What is CAPTCHA and How it Works?

What is CAPTCHA and How it Works?


CAPTCHA or Captcha (pronounced as cap-ch-uh) which stands for “Completely Automated Public Turing test to tell Computers and Humans Apart” is a type of challenge-response test to ensure that the response is only generated by humans and not by a computer. In simple words, CAPTCHA is the word verification test that you will come across the end of a sign-up form while signing up for Gmail or Yahoo account. The following image shows the typical samples of CAPTCHA.

Almost every Internet user will have an experience of CAPTCHA in their daily Internet usage, but only a few are aware of what it is and why they are used. So in this post you will find a detailed information on how CAPTCHA works and why they are used.

What Purpose does CAPTCHA Exactly Serve?

CAPTCPA is mainly used to prevent automated software (bots) from performing actions on behalf of actual humans. For example while signing up for a new email account, you will come across a CAPTCHA at the end of the sign-up form so as to ensure that the form is filled out only by a legitimate human and not by any of the automated software or a computer bot. The main goal of CAPTCHA is to put forth a test which is simple and straight forward for any human to answer but for a computer, it is almost impossible to solve.

What is the Need to Create a Test that Can Tell Computers and Humans Apart?

For many the CAPTCHA may seem to be silly and annoying, but in fact it has the ability to protect systems from malicious attacks where people try to game the system. Attackers can make use of automated softwares to generate a huge quantity of requests thereby causing a high load on the target server which would degrade the quality of service of a given system, whether due to abuse or resource expenditure. This can affect millions of legitimate users and their requests. CAPTCHAs can be deployed to protect systems that are vulnerable to email spam, such as the services from Gmail, Yahoo and Hotmail.

Who Uses CAPTCHA?

CAPTCHAs are mainly used by websites that offer services like online polls and registration forms. For example, Web-based email services like Gmail, Yahoo and Hotmail offer free email accounts for their users. However upon each sign-up process, CAPTCHAs are used to prevent spammers from using a bot to generate hundreds of spam mail accounts.

Designing a CAPTCHA System

CAPTCHAs are designed on the fact that computers lack the ability that human beings have when it comes to processing visual data. It is more easily possible for humans to look at an image and pick out the patterns than a computer. This is because computers lack the real intelligence that humans have by default. CAPTCHAs are implemented by presenting users with an image which contains distorted or randomly stretched characters which only humans should be able to identify. Sometimes characters are striked out or presented with a noisy background to make it even more harder for computers to figure out the patterns.

Most, but not all, CAPTCHAs rely on a visual test. Some Websites implement a totally different CAPTCHA system to tell humans and computers apart. For example, a user is presented with 4 images in which 3 contains picture of animals and one contain a flower. The user is asked to select only those images which contain animals in them. This Turing test can easily be solved by any human, but almost impossible for a computer. 

Breaking the CAPTCHA

The challenge in breaking the CAPTCHA lies in real hard task of teaching a computer how to process information in a way similar to how humans think. Algorithms with artificial intelligence (AI) will have to be designed in order to make the computer think like humans when it comes to recognizing the patterns in images. However there is no universal algorithm that could pass through and break any CAPTCHA system and hence each CAPTCHA algorithm must have to be tackled individually. It might not work 100 percent of the time, but it can work often enough to be worthwhile to spammers.

WEB 2.0

TECHNOLOGICAL REVOLUTION

21^st century has proved to be a remarkable journey in terms of technology and gadgets. In fact, the seeds were sown in two centuries back with the industrial revolution. Since then science has kept reinventing things and today life has become much easier and comfortable. Things no more moves at languishing pace and time is now counted in terms of nano-second. The one word that is ruling the roost is convergence. Now, you see mobile phones acting as camera and computer functioning as TV. We keep coming across the news of new inventions on a daily basis. Communication and commerce have been greatly benefitted by advent of technology. In fact, business world would not have reached the advance stage where it is today without the help of technology. Many new industries have flourished solely on the basis of speed of technology. World has truly become a global village with the aid of technology.

Take any invention and you will find all of them have become necessities in our lives. Right from cameras, televisions, mobile phones, computers, satellites, DVD players, palm tops, automatic geysers, vacuum cleaners and what not. Such is the pace of technological advancement that what was in fashion yesterday is no more valid anymore. Things are fast turning out to be obsolete. World is truly within your reach.

Advancing technologies play a crucial part in our day to day lives. Spheres like home security, business, software developments, information technology, national security, warfare, fast communication etc have been hugely benefitted by latest technologies. In the context of amazing role played by technology how could we resist the temptation of providing latest news and information about this fascinating world? So, this site aims to discuss and share information regarding latest technologies and gadgets. So, gear up for a fascinating ride of world of technology

WEB 2.0

Our online world has changed so much in last few years. Every day, we listen about some new events, new software or a new technology that keeps making our world a easier place to place. What we have now is, Web 2.0. If you are not aware of it then let me tell you, it is also considered as the ‘second generation’ of the Internet. Web 2.0 is a concept. Don’t go by its name and it is not something that can be purchased neither it is an updated version of any software. In other words, Web 2.0 is a way of doing thing on internet in a different way.

Let me explain you. Remember those old days of early 90s? We used to surf web, download software and use it. There were things like chat messenger, online forums etc. Now, what we have is much more than that. We are not just restricted to these mundane activities. We interact with internet. We use blogs and use social bookmarking. There are number of good social networking sites using which we interact with the rest of the world. We can now develop a website in a single day and have it up and running.

Web 2.0 has its core several new concepts and specific technologies. But the essence is interactivity. Sites catering to web 2.0 are becoming increasingly popular because people can interact with and through them. And how can we forget importance of video in this concept. Remember, Youtube.com? Internet marketers are making full use of this concept. Of course, there is lots of money to be made. Now, all we are waiting for is Web 3.0. Who knows, what fortune that will bring to us!

CBI INQUIRY IN TO THE 2G SPECTRUM

CBIinquiry into the 2G spectrum scam allegedly involving former telecom minister A. Raja.

File photo of former telecom minister A. Raja.

A bench of Justices A.K. Ganguly and G. Singhvi directed the CBI to probe the grant of spectrum licences since 2001, thereby bringing the previous NDA government under the ambit of the inquiry.

The court sent out a strong message to the CBI and the Enforcement Directorate not to be influenced by anybody in the 2G probe. The CBI has been asked to file a status report on the probe by February 10 next year.

The court told the agency to find out why the Telecom Regulatory Authority of India (TRAI) did not take action against those ineligible for spectrum licences.

The court also ordered the income tax department to hand over to the CBI transcripts of the tapped phone conversations of corporate lobbyist Nira Radia.

The probe will also cover disbursement of loans by PSU banks and find if telecom department officials were signatories to the licence agreements.

The two-judge bench pulled up the Delhi High Court for disallowing a petition seeking a CBI probe.

Moily welcomes verdict

The government welcomed the verdict. Union Law Minister M. Veerappa Moily said the government was always in favour of a Supreme Court-monitored probe into the 2G scam.

Moily said the BJP was politically motivated and lacked faith in the judiciary.

The Congress said the Supreme Court's ruling vindicated the party's stand against a joint parliamentary committee probe into the 2G scam.

wiki leaks

wiki leaks

Wide ramification

WikiLeaks seems to have tarnished everyone it touched. But there were plenty of politicians and celebrities who did not need help from the internet whistle-blower to get themselves into trouble in 2010. WikiLeaks' release of cables from US embassies to Washington - often bluntly written accounts of confidential discussions - have in most cases only confirmed what was already widely suspected in international relations. But they have nevertheless embarrassed US friends and foes alike and risk undermining US diplomacy. Text: IANS, Photo: AP

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