RAMESH KUMAR
“Can you help me decipher this stupid word?” called out my spouse from the living room. For the past hour or so she has been busy logging into her mutual fund online accounts. A few days ago, both of us visited the offices of all asset management companies wherein we had bought units over the past several years for ‘rainy days’. Until now, we were receiving all communication from them regarding allotment of fresh units, dividend announcement and other statements through physical mail. Many times they were lost in transit and we had to mount a major battle to receive copies of the original. Now, we decided to go online and the unit selling companies have accepted our request and sent the “how-to-do” documents.
This is where the challenge arose. The “stupid words” – actually, they were a jumble of letters and numerals - my spouse hollering about was “captcha”. You know, “captcha”? Don’t know? Okay. Captcha is an acronym or short form for "Completely Automated Public Turing Test to Tell Computers and Humans Apart". Pretty long, I agree. That’s why they came out with a short form: Captcha. They are designed to prevent automated account registration, blog spam, log-in brute-force, password recovery etc. Simply to stop machines masquerading as human beings. That’s it. The obfuscated-text-in-an-image variety is the one most commonly used. There is an audio version as well for the visually impaired. Just about everyone who has gone on-line has seen one typed in one of these by now, even if they didn't know exactly what it was for.
How effective are these artificial intelligence tools in stemming bots’ intrusion where they are unwelcome? Jeremiah Grossman says, “Not all Captcha systems are created equally. Some are superior to others, but it’s difficult to tell exactly why.” According to him, captcha test should be administered where the human and the server are remote over the network. It should be simple for humans to pass wherein they should fail less than 0.1% on the first attempt.
Significantly, he adds that the test should be solvable by humans in less than a several seconds and be solvable by the human to which it was presented. The chance of bots guessing the right answer should be less than 1 in 1,000,000, even after 24-hours of analysis. Besides, knowledge of previous test questions, answers, results, or combination thereof should not impact the predictability of following tests. To cap it, Grossman emphasizes that test should not possess a geographic, cultural, or language bias. In spite of all these challenges, if bots were to outbeat, hats off to them!
Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford of Carnegie Mellon University who coined the term in 2000 might not have anticipated the popularity of this terminology. The need for captchas was felt following a 1999 online poll. The www.slashdot.org conducted an online poll asking surfers which was the best graduate school in computer science. Despite precautions taken to prevent multiple voting from single IP address, students of Masachussetts Institute of Technology and Carnegie Mellon University managed to stuff vote boxes and manipulated results in their favour by a huge margin with the use of computer programming to generate multiple logins. Look at the results: MIT finished with 21,156 votes, Carnegie Mellon with 21,032 and every other school with less than 1,000. That was in the pre-captcha era.
Interestingly, captcha signifies a war between computers and human beings. The present day computing technology cannot solve captchas. It’s beyond their ken! Their inability to decode text or image confirms the superiority of human race and the advancement in artificial intelligence. On the other hand, if bots can solve captchas, then again it is a victory for mankind for making computers to think like them. It is a win-win situation, sort of. Or an “Aha-moment”. For whom: men or machine? Right now, men have an upper hand. Don’t know, how long.
This appeared in OMAN TRIBUNE, April 1, 2010
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