Question

I’m trying to create a captcha code but the code that is being created isn’t being stored in the session variable. Here is the file I’m using to create the code and store the value. I have a session_start() on my php page that will display the captcha as well.

<?php session_start();
class CaptchaSecurityImages {

var $font = './monofont.ttf';

function generateCode($characters) {
    /* list all possible characters, similar looking characters and vowels have been removed */
    $possible = '23456789bcdfghjkmnpqrstvwxyz';
    $code = '';
    $i = 0;
    while ($i < $characters) { 
        $code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
        $i++;
    }
    return $code;
}

function CaptchaSecurityImages($width='120',$height='40',$characters='6') {
    $code = $this->generateCode($characters);
    /* font size will be 75% of the image height */
    $_SESSION['security_code'] = $code;
    $font_size = $height * 0.75;
    $image = @imagecreate($width, $height) or die('Cannot initialize new GD image stream');
    /* set the colours */
    $background_color = imagecolorallocate($image, 255, 255, 255);
    $text_color = imagecolorallocate($image, 20, 40, 100);
    $noise_color = imagecolorallocate($image, 100, 120, 180);
    /* generate random dots in background */
    for( $i=0; $i<($width*$height)/3; $i++ ) {
        imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
    }
    /* generate random lines in background */
    for( $i=0; $i<($width*$height)/150; $i++ ) {
        imageline($image, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $noise_color);
    }
    /* create textbox and add text */
    $textbox = imagettfbbox($font_size, 0, $this->font, $code) or die('Error in imagettfbbox function');
    $x = ($width - $textbox[4])/2;
    $y = ($height - $textbox[5])/2;
    imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code) or die('Error in imagettftext function');
    /* output captcha image to browser */
    header('Content-Type: image/jpeg');
    imagejpeg($image);
    imagedestroy($image);
}

}

$width = isset($_GET['width']) ? $_GET['width'] : '120';
$height = isset($_GET['height']) ? $_GET['height'] : '40';
$characters = isset($_GET['characters']) && $_GET['characters'] > 1 ? $_GET['characters'] : '6';

$captcha = new CaptchaSecurityImages($width,$height,$characters);

?>

I can store other items in sessions and they work just fine. I’m not sure why this value won’t store. I’ve found other posts about getting captcha’s working but nothing about issues with storing the value in sessions. Any suggestions?

Thanks
Robert

Answer 1

I did end up using reCAPTCHA to accomplish this task.