CAPTCHA Captures Spam for Yahoo, Writes Computerworld


June 16, 2003

Computerworld features the "completely automatic public Turing test to tell computers and humans apart" (CAPTCHA), a technology that fights robots on the Internet that gather personal information from chat rooms, illegally sell products, and blast spam from free email accounts. CMU started developing related research for Yahoo Inc. in 2000 and invented Gimpy, a CAPTCHA which "distorts and overlays words via clutter software." Yahoo uses E-Z Gimpy to distinguish humans from computers when they register. The article cites Manuel Blum, the Nelson Professor of Computer Science at Carnegie Mellon:

"The idea was to create a computer program that could distinguish bots from humans. The program would have to serve as a sentry, but it couldn't itself pass the very test it gives," said Blum.

CAPTCHA programs use databases of names, images, and other files to make and grade tests that people can easily solve, but computers have a hard time cracking. In fact, the machines aren't given the solutions to any of the puzzles, to prevent hackers from finding them.

A CAPTCHA may use words that are distorted by the computer, images overlapping with other images, or audio clips with background noise. Tests like CAPTCHA could lead to strides in the machine vision and AI fields, according to the report. (Source: Computerworld.)


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