Re: CAPTCHA image validation in web form

["Guillermo Andrades, CPI Software" <gab@xxxxxxx>]

Nathan,

<<Over a large enough number of iterations a bot could ....
sure, but I'm not pretending resolve all the security holes in the world,
I think this base idea could be improved i.e. each two months adding new
images and peer-descriptions, even remove some others....

Guillermo.



On Wed, Sep 3, 2008 at 6:49 AM, Nathan Andelin <nandelin@xxxxxxxxxxxx>wrote:

> > From Guillermo Andrades:
> > please select the image:
> > _ ICE  _ BOAT  _ GIRL  _ THE MOON  _ FLOWERS  _ GUITAR  _ THE SUN
>
> The nice thing about that idea is that a bot with an OCR reader couldn't
> decipher an image of a boat, for example.
>
> But there's a 1/7 chance that a bot could pick the right image the first
> time, and over a large enough number of iterations a smart bot could
> learn which radio button descriptions were paired with which image
> files.  Over a large enough number of iterations a bot could esentially
> download & duplicate your entire image library and cross-reference
> table.
>
> Nathan.
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