SHA question

Philip Newton philip.newton at
Wed Jan 13 14:40:24 GMT 2010

On Wed, Jan 13, 2010 at 15:06, James Laver <james.laver at> wrote:
> Thirdly, be aware of what hashing guarantees. It does *not* guarantee
> uniqueness, it just gives you a very low chance that two files with
> the same hash are different.

Well, that said, is the "very low chance" not on the order of the
chance that you'll be run over by a bus in the morning, or that one of
the files will be changed through cosmic rays or bit rot in the
magnetic domains of the hard disk platter?

In other words, is 1x10^-64 (or whatever it might be) not so small as
to be effectively zero, since there are much "higher" risks (say,
1x10^-32) which you do not guard against, either?

Philip Newton <philip.newton at>

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