PHP Captcha without session

Question

Ok, here is an issue: in the project i\'m working on, we can\'t rely on server-side sessions for any functionality.

The problem is that common captcha solutions fro

Answer 1

How about this solution? I found this "Sessionless PHP Captcha" article on google and I used on one of my projects, it's simple, no session and it's free. Any security concerns on RC4?

http://www.mythos-rini.com/blog/archives/732