Comments on: How NOT to invent the next-gen CAPTCHA

By: としあき

としあき — Tue, 20 Oct 2009 19:37:41 +0000

I think you did not cover one important factor when trying to design a CAPTCHA and that is the characteristics of those humans that are supposed to be able to pass it. Not every CAPTCHA needs to be designed so that /any/ human can solve it. A good example of this is the one used by http://random.irb.hr/signup.php which generally requires higher level mathematical knowledge. This is not unreasonable as if their resource is to be of any use to you you would likely already possess the required skills to solve them. One might even want to require cultural knowledge for a CAPTCHA as this will hinder human CAPTCHA farms being paid per CAPTCHA (however, they can still just send them to people looking for porn to solve).

By: Jach

Jach — Tue, 20 Oct 2009 19:18:13 +0000

Non-image based captchas work just as well in my opinion, if not better. If you’re using a third party captcha system lots of other places use, it’s bound to be under several attacks. Asking the user a logic question (or “what image is this? (cat/dog/elephant)” works, as does forcing JavaScript on to set a hidden field at the form submit. The future of captchas isn’t in fancier images, but in just using a variety of techniques.

By: Michael Buckbee

Michael Buckbee — Tue, 20 Oct 2009 14:27:19 +0000

I really just wish that there were more CAPTCHA implementations running around (and constantly evolving) so that the price and hassle to the spammers would go up.