Question of the week: 2/25/08-2/29/08

[This week's QOW is due on Friday, 2/29/08, by 5:00 PM. Since we meet 3 times, your QOW response should be at least 300 words.]

Question of the week: Computer programs (like Eliza) can imitate people to create logins, access bank accounts, send email, and more. A program to distinguish people from computer programs is called a Captcha. Do you think a Captcha can be effective in distinguishing people from computers? (Be sure to give your reasons why or why not.) How would you use a captcha?

Background: Computer security is a major topic in computer science. One aspect of it is preventing computer generated spams and hacker activities from invading web sites. For example, if a computer program can gain access to YOUR email account, thousands of fake emails can be sent in your name -- and you can be penalized. Web sites like Hotmail, Yahoo Mail, and Google Mail try to keep out spammers and computer programs from creating hundreds of fake email accounts by requiring people to respond to a captcha. From Wikipedia, a captcha is: a type of challenge-response test used in computing to determine whether the user is human.
The full Wikipedia definition is here: http://en.wikipedia.org/wiki/Captcha

More info may be found at: http://recaptcha.net/captcha.html

and at http://www.captcha.net/news/ai.html

One way that spammers get around captchas is by using humans to read and respond to a captcha without the user knowing that he is doing it. Users of porn web sites are often used for this purpose:

"Someone designed a software robot that would fill out a registration form and, when confronted with a CAPTCHA test, would post it on a free porn site. Visitors to the porn site would be asked to complete the test before they could view more pornography, and the software robot would use their answer to complete the e-mail registration.

It's not a practice that rapidly or easily overcame the CAPTCHA test, but the tactic of getting humans to unwittingly do cognitive work for a computer program inspired [Luis] Von Ahn to develop the ESP Game."

The full article is here: http://www.post-gazette.com/pg/03278/228349.stm