[cryptography] CAPTCHA as a Security System?

Marcus Brinkmann marcus.brinkmann at ruhr-uni-bochum.de
Tue Jan 3 07:51:10 EST 2012


On 01/03/2012 04:08 AM, John Levine wrote:
> unsusual, so if I were a scalper, I'd have a network of web proxies,
> to make it hard to tell that they're all me, a farm of human CAPTCHA
> breakers in Asia who cost maybe 5c per CAPTCHA, a large set of
> employees, friends, and relatives who will let me use their names and
> credit cards (for a small commission) and scripts that blast through
> Ticketmaster's web pages as fast as they can, so they can buy the
> tickets the moment they go on sale, before real humans can.

That's overstating the costs of captcha solving by several orders of magnitude:

$1.39 per 1000 captchas from http://www.deathbycaptcha.com/
$0.7-$1 per 1000 captchas from http://antigate.com/
$2 (in 2009) for 1000 captchas from http://www.decaptcher.com/ (defunct)
$7 for 1000 captchas from http://www.decaptcher2.com/

This is just from their websites and forums, so I can not vouch for the
quality of their service.

Thanks,
Marcus



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