full-disclosure - Visual Captchas AKA Word Verification Systems

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Message-ID: <200406140044.i5E0iiXw003514@turing-police.cc.vt.edu>
From: Valdis.Kletnieks at vt.edu (Valdis.Kletnieks@...edu)
Subject: Visual Captchas AKA Word Verification Systems 

On Sun, 13 Jun 2004 18:27:22 -0000, Tom K <keetch_tw@...mail.com>  said:

> Secondly, would it be possible if anyone could kindly supply me with a few 
> links to practical information on Optical Character Recognition, since I am 
> still trying to improve my character recognition rate which is currently at 
> 20-50% depending on the obfuscations applied. i.e. Grids, lines and fuzzing 
> are easily removed, skewing is less so.

If you want close to 100%, just take the image you get passed, and drop it
as the "secret leet key" to get access to a free porn site, and let the users
decrypt it for you.  This is currently reported as a technique in active use
by spammers to work around those captchas.....
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