reCAPTCHA helper and validation function (easy-to-use captcha)

[eluser]vendiddy[/eluser]
This is a widely used captcha implementation. It's used at big sites like Facebook and CraigsList.

Steps to Use

1. Sign up for an access key at http://recaptcha.net/

2. Get recaptchalib.php from the zip archive located at http://code.google.com/p/recaptcha/downl...lib-Latest.

3. Rename recaptchalib.php to recaptcha_helper.php and put it in your helpers folder.

4. Add the following function to recaptcha_helper.php:

Code:

function recaptcha()
{
    $CI =& get_instance();
    $CI->config->load('recaptcha');
    $public_key = $CI->config->item('recaptcha_public_key');
    $message = isset($CI->validation->recaptcha_error)
             ? $CI->validation->recaptcha_error : '';
    return recaptcha_get_html($public_key, $message);
}

4. Add the following function to your MY_Validation class as seen below in the libraries folder. (If you don't already have one a MY_Validation class, make one.)

Code:

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class MY_Validation extends CI_Validation
{
    
    function MY_Validation()
    {
        parent::CI_Validation();
    }
    
    function recaptcha_matches()
    {
        $CI =& get_instance();
        $CI->config->load('recaptcha');
        $public_key = $CI->config->item('recaptcha_public_key');
        $private_key = $CI->config->item('recaptcha_private_key');
        $response_field = $CI->input->post('recaptcha_response_field');
        $challenge_field = $CI->input->post('recaptcha_challenge_field');
        $response = recaptcha_check_answer($private_key,
                                           $_SERVER['REMOTE_ADDR'],
                                           $challenge_field,
                                           $response_field);
        if ($response->is_valid)
        {
            return TRUE;
        }
        else
        {
            $CI->validation->recaptcha_error = $response->error;
            $CI->validation->set_message('recaptcha_matches', 'The %s is incorrect. Please try again.');
            return FALSE;
        }
    }
    
}

5. Create a recaptcha.php in your config folder and add your public and private keys (the ones you got from registering) as seen below:

Code:

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
$config['recaptcha_public_key'] = "...";
$config['recaptcha_private_key'] = "...";

Example usage in a controller:

Code:

public function register()
    {
        $this->load->library('validation');
        $this->load->helper('recaptcha');
        
        $rules['username'] = 'trim|required|unique[users.username]';
        $rules['password'] = 'required|password|matches[password_confirm]';
        $rules['password_confirm'] = 'required';
        $rules['email'] = 'trim|required|valid_email|unique[users.email]';
        $rules['recaptcha_challenge_field'] = 'required|recaptcha_matches';
        
        $this->validation->set_rules($rules);
        
        $fields['username'] = 'username';
        $fields['password'] = 'password';
        $fields['password_confirm'] = 'password confirmation';
        $fields['email'] = 'email';
        $fields['recaptcha_challenge_field'] = 'answer to the security question';
        
        $this->validation->set_fields($fields);
        
        if ($this->validation->run() == FALSE)
        {
            $this->load->view('user_registration');
        }
        else
        {
            echo 'Success!';
        }
    }

In the view, you can create the captcha form element by echoing <?= recaptcha() ?>
I can package all of this into a zip file upon request.