How To: Use Re-Captcha in Codeigniter based website?

Re-captcha is a free web service to add a secured captcha on your website to avoid spams. Spams filled up your inboxes with unnecessary emails or messages which you have no need. Re-captcha is provided by Carnegie Mellon University which are serving over 60 millions captchas in a day.

Here are some simple steps to complete this whole process.

1- Just go to re-captcha sign up page and enter your information. You need to add your site url there. And each of your site which you need to be deployed with re-captcha must have its domain name on your account in re-captcha site.

2- You will get public and private kep after entering your domain name and clicking on Create Key button. Save these codes into a notepad.

3- Download re-captcha library (recaptchalib.php) which will be used to interact with re-captcha API.

4- We will use this library as helper in codeigniter. Because this library holds a list of function which interacts re-captcha API. Paste this helper in to your system/application/helpers folder.

5- Now the work has been done at configuration level. Call your helper in controller.

$this-&gt;load-&gt;helper('recaptchalib');

1	$this->load->helper('recaptchalib');

6- In your controller, paste this code. Here the recaptcha_check_answer is used to get what code a user entered.

function recaptcha_validation($string)
{
	$return = recaptcha_check_answer($this-&gt;config-&gt;item('private_recaptcha_key'),
									$_SERVER["REMOTE_ADDR"],
									$this-&gt;input-&gt;post("recaptcha"),
									$this-&gt;input-&gt;post("recaptcha"));

	if(!$return-&gt;is_valid) 
       {
		$this-&gt;session-&gt;set_userdata("Mesg",'Code entered is invalid !');
		return FALSE;
	}
	else 
       {
		return TRUE;
	}
}

function login_user_function()
{
	$this-&gt;load-&gt;library('validation');
	$this-&gt;load-&gt;helper('recaptcha_helper');

	$rules['recaptcha'] = 'required|callback_recaptcha_validation';
	$this-&gt;validation-&gt;set_rules($rules);

	$fields['recaptcha'] = 'Code';
	$this-&gt;validation-&gt;set_fields($fields);

	if($this-&gt;validation-&gt;run() == FALSE) {
	   // code is not correct
	}
	else 
       {
		// Code is verified now submit the form
	}
}

function recaptcha_validation($string)

{

$return = recaptcha_check_answer($this->config->item('private_recaptcha_key'),

$_SERVER["REMOTE_ADDR"],

$this->input->post("recaptcha"),

$this->input->post("recaptcha"));

if(!$return->is_valid)

{

$this->session->set_userdata("Mesg",'Code entered is invalid !');

return FALSE;

}

else

{

return TRUE;

}

function login_user_function()

{

$this->load->library('validation');

$this->load->helper('recaptcha_helper');

$rules['recaptcha'] = 'required|callback_recaptcha_validation';

$this->validation->set_rules($rules);

$fields['recaptcha'] = 'Code';

$this->validation->set_fields($fields);

if($this->validation->run() == FALSE) {

// code is not correct

}

else

{

// Code is verified now submit the form

}

In codeigniter we use config file to hold some global constant types values so i put private recaptcha key (private_recaptcha_key) in config file.

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