# encryption algorithm

Matt D md123 at nycap.rr.com
Wed Dec 18 01:48:29 CET 2013

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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
> 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)
>
> 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?

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