Math Captcha

#1. Features

• Replacement for standard php-captcha
• Simple 2-digit integers in questions
• Bruteforce, XSS and replay attack protection
• Easy API to implement mcaptcha in other plugins

#2. Requirements

This plugin is recommended for use with CAPTCHA Manager.
Siena version of this plugin ships with the CMS by default.

#3. Installation

1. Unpack the plugin into your plugins folder.
2. Install in Administration => Plugins.
3. Configure the plugin. Do not limit attempts if you use mcaptcha in such plugins like comments and shoutbox.
4. Use same tags in users.register.tpl:
   {USERS_REGISTER_VERIFYIMG},{USERS_REGISTER_VERIFYINPUT}

#4. API

Use this function to generate mcpatcha question:

$t->assign(array(
	'SOMETHING_MCAPTCHA' => mcaptcha_generate(),
	'SOMETHING_VERIFY' => '<input type="text" name="rverify" size="4" />',
));

Then check mcaptcha on form processing:

$rverify = sed_import('rverify', 'P', 'INT');
if(!mcaptcha_validate($rverify))
{
	$error_string .= $L['captcha_verification_failed'].'<br />';
}

#5. Limitations

• One mcaptcha per page. If it appears more than one times (like in header and main parts), the mcaptcha will reset itself and result into errors.