Full Disclosure mailing list archives

Re: Time Expiry Alogorithm??


From: Andrew Farmer <andfarm () teknovis com>
Date: Tue, 23 Nov 2004 12:36:52 -0800

On 22 Nov 2004, at 12:47, Florian Weimer wrote:
* Georgi Guninski:
would prefer to keep my secrets encrypted with algorithm whose breaking
requires *provable* average runtime x^4242 or even x^42 instead of
*suspected runtime* 2^(x/4).

It depends on the constant factors you omitted, including those in the
lower-order terms. 8-)

AES can be broken with O(1) effort, but the constant is so huge that
it's considered impractical.  IIRC, OpenPGP has an upper bound for key
length, too, so it too can be broken with O(1) effort as well.
Obviously, this isn't particularly meaningful.

Especially considering that there aren't enough atoms in the universe to
store all that precalculated data, nor enough energy to do all the
calculations.

(Schneier says that there's enough energy in a supernova to do about 2^224 operations on a 100% efficient computer. And remember that AES or PGP take
multiple operations to calculate results...)

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