On Mittwoch, 25. Februar 2009, Christensen Stefan wrote: > Behalf Of Daniel Phillips > Sent: Wednesday, February 25, 2009 10:39 AM > > It should be a cryptographically secure hash, just to make sure > it is collision resistant. That's the question ... if it's "cryptographically secure", it means (AFAIU) that it's "hard" to get collisions ... but it's not impossible. Really, it's *guaranteed* that on a large-enough filesystem (some TB, anyone?) you'll get two blocks with the same hash value.
Therefore I asked whether the risk is acceptable ... there has been some filesystem (I think that was more than 10 years ago, didn't find a link) that tried deduplication by some hash - but got shot down, because without *verification* that the data is identical you might *silently* shoot yourself (and all others) in the foot. > It might be an idea to follow the > SHA-3 competition by NIST. It can be fount here: > http://csrc.nist.gov/groups/ST/hash/sha-3/index.html > > An offsite wikipedia regarding SHA-3 can be found here: > http://ehash.iaik.tugraz.at/wiki/The_SHA-3_Zoo > > The idea behind SHA-3 is to find a hash that is as resilient as > SHA-2 (256,512bit), but a lot faster. Ok. But if verification is needed anyway, then something *much* simpler (and *much* faster) would be ok, too. Regards, Phil _______________________________________________ Tux3 mailing list Tux3@tux3.org http://mailman.tux3.org/cgi-bin/mailman/listinfo/tux3
