Text_CAPTCHA

require_once 'Text/CAPTCHA.php';

// Set CAPTCHA options (font must exist!)
$options = array(
    'font_size' => 24,
    'font_path' => './',
    'font_file' => 'COUR.TTF'
);
           
// Generate a new Text_CAPTCHA object, Image driver
$c = Text_CAPTCHA::factory('Image');
$retval = $c->init(200, 80, null, $options);
if (PEAR::isError($retval)) {
    echo 'Error generating CAPTCHA!';
    exit;
}

// Get CAPTCHA secret passphrase
$_SESSION['phrase'] = $c->getPhrase();

// Get CAPTCHA image (as PNG)
$png = $c->getCAPTCHAAsPNG();
if (PEAR::isError($png)) {
    echo 'Error generating CAPTCHA!';
    exit;
}
file_put_contents(md5(session_id()) . '.png', $png);

session_start();
$ok = false;
$msg = 'Please enter the text in the image in the field below!';
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    if (isset($_POST['phrase']) && isset($_SESSION['phrase']) &&
        strlen($_POST['phrase']) > 0 && strlen($_SESSION['phrase']) > 0 &&
        $_POST['phrase'] == $_SESSION['phrase']) {
        $msg = 'OK!';
        $ok = true;
        unset($_SESSION['phrase']);
    } else {
        $msg = 'Please try again!';
    }
    unlink(md5(session_id()) . '.png');
}
print "<p>$msg</p>";

if (!$ok) {
    // create the CAPTCHA as seen above
    // and send it to the client
}