In the Hitchhiker’s Guide to the Galaxy, Douglas Adams wrote about a device called an electronic thumb. Electronic thumbs were used by hitchhikers to flag down passing spaceships and help them get on board. Since not all spaceship captains were inclined to give hitchhikers lifts, some engineers spent all their time creating new devices to protected against electronic thumbs. This lead to the engineers creating electronic thumbs that could defeat these new devices, leading to even more anti-thumb devices, leading to better electronic thumbs, leadi…. you get the idea.

The people who create CAPTCHAs and the programmers who work for the spammers are locked in a similar epic battle.

I’ve had a CAPTCHA of one sort or another on my blog for a while now. Some of them have worked better than others, but they’ve all been based on distorted text. The spammers have been working diligently to come up with ways to allow their ‘bots to automatically decode the distorted text. Lately, I’ve noticed an increase in the number of comments making it past the SI CAPTCHA I’ve been using, so I’ve installed a new type of CAPTCHA that requires the user to count objects in the CAPTCHA image rather than decode distorted text.

Hopefully the Ironclad CAPTCHA by Security Stronghold lasts longer than the text-based CAPTCHAs I’ve been using.