Wednesday, April 13, 2005

Captcha T-Shirt




Sometime ago Slashdot released an online poll asking for the best school in computer science (a dangerous question to ask over the web!). As it is the case with most online polls, IP addresses of voters were recorded in order to prevent single users from voting more than once. However, students at Carnegie Mellon gured out a way to stuff the ballots using programs that voted for CMU thousands of times. CMU's score started growing rapidly. The next day, students at MIT wrote their own program and the poll became a contest between voting bots. MIT finished with 21,156 votes, Carnegie Mellon with 21,032 and every other school with less than 1,000. And, in fact, any other online poll suffers from this weakness against bots.

Captchas offer a solution: voters should show they are human before being allowed to vote. [1]. Capthca is an acronym for "Completely automated public Turing test to tell computers and humans apart". It is a type of test used by applications to tell whether or not the user is human.

A common type of captcha requires that the user type the letters of a distorted and/or 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. [2]

Spammers have found a creative way to circumvent Captcha tests. First, the spammers open and advertise a Web site containing pornography. Visitors to the porn site are asked to enter the word contained in a Captcha graphic before they are granted access.

In the background, spammers have already used scripts to automate the Web mail accounts opening process to the point where they need a human to "read" the Captcha graphics. The Captcha graphics from the Web mail site are transferred to the porn site, where the porn consumers interpret the Captcha words. As soon as they enter the correct word, the script can complete its application process and the visitors are rewarded with free porn. [3]

I thought a Captcha would look great on a T-Shirt. So just for fun, I have made one such T-Shirt available from my store at Cafepress :) Drop me a comment if you know of a service equivalent to Cafepress in India.

References [1], [2] and [3].

2 comments:

Abhimanyu said...

Wonderful Idea. Very Creative...both- the spammers' idea and yours(T-Shirt).

In Delhi, a store called "Giggles" prints whatever you want on plain T-Shirts (this started around 10 years ago). So, I am sure there will be stores in all major Indian cities which do this.

A service like CafePress in India...well, not too sure whether there is any.

Sid said...

Yay! Thanks! :-)