Backing up Private Keys

[Robert J. Hansen]

On 4/15/2013 7:33 AM, Ashley Holman wrote:
> So 65 years.  I know this is a really long time, but it's not as
> impressive as millions of years would be.  Does this mean that people in
> the 22nd / 23rd century might be able to crack old passphrased keys
> really easily?

No.  This isn't the sort of question that Moore's Law is useful in
addressing.  You need to get down into the physical limits of the
universe -- particularly things like the Bekenstein and Landauer bounds,
the Margolus-Levitin limit, and so on.  This has been discussed at
length on this list before.  A good synopsis can be found at:

http://lists.gnupg.org/pipermail/gnupg-users/2010-December/040123.html

It's worth noting that these limits are all physical constraints of the
universe.  As such, if a computer operating at the physical limits of
the universe can't brute-force something, it's fair to say that it
simply cannot be brute-forced.