Introduction
CAPTCHA stands for Completely Automated Public Turing test to tell
Computers and Humans Apart. Its now an astonishing term in the field of
security from the last few years. In present developing world where everything
is based and related to internet the security and privacy becomes a major
threat, all the deemed and established multinational companies like Google,
Microsoft, Yahoo etcetera have moved toward the CAPCHA to ensure
security and privacy to their customers.
In order to understand CAPCHA one needs to understand the term TURING,
It was coined by Alan Turing’s in 1950 in an article Computing Machinery
and Intelligence discussed conditions for considering a machine to be
intelligent
– “Can machines think?” “Can machines behave intelligently?”
– The Turing test (The Imitation Game): Operational definition of
intelligence.
This test consist of 3 room one of each room have an interrogator, machine
and the person.
Through the help of teleprinter the interrogator tries to communicate with the
Other two.
The interrogator tries to identify that which one is person which one is the
machine
If the machine is able to make believe to interrogator that he is the human
And If the machine succeeds in making interrogator believe, then it could be
Concluded that machine are intelligent enough to make fool of humans.
This is the thought behind building the capcha but it is not exactly same as the
TURING test, in capcha puzzles and blurry images are used in order to understand
the person who is using the device (computer, laptop, mobile) is a human or
computer. The puzzles and the images used could only be understood by a human not
by today’s machines.
Basically it is a computer program based on Artificial Intelligence that defend
various websites from web-bots, automated created attacks by other machines by
generating puzzles like tests that computer cannot pass but human can pass
Nowadays, it is exigent to take security related issue seriously because there are
many spammers ready to exploit privacy of others specifically who creates scripts
and programs that electronically submit various forms. However, technologies like
captcha are developed to deal with these kind of problems.
Types of CAPCHA
CAPACHAS are mainly classified into two categories visual and audio based
captchas
1 VISUAL based captchas– As the name suggest the meaning that these
captchas are visible to eyes. These type of captchas are very common as these
are easy to use these are broadly classified into 2 parts
A. TEXT based captchas – This type of captchas are very usual type of
captchas can be seen on almost every website as these are very easy to use, in
text based captcha, text is given in a distorted way which can be easily
understood by human but it will be a difficult job for the machines.
Various example of text based are
GIMPY it is an text based captcha stands for general image manipulation
program, it uses the technique of optical recognition the images are in
distorted manner such as the shape of the words are irregular which could be
easily understood by a human but will be difficult for a machine
BAFFLE text – the text is been picked randomly from various character or
alphabets to make a text that could be pronounceable
B.IMAGE based capchas– As the name suggests these kind of captchas consist of
images, the user are required to choose the result from various images provided to it
this type of captchas could also be seen in various websites. Various examples of
these captchas are
PIX- This is an IMAGE based captchas it select the pictures from the databases the
pictures could be of anything from daily life such as traffic signal, zebra crossing,
bridges etc, the user need to determine the object in the image there could be a
number of images one after the another it is just like the puzzle.
BONGO- This is another type of image captcha that consist of two types of images
that is left image and right images. Both the images differs from each other
sometimes there is one or two common type of image in both sides. It is a type of
pattern recognition problem where the user decide to which set the image belongs to.
Usually these type of captchas are not in used as these do not provide good security.
- AUDIO based captchas- This captchas is basically for the people who are visually
challenged or do not have proper vision. This captcha consist of audio such as words,
number or it could be mixture of both provided with some kind of noises the user
task is to hear to the audio and provide the details related to the audio. - VIDEO based captchas– This type of captchas consist of videos , the video taken
from the database consists of various words the user task is to play the video and
observe the details provided in the video in order to fill the details which is been
asked in the captcha.
Applications of CAPCHA
There are a large number of application of captcha in today’s world in terms of
security as it is in demand technology several are mention below:-
- Restrain the comments in the blogs- with the help of captchas users need not
to worry about the comment spam as with the help of captchas the unnecessary
sign in for comments can be prevented. - Security- This is the biggest advantage of captchas as they prevent the
unnecessary spammer to threat the privacy of the user. - Assure registration on websites and the E-mails – There are large number of
spammers who spam with free emails but with invent of captchas only the
humans can register with free emails and also with the various websites that
provide the services. As captchas hide the mechanisms of emails from the
scrapers. - Provides restriction during the online polls- In online polls one person is
required with one vote but during the online polls hackers or spammers can
hack the system in order to win the poll but with captchas this problem is
resolved.
Conclusion
Internet is a boon to human kind as it provides a lot of information on hand
and saves a lot of time but as the machines are getting automatic and advanced
day by day the privacy becomes an issues.
CAPTCHA is based on artificial intelligence which is an emerging and
advanced field and no technology is that build up that it could fool CAPTCHA
in present scenario. So CAPTCHA is currently the best technology for
providing the security, as every technology has its merits and demerits so does
captchas have but in the long run these demerits could be resolved.
There are a lot of application of captchas which make it difficult for the
spammers to spam and create a threat to the security.
As today many big companies have moved towards the CAPTCHA for their
security and privacy. In coming future there would be more modification
related to security.
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