Paul Gilmartin wrote:
On Fri, 21 Aug 2015 09:53:49 -0400, Thomas David Rivers wrote:
So - perhaps I'm confused... but are you saying you want
a procedure that potentially reads the entire data set to determine
if you need to read the entire data set?
If the hash is sufficiently strong, you needn't read the entire data set
more than once, nor preserve the older version(s), but only the hash.
If a collision is unlikely within the lifetime of the universe, don't worry.
OTOH:
.... Ron Rivest estimated in 1977 that factoring a 125-digit
number would require 40 quadrillion years, ...
but with technological advances such a problem was solved 17
years later.
https://en.wikipedia.org/wiki/The_Magic_Words_are_Squeamish_Ossifrage
-- gil
How do you compute this sufficiently strong hash on the file to see
if it matches the one you have from a previous computation, without
reading (probably) the entire file? If something could be devised, it would
be a good tool in the toolbox...
- Dave R. -
--
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