Building a Better CAPTCHA

jcatcw writes "Steven J. Vaughan-Nichols reports that CAPTCHA cracking isn't that difficult these days. It has even become a business. For example, DeCaptcher.com will solve CAPTCHAs for your spamming needs at a rate of $2 per 1,000 successfully cracked CAPTCHAs. In response, newer systems are in development. Both Carnegie Mellon and Penn State (is there something about the water in PA?) are working on image-based systems. ESP-PIX and SQ-PIX both require the viewer to interpret pictures. Imagination CAPTCHA from Penn has the user find the center of an image. The idea is that humans are better at image recognition that computers, but humans can legitimately disagree on their interpretations and some humans are color blind. Problems remain. For now, sites would be well advised to look at reCAPTCHA — the system that works with Google Books and the Internet Archive to digitize printed texts — which comes with a wide variety of application and programming plug-ins and an open API."

Comments

Build a database of inputs and outputs

[KPexEA]

Any CAPTCHA system can easily be cracked by building a large database with the inputs and outputs that was actually solved by humans and then saved into the database for lookup later. The inputs don't need to be text, they can contain images ( or hash codes representing images ), or css or whatever is needed to define the input data. The only feasable way to stop this kind of caching of answers is to have no duplicate tests. For example, a large field of randomly colored circles that all vary in size and position and move slowly around, then tell the user to hover the mouse over the largest blue circle and then next have them move the mouse over the green triangle, etc. Then base their "pass or fail" on how well they could move the mouse fast enough. And change the test often, like, put the mouse over the shape that looks like a bunny etc.

I really hate

[BetterSense]

I really hate image-based CAPTCHAS, because they discriminate against lynx users. I seriously remember at least one occasion where I was using lynx for whatever obscure reason, and I came upon "enter the text shown in the box at the left". Fail. I like the math problem ones better.

COLORblind? How about BLIND blind?

[Ungrounded Lightning]

The idea is that humans are better at image recognition that computers, but humans can legitimately disagree on their interpretations and some humans are color blind.

COLOR blind? Some humans are BLIND blind. Others have various vision or vision processing impairments that would make meatware-visual-coprocessor-test CAPTCHAs reject them.

IMHO most CAPTCHAs are already and obviously violating of the Americans with Disabilities Act. So now, in the info-war between weapons and armor (which weapons always win anyhow), even more of us less-than-Aryan-Supermen become collateral damage.

Dogs are (allegedly) color blind and "... on the Internet nobody can tell you're a dog!". Well, maybe PEOPLE can't. But now the web applications can. B-(

The solution to being attacked by better weapons is not better armor. That's only a stopgap. The solution is to hunt down those who misuse weapons and make them incapable of or unwilling to continue.