> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Bakul Shah > > See http://en.wikipedia.org/wiki/Birthday_problem -- in > particular see section 5.1 and the probability table of > section 3.4.
They say "The expected number of n-bit hashes that can be generated before getting a collision is not 2^n, but rather only 2^(n/2)." While that is not necessarily incorrect, the operative word is "expected." They're looking for some probability threshold... I did not assign any particular threshold to call something "expected" or "not expected." I simply calculated the probability. And compared it to the number of molecules in Earth. ;-) Two paragraphs earlier, they show a formula, "The generic [probability] can be derived using..." p(n:d) ~= 1 - ( ( (d-1)/d ) ^ ( n*(n-1)/2 ) ) In the case that I looked at, d=2^256 and n=2^35 p(n:d) ~= ... unfortunately excel calculated this so small it resulted in "0" _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
