What is a CAPTCHA and what is it used for in Web browsing?

If you've tried accessing a webpage, leaving a comment, or signing up for a particular service on the internet, there's a high possibility you've been blocked by a special wall called a Captcha. Now, a Captcha is just an acronym for ''Completely Automated Public Turing test to tell Computers and Humans Apart". A Turing test is an examination or a method of inquiry in an artificial intelligence used in determining if a computer is capable of thinking like a human being. So a Captcha is certainly a Turing test, but in reverse as it is a computer creating the scripts. Basically, the purpose of a Captcha is to tell if the entity sending the requests is a human or not. To dive fully into the Captcha business, first some history.

1.0: Brief history of Captchas:

 The Turing test as stated above was invented by an English Mathematician and computer analyst named Alan Turing. Turing proposed that a computer can be said to possess artificial intelligence if it can mimic human responses under specific conditions. This would be the base for the Captcha technology.

  In 1990, internet users tried to make text illegible unintelligible to computers. The first of such people were hackers, posting about sensitive topics to Internet forums they thought were being automatically monitored on keywords. To defeat such filters, they replaced a word with character that looks like it. SWEET could become  or $\/\/££⍅, as well as numerous other variants, such that a filter could not possibly detect all of them. This later became known as leetspeak (a system of modified spellings used primarily on the Internet).

 

One of the earliest commercial uses of CAPTCHAs was in the Gausebeck–Levchin test. In 2000, idrive.com began to protect its signup page with a CAPTCHA and prepared to file a patent on this seemingly novel technique. The term CAPTCHA was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford of Carnegie Mellon University.

2.0: What is a Captcha?:

 A CAPTCHA is usually a graphic image with a series of distorted letters on an equally distorted or multicolored background. Other types of CAPTCHA challenges require a user to identify photos, do simple arithmetic problems, provide a response to an audio snippet or simply click a box that says, "I'm not a robot.". A CAPTCHA is also what is called a challenge-response test. One party presents a question or challenge and the other party must provide a valid answer or response in order to be authenticated. CAPTCHAs are additionally fully automated, needing little to no human maintenance  to administer, producing benefits in reliability and cost effectiveness.

 The test makes sure only humans perform their needed actions and protects websites from spams and automated queries. A CAPTCHA differentiates between human and bot by setting some task that is easy for most humans to perform but is more difficult and time-consuming for current bots to complete. At present, computer programmes lack the sophistication that humans have when it comes to processing visual data. Human minds are hard-wired to pick up on patterns in everything they see. People often see patterns where they are none – such as a face in the moon or the outline of Elvis on a burnt bit of toast. This phenomenon is called Pareidolia.

3.0: What are the uses of Captchas?:

 Definitely separating computers from humans aren't the only uses of the system. It can perform a great host of functions, some of which are:

3.1: Protecting the sign up and Certification of Websites:

Getting free emails today is definitely more easier than it was previously. Notably from Yahoo, Google and Microsoft. Up until a few years ago, most of these services suffered from a specific type of attack: "bots" that would sign up for thousands of email accounts every minute. The solution to this problem was to use CAPTCHAs to ensure that only humans obtain free email accounts.

3.2: Protecting Email Addresses and Passwords From Scrapers:

 After getting your free email address, the next is to protect it from spammers who would send you thousands of ads and unwanted emails. Spammers run around the Web in search of email addresses posted in clear text. CAPTCHAs provide an effective mechanism to hide your email address from them. The idea is to require users to solve a CAPTCHA before showing your email address. A Captcha can also protect your password from bots which may try to have it permutated

3.3: Preventing Comment Spam in Blogs:

Comment spam is a term referencing a broad category of spambot or spammer postings which abuse web-based forms to post advertisements as comments on forums, blogs and wikis. Most bloggers are familiar with programs that submit bogus comments, usually for the purpose of raising search engine ranks of some . This is called comment spam. By using a CAPTCHA, only humans can enter comments on a blog. There is no need to make users sign up before they enter a comment, and no legitimate comments are lost in the process.

3.4: Search Engine Bots:

It is sometimes desirable to keep webpages unindexed to prevent others from finding them easily. There is an HTML(Hyper text markup language) tag to prevent search engine bots from reading web pages. The tag, however, doesn't guarantee that bots won't find and read a web page; it only serves to say "no bots allowed" Search engine bots, since they usually belong to large companies, respect web pages that don't want to allow them in. However, in order to truly guarantee that bots won't enter a web site, CAPTCHAs are needed.

3.5: Increase the security of online shoppers and online polls:

 No one would like to lose money while shopping online....especially to a bot. Some online stores checkout might include Captchas to maximise security.

3.6: Training Artificial intelligence(AI):

 Certainly a CAPTCHA is an important instrument for training AI. Any given test could only ever be temporary, something its inventors acknowledged at the outset. With all those researchers, scammers, and ordinary humans solving billions of puzzles just at the threshold of what AI can do, at some point the machines were going to pass us by. In fact, In 2014, Google pitted one of its machine learning algorithms against humans in solving the most distorted text CAPTCHAs: the computer got the test right 99.8 percent of the time, while the humans got a mere 33 percent. 

While used mostly for security reasons, CAPTCHAs also serve as a benchmark task for artificial intelligence technologies. According to an article by Ahn, Blum and Langford, "any program that passes the tests generated by a CAPTCHA can be used to solve a hard unsolved AI problem.''

4.0: Accessibility of Captchas:

 Due to the confusing nature of these tests, it is possible that Captchas will pose a problem to some people, such as the aged or visually impaired (Non-sight or colour blind).Because CAPTCHAs are designed to be unreadable by machines, common assistive technology tools such as screen readers cannot interpret them. Since sites may use CAPTCHAs as part of the initial registration process, or even every login, this challenge can completely block access. In certain jurisdictions, site owners could become targets of litigation if they are using CAPTCHAs that discriminate against certain people with disabilities. In other cases, those with sight difficulties should be able to choose to identify a word being read to them.

5.0: Can Captchas be avoided by the computers?:

 Just as Captchas are evolving so is the bots that try to surpass them. Here are notable ways Captchas have been beaten at the game.

5.1: Machine-learning:

 In its earliest iterations there was not a systematic methodology for designing or evaluating CAPTCHAs. As a result, there were many instances in which CAPTCHAs were of a fixed length and therefore automated tasks could be constructed to successfully make educated guesses about where segmentation should take place. others made the mistake of relying too heavily on background confusion in the image. In each case, algorithms were created that were successfully able to complete the task by exploiting these design flaws. These methods proved brittle however, and slight changes to the CAPTCHA were easily able to thwart them. Modern CAPTCHAs like  the reCAPTCHA no longer rely just on fixed patterns but instead present variations of characters that are often collapsed together, making segmentation almost impossible. These newest iterations have been much more successful at warding off automated tasks.

5.2: Manual or human labour method:

 CAPTCHAs can potentially be avoided by relaying them to a shop of human operators who are employed to decode CAPTCHAs. A 2005 paper from a W3C working group stated that such an operator could verify hundreds per hour. In 2010 the University of California at San Diego conducted a large scale study of those CAPTCHA's farms and found out that the retail price for solving one million CAPTCHAs is as low as $1,000.

5.3: Resource re-direction:

 Similar to the human labour, but differs in the sense that the labour here is unwitting. This consists of using a script to re-post the target site's CAPTCHA as a CAPTCHA to a site owned by the attacker, such as a pornography site, which unsuspecting humans visit and correctly solve within a short while for the script to use. However, there is a debate around the economic viability of such an attack.

5.4: Helping Companies:

Some companies on the web can help block and avoid Captchas for a fee. These Services Include APIs and libraries that enable users to integrate CAPTCHA circumvention into the tools that CAPTCHAs were designed to block in the first place.

6.0: What is reCaptcha?:

 reCAPTCHA is a CAPTCHA-like system designed to establish that a computer user is human (normally in order to protect websites from bots) and, at the same time, assist in the digitization of books or improve machine learning. reCAPTCHA was originally developed by Luis von Ahn, David Abraham, Manuel Blum, Michael Crawford, Ben Maurer, Colin McMillen, and Edison Tan at Carnegie Mellon University's main Pittsburgh campus. It was acquired by Google in September 2009.

reCAPTCHA has completely digitized the archives of The New York Times and books from Google Books, as of 2011. The archive can be searched from the New York Times Article Archive, where more than 13 million articles in total have been archived, dating from 1851 to the present day. Through mass collaboration, reCAPTCHA was helping to digitize books that are too illegible to be scanned by computers, as well as translate books to different languages, as of 2015.

The system has been reported as displaying over 100 million CAPTCHAs every day, on sites such as Facebook and twitter.

7.0: Are Captchas really getting harder?:

One can notice that our traditional captcha are getting harder as time progresses. This is because the usage of latest advanced pattern recognition and machine learning algorithms are capable of solving simpler captcha, so the latter should be in a position to defeat the former. Previously robots were more modern but they were not as intelligent as humans due to them not being able to open a captcha script. Significantly, robots have always been able to read-only written words and are not able to solve the image captcha, as the admin of robot only sets the command to the specific task and in Captcha solving, text video, images may come and changes every time, so the admin of Robots could not able to set the rules and cause of changing of the question in captcha.

Certainly robots are getting better at Captcha solving, and even more than humans. So captchas must be more difficult to defeat them....at the expense of human efficiency sadly.

7.2: Can AI assistants like Apple's Siri and Google's assistant beat a captcha test?:

 Not really, as Captchas are mostly images with jumbled words rather than a word itself. Siri and Google's assistant mostly work on plain and straight commands, while a Captcha is more of a distorted command. Machine-learning capabilities can be used though, but not in this case.

7.3: Is there any disadvantage to us seeing Captchas?:

 Surely Captchas are really annoying and time wasting. Well, next time you are confronted by one of these, you can take pride in the fact that you are doing your part to preserve history.

Yes, those annoying CAPTCHAs are actually being used to help digitalise decades of old texts — books, magazines and newspapers — that scanning programs struggle to decipher.

8.0: Captcha Fun: 

Check out some memes and funny pictures about captchas, can you solve them?

So that brings us to the end of the post. What do you think of captchas? Annoying, useful? ineffective? Let us know what you think in the comment section.