Annoy the User
In the beginning of this chapter, we described passwords as a necessary evil. Evil, like beauty, rests in the beholder's eye. Web sites wary of attacks, such as brute force or spamming comment fields, use a Completely Automated Public Turing[B] test to tell Computers and Humans Apart (CAPTCHA) to better distinguish between human users and automate scripts. A CAPTCHA is an image that contains a word or letters and numbers that have been warped in a way that makes image analysis difficult and, allegedly, deciphering by humans easy. Figure 5.1 shows one of the more readable CAPTCHAs.
B Alan Turing's contributions to computer science and code breaking during WWII are phenomenal. The Turing Test proposed a method for evaluating whether ...
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