Validasi Harus Input Recaptcha Google pada verifikasi pendaftaran

Assalamualaikum Warahmatullahi Wabarakatuh... mas saya punya controller verif pendaftran siswa baru pada sikolag yang saya buat seperti ini, recaptcah udah muncul cuma bagaimana cara menambahkan validasi harus input recaptcha nya karena saya coba tanpa isi recaptcha data tersimpan, kalau untuk validasi inputan harus sama di recaptcha sudah otomatis ya mas, jadi ga usah pake validasi lagi kalau untuk inputan harus sama
 
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Auth extends CI_Controller {
	public function index(){
		$data['title'] = 'Registrasi';
		$data['description'] = description();
		$data['keywords'] = keywords();
		$this->template->load(template().'/template',template().'/view_register',$data);
	}
 
	public function register(){
		if (isset($_POST['submit'])){
			$config['upload_path'] = 'asset/foto_siswabaru/';
            $config['allowed_types'] = 'gif|jpg|png|JPG|JPEG';
            $config['max_size'] = '2000'; // kb
            $this->load->library('upload', $config);
            $this->upload->do_upload('al');
            $hasil=$this->upload->data();    
			if ($this->input->post() && (strtolower($this->input->post('secutity_code')) == strtolower($this->session->userdata('mycaptcha')))) {			
	            if ($hasil['file_name']==''){
	                    $data = array('nama'=>cetak($this->input->post('a')),
	                                    'jk'=>cetak($this->input->post('b')),
	                                    'nisn'=>cetak($this->input->post('c')),
	                                    'nik'=>cetak($this->input->post('d')),
	                                    'tempat_lhr'=>cetak($this->input->post('e')),
	                                    'tgl_lhr'=>cetak($this->input->post('f')),
	                                    'citacita'=>cetak($this->input->post('g')),
										'hobi'=>cetak($this->input->post('h')),
										'jml_sdr'=>cetak($this->input->post('i')),
										'anakke'=>cetak($this->input->post('j')),
										'alamat'=>cetak($this->input->post('k')),
										'kode_pos'=>cetak($this->input->post('l')),
										'no_hp'=>cetak($this->input->post('m')),
										'no_kk'=>cetak($this->input->post('n')),
										'nik_ayah'=>cetak($this->input->post('o')),
										'nama_ayah'=>cetak($this->input->post('p')),
										'lhr_ayah'=>cetak($this->input->post('q')),
										'pend_ayah'=>cetak($this->input->post('r')),
										'pekerjaan_ayah'=>cetak($this->input->post('s')),
										'nik_ibu'=>cetak($this->input->post('t')),
										'nama_ibu'=>cetak($this->input->post('u')),
										'lhr_ibu'=>cetak($this->input->post('v')),
										'pend_ibu'=>cetak($this->input->post('w')),
										'pekerjaan_ibu'=>cetak($this->input->post('x')),
										'penghasilan_ortu'=>cetak($this->input->post('y')),
										'nama_wali'=>cetak($this->input->post('z')),
										'lhr_wali'=>cetak($this->input->post('aa')),
										'pend_wali'=>cetak($this->input->post('ab')),
										'pekerjaan_wali'=>cetak($this->input->post('ac')),
										'penghasilan_wali'=>cetak($this->input->post('ad')),
										'seleksi'=>cetak($this->input->post('ae')),
										'asal_sekolah'=>cetak($this->input->post('af')),
										'npsn'=>cetak($this->input->post('ag')),
										'nopes'=>cetak($this->input->post('ah')),
										'skhun'=>cetak($this->input->post('ai')),
										'ijazah'=>cetak($this->input->post('aj')),
										'no_pendaftaran'=>date('YmdHis'),
										'status'=>('Proses'),
										'nilai_un'=>cetak($this->input->post('ak')));
	            }else{
	                    $data = array('nama'=>cetak($this->input->post('a')),
	                                    'jk'=>cetak($this->input->post('b')),
	                                    'nisn'=>cetak($this->input->post('c')),
	                                    'nik'=>cetak($this->input->post('d')),
	                                    'tempat_lhr'=>cetak($this->input->post('e')),
	                                    'tgl_lhr'=>cetak($this->input->post('f')),
	                                    'citacita'=>cetak($this->input->post('g')),
										'hobi'=>cetak($this->input->post('h')),
										'jml_sdr'=>cetak($this->input->post('i')),
										'anakke'=>cetak($this->input->post('j')),
										'alamat'=>cetak($this->input->post('k')),
										'kode_pos'=>cetak($this->input->post('l')),
										'no_hp'=>cetak($this->input->post('m')),
										'no_kk'=>cetak($this->input->post('n')),
										'nik_ayah'=>cetak($this->input->post('o')),
										'nama_ayah'=>cetak($this->input->post('p')),
										'lhr_ayah'=>cetak($this->input->post('q')),
										'pend_ayah'=>cetak($this->input->post('r')),
										'pekerjaan_ayah'=>cetak($this->input->post('s')),
										'nik_ibu'=>cetak($this->input->post('t')),
										'nama_ibu'=>cetak($this->input->post('u')),
										'lhr_ibu'=>cetak($this->input->post('v')),
										'pend_ibu'=>cetak($this->input->post('w')),
										'pekerjaan_ibu'=>cetak($this->input->post('x')),
										'penghasilan_ortu'=>cetak($this->input->post('y')),
										'nama_wali'=>cetak($this->input->post('z')),
										'lhr_wali'=>cetak($this->input->post('aa')),
										'pend_wali'=>cetak($this->input->post('ab')),
										'pekerjaan_wali'=>cetak($this->input->post('ac')),
										'seleksi'=>cetak($this->input->post('ae')),
										'asal_sekolah'=>cetak($this->input->post('af')),
										'npsn'=>cetak($this->input->post('ag')),
										'nopes'=>cetak($this->input->post('ah')),
										'skhun'=>cetak($this->input->post('ai')),
										'ijazah'=>cetak($this->input->post('aj')),
										'nilai_un'=>cetak($this->input->post('ak')),
										'foto'=>$hasil['file_name'],
										'no_pendaftaran'=>date('YmdHis'),
										'status'=>('Proses'),
										'penghasilan_wali'=>cetak($this->input->post('ad')));
						}   	            
				$this->model_app->insert('siswabaru',$data);
 
 
			}
				redirect('auth/register');
 
		}else{
			$data = array(
            'action' => site_url('welcome/login'),
            'username' => set_value('username'),
            'password' => set_value('password'),
            'captcha' => $this->recaptcha->getWidget(), // menampilkan recaptcha
            'script_captcha' => $this->recaptcha->getScriptTag(), // javascript recaptcha ditaruh di head
			);
			$data['title'] = 'Registrasi';
			$data['pend'] = $this->model_app->view_ordering('pendidikan','kd_pend');
			$data['pekerjaan'] = $this->model_app->view_ordering('pekerjaan','kd_pekerjaan');
			$data['penghasilan'] = $this->model_app->view_ordering('penghasilan','kd_penghasilan');
			$recaptcha = $this->input->post('g-recaptcha-response');
			$response = $this->recaptcha->verifyResponse($recaptcha);
			$this->template->load(template().'/template',template().'/view_register',$data);
		}
	}
 
}