Bitprison CAPTCHA System for PHP

Posted by Joey on May 26th, 2008 at 8:34 pm

Tags: PHP • security • spam • web

I've made a CAPTCHA system what is ease of use for any PHP website. This is a full object oriented class library. Ease of use and ease of customisation. Try it! Feel free to download and use it. Please leave a comment.

Features

Very minimal software requirements
Ease of customisation (parameters or class extending)
Full object oriented library
One file one class
API documentation
Totally free and Open Source! Download

Customisation with parameters

Set number of characters
Set size of captcha

Requirements

PHP 5.0 or above
GD 2.0 or above
Only (Ubuntu) Linux tested, but theoretically works on Windows too, but I haven't got Windows.

Example and Demo

Example of BitPrison CAPTCHA image:

Try the demo page and download BitPrison CAPTCHA include the demo.

Code Example

Generate image

/**
* This is an example of how to genereate captcha with this class library.
* 1. Include Captcha class!
* 2. Generate CAPTCHA with interface of Captcha class.
* 3. Send session cookie. And save to session the captcha object.
* 4. Print Captcha to std. output. Return as an image.
*/
require_once("captcha.class.php");
session_start();
 
// 5 character long, 1.4x size, horizontal space, vertical space
$c = new Captcha(5, 1.4, 100, 50); 
// Captcha() whitout parameters is also work
 
// save the object to session
$_SESSION['captcha'] = $c;
 
// draw it
$c->draw();

Check CAPTCHA string

require_once('captcha.class.php');
session_start();
 
if (is_object($_SESSION['captcha']) && 
  $success = $_SESSION['captcha']->check($_POST['c'])) 
{
    $message = "You are Human.";
    // do something
} elseif ($_POST['c'] != '') {
    $message = "Are you spammer?";
    // do something
}

Ubuntu compatibility

This class library use only necessary image functions. Work under Ubuntu linux because not use imageantialias() or imagerotate() functions, what ubuntu packaged PHP-GD library don't support.