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[nycphp-talk] easily defeating captchas using automated imageanalysis

Allen Shaw ashaw at iifwp.org
Tue Nov 2 17:10:28 EST 2004


 > John wrote:
 > The point of a captcha was to get past that observation (if a system
 > built it, a system can beat it). The Captcha was to be a turing 
test.. > something that only a human could solve.
 > ...
 >  this is simply not a turing test. What wouldit take to build a
 > massive Internet database of cursive words, collected continuously and
 > used for captchas? Universal pen input, probably. until then, what do
 > we have?


I've seen (or seen theorized) captchas that require a user to enter a 
keyword based on three or more different pictures -- for example, show 
the user a Frosted Flakes box cover, that famous Nike-branded golfer, 
and a Cincinatti Bengals logo, and most users (depending on the target 
audience) could get in by typing "tiger".  One idea was also to say 
"three out of these 4 pictures" and then throw in a bogus picture of 
Bambi or the Eifel Tower. I'm sure somebody could program linguistic and 
cultural knowledge like this, but that seems a lot more "human" than 
what these guys are able to do.  ... Um, right?

- Allen



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