The most common CAPTCHA test is a a set of distorted letters. The user would then need to type the letters they see into a box. If they match the distorted letters presented, then the computer carries on with the intended actions, like creating an account for a website or buying tickets. Although the distorted letters are the most common type of CAPTCHA, there is usually also an option for an audio CAPTCHA.
Why might these kinds of tests be useful? A common use is in online polls. In 1999, before CAPTCHAs were popularized, a website ran a poll to determine which computer science program at certain schools was better. Students at MIT and Carnegie Mellon coded programs to continuously vote for their schools. Because there was no CAPTCHA to prevent these bots from doing so, there was an endless amount of votes. Another common use, as I mentioned before, is in online ticket sales. This prevents ticket scalpers from creating bots to buy mass amounts of tickets and sell them at a higher rate. CAPTCHAs are incredibly useful and basically essential in the online world!
It is important for computers to randomly create these tests, because if every user was presented the same CAPTCHA, it would be incredibly easy to code a program and simply input the predetermined answer. To combat this, many programs will simply generate a random string of letters and numbers. It then takes this string and distorts it in some way, like stretching the letters. This makes it difficult for computers to interpret the message.
This system works well for now, but creating indecipherable CAPTCHA tests is becoming much harder. Computer programs are being created to decrypt the audio messages as well as the less complex visual ones. The bright side here is that every time a computer can figure out a CAPTCHA test, we are getting closer and closer to artificial intelligence. This is cool, but a little scary in terms of security, in my opinion. What do you think??
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https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTYPyWcklqg3edeqNizl62fAAynSzaiV4TFjT-5_9ZW_WmvaBFs3Q
http://www.captcha.net/images/recaptcha-example.gif
http://computer.howstuffworks.com/captcha5.htm
This was such a good selection for a blog post! I never really considered exactly how the test was working, or why exactly it started. I think it is very interesting that the tests are created by computers, but other computers are not able to decipher the code. I wonder what kind of security will be next when these inevitably stop working as well as they have in the past.
ReplyDeleteLeah, this is super interesting. I have definitely seen the CAPTCHA test and always wondered how it worked! I also have seen ones where you simply check a box saying that you aren't a robot and that's it! What do you think about that? Is that as secure as having to type a full word? Thanks!
ReplyDeleteCAPTCHA is a very interesting topic! Security from bots is a very real requirement for websites nowadays, which could be a topic in itself! It's almost a race, see whether making a smarter more "human" bot will outpace making a tougher to crack code. Regardless, it's causing advancement in TWO fields at once, but it may not be for the best in one of them!
ReplyDeleteI always thought these things were so annoying. I still think they're annoying, but now I think they're pretty interesting too. I think how funny it is though how far people will go to try to het around these tricky little devils. I wonder how hard cracking one of these really is.
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