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3D-Based CAPTCHAs Become a Reality
mateuscb writes "A new way of creating a CAPTCHA using 3D objects has become a reality. The idea was thought up independently by blogger Taylor Hayward and by the folks at YUNiTi.com. 'Similar to Hayward's idea, this new technology relies on our ability to identify objects in 3D instead of using alphanumeric characters. YUNiti's 3D Captcha, however, has three objects in the challenge and extends the list of images to any object, not limiting it to animals as in Hayward's idea. This increases the challenge's level of complication to prevent computers from successfully making the correct guesses.' I, for one, welcome the thought of not having to read more and more complex CAPTCHA. Lately, I've been having a hard time getting CAPTCHA to work the first time."
Let's see now. If the spammers and robot makers went outside, done something worthwhile and produced something the world badly needs (food) then this nonsense wouldn't exist, I could surf in peace and the starving millions would live a little longer. The very existence of CAPTCHA's proves the human race is badly in need of a reset.
CAPTCHAs are among the best motivators for progress in AI research since DARPA began throwing gobs of money around. The question is, what will happen to online forums and social/financial networks when machines become indistinguishable from humans?
If it requires actual workers, then it is a perfectly working CAPTCHA. "Completely Automated Public Turing test to tell Computers and Humans Apart." Don't think of it as a way to keep bad posts from your forum, because it isn't. It just tries to increase the likelihood that a human was involved in the process. If you want to limit abuse, getting a guarantee that a human was involved is only one small step in the process.
As is, this seems relatively easy to defeat and well within reach of available technology. The number of 3D models is rather low and they have a very clear silhouette and also a very distinct one for each models. So all one has to do is to search for the best matching silhouette.
The good thing however is that 3d models have enough flexibility so that one could conquer many attacks, adding background images and texture would make it much more difficult to get a clear silhouette and one could of course easily introduce many more models into the mix.
Like steering and changing gear?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Or as an alternative, we could actually track down the people who continue to make the Internet a swamp, beat them within an inch of their lives, let them spend a hot humid summer in full body traction, and maybe not only wouldn't they do it again but others might not either.
And put it on YouTube afterwards.
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
Pfft. Mere mortal.
Kinda defeats the purpose of a captcha if it looks like noise to a human, but is solvable by a computer.
Everyone has a great idea for a CAPTCHA, but very few people know what the hell is really going on. Remember that the machine doesn't need to solve the CAPTCHA every time, that machines are infinitely patient and have huge memories, and that another machine needs to make sure the human gave the right answer!
Ideas that won't work:
Really, it's very easy to think you've come up with a very clever CAPTCHA. When you think that, all you've done is stoked your ego and screwed yourself over. It's the same reason why we don't roll our own cryptography: CAPTCHA-making is a very hard problem, mainly because your problem space must be infinite (to avoid an attacking machine simply memorizing answers), the answers verifiable by a machine, but the problems not solvable by a machine.
How many questions can be checked by machines but not answered by them?
Not many; fewer every day. There are no questions that can't be answered by a computer (and which can be answered by a human mind). The Church-Turing thesis has some validity: the human mind is no more powerful than a turing machine, and ultimately, computers and our brains are equivalently computationally. There's nothing a computer can't solve: there are just things we haven't figured out yet.
Oh, and there are problems computers can't (easily) solve, but can verify. The problem is that human brains can't solve these problems either!
Before someone jumps in with "humans can solve the halting problem!" -- we really can't. There are problems that obviously halt, and programs that obviously don't. We can tell these apart, but so can computers. It's the complicated, borderline cases that trip up both people and computers.
Furthermore, there are important caveats to the halting problem: first, you can tell whether a program halts in a given time. You just run it and see whether it halts! Human beings do this all the time when debugging hanging programs. We use a good heuristic that says "if a program doesn't quit after a good long while, it probably won't quit at all." (And that holds in most cases.)
Second, the halting problem can be solved, via brute force if necessary, for a restricted-memory machine. Make the available memory size small enough and you can actually perform useful validation. The proof of the halting problems' unsolvability applies only to unrestricted turing machines.
A true turing machine has never been built, and can't exist in our universe. Every computer is a limited-memory approximation.
If the spammers have to pay to spam, we've already won.
You know, it really wasn't using both hands at the same time that was the problem. At least for me, the real problem was coordinating the two feet at the same time. Unless we're driving a motorbike...
At what point will certain disabled humans no longer be able to solve captchas? Autistics apparently have difficulty recognizing objects out of context.