A complicated calculus-based anti-spam CAPTCHA

Eggheads at the Ruđer Bošković Institute in Zagreb, Croatia, are having some geeky fun with their web forms.

If you want to login to the institute’s Quantum Random Bit Generator service, you will be asked the usual questions like your username and password, but then you’ll be faced by a mathematical problem that may give you a nighmarish memories of your schooldays doing advanced calculus.

Complicated calculus-based anti-spam CAPTCHA

Hmm.. it’s a bit more complicated than the typical sort of CAPTCHA used by websites around the world to try to block spam bots and automated systems:

Simple CAPTCHA

Sometimes, of course, these randomly-generated CAPTCHAs can go very wrong – potentially causing unintended offense to some amusement.

Sign up to our free newsletter.
Security news, advice, and tips.

Somehow I don’t think the calculus-based CAPTCHA is going to catch on with the general public.

Hat-tip: Los Angeles Times via The Register.


Graham Cluley is an award-winning keynote speaker who has given presentations around the world about cybersecurity, hackers, and online privacy. A veteran of the computer security industry since the early 1990s, he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows, makes regular media appearances, and is the co-host of the popular "Smashing Security" podcast. Follow him on Twitter, Mastodon, Threads, Bluesky, or drop him an email.

What do you think? Leave a comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.