CAPTCHA, an acronym for “Completely Automated Public Turing test to tell Computers and Humans Apart,” is a type of challenge-response test used in computing to determine whether the user is human. The most common type of CAPTCHA was first invented in 1997. reCAPTCHA, a CAPTCHA system owned by Google, was created by Guatemalan computer scientist Luis von Ahn in 2007. It enables web hosts to distinguish between human and automated access to websites.
Origins and the Need for Authentication
The need for CAPTCHA and reCAPTCHA arose from the increasing presence of bots and automated software on the internet, which could engage in abusive activities such as spamming and raiding websites. CAPTCHAs were designed to prevent spam on websites and protect them from bot-generated abuse.
The original version of reCAPTCHA was text-based and doubled as a transcription tool. It was designed as a mass collaboration platform for digitizing books, particularly those too illegible to be scanned by computers. The verification prompts utilized pairs of words from scanned pages, with one known word used as a control for verification and the second used to help digitize the text.
Assisting in Translating Scanned Documents and Books
reCAPTCHA has played a significant role in digitizing books and other documents. It 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 The archive can be searched from the New York Times Article Archive, where more than 13 million articles have been archived, dating from 1851 to the present day. Through mass collaboration, reCAPTCHA helped digitize books that were too illegible to be scanned by computers and translate books into different languages.
Current Status and Accuracy
Since its inception, reCAPTCHA has evolved through several versions. reCAPTCHA v2 introduced the “I am not a robot” checkbox and invisible reCAPTCHA badge challenges. The current version, reCAPTCHA v3, returns a score for each request without user friction. The score is based on interactions with the site and enables website owners to take appropriate actions. reCAPTCHA v3 is intended to run automatically when users load pages or click buttons, without interrupting users.
In terms of accuracy, Google’s algorithm has been able to bust CAPTCHA with 99.8% accuracy. However, Google claims that reCAPTCHA is not broken or ineffective, partly due to updates that added advanced risk analysis techniques. The system considers the user’s engagement with it before, during, and after they interact with it. Despite advancements in AI, reCAPTCHA remains a reliable tool for distinguishing between humans and bots.
CAPTCHA and reCAPTCHA have played a crucial role in authenticating human users and protecting websites from bots. From its origins as a transcription tool to its current status as an advanced risk analysis engine, reCAPTCHA has evolved to maintain its effectiveness in the ever-changing landscape of the internet.