At 4:39 PM -0400 4/9/07, Robert Cummings wrote:
On Mon, 2007-04-09 at 22:27 +0200, Tijnema ! wrote:
> This is exactly what tedd did in his last arrow example. He edited the
header of the GIF image, and so that would result in different MD5.
Finding this part and skipping it in the MD5 check would do the job. :)
Yep, that's an obvious solution since it's the same way virus signatures
are matched. The entire image needs some kind of permutation. Passing a
couple of curved ripples across the image as a transformation, and in
different directions should suffice to obfuscate the image signature
without obfuscating the image itself :) Similarly watermarking the image
using fractal patterns should also provide good noise.
Cheers,
Rob.
Rob:
It doesn't need to be complicated, just random placed pixels on the
image from a selection of colors would provide millions of
permutations.
Cheers,
tedd
--
-------
http://sperling.com http://ancientstones.com http://earthstones.com
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
