How Does Recaptcha Checkbox Work
How does the “I’m not a robot” checkbox work? – Medium
Asking you to click a checkbox to confirm that you are, in fact, human seems curiously today’s age, there’s a high chance that you, dear reader, are a machine. Maliciously-programmed internet bots (software applications that can run automated tasks) are an unfortunate commonplace on the internet. They can be used at various scales from generating fake social media accounts, to rapidly booking out all tickets for a popular concert and orchestrating a large-scale Distributed Denial of Service (DDoS) attack; a DDoS is an attempt to make an online service unavailable by overwhelming it with traffic. It’s the type of high-profile attack that can take down everything from banks to government websites. A dystopian world like this needs a reliable way to differentiate an evil bot from a well-intentioned human. How can a banking website be sure that an innocent grandma who is logging in to check that the holiday gift money was successfully transferred to her grandchildren, is in fact, an innocent grandma? Enter, the “Completely Automated Public Turing test to tell Computers and Humans Apart”, or more simply, the like internet bots themselves, and like much of the innovation on the internet, CAPTCHAs find their origin in the hacker community. Back in the ancient 1980s the hackers invented leetspeek to bypass security filtering on internet chat forums. Leet is a method of converting words to lookalike characters or abbreviations that cannot easily be interpreted by a computer:leet > I33tcensored > c3n50redporn (pornography) > pr0nIn the pre-Google days of the internet, websites would be manually submitted to search engines. In order to prevent the submission of fake websites, AltaVista implemented the first CAPTCHA-like system that required a user to type a series of distorted characters into a box. This approach, which we often still encounter when registering new accounts or submitting information on the internet, is based on three principles:Humans can more easily recognise highly distorted, rotated or skewed can more easily visually separate overlapped can more easily draw on context to understand visually distorted characters, for example, identifying a character based on the full word that it appears search engine Alta Vista was one of the first popular websites that introduced a CAPTCHA-like protection when submitting new websites to its 2003, a research team from Carnegie Mellon University published a pioneering research paper that described many different types of software programs that could distinguish humans from computers. It was this group that also coined the catchy acronym. As CAPTCHAs became a status quo of security on the Internet, Luis von Ahn, a member of the original research team, became increasingly uncomfortable with how much valuable time was being wasted on solving these mini puzzles. In a wonderful 2011 TED Talk, von Ahn estimated that humanity as a whole was wasting 500, 000 hours a day on completing Von Ahn discusses how the collective amount of time wasted on filling out CAPTCHAs inspired the reCAPTCHA ioning whether this time could be put to more powerful and meaningful use, he developed reCAPTCHA, which was eventually sold to Google in 2009. These days, there are a number of projects and companies (including Google Books, the Internet Archive, Amazon Kindle and The New York Times) that are scanning and indexing large numbers of books, documents and images for use on the web. reCAPTCHA works by taking any of the scanned words that cannot be recognised and presenting them to a human alongside a known word for interpretation. By typing the known word correctly, you identify yourself as a human and the reCAPTCHA system gains some confidence that you have correctly digitised the second. If 10 other people agree on the transcription of the unknown word, the system will assume this to be correct. Today reCAPTCHA helps to digitise millions of books a year and has also extended to support other efforts like digitising street names and numbers on Google Maps or recognising common objects in photos for Google original reCAPTCHA asks you to type a known scanned word to identify yourself as a human and to help transcribe another word that a computer was not able to forms of CAPTCHAs are also being used to help index images and data captured by Google Street are many other forms of CAPTCHAs, including an audio version for the visually impaired. But it is the curiously simple variety — the “I’m not a robot” checkbox seen on many of today’s websites — that inspired the original question behind this article. This checkbox, endearingly called the “no CAPTCHA reCAPTCHA”, is a Google product that unsurprisingly uses a combination of advanced Google technology to produce a very simple result. Google will analyse your behaviour before, during and after clicking the checkbox to determine whether you appear human. This analysis might include everything from your browsing history (malicious bots don’t necessarily watch a few YouTube videos and check their Gmail before signing up for a bank account), to the way you organically move your mouse on the page. If Google is still unsure of your humanness after clicking the checkbox, you will be shown a visual reCAPTCHA (with words, street signs or images) as an additional security measure. This multi-faceted approach is necessary as computers become more skilled at complex image recognition and with the rise of CAPTCHA sweatshopping (think a large room of underpaid workers tasked with generating a heap of fake social media accounts).
How does Google’s “No Captcha reCaptcha” work?
This isn’t really a great question for stackexchange as Google is keeping its algorithms secret so all we can really do is make guesses about how it works, but my understanding is that the new system will analyze your activity across all of Google’s services (and possibly other sites that Google has some control over, such as websites that have Google ads).
Thus, it is likely that the checks are not limited to just the page that has the checkbox on it. For example, if they detect that your computer/IP address you are using was also used in the past to do things that a normal human would do – things like checking Gmail, searching on Google search, uploading files to Drive, sharing photos, browsing the web etc. – then it can probably be reasonably sure that you are a human and allow you to skip the image verification. On the other hand, if it can’t associate your computer with any previous human-like activity, then it would be more suspicious and give you the image verification. Though the mouse behavior as it clicks the checkbox may be one factor it analyzes, there is almost certainly a lot more to it.
Again, we don’t know for sure how it works. This is just my best guess based on what little Google has said:
While the new reCAPTCHA API may sound simple, there is a high degree
of sophistication behind that modest checkbox. CAPTCHAs have long
relied on the inability of robots to solve distorted text. However,
our research recently showed that today’s Artificial Intelligence
technology can solve even the most difficult variant of distorted text
at 99. 8% accuracy. Thus distorted text, on its own, is no longer a
dependable test.
To counter this, last year we developed an Advanced Risk Analysis
backend for reCAPTCHA that actively considers a user’s entire
engagement with the CAPTCHA—before, during, and after—to determine
whether that user is a human. This enables us to rely less on typing
distorted text and, in turn, offer a better experience for users. We
talked about this in our Valentine’s Day post earlier this year.
To me the point about “before, during, and after use” is a strong hint that they analyze previous browsing behavior, but my interpretation could be wrong.
Here’s a quote from WIRED:
Instead of depending upon the traditional distorted word test,
Google’s “reCaptcha” examines cues every user unwittingly provides: IP
addresses and cookies provide evidence that the user is the same
friendly human Google remembers from elsewhere on the Web. And Shet
says even the tiny movements a user’s mouse makes as it hovers and
approaches a checkbox can help reveal an automated bot.
There is another thread on stackoverflow discussing this as well:
As for image verification, you’re not going to be able to find those images with reverse image search, or compile a database of them. They are usually random street signs or house numbers captured by Google’s Street View cars, or words from books that were scanned for the Google Books project. There is a good purpose behind this – Google actually makes use of what people type into reCaptcha to improve their own databases and train OCR algorithms. reCaptcha gives the same image to a number of users, and if they all agree on what it says, then the picture becomes training data for Google’s AI.
From wikipedia:
The reCAPTCHA service supplies subscribing websites with images of
words that optical character recognition (OCR) software has been
unable to read. The subscribing websites (whose purposes are generally
unrelated to the book digitization project) present these images for
humans to decipher as CAPTCHA words, as part of their normal
validation procedures. They then return the results to the reCAPTCHA
service, which sends the results to the digitization projects.
reCAPTCHA has worked on digitizing the archives of The New York Times
and books from Google Books. [3] As of 2012, thirty years of The New
York Times had been digitized and the project planned to have
completed the remaining years by the end of 2013. The now completed
archive of The New York Times 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.
How does the checkbox captcha work?: askscience – Reddit
trying to decompile the captchaThe captcha javascript code is obscured behind some very clever google processes. Furthermore, the success/failure/trustscore is all done on a google backend server, making it totally unknowable. All the captcha does it collect information and send it to captcha gives you a token. That token is not trusted by google. You then click on the captcha, and a bunch of information about your browser/history/session/clicking/etc is sent to google to process. If it trusts you, that token is trusted and can be used when you submit the form (you enter a username + password, you get token 112, you click submit on that registration form, the website submits 112 to google and checks if it is trusted or not, if it is it creates an account for you with your username + password, if it isn’t it doesn’t) down by information provided to google, I would say that the captcha has three main checks:Who are you: What is your browsing history, captcha success/failure history, etc (this is gathered from the google cookies)How legit is your environment (browser). This is the meat of the process. It sends info about what plugins are installed, your user agent, how your browser renders items, whether its rendering of a canvas element matches how that browser is expected to render it, did you click the button. This is the execution time, the number of mouse/keyboard/touch actions made in the captcha iframe, and mouse movement/entry point/etc within the takes all that info, and gives it to some black box to process. We know there are minimum and maximum times you must enter it by, we know that some browsers and plugins etc are automatically considered untrustworthy, and we know that the more history you have, the more trustworthy you is widely believed that some fancy learning algs are at use in the google backend, trying to make sure if the same bots uses the same algorithms to create a mouse path and click behaviour, it will start trusting it less and less.
Frequently Asked Questions about how does recaptcha checkbox work
How does the check box CAPTCHA work?
reCAPTCHA works by taking any of the scanned words that cannot be recognised and presenting them to a human alongside a known word for interpretation. By typing the known word correctly, you identify yourself as a human and the reCAPTCHA system gains some confidence that you have correctly digitised the second.Jun 13, 2019
How does Google CAPTCHA work?
and let they solve.After receiving click cooridinates from captcha solver use your Human Mouse move Funktion to move and Click Recaptcha Images.Use your Human Mouse Move Funktion to move and Click to the Recaptcha Verify Button.May 11, 2016
How does reCAPTCHA know I’m not a robot?
Instead of depending upon the traditional distorted word test, Google’s “reCaptcha” examines cues every user unwittingly provides: IP addresses and cookies provide evidence that the user is the same friendly human Google remembers from elsewhere on the Web.Dec 3, 2014
