Captcha with ASIRRA?

Hi!

A lot of people today are dyslectic, and they have enormous problems with letter/number captchas. It is also difficult for people with sight impairments and some other functional disorders to use ordinary captchas. So, Microsoft and Petfinder created "ASIRRA", (http://research.microsoft.com/asirra/) as an alternative.

This replaces distorted text with images of cats and dogs, and the visitor is asked to identify the cats. Since the database contains over two million animals, it is difficult to reproduce for an attacker.

I’d like that as a replacement for the captcha we have in MODx today. I haven’t looked in to the code in MODx myself, and it may be that it is trivial to replace, but I really don’t have the time right now to do it. Is anyone else interested and able?

That link just produced a 500 error for me. (I will withhold the obvious Microsoft jokes).

Used a Google cache; it has this to say:

Asirra consists of two components:

* A JavaScript client component that you add to your web page inside a form. Our code will add an Asirra challenge to your web page. If the challenge is solved correctly, the client code gets an Asirra Ticket from our server, and adds it to your form as a hidden input field.
* A web service at Microsoft Research that your form processor should call each time a user form is submitted, to check that the ticket provided is valid.