A recent wave of admiration for new 3D-flavoured CAPTCHAs got me thinking about CAPTCHAs. The whole model just doesn’t hold up to technological or economic scrutiny. CAPTCHAs are doomed, because of three important “CAPTCHA gotchas”.
The CAPTCHA idea sounds simple: prevent bots from massively abusing a website (e.g. to get many email or social network accounts, and send spam), by giving users a test which is easy for humans, but impossible for computers. Then the account-opening process can’t be automated, which slows down the spammers and other Net nuisances. But does such a test really exist, and will it save us from cybercrime?