CAPTCHAs: The struggle to tell real humans from fake

(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)

Tam Nguyen, University of Dayton

(THE CONVERSATION) CAPTCHAs are those now ubiquitous challenges you encounter to prove that you’re a human and not a bot when you go to log in to many websites.

Websites and mobile apps have long been attacked by bots on a massive scale. Those malicious bots are programmed to automatically consume a large amount of computing resources, post spam messages, collect data from websites and even register and perform user authentication. This state of affairs led to the introduction of CAPTCHA, which stands for Completely Automated Public Turing test to tell Computers and Humans Apart.

As a computer scientist, I see CAPTCHAs as an effective shield for websites to prevent automated attacks, enhance cybersecurity and improve user experience – at least in the short term. For example, denial-of-service attacks create a bottleneck and cause a web server to become overloaded and unresponsive. CAPTCHAs help stop automated bots from executing such denial-of-service attacks and even fraudulent activities such as sending spam messages and creating fake accounts.

Meanwhile, financial institutions...