Summary: Windows GUI recommendation for USB disk

[Robert J. Hansen]

David SMITH wrote:
> ...at the moment.

Welcome to the Second Law of Thermodynamics!  Enjoy your stay.



By the Second Law, every time a bit of information is erased you have to
pay the entropy tax of (kT * ln 2) J.  Let's assume that for each key
you try, you have to erase 1000 bits of information--this is wildly
optimistic, given how complex key schedules usually are, but it'll make
for nice numbers.

On average you'll have to brute-force 2**127 keys before you find the
proper 128-bit AES key.

1000 = 10**3
2**127 approx. eq. 10**38

10**41 * (3 * 10**-21) = 3 * 10**20 J

A one-megaton nuclear weapon liberates approximately 10**15 J of energy.

3 * 10**20 J divided by 10**15 J = 300,000 megatons

By comparison, the 1863 Krakatoa explosion liberated about 21,000 megatons.

If you're interested, we can also do a quantum-mechanical analysis of
the minimum time required to do this computation.  It gets equally silly.

http://en.wikipedia.org/wiki/Rolf_Landauer
http://en.wikipedia.org/wiki/Margolus-Levitin_theorem





... It's true that quantum computers and reversible computing will both
reduce this number considerably.  However, if you're going to talk about
science fiction--which is what large-scale quantum and reversible
computing is nowadays--then why not go whole-hog and posit the existence
of a psychic who's 100% effective in predicting keys?