Yes, I think that would work.

A workaround might be quite easy though.

Produce 2 md5s. One from the whole file and another from the file minus 1 byte (first, last or middle). Or make the second md5 just the first half of the file; or from just the 10th, 20th, 30th etc. bytes (or whichever bytes the attack modifies to compromise the md5).

Now the attackers not only have the task of finding a duplicate file with the same md5, they have to produce one that matches two md5s.

Again, my math lets me down, but doesn't that make their job much, *much* harder?

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
"Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon

In reply to Re^8: On showing the weakness in the MD5 digest function and getting bitten by scalar context by BrowserUk
in thread On showing the weakness in the MD5 digest function and getting bitten by scalar context by grinder

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