Re: CAPTCHA image validation in web form

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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