Cute Captcha

This is my first WordPress plugin that i made it for personal use and to learn how to build plugins.
This plugin replaces the submit button on the post comment section with a set of buttons from images.
A small message provides the user a hint on what button to use to submit the comment.
Demo: http://www.arcweb.ro/blog/2011/12/21/testing-cutecaptcha-plugin/

Requirements:
PHP mcrypt should be available on the server, i will add more encryption methods if required.
Session support is optional, supports caching of post pages without session but with lower security.

Customize:
All the information and parameters to configure are in cutecaptcha.php
The images and messages can be customized and should be quite fun to adapt it with the
subject of each website, especially expecting that anybody th…