My absolute favorite captcha to date.

[intraman]

http://www.josscrowcroft.com/demos/motioncaptcha/

Superb. What do you guys think to it?

[baja_yu]

Interesting idea but I think bots will be able to fake this much easier. More importantly, I prefer re-Captcha because it's actually doing good by digitizing content like books and maps in the process.

[TheBigB]

That's actually the most useless captcha ever.

It basically doesn't work. It's security mechanism is that the submit button is disabled until you've drawn the figure. That's it. A spammer would simply do a direct POST to the server, completely bypassing the system that is to prevent spamming.

A real captcha stores the characters server-side (in a session variable) and sends the image to the client. Finally it expects the POSTer to submit the same value as it has stored in the session variable. And that is a proper way to deflect spammers.

[BlindSniper]

That's actually the most useless captcha ever.

It basically doesn't work. It's security mechanism is that the submit button is disabled until you've drawn the figure. That's it. A spammer would simply do a direct POST to the server, completely bypassing the system that is to prevent spamming.

A real captcha stores the characters server-side (in a session variable) and sends the image to the client. Finally it expects the POSTer to submit the same value as it has stored in the session variable. And that is a proper way to deflect spammers.

And even if that gets fixed...
This afternoon I wrote a piece of code, It grabs a screenshot of the website, finds the captcha image, turns it into a binary image, and I already have a pretty good idea on how to calculate the path that the mouse needs to follow. Then all I need to do is send a few mouse events and the captcha is done for.