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Re: Hash algorithm analysis




On Tue, 12 Jun 2018, Ævar Arnfjörð Bjarmason wrote:

From a performance standpoint, I have to say (once more) that crypto
performance actually mattered a lot less than I originally thought it
would. Yes, there are phases that do care, but they are rare.

One real-world case is rebasing[1]. As noted in that E-Mail of mine a
year ago we can use SHA1DC v.s. OpenSSL as a stand-in for the sort of
performance difference we might expect between hash functions, although
as you note this doesn't account for the difference in length.

when you are rebasing, how many hashes do you need to calculate? a few dozen, a few hundred, a few thousand, a few hundered thousand?

If the common uses of rebasing are on the low end, then the fact that the hash takes a bit longer won't matter much because the entire job is so fast.

And at the high end, I/O will probably dominate.

so where does it really make a human visible difference?

David Lang