Custom captcha question

[crazy4cars69]

How to get started with writing custom captcha?
What are the things necessary for it to work with vichan?
I'm looking to write similar to one in /inc/captcha/ but wanting to write my own

[crazy4cars69]

I got to working on captcha, but ran into some errors.
I'm using Bazukachan fork.
For /templates/post_form.html

<img src="{{ config.captcha.provider_get }}">
<br>
<input type="text" name="captcha_text">
<br>
<input type="hidden" name="captcha_cookie" value="{{ captcha_cookie }}">

For /inc/captcha/captcha2.php

session_start();
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Content-type: image/png');
$captcha = rand(1000, 9999);
$im = imagecreatetruecolor(180, 50); 
$bg = imagecolorallocate($im, 20, 20, 30);
$fg = imagecolorallocate($im, 255, 255, 255);
imagefill($im, 0, 0, $bg);
imagestring($im, rand(1, 7), rand(1, 7), rand(1, 7),  $captcha, $fg);
$_SESSION['captcha_cookie'] = $captcha;
$_SESSION['captcha_text'] = $captcha;
imagepng($im);
imagedestroy($im);

The error it gives me You seem to have mistyped the verification.

[frozenpandaman]

@crazy4cars69, did you ever get this working?

[perdedora]

you probably fucked up something in the captcha verification in post.php

[frozenpandaman]

The following code was posted by a user on August 14 and then deleted. I saved the email where I got notified of it, in case it's helpful to anyone:

<?php
session_start();


function rand_string($length, $charset) {
  $ret = "";
  while ($length--) {
    $ret .= mb_substr($charset, rand(0, mb_strlen($charset, 'utf-8')-1), 1, 'utf-8');
  }
  return $ret;
}

		//$ch = curl_init($config['domain'].'/'.$config['captcha']['provider_check'] . "?" . http_build_query([
		//	'mode' => 'check',
		//	'text' => $_POST['captcha_text'],
//	'extra' => $config['captcha']['extra'],
//
$mode = $_GET['mode'];
$extra = isset($_GET['extra']) ? $_GET['extra'] : '12345678'; // what is doing??

if ($mode == 'get') {
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Content-type: image/png');
$captcha = rand(1000, 9999);
$im = imagecreatetruecolor(180, 50); 
$bg = imagecolorallocate($im,  20, 20, 30);
$fg = imagecolorallocate($im, 255, 255, 255);
imagefill($im, 0, 0, $bg);
imagestring($im, rand(5, 12), rand(5, 12), rand(5, 12),  $captcha, $fg);
$_SESSION['captcha_cookie'] = hash("md5",$captcha);
$_SESSION['captcha_text'] = hash("md5",$captcha);
imagepng($im);
imagedestroy($im);
} else if ($mode == 'check') {
	//var_dump($_GET);
	//var_dump($_GET);
	$text = $_GET['text'];
	$extra = $_GET['extra'];
	$cookie = $_GET['cookie'];
	//echo($_SESSION['captcha_text']);
	//die($text);

	if ( hash("md5",$text) == $cookie )
	{
		print(1);
		exit(0);
	}
	
	print(0);
}

at inc/secrets.php
$config['domain'] = 'localhost:N'; // or your clearnet address