-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 12/17/2013 04:54 PM, Robert J. Hansen wrote: >> Lets assume the people I email have the same preferences. So >> how long, and at what cost would it take to brute force crack a >> captured message? > > [sigh] > > Not this again. I get very tired of answering this question. > > The Second Law of Thermodynamics puts a minimum energy requirement > on how much energy it takes to change the state of a bit. That's > given by kT ln 2, or on the order of 10**-23 joules. > > You want to exhaust keys in random order, because otherwise it > would give the defender an easy way to make things hard for you: > just use a key that's close to the end of your search order. By > exhausting random keys you foil that defense. Between setting and > clearing registers on the CPU, loading instructions into memory and > so on, let's say that each rekeying operation takes 10,000,000 bits > (10**7) being changed. (That's a wildly optimistic number, > incidentally.) > > Finally, 2**255 (the average number of keys you'll have to exhaust) > is about 10**77. > > 10**77 keys * 10**7 bitflips per rekeying * 10**-23 joules per > bitflip equals... 10**61 joules of energy. > > A supernova releases 10**44 joules of energy. You'll need 10**17 > of them just to power the computer to brute-force a 256-bit cipher. > The Milky Way has about 10**11 stars; you'll need about 60 galaxies > to go supernova all at once. This turns out to be about the same > size as the Virgo Supercluster, which is the region of the universe > the Milky Way is in. > > The amount of energy we're talking about here is so large there is > a non-zero chance it would disturb the false vacuum of spacetime > and annihilate the cosmos. > > People always seem to ask me if I'm making these numbers up. No, I > am not, nor am I joking. > > No one will ever. Ever. Brute-force a 256-bit cipher.
what about the 2048-bit DSA part of it? -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.21 (GNU/Linux) Comment: MacGPG2 - http://www.gpgtools.org/macgpg2.html Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJSsPDdAAoJECrdp7MWSIVbcdkH/ReJxrw76Vdx/cSVJFY20sGg OcH8hmdrB4gOCrvt1SJj3KiRl0bTgZyLkEpWR2UT3x4Zvd9Kni0gRsXSyNR6AlcE SCSIPOgDxeiWRWIuNSaRn9MBlzmpPnKWyECgeQ4S5HnDbZS+dApme+7AOZM54tm6 XPG57Ii2giUV6gmOdF0xMAt0uHd56hkoO09IYfkvbF4Vsk8vS4a0JCpCFzD4uaVa R007MRRUvTfmoukGoiaIC3315ZhQZHbN5jK4LRia02Zoy6t6dAjkInC+Y4aiE0pb 6nUiDg4s7dGzLUBfwsUqhcZ3/1Kr3MU6pLKsHOz4azP/u42DOjvQ9cvWvlqQN3A= =CUTC -----END PGP SIGNATURE----- _______________________________________________ Gnupg-users mailing list Gnupg-users@gnupg.org http://lists.gnupg.org/mailman/listinfo/gnupg-users