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Captchas was Re: ISP wants to stop outgoing web based spam

  • From: Simon Waters
  • Date: Thu Aug 10 03:53:03 2006

On Thursday 10 Aug 2006 01:14, Paul Jakma wrote:
> On Thu, 10 Aug 2006, Stefan Bethke wrote:
> > Do you have any links or references?
> Just ask the user some basic question. E.g.:
>   	What is 2 added to 23?: <textbox>

I've no doubt some captcha can be invented in ASCII, but this isn't it. AI 
already substantially out performs all but a small minority of humans on 
mathematical style IQ test (they were over 160 when I was a kid), and it 
would be relatively trivial to code it to handle the types of questions for 
this kind of test.

It would work for a minority use. Indeed I've already used a BBS that expected 
you to understand about factoring numbers or some such question on joining.

Something requiring real world knowledge would be better, but it is very hard 
to automatically generate questions (and answers), that can't be 
automatically answered. And remember in most cases you need questions that 
are consistently hard, as the machines won't get bored retrying. If you 
generate them manually (at least the first time one is encountered). Visual 
noise (and auditory noise) is something we are good are consistently good at 
removing,and machines are still playing catch-up. But then some of the 
automated captcha solvers aren't that much worse than a lot of people.

On the upside such captchas might spark more research into AI, as whilst 
recognising badly mangled images of text is kind of useful for the post 
office and other handwriting recognition, it has limited applications