Captcha

gistfile1.php

<?php
class Captcha 
{
    private static function generate() {

        $fontFile = './captcha.ttf';
        $fontSize = 18;
        $charsAmount = 5;
        $chars = '23456789BCDFGHJKMNPQRSTVWXYZ';
        $stringOffsetX = 5;
        $stringOffsetY = 25;
        $captchaString = '';
        for($i=0; $i<$charsAmount; $i++) {
            $captchaString .= $chars[mt_rand(0,strlen($chars)-1)]; 
        }
        $_SESSION['captcha'] = strtolower($captchaString);
        ob_start();
        $image = imagecreatetruecolor(80, 25);
        $color = imagecolorallocatealpha($image, 0, 0, 0, 127);
        imagefill($image, 0, 0, $color);
        imagesavealpha($image, true);
        imagefttext($image, $fontSize, 0, 0, 20, 0x000000, $fontFile, $captchaString);
        imagepng($image);
        imagedestroy($image);
        $image_data = base64_encode(ob_get_contents());
        ob_end_clean();
        return $image_data;
        
    }

    public static function create() {

    echo '<img src="data:image/png;base64,' . self::generate() . '">';

    }
}