Download Vivian Billy Vivian Dr. Oblitey COSC 316 5 December 2013 The

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Billy Vivian
Dr. Oblitey
COSC 316
5 December 2013
The CAPTCHA Program
For the past half century computers have been used to solve problems a lot faster than the
human mind can. The problem could be very small such as simple algebra or something along
the lines of advanced level calculus. Overall computers have made performing tasks easier and
people's time has been used more efficiently. But as computers evolve there are new problems
that arise that everyone needs to be aware of. Viruses are everywhere and can infect a machine
any minute; also there are people who will spam your inbox until it blows up. Spam could be
from all of the different free email accounts that can be created using Yahoo, Gmail, AOL, etc.
Anybody can sign up for those create a bot to send out millions of email at once and even if just
one person opens it, they make some money. This is a very tiny problem compared to the power
of bots. The advancement of technology has lead into replacing human tasks. For example, a
human can write a program to create a free email address and then send out the massive amounts
of spam in just one click. That is how far technology has advanced in the past half century. With
that there needs to be a counter act. To make sure that bots do not run the computing world there
was a test created by Professors at Carnegie Mellon in 2000. This test is called CAPTCHA. The
completely automated Turing test to tell computers and humans apart is alive and here is a little
more detail about its origin, what exactly does it do and further projects that have evolved from
this test.
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At Carnegie Mellon University in 2000, Luis Von Ahn, Manuel Blum, Nicolas Hopper
and John Langford came up with the idea of the CAPTCHA. This test was named after the
famous Alan Turing from the 1950s. Turing came up with the question of "can computers
think?" Ever since then, people have studied if this is true or not and if not how can people
advance different machines to be able to think like humans. Turing created the "Imitation
Game." This game consists of one person being an interrogator and asking questions to two
different participants, one being another human and the other is a computer. The point of this is
for the computer to try and stumping the interrogator into thinking there are two other humans in
the room. If the computer can answer 70% of the answers that are asked correctly then it is said
"to be in the presence of intelligence." This is the idea of artificial intelligence which will be
looked into in my detail later. So with that, the computer scientists of Carnegie Mellon dove into
this idea of "can computers think?" What they came up with is a reverse Turing test. In the
Turing test a human interrogates to see if the responses are coming from humans or a machine.
While in a CAPTCHA a computer interrogates whoever is trying to access the requested
services. This is how it is a reverse Turing test.
An easy way to understand what a CAPTCHA looks like, is to remember any time trying
to sign up for a social media site or free email service, there is a picture with a few distorted
letters. What you have to do is successfully enter in the letters that are presented correctly to
advance further. That is a CAPTCHA. Simple enough right? For humans that are able to process
information past zeros and ones this is very simple because we can decipher an image for what it
really is instead of analyzing the RGB color scale or how different lines are intersecting. The
main point of a CAPTCHA is to make a test that is easy for a human to answer correctly but not
for a computer. The whole idea of being able to "think" is what drives the success of CAPTCHA.
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There are many different uses such as the original spam idea. Anybody can make a bot to sign up
to a free email account and then send massive amount of unnecessary email just to make some
money. Well that bot may be able to send out email but it might not be able to successfully sign
up a site if it cannot pass the CAPTCHA test. There is also a problem with websites that sell
tickets to various sporting events or any event that is popular. Someone can create another bot to
buy all of those tickets to try and scalp them and sell them for a higher price since there are none
left. In that case this is to protect people's chances of being able to get to the event and not have
to pay an astronomical amount because someone bought all of the tickets at one time just by a
program. One of the big reasons why this all came about was because of an online poll in 2009
that was put up by SlashDot.org that asked "who has the best computer science graduate
program?" Students at Carnegie Mellon created a bot to vote thousands of times to alter the
results. The very next day MIT gets involved and creates bots of their own. In the end, MIT has
21,156 votes to Carnegie Mellon's 21,032 and every other school had less than one thousand
because they did not create bots. If a student how is about to graduate college sees this how are
they going to be able to get accurate results from this? It is not possible; all one sees is that these
two schools voted a lot or cheated the system somehow. When going to vote on a poll, a
CAPTCHA is put there so this does not happen anymore. Lastly there are search engine bots.
These are bots that go around and post on different sites to try and make different website
rankings higher so when someone types something into a search engine a website that is
irrelevant might show up. CAPTCHAs are used to try and defer these bots from being able to do
these different things.
While CAPTCHA has tried to stop spammers and bots from accessing resources, this
program is evolving into something for the greater good. CAPTCHA is now involved in a project
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called reCAPTCHA. This project involves trying to solve CAPTCHAs but for other purposes.
Different reasons for trying to solve CAPTCHAs are to make old books and newspapers digital.
In a world where the Internet brings information to people's fingertips, why not have information
from hundreds of years ago available? This works by photographically scan the text and the
transforms the text using an Optical Character Recognition (OCR). The OCR is not perfect but it
scans all of the words and is able to defer less than 50% of the text. This is where reCAPTCHA
comes in to try and figure out the other 50% of the text. A reCAPTCHA takes a word that is
known from the OCR and then makes a CAPTCHA with that word, which is known as the
control word, and paired with a word not deciphered by the OCR, called an unknown word. In a
reCAPTCHA, the computer is kind of making an assumption but using an algorithm involved.
The control word and the unknown word are paired together and made into a CAPTCHA. When
someone tries to decipher the text, if the control word is guessed correctly, the answer tells the
computer that the answer for the unknown word is a plausible answer. The answers are saved
and the same CAPTCHA is used on others. When three different human guesses are correct for
this particular CAPTCHA than the unknown word now becomes a control word. That is the only
way that an unknown word can automatically become a control word. There is a voting system
involved in the case that the first three answers are not answered the same way. A human answer
counts as one point and an OCR guess counts as half of a point. When enough points are added
up to two and a half then this unknown word is now a control word. When six people mark a
word as undecipherable the word is thrown away. This system is going to make newspapers such
as the New York Times from the 1800s available on the Internet.
As computer scientists jump into this idea of computers being able to solve CAPTCHAs,
this is starting to evolve artificial intelligence. It is kind of like a see saw, as artificial intelligence
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keeps advancing and getting better, CAPTCHAs have to get better and smarter to try and stop
these "smart, thinking" machines from accessing the desired resources. Technology is going to
keep advancing and with that we all need to be ready to stay on our toes about the different
security measures that come with technology.
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Works Cited
Artificial Intelligence Will Defeat CAPTCHA -- How Will We Prove We're Human Then?
Forbes.net.
“cryptography.” http://www.captcha.fr/
reCAPTCHA: Human-Based Character
Recognition via Web Security Measures. 12 Sept.
2008. PDF File.
“The Official CAPTCHA Site.” CAPTCHA.NET.
“Vicarious AI passes first Turing Test: CAPTCHA.” News.Vicarious.com.