At 1:17 PM -0400 4/10/07, Robert Cummings wrote:
-snip-
That should have read: "... since no subset of..."
Oh well, now it makes sense ! :-)
Actually, I see exactly what you are saying. If you take a small
portion of a file and MD5 it, it will give you a signature. If I
simply change a single pixel in the image and that pixel is NOT
included in the small portion you use for your MD5, then the MD5
check will return the same signature as before the alteration.
However, if your portion includes the pixel change, then the
resultant MD5 will be different. That's the reason why you need to
alter a significant portion of the image so that smaller portions
will probably contain some alteration.
Thanks for explaining that.
tedd
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