[Cryptography] information, Shannon, and quantum mechanics

[Dave Horsfall]

On Wed, 25 Feb 2015, Jerry Leichter wrote:

> I had done a back-of-the-envelope estimate and came up with a QM limit 
> for K of somewhere between 128 and 256.  I later asked a physicist I 
> knew, and he did a more accurate estimate.  It turns out that this 
> hypersphere could do about 2^315 bit flips - and store about 2^315 bits 
> of information.  So AES-256 "can be broken in principle" in 100 years by 
> brute force - but you don't need to make the keys all that much larger 
> to eliminate that possibility.  :-)

For the morbidly curious, my trusty HP-42S says it's 6.67E94 (that's a 
pretty big number, as numbers go); I'm not game enough to fire up "bc" on 
my Unix/Linux/Mac boxen to get all the figures...

-- 
Dave Horsfall DTM (VK2KFU)  "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)