post('email') == $user->email && 
            password_verify($this->input->post('password'), $user->password)
        ) {
            $this->session->set_userdata('is_login', true);
            $this->load->helper('url');
            redirect("/topic");
        } else {
            $this->session->set_flashdata('message', '로그인에 실패 했습니다.');
            $this->load->helper('url');
            redirect('/auth/login');
        }
    }