Image Auth – CAPTCHA component

A human verification system through a text image

1. Include the component.
var  $components =array (‘xxx’,'yy’,'imageAuth’);

2. In the login action:
$this->imageAuth->generate();

3.
Create a new action for showing the image: /login/image_auth
function image_auth()
{
    $this->imageAuth->show();
}

4.
In the login form:
<img src=”<?=$html->url(’/login/image_auth’)?>” />

5. Put this in vendors/image_auth/

6. In your post-action:

if (! $this->imageAuth->check( $this->params['data']['text'] ))
{
    echo ‘Wrong text entered’;
}

7. Put this code in controllers/components/image_auth.php
<?php
/*
 * Image Auth component.
 * Real human verification system for forms
 *
 * @author      RosSoft
 * @version     0.1
 * @license        MIT
 *
 * @link http://phpbuilder.com/columns/patterson20060301.php3
 */
class ImageAuthComponent extends Object
{
    var $components = array(‘session’);
    var $controller;
   
    /** Font file */
    var $font=’ProggyCleanSZBP’;
   
    /** some background colors */
    var $bg_colors = array(
                                    ’176.196.222′, // Blue
                                    ’204.153.204′, // Purple
                                    ’204.204.204′, // Gray
                                    ’227.81.82′,     // Red
                                    ’150.200.162′  // Green
                                    );
                                   
    /** Some font colors */
    var $font_colors = array(
                                    ’0.0.139′, // Blue
                                    ’104.34.139′, // Purple
                                    ’79.79.79′, // Gray
                                    ’128.0.0′, // Red
                                    ’59.94.15′     // Green
                                    );
    /** Image width */                                
    var    $img_width = 170;
   
    /** Image height */
    var $img_height = 75;
   
    /** Font size */
    var $fnt_size = 24;
   
    /** Letter spacing */
    var $let_space = 10;

    /** Length of random string */       
    var $str_length = 6;
                                                           

    function startup(&$controller)
    {
        $this->controller=$controller;       
    }
   
    /**
     * Generates a new random string and stores on session
     * @param boolean $regenerate. If false and already exists a random string then it’s reused
     */   
    function generate($regenerate=true)
    {
        if (! $regenerate)
        {
            $regenerate= ! $this->session->check(‘image_auth_string’);
        }   
        if ($regenerate)
        {
            $rnd_str = $this->_gen_random_string($this->str_length);   
            $this->session->write(‘image_auth_string’,$rnd_str);       
        }
                   
    }
   
    /**
     * Outputs the random string as an image.
     * The string is readed from the session
     */
    function show()
    {
        $this->generate(false); //Generates a new string if there isn’t a generated one
        $rnd_str=$this->session->read(‘image_auth_string’);
       
        // Set GD font path
        putenv(‘GDFONTPATH=’.realpath(VENDORS . ‘image_auth’));
        /**
         * Image functions
         */
        // Create the image
        $img = imagecreate($this->img_width, $this->img_height) or die(‘Can not initialize GD Image Library’);

        // Define Background & Text colors
        list($br, $bg, $bb) = explode(‘.’, $this->bg_colors[rand(0, count($this->bg_colors)-1)]);
        list($tr, $tg, $tb) = explode(‘.’, $this->font_colors[rand(0, count($this->font_colors)-1)]);
        $bg_color = imagecolorallocate($img, $br, $bg, $bb);
        $txt_color = imagecolorallocate($img, $tr, $tg, $tb);
        $line_clr = imagecolorallocate($img, 0, 0, 0);
        // Create box around image
        imageline($img, 0, 0, $this->img_width, 0, $line_clr); // Top left to top right
        imageline($img, 0, 0, 0, $this->img_height, $line_clr); // Top left to bottom left
        imageline($img, 0, $this->img_height-1, $this->img_width, $this->img_height -1, $line_clr); // Bottom Left to Bottom right
        imageline($img, $this->img_width-1, 0, $this->img_width-1, $this->img_height, $line_clr); // Top right to bottom Right

        //     Write string into image
        for($i=0; $i
        {
            imagettftext($img, (rand() % $this->fnt_size / 1.5) + $this->fnt_size, rand(-30, 30), (($i*$this->fnt_size)+$this->let_space), rand($this->fnt_size+5, ($this->img_height – $this->fnt_size-5)), $txt_color, $this->font, $rnd_str{$i});
        }
        imagefilter($img,IMG_FILTER_GAUSSIAN_BLUR,200);
           header(“Pragma: public”);
           header(“Expires: 0″);
           header(“Cache-Control: no-store, no-cache”);
           header(“Cache-Control: must-revalidate, post-check=0, pre-check=0″);
           header(“Cache-Control: public”);
        if (function_exists(‘imagepng’))
        {
            header(“Content-type: image/png”);
            imagepng($img);
        }
        else
        {
            header(“Content-type: image/jpeg”);
            imagejpeg($img);
        }
        $this->controller->autoRender=false;
    }
   
    /**
     * Checks the string passed against session for a valid auth
     * @param string $string String to be checked
     * @return boolean. True if valid  
     */   
    function check($string)
    {
        return ($string === $this->session->read(‘image_auth_string’));
    }

   
    /**
     * Random string generation function
     */
    function _gen_random_string($length=5, $str=”)
    {
        for($i=1; $i<=$length; $i++)
        {
            $ord = rand(48, 90);

            if( ( ($ord>=48) && ($ord<=57) ) || ( ($ord>=65) && ($ord<=90) ) )
            {
                $str .= chr($ord);
            }
            else
            {
                $str .= $this->_gen_random_string(1);
            }
        }
        return $str;
    }   
}