login captcha

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Auth extends CI_Controller {

    public function index() {
        //$this->load->view('index');

    $cap = $this->buat_captcha();
    $data['cap_img'] = $cap['image'];
    $this->session->set_userdata('kode_captcha', $cap['word']);
    $this->load->view('index', $data);
    }
    public function cek_login() {
        $data = array('UserName' => $this->input->post('NUser', TRUE),
                        'Password' => md5($this->input->post('NSandi', TRUE))
            );
        $this->load->model('Model_user'); // load model_user
        $hasil = $this->Model_user->cek_user($data);
        if ($hasil->num_rows() == 1) {
            foreach ($hasil->result() as $sess) {
                $sess_data['logged_in'] = 'Sudah Loggin';
                //$sess_data['uid'] = $sess->uid;
                $sess_data['UserName'] = $sess->UserName;
                $sess_data['level'] = $sess->Level1;
                $this->session->set_userdata($sess_data);
            }
            if ($this->session->userdata('level')=='admin') {
                redirect('admin/c_admin');
            }
            elseif ($this->session->userdata('level')=='member') {
                redirect('member/c_member');
            }
        }
        else {
            echo "<script>alert('Gagal login: Cek username, password!');history.go(-1);</script>";
        }
    }




 public function buat_captcha()
 {

  $this->load->helpers('captcha');
  $vals = array(
  'img_path' => './captcha/',
  'word' => random_string('numeric', 4),
  'img_url' => base_url().'captcha/',
  'font_path' => FCPATH.'/font/timesbd.ttf',
  'img_width' => '120',

  'img_height' => 50,
  'expiration' => 60,

  );
  $cap = create_captcha($vals);
  return $cap;
 }

 public function post()
 {
  $this->form_validation->set_rules('kode_captcha', 'Kode Captcha', 'required|callback_cek_captcha');
  $this->form_validation->set_error_delimiters('<div style="border: 1px solid: #999999; background-color: #ffff99;">', '</div>');

  if ($this->form_validation->run() === FALSE)
  {
   $cap = $this->buat_captcha();
   $data['cap_img'] = $cap['image'];
   $this->session->set_userdata('kode_captcha', $cap['word']);

   $this->load->view('form_captcha', $data);
  } else  {
   $data['title'] = 'Captcha Benar!';
   $this->session->unset_userdata('kode_captcha');
   $this->load->view('captcha_sukses', $data);
  }
 }

 public function cek_captcha($input)
 {
  if($input === $this->session->userdata('kode_captcha')){
   return TRUE;
  } else {
   $this->form_validation->set_message('cek_captcha', '%s yang anda input salah!');
   return FALSE;
  }
 }
}
//akhir dari autentikasi controller