July 20, 2007

links for 2007-07-21

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July 19, 2007

CAPTCHA- Completely Automated Public Turing Test to tell Computers and Humans Apart

A CAPTCHA is a type of challenge-response test used in computing to determine whether the user is human. “CAPTCHA” is an acronym for “Completely Automated Public Turing test to tell Computers and Humans Apart”, trademarked by Carnegie Mellon University. A CAPTCHA involves one computer (a server) which asks a user to complete a test. While the computer is able to generate and grade the test, it is not able to solve the test on its own. Because computers are unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human. The term CAPTCHA was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper (all of Carnegie Mellon University), and John Langford (of IBM). A common type of CAPTCHA requires that the user type the letters of a distorted image, sometimes with the addition of an obscured sequence of letters or digits that appears on the screen. Because the test is administered by a computer, in contrast to the standard Turing test that is administered by a human, a CAPTCHA is sometimes described as a reverse Turing test.

Human solvers

CAPTCHA is vulnerable to a relay attack that uses humans to solve the puzzles. One approach involves relaying the puzzles to a sweatshop of human operators who can solve CAPTCHAs. In this scheme, a computer fills out a form and when it reaches a CAPTCHA, it gives the CAPTCHA to the human operator to solve. If the humans are dedicated employees who receive minimum wage this is not likely to be viable. Another variation of this technique involves copying the CAPTCHA images and using them as CAPTCHAs for a high-traffic site owned by the attacker. With enough traffic, the attacker can get a solution to the CAPTCHA puzzle in time to relay it back to the target site.

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June 13, 2007

Windows Vista Aero and Ubuntu Beryl

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May 12, 2007

Send Free SMS Text Messages to Canada

Send Text messages to Cell phones.

Free Text Messages to any Bell, Virgin, Telus, Fido and Rogers Cell phone customer in Canada.

Very easy to use interface.

Powered by ScribeFire.

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March 30, 2007

links for 2007-03-31

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March 29, 2007

links for 2007-03-30

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March 28, 2007

links for 2007-03-29

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March 27, 2007

links for 2007-03-28

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March 26, 2007

links for 2007-03-27

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March 25, 2007

links for 2007-03-26

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