Posted on Wednesday 7th of March 2007 at 09:38 in The Internet

CAPTCHA 101

Days come and go with ease and yet the world still seems ignorant to usability on the most part, especially with CAPTCHA's (Completely Automated Public Turing test to tell Computers and Humans Apart). Basically they're the often confusing random set of characters hidden in an image that you must enter in order to do something. I have a very basic one at the bottom of the articles for when users wish to post a comment. They're great when they're simple because they're not challenging and it stops the low-level bot-spam that is oh-so-annoying.

No, we don't want viagra. Thanks though.
Low level spam is often bots patrolling the internet looking for unprotected forums and comment boxes that they can spam with links to products; creating backlinks and increasing their pagerank in a two-fold assault on your site. The introduction of a really basic system (JohnChow.com has a great one, asking you to enter the current year) stops the dumb bots while maintaining high usability (and not frustrating users by asking the impossible). I follow this logic because dumb bots are easily stopped, while the smart ones that implement OCR (optical character recongition) are fewer and far between and worthy of manual filtering.

High level CAPTCHA's cause headaches
Because the anti-captcha systems are more advanced, the captchas also increase in complexity. Attempts to avoid OCR and all the clever algorithms that are devised mean the systems you need to pass an increasingly complicated set of tasks. As can be seen from the example on the right (taken from Reddit I might add) they can be VERY hard to solve because they're randomly generated and deliberately difficult to deceive the bots.

Oli had the answer

Oli developed KittenAuth last year; a system that dynamically pillages Flickr for images on a certain category, renames them and outputs them in a grid. You're then requested to "Click all the *something*". Something is always cute. Hence the name, KittenAuth. See below for a screenshot of KittenAuth or opt to try it out for real.



The logic is that you click all the things you're requested to do and that proves you're not a bot. I chatted to him at length around the original implementation and making it more secure and he's hit a good mix now. It's actually simple enough that an infant could manage it and that's an excellent level of usability. Ask yourself, what would you rather use? The reddit one or KittenAuth? Exactly.

Visit Kittenauth.com or ThePCSpy.com for more information on the project. The creator is a nice chap and will actually answer you if you choose to contact him.

 

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