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| "CAPTCHAs": Completely Automated Public Turing Tests to Tell Computers and Humans Apart What is a CAPTCHA?A CAPTCHA is an automated test that can distinguish between machines and humans online. It can generate and grade tests automatically that accepts virtually all humans and rejects virtually all machines. For example, human can generally read degraded images, but OCR machines cannot.
Why is it useful?CAPTCHAs
are designed to prevent bots – programs that pose as humans on the Internet
– from abusing internet services. Bots, driven not to dominate but to sell, sign up for thousands of
free email accounts every minute, sending millions of spam messages from them.
They infiltrate chat rooms, collecting personal information and posting links to
promotional sites. They generate worms, break password systems, invade privacy,
and drain resources. To defend e-commerce systems from bots, an increasing number of companies are arming themselves with CAPTCHAs. For example, users registering on Yahoo must first correctly recognize a distorted word displayed against a cluttered background and type it into a box to prove they are human. Such reading-based CAPTCHAs exploit the large gap between humans and machines in their ability to read images of text. What are we doing?We are in the process of developing better CAPTCHAs. The best CAPTCHA would allow all human to pass through, while rejecting all machines. Currently, we have completed 2 CAPTCHAs: PessimalPrint and BaffleText. We would like to test these CAPTCHAs and invite both users and bots to attack them. See our CAPTCHAs!We are also in the process of getting our CAPTCHAs online. Check back soon to interactively attempt to break our CAPTCHAs.
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