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Text of the page (random words):
pairs of words from scanned pages with one known word used as a control for verification and the second used to crowdsource the reading of an uncertain word 4 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 5 it was acquired by google in september 2009 6 the system helped to digitize the archives of the new york times and was subsequently used by google books for similar purposes 7 by 2010 the system was reported as displaying over 100 million captchas every day 8 on sites such as facebook ticketmaster twitter 4chan cnn com stumbleupon 9 craigslist 10 and the u s national telecommunications and information administration s digital tv converter box coupon program website as part of the us dtv transition 11 in 2014 google pivoted the service away from its original concept with a focus on reducing the amount of user interaction needed to verify a user and only presenting human recognition challenges such as identifying images in a set that satisfy a specific prompt if behavioral analysis suspects that the user may be a bot in october 2023 it was found that openai s gpt 4 chatbot could solve captchas 12 the service has been criticized for lack of security and accessibility while collecting user data with a 2023 study estimating the collective cost of human time spent solving captchas as 6 1 billion in wages 13 origin edit distributed proofreaders was the first project to volunteer its time to decipher scanned text that could not be read by optical character recognition ocr programs it works with project gutenberg to digitize public domain material and uses methods quite different from recaptcha the recaptcha program originated with guatemalan computer scientist luis von ahn 14 and was aided by a macarthur fellowship an early captcha developer he realized he had unwittingly created a system that was frittering away in ten second increments millions of hours of a most precious resource human brain cycles 15 operation edit recaptcha v1 human assisted ocr edit image identification captcha which requires users to select the appropriate images to verify they are human scanned text is subjected to analysis by two different ocrs any word that is deciphered differently by the two ocr programs or that is not in an english dictionary is marked as suspicious and converted into a captcha the suspicious word is displayed out of context sometimes along with a control word already known if the human types the control word correctly then the response to the questionable word is accepted as probably valid if enough users were to correctly type the control word but incorrectly type the second word which ocr had failed to recognize then the digital version of documents could end up containing the incorrect word the identification performed by each ocr program is given a value of 0 5 points and each interpretation by a human is given a full point once a given identification hits 2 5 points the word is considered valid words that are consistently given a single identity by human judges are later recycled as control words 16 if the first three guesses match each other but do not match either of the ocrs they are considered a correct answer and the word becomes a control word 17 when six users reject a word before any correct spelling is chosen the word is discarded as unreadable 17 the original recaptcha method was designed to show the questionable words separately rather than in the original sentence such as within a phrase of five words from the source document 18 yet the control word might mislead the context for the second word such as a request of metal fife being entered as metal file due to the logical connection of filing with a metal tool being considered more common than the musical instrument fife citation needed in 2012 recaptcha began using photographs taken from the google street view project in addition to scanned words 19 it asks the user to identify images of crosswalks street lights and other objects it has been hypothesized that the data is used by waymo a google subsidiary to train autonomous vehicles though an unnamed representative has denied this claiming the data was only being used to improve google maps as of mid 2021 20 google charges for the use of recaptcha on websites that make over a million recaptcha queries a month 21 recaptcha v1 was declared end of life and shut down on march 31 2018 22 recaptcha v2 checkbox edit the nocaptcha recaptcha in 2013 recaptcha began implementing behavioral analysis of the browser s interactions to predict whether the user was a human or a bot the following year google began to deploy a new recaptcha api featuring the no captcha recaptcha where users deemed to be of low risk only need to click a single checkbox to verify their identity a captcha may still be presented if the system is uncertain of the user s risk google also introduced a new type of captcha challenge designed to be more accessible to mobile users where the user must select images matching a specific prompt from a grid 2 23 recaptcha v3 and recaptcha enterprise invisible edit in 2017 google introduced a new invisible recaptcha where verification occurs in the background and no challenges are displayed at all if the user is deemed to be of low risk 24 25 26 according to former google click fraud czar shuman ghosemajumder this capability creates a new sort of challenge that very advanced bots can still get around but introduces a lot less friction to the legitimate human 26 implementation edit the recaptcha tests are displayed from the central site of the recaptcha project which supplies the words to be deciphered this is done through a javascript api with the server making a callback to recaptcha after the request has been submitted the recaptcha project provides libraries for various programming languages and applications to make this process easier recaptcha is a free of charge service provided to websites for assistance with the decipherment 27 but the recaptcha software is not open source 28 furthermore recaptcha offers plugins for several web application platforms including asp net ruby and php in order to ease the implementation of the service 29 security edit an example of how recaptcha challenges were presented in 2010 30 containing the words and chisels the main purpose of a captcha system is to block spambots while allowing human users on december 14 2009 jonathan wilkins released a paper describing weaknesses in recaptcha that allowed bots to achieve a solve rate of 18 31 32 33 on august 1 2010 chad houck gave a presentation to the def con 18 hacking conference detailing a method to reverse the distortion added to images which allowed a computer program to determine a valid response 10 of the time 34 35 the recaptcha system was modified on july 21 2010 before houck was to speak on his method houck modified his method to what he described as an easier captcha to determine a valid response 31 8 of the time houck also mentioned security defenses in the system including a high security lockout if an invalid response is given 32 times in a row 36 on may 26 2012 adam c p and jeffball of dc949 gave a presentation at the layerone hacker conference detailing how they were able to achieve an automated solution with an accuracy rate of 99 1 37 their tactic was to use techniques from machine learning a subfield of artificial intelligence to analyze the audio version of recaptcha which is available for the visually impaired google released a new version of recaptcha just hours before their talk making major changes to both the audio and visual versions of their service in this release the audio version was increased in length from 8 seconds to 30 seconds and is much more difficult to understand both for humans and bots in response to this update and the following one the members of dc949 released two more versions of stiltwalker which beat recaptcha with an accuracy of 60 95 and 59 4 respectively after each successive break google updated recaptcha within a few days according to dc949 they often reverted to features that had been previously hacked on june 27 2012 claudia cruz fernando uceda and leobardo reyes published a paper showing a system running on recaptcha images with an accuracy of 82 38 the authors have not stated whether their system can solve recent recaptcha images although they claim it is an intelligent ocr and robust to some if not all changes in the image database in an august 2012 presentation given at bsideslv 2012 dc949 called the latest version unfathomably impossible for humans they were not able to solve them either 37 the web accessibility organization webaim reported in may 2012 over 90 of respondents screen reader users find captcha very or somewhat difficult 39 criticism edit the original iteration of recaptcha was criticized for using unpaid work to assist in transcribing efforts 40 a 13 month study published in 2023 dazed confused a large scale real world user study of recaptchav2 found that recaptcha provides little security against bots and is primarily a tool to track user data and has cost society an estimated 819 million hours of unpaid human labor 41 13 privacy edit the current iteration of the system has been criticized for its reliance on tracking cookies and promotion of vendor lock in with google services administrators are encouraged to include recaptcha tracking code on all pages of their website to analyze the behavior and risk of users which determines the level of friction presented when a recaptcha prompt is used 42 google stated in its privacy policy that user data collected in this manner is not used for personalized advertising it was also discovered that the system favors those who have an active google account login and displays a higher risk towards those using anonymizing proxies and vpn services 24 concerns were raised regarding privacy when google announced recaptcha v3 0 as it allows google to track users on non google websites 24 in april 2020 cloudflare switched from recaptcha to intuition machines hcaptcha service citing privacy concerns over google s potential use of the data collected through recaptcha for targeted advertising the intermittent blocking of google services in some regions including china and a desire to cut down on operating costs as a result of google beginning to charge service providers for recaptcha 43 in response google told pc magazine that the data from recaptcha is never used for personalized advertising purposes 21 accessibility edit google s help center states that recaptcha is not supported for the deafblind community 44 effectively locking such users out of all pages that use the service recaptcha s version 3 might improve accessibility as it is an invisible captcha meaning users do not have to do anything manually instead verification and differentiation between humans and robots occurs in the background based on other criteria in reality many site owners still use the fallback feature of recaptcha v2 and its visual or audio challenges this combination of invisible recaptcha with recaptcha v2 fallback challenges is considered problematic for users with disabilities 45 interface edit in one of the variants of captcha challenges images are not incrementally highlighted but fade out when clicked and replaced with a new image fading in resembling whack a mole criticism has been aimed at the long duration taken for the images to fade out and in 46 requiring google play services edit google has tied the use of its recaptcha system to its google play services system which prevents recaptcha from working on degoogled android systems 47 48 derivative projects edit recaptcha also created the mailhide project which protects email addresses on web pages from being harvested by spammers 49 by default the email address was converted into a format that did not allow a crawler to see the full email address for example mailme example com would have been converted to mai example com the visitor would then click on the and solve the captcha to obtain the full email address one could also edit the pop up code so that none of the addresses were visible mailhide was discontinued in 2018 because it relied on recaptcha v1 50 references edit recaptcha inc opencorporates august 28 2007 archived from the original on august 20 2023 retrieved august 20 2023 1 2 shet vinay december 3 2014 are you a robot introducing no captcha recaptcha archived from the original on september 3 2020 retrieved february 24 2021 recaptcha v3 archived from the original on september 25 2020 retrieved september 8 2020 ahn luis von december 6 2011 massive scale online collaboration archived from the original on july 15 2020 retrieved april 14 2020 recaptcha about us archived from the original on june 11 2010 retrieved august 14 2018 teaching computers to read google acquires recaptcha archived from the original on may 19 2013 retrieved september 16 2009 deciphering old texts one woozy curvy word at a time the new york times march 28 2011 archived from the original on november 17 2017 retrieved november 20 2017 recaptcha faq archived from the original on july 5 2010 retrieved june 12 2011 rubens paul october 2 2007 spam weapon helps preserve books bbc archived from the original on may 18 2013 retrieved october 3 2007 fight spam digitize books craigslist blog june 2008 archived from the original on july 6 2010 retrieved june 17 2008 tv converter box program dtv2009 gov archived from the original on november 4 2009 edwards benj october 2 2023 dead grandma locket request tricks bing chat s ai into solving security puzzle ars technica archived from the original on october 10 2023 retrieved october 25 2023 1 2 frauenfelder mark february 7 2025 recaptcha 819 million hours of wasted human time and billions of dollars in google profits boing boing archived from the original on february 11 2025 retrieved february 11 2025 full interview luis von ahn on duolingo spark november 2011 canadian broadcasting corporation november 30 2011 archived from the original on june 3 2012 retrieved july 10 2013 hutchinson alex march 12 2009 human resources the job you didn t even know you had the walrus archived from the original on december 3 2015 retrieved december 7 2015 timmer john august 14 2008 captchas work for digitizing old damaged texts manuscripts ars technica archived from the original on january 24 2009 retrieved december 9 2008 1 2 luis maurer ben mcmillen colin abraham david blum manuel 2008 recaptcha human based character recognition via web security measures science 321 5895 1465 1468 bibcode 2008sci 321 1465v doi 10 1126 science 1160379 pmid 18703711 s2cid 18371056 questionable validity of results if words are presented out of context google groups august 29 2008 archived from the original on april 30 2011 retrieved july 10 2013 perez sarah march 29 2012 google now using reca...