The best security against spammers? Advanced math!
If you don't want spam-bots or bad guys breaking into your site, make them do calculus.
That's the approach the folks at a Croatia's Ru?er Boškovi? Institute are taking. Before you can log in to the research institute's Quantum Random Bit Generator service, you have to enter your name, password and affiliated organization, and then solve a math problem that would make most people run for the hills.
The challenge is an extra-hard version of a regular CAPTCHA-type question (see image here), where users are prompted to retype a set of letters from a blurry image. And, like CAPTCHAs, users are given clemency if they can't get the first one right. "If you don't know the answer to this question," it says, "reload the page and you'll (probably) get another, easier question."
