Using recaptchlib in your projects

  1. Installation
  2. How to use

It is good when someone writes extensions for us but trust, sometimes we forget about other approaches that, if we know the library, we shouldn't forget.

This small tutorial is to explain how to make use of the well known library recaptcha.

Please note that I don't have any problems with Yii's captcha feature, nevertheless we should admit that the design of recaptcha is much more appealing, isn't it?


1) First of all we need to download the correspondent recaptcha php libraries

2) Unzip and move to your applications/protected/extensions folder

3) Now, you need to go to and add your domain to get your public and private keys - dont worry for the sake of this tutorial I already have the keys for the domain 'localhost', so we can test it in our computers. Here they are:

a) Public Key: 6LfgNLoSAAAAAGMmhFTEpmRKN82P9z98MqjmI_s3

b) Private Key: 6LfgNLoSAAAAAGBVyqeKK9qH_wG5HIGIDd2KotLB

Ok, we are set... lets use the library

How to use

There are two parts we have to take into account: 1) the display -in our view 2) and the confirmation -in our controller

The Display

At the top part of our view we include the recaptcha library and set our public key like this:


$publickey = "6LfgNLoSAAAAAGMmhFTEpmRKN82P9z98MqjmI_s3";

The public key is important as afterwards in the view (wherever we are going to render the captcha in our form) we are going to tell the library to render the captcha with the key as a parameter:

echo recaptcha_get_html($publickey); ?>
The Confirmation

In our last step, we need to code the following in the controller action that is going to receive the form parameters:

.... actionWhatever(){

// I check against a value instead of isPostRequest
// but this is something that is up to you
if(Yii::app()->request->getParam( 'submit' )){

    // importing the library -I am forcing include
    Yii::import ( 'ext.recaptchalib', true );

    // remember our private key?		
    $privatekey = '6LfgNLoSAAAAAGBVyqeKK9qH_wG5HIGIDd2KotLB';

    // here comes the good part
    // lets check if the code submitted is the correct one
    $resp = recaptcha_check_answer( 
       $privatekey, // our private key
       $_SERVER ["REMOTE_ADDR"], // here it will check our domain
       // the challenge of the recaptcha library posted
       Yii::app()->request->getParam( "recaptcha_challenge_field" ),
       // the code inserted by the user in the captcha field
       Yii::app()->request->getParam( "recaptcha_response_field" ) 

    // recaptcha_check_answer returns a ReCaptchaResponse object 
    // which has two properties: is_valid and error.
    // I dont think I need to explain that
       // ... success
       // .. failure

And that's it, your very own recaptcha implementation.