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CAPTCHA and reCAPTCHA - Explained!


Table of Content


Introduction to CAPTCHA

With hacking attacks on the rise, most websites have become more diligent in their efforts to protect themselves from any potential cyber-attack. Captcha is a type of security check that has been around for a long time and is commonly utilized by numerous websites. Captcha is a challenge-response test that can be completed on a website. This is used to determine whether the user is a real person or a robot. John Langford, Nicholas Hopper, Luis von Ahn, and Manuel Blum invented Captcha in 1997 and officially launched it in 2003.

A proprietary coding language is used to create the internet and computers. Human languages, with their weird and complex norms, as well as the slang they employ, are tough for computers to comprehend. CAPTCHA works by relying on a person’s ability to recognize and recognize unexpected patterns based on a variety of previous experiences. Bots are unlikely to estimate the correct combination correctly due to this restriction. Bots, on the other hand, are usually able to simply follow established patterns or enter random characters.

CAPTCHA is a type of verification tool used on various websites to ensure that the user is not a robot. CAPTCHA is first and principally used to verify internet polls. In 1999, Slashdot posted a poll in which visitors were asked to vote for the finest graduate school for computer science. Students from Carnegie Mellon and MIT constructed bots, or automated programmes, to vote for their schools frequently. Thousands of votes were cast for several schools, whereas only a few hundred were cast for others. CAPTCHA was included to prevent people from abusing the polling mechanism.

What are CAPTCHAs, and how do they work?

A captcha text is made up of deformed alphabets or alphanumeric letters. To be validated, the user must input this into a text field. CAPTCHA is an acronym for the Completely Automated Public Turing Test to Tell Computers and Humans Apart. CAPTCHAs are technologies that let you distinguish between human users and automated users like bots. CAPTCHAs are challenges that are difficult for machines to complete but relatively simple for people to achieve—identifying stretched characters or digits, for example, or clicking in a specific spot. CAPTCHAs are used by any website that wants to prevent bots from accessing it.

CAPTCHAs are used for a variety of purposes

  • Maintaining poll accuracy—By verifying that each vote is input by a human, CAPTCHAs can avoid poll skewing. While this does not limit the total number of votes that can be cast, it lengthens the time it takes to cast each vote, discouraging multiple voting.

  • Limiting service registration—services can use CAPTCHAs to prevent bots from spamming registration systems and creating bogus accounts. Limiting account creation saves a service's resources from being wasted and decreases the risk of fraud.

  • Ticket inflation can be avoided by using CAPTCHA in ticketing systems to prevent scalpers from acquiring large quantities of tickets for resale. It can also be used to prevent bogus free event registrations. Captchas can prevent bots from spamming message boards, contact forms, and review sites by preventing bogus comments. The additional step required by a CAPTCHA can also help to reduce online harassment by inconveniencing people.

  • CAPTCHAs also prevent spammer software from leaving comments on pages or making multiple purchases at once. An image with numerous distorted letters is the most prevalent type of CAPTCHA. It's also normal to choose among a large number of photographs to come up with a common subject.

Types of CAPTCHAs

Text-based CAPTCHAs

Text-based CAPTCHAs were the first method of human verification. These CAPTCHAs can be made up of well-known words or phrases and random digits and letters. Some text-based CAPTCHAs also include variations in capitalization. The CAPTCHA shows these characters in an alienating and enigmatic manner that necessitates interpretation. Scaling, rotation and distorting characters are all examples of alienation. Overlapping characters with visual features such as colour, background noise, lines, arcs, or dots can also be used. This estrangement protects humans from bots with weak text recognition algorithms, but it can be difficult to read for humans.

Image-based CAPTCHAs

Text-based CAPTCHAs have been phased out in favour of image-based CAPTCHAs. These CAPTCHAs use graphical components that are easily recognized, such as animal images, shapes, or scenery. Image-based CAPTCHAs typically demand users to select images that match a theme or identify ones that don't. It's worth noting that an image rather than text defines the topic. Text-based CAPTCHAs are often more difficult for humans to decipher than image-based CAPTCHAs. On the other hand, these tools have significant accessibility concerns for visually challenged users. Image-based CAPTCHAs are more difficult for bots to decipher than text-based CAPTCHAs since they involve both image recognition and semantic classification.

CAPTCHAs with audio

Audio CAPTCHAs were created as an alternative that allows visually impaired people to participate. These CAPTCHAs are frequently used in conjunction with CAPTCHAs that are based on text or images. Audio CAPTCHAs play a recording of a series of letters or numbers, which the user must then type in. Bots are unable to distinguish relevant characters from background noise in these CAPTCHAs. These techniques, like text-based CAPTCHAs, can be challenging for people as well as machines to decipher.

Word or Math Problems

Some CAPTCHA systems require users to answer a simple mathematical question, such as "3+4" or "18-3." The premise is that a bot will have trouble identifying the inquiry and formulating an answer. A word problem, for example, requires the user to type the missing word in a sentence or to complete a sequence of multiple related terms. These types of issues are accessible to vision-impaired persons, but they may also be easy for malicious bots to address.

Video Captcha

In this sort of captcha, the user is shown a film and requested to input the letters that are moving or displayed in the video. For instance, if the letters are moving with white and red characters, and the user is required to input the red letters in the specified box.

Slide Captcha

When using slide Captcha, the user can only submit data after unlocking the locked slide. Because the user only has to move the slide button from one end to the other, this captcha takes relatively little time. The slide Captcha is useful for preventing spam on blogs.

Puzzle based Captcha

The image or photo is separated into several sections or segments in puzzle Captcha. The user is requested to put these bits or segments together to complete the picture, or they can be given various forms of math-based puzzles.

Advantages of using CAPTCHA

  • Increases security

  • Reduces spams

  • Blocks automated increased usage of services

  • It makes online activity safer

  • Differentiates human and computers

CAPTCHA's most significant advantage is that it is extremely effective against all but the most sophisticated evil bots. CAPTCHA methods, on the other hand, can have a detrimental impact on your website's user experience:

Disadvantages of CAPTCHA

  • Users find it inconvenient and frustrating

  • For some audiences, it may be difficult to comprehend or use

  • Some CAPTCHA types aren't compatible with all browsers

  • Some CAPTCHA types are inaccessible to people who use screen readers or assistive technology to access a website

What is reCAPTCHA?

ReCaptcha is currently the most widely used implementation of Captcha, which Google acquired in 2009.

For more than a decade, Google has used reCAPTCHA to protect millions of websites. reCAPTCHA is based on the existing reCAPTCHA API and distinguishes between humans and bots using advanced risk analysis techniques. Similar to CAPTCHA, people use reCAPTCHA to defend their site against spam and abuse and detect other sorts of fraudulent activity such as credential stuffing, account takeover, and automated account creation. To safeguard corporate enterprises, reCAPTCHA provides enhanced detection with more granular scores, explanation codes for problematic occurrences, mobile app SDKs, password breach/leak detection, Multi-factor authentication (MFA), and the option to customize your site-specific model.

How does reCAPTCHA Work?

Artificial Intelligence (AI) is used in the reCAPTCHA verification process to distinguish human behaviour that bots cannot. Any human user, regardless of age, gender, education, or language, should be able to pass the tests. CAPTCHAs are all automated, allowing a computer programmer to grade the test without the need for human intervention. As a result, as both the CAPTCHA AI and dangerous bots get more advanced, the tests are continually developing.

Evolution of reCAPTCHAs

Previously, this was a sufficient deterrent because bots had trouble detecting these deformed letters or numbers.

On the other hand, more complex bots have been built with the ability to quickly overcome standard CAPTCHAs using pattern recognition algorithms. reCAPTCHA v1 was developed around 2007 to replace traditional CAPTCHAs with more complicated tests.

These reCAPTCHA experiments employed a computer-generated word and warped text from old books or news stories as well as a computer-generated word. This version, however, is no longer available because it was discovered to be too easy for bots and too difficult for human users. reCAPTCHA v1 was declared end-of-life and shut down on March 31, 2018.

Following that, reCAPTCHA v2 was released in 2014 to provide more sophisticated tests that would dissuade bots while still being solvable by humans.

Users must select images that match a theme or click a box next to the text that says "I'm not a robot" in this new reCAPTCHA test.

A recent version, reCAPTCHA v3, made available around 2018, strives to keep the user experience smooth. This version restricts user engagement by assigning a score based on the user's current behaviour and history. In a preliminary Turing test, computers determine the user's score.

The website owner has three options based on the score: give access, block the user, or use reCAPTCHA v2 tests. The two tests available for this approach are the image reCAPTCHA and the checkbox reCAPTCHA.

Types of reCAPTCHA


The reCAPTCHA image recognition test uses nine or sixteen lower resolution real-life images in the shape of a square. Users will find instructions on which image sections should be selected displayed above these images. Users might be instructed to choose all squares with crosswalks or fire hydrants. The computer programme will compare the response to other responses after the user has selected the squares. The user passes the test if their response matches that of the majority of other users. The exam uses images that people view on a daily basis and can easily recognize. Even the most advanced bots will struggle to identify things in low-resolution photographs.

Checkbox reCAPTCHA

To pass the checkbox reCAPTCHA test, users do not need to solve or recognize anything. Simply check the "I'm not a robot" box next to the sentence. As it approaches the checkbox, the cursor movement is tracked in this test to distinguish humans from bots. When users click the box, a green check icon will appear if the cursor movement indicates that the user is human. Even on a microscopic level, even the most stable human user will show some variability in cursor movement. On the other hand, a bot is unlikely to be able to emulate this type of movement, preferring instead to go in a straight path. This test evaluates HTTP cookies and history in the web browser in addition to observing the cursor movement.

Invisible reCAPTCHA Badge

The user does not have to click a checkbox to activate the reCAPTCHA badge; instead, it is activated when the user clicks on an existing button on your site or via a JavaScript API call. When the reCAPTCHA verification is complete, the integration requires a JavaScript callback. Only the most suspect traffic will be asked to solve a captcha by default. Go to advanced settings and change your site security preference to change this behaviour.

Advantages of using reCAPTCHA

By blocking spam, abuse, and data theft from bots, reCAPTCHA actively safeguards the integrity of your site.

The following are some of the most important advantages of adopting reCAPTCHA:

  • This service is available to everyone at no cost.

  • The test guards against spam, fraud, and abuse on websites. This test adds an extra degree of security to websites that have sign-up forms and comment sections.

  • There are numerous types of tests accessible and the possibility of using different tests for different types of forms.

  • Avoid attacks that could transmit malware or divert your visitors to harmful websites to help preserve the integrity of your site.

  • Only provide services to real users to save time.

  • The test stops bots from flooding your business or comment section with bogus users.

As bots get more sophisticated, reCAPTCHA updates its tests using a machine learning algorithm on a regular basis. This allows reCAPTCHA tests to adapt to the capabilities of bots.

Disadvantages of reCAPTCHA

While reCAPTCHA offers a variety of options and methods for protecting a website from spam and abuse, it is not without flaws. The following are some of the disadvantages of utilizing the tool:

  • The test disrupts a user's ability to complete their task, perhaps resulting in a terrible user experience. Visitors may even abandon the site as a result of the test.

  • Some older reCAPTCHA tests can be fooled by bots.

Bots can be coordinated to gather data from a site, abuse the mechanics of a site, or even disrupt its services with a full-scale DDoS (Distributed Denial of Service) attack. Experts devised CAPTCHA and reCAPTCHA tests to distinguish people from bots in order to combat the growing menace of bots and enable bot control. They were previously the gold standard in bot mitigation, but they are no longer as appealing as they once were.

Patent Data Analysis

6,463 patents were filed in the domain out of which 15% of the patents are owned by top 10 players.

With 4 million software developers and more than 1,00,000 Software development agencies, the United States saw 2332 patents, the highest number of patents filed in this domain. USA is indeed the technology leader when it comes to software and computer application development. Next in line is China which is one of the leading outsourcing destinations. Thanks to its large population, many tech students graduate each year, adding to their already vast developer pool. No wonder China bagged the second position with 1035 patents! The European Patent office saw 416 and ranked third. India stood fourth with 217 while Japan stood fifth with 193. Great Britain saw 183, Germany and Korea saw 182 patents each. Canada and France recorded 167 and 129 patents, respectively.

IBM is the market leader with 149 patents. IBM's success is the result of a devoted labor base and progressive corporate culture well ahead of its time. It is the only company in the industry that has reinvented itself through multiple technology eras and economic cycles. Also, the business model of IBM has a pretty robust and amazing IT infrastructure that is able to serve the growing demand for its services. Crawling right behind it is Microsoft Technology Licensing with a total number of 143 patents. Microsoft has always been a pioneer of breakthrough software solutions and continues to be so. Live Nation Entertainment had 133 while Google recorded 129. Amazon Technologies, Ebay, Alibaba Holding saw a 107, 104 and 79, respectively. Microsoft and Live Nation Worldwide saw 78b and 75 patents, respectively. Tencent Technology Shenzhen had 71 patents to their name. All these corporations have been in the industry for many years and have invested a lot to reach their position today.

The ever-increasing drive toward digital transformation has resulted in a significant demand for software development solutions. The majority of businesses have embraced or plan to use software development as a digital-first business strategy. Softwares are therefore a crucial business asset today. The patent trend in the industry saw a rather humble beginning, with the filings in the initial four years seeing just 2-digit entries. The fifth-year recorded 105 patents, followed by 165 and 249 in the sixth and seventh years, respectively. However, the eighth year saw a slight fall in the number of patent records with a 238 registered count. The years 9 to 15 saw an exponential 290, 362, 417, 484, 500, 560 and 632, respectively. Further, the sixteenth and seventeenth years saw a dip with 550 and 544 patents. The numbers again rose to 583 in the eighteenth year but fell to 452 and 252 in the years ahead. The fall in the number of patent applications can be attributed to the fact that great advancements are made in AI, the problems CAPTCHAs create in the user experience and its efficacy. Having said that, there will be a need for technology that distinguishes human users from spambots as long as spammers attempt to create fake accounts. As a result, CAPTCHA technology will always exist in some form, growing in tandem with AI.






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