Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Hardest captcha ever?

random.irb.hr

Post reply on HN
Print view View original

51–60 of 125 posts

Re: Hardest captcha ever?

#51

Post by timtadh »

iy56 wrote: post #45
mvalle wrote: post #11

I don't think it would be hard to do, in fact, they reverse the whole point of a CAPTCHA. A CAPTCHA is supposed to be a task that is easy for humans, but difficult for computers. High-level mathematics is difficult for humans but easy for computers. They do have some success of telling computers and humans apart, though.

High-level mathematics is difficult for humans and provably impossible for computers.

Correct. For those that don't agree see the Incompleteness Theorem. It was once thought (by Hilbert no less) that computers would one day be able to derive all mathematical truths for us. Alas, G\:{o}del came along and ruined all of those grand plans by proving such an endeavor was in possible. He also showed the limits of human reason. Computers may or may not be "dumber" than humans, but we know that they can't be "smarter."

Re: Hardest captcha ever?

#52

Post by georgecmu »

I've seen harder (limits of converging sequences, etc), but wolfram alpha made them harder for humans than for automated scripts.

My captcha was to find the least zero of this polynomial: http://random.irb.hr/latexrender/pictures/c46ad0f30d7575c609...

and all I had to do was to OCR the formula: http://www.wolframalpha.com/input/?i=x^3+%2B+3x^2-4x+-12+%3D...

Re: Hardest captcha ever?

#53

Post by farout »

jcl wrote: post #47
farout wrote: post #27

Earlier quoted context omitted.

As you stated: If computer wanted to hack it - sure it is easy enough. But I was looking for a easy way to do some verification. I asked this because I was creating a reddit clone and wanted a captcha system. I detest the ones that exist right now.

The point of most captchas is to stop someone from writing a program that abuses your system. If you're not doing that, what exactly are you "verifying"?

I want to make sure a person votes only once. But if they want to game the system fine as long as they are willing to submit a captcha

For another website, I used to store the IP address and do checks but for a simple system that seem to be overkill.

All of the websites have no user accounts.

Is there another way to do this? Where you want some voting to happen but with no user accounts. And you want it to be dirt simple.

Re: Hardest captcha ever?

#55

Post by pbhjpbhj »

artmageddon wrote: post #20
drndown2007 wrote: post #18

Am I the only one saddened by the fact that this would have been a piece of cake back in high school/college, but can't remember how to do them (integrals) anymore? :(

The notion of "use it or lose it" is always disappointing, but honestly if you learned them once you can learn them again.

>if you learned them once you can learn them again

I doubt this personally. I didn't have any problems with the partial differential I was set. I mean on a general level that something once learnt can be relearned.

Re: Hardest captcha ever?

#57

Post by qeorge »

robinhouston wrote: post #31

The hardest captcha I've come across is the audio one used by Google on https://www.google.com/accounts/NewAccount . Click the little wheelchair icon to hear it. It's so hard to decipher, it almost comes across as a cruel joke at the expense of blind people. These are much easier, in that I can actually understand them.

I assume its because audio captchas are so easy to break with a computer (hence you have to distort the hell out of it):

http://blog.wintercore.com/2008/03/05/breaking-gmails-audio-...

Re: Hardest captcha ever?

#58

Post by [deleted] »

mrspeaker wrote: post #23
mvalle wrote: post #11

I don't think it would be hard to do, in fact, they reverse the whole point of a CAPTCHA. A CAPTCHA is supposed to be a task that is easy for humans, but difficult for computers. High-level mathematics is difficult for humans but easy for computers. They do have some success of telling computers and humans apart, though.

Precisely the reason I wrote the very useful "human.txt" captcha: http://www.mrspeaker.net/2010/07/15/humans-txt/ Stops those pesky humans wasting precious robot bandwidth and is quite a bit harder than the Quantum Random Bit Generator captcha ;)

[deleted]

Re: Hardest captcha ever?

#59

Post by artmageddon »

pbhjpbhj wrote: post #55
artmageddon wrote: post #20

Earlier quoted context omitted.

The notion of "use it or lose it" is always disappointing, but honestly if you learned them once you can learn them again.

>if you learned them once you can learn them again I doubt this personally. I didn't have any problems with the partial differential I was set. I mean on a general level that something once learnt can be relearned.

You may not be as sharp at it as you were when you spent hours pounding it into your head on a frequent basis, but it's surely within a person's grasp. At least as far as math goes; something like language fluency may be another story.
Post reply on HN