demo google recaptcha on codeigniter form
open config file recaptcha.php in application/config/recaptcha.php , and change site_key and secret with your key
$config['recaptcha_sitekey'] = 'YOUR_RECAPTCHA_SITE_KEY'; //ganti dengan site key yang didapat saat mendaftarkan website pada google recaptcha
$config['recaptcha_secretkey'] = 'YOUR_RECAPTCHA_SECRET_KEY'; //ganti dengan secret key yang didapat saat mendaftarkan website pada google recaptcha
$config['lang'] = "";