On Donnerstag, 26. Juni 2008, Alan McKinnon wrote:
> On Thursday 26 June 2008, Sebastian Wiesner wrote:
> > Alan McKinnon <firstname.lastname@example.org> at Thursday 26 June 2008,
> > 10:54:43
> > > The calculation is quite simple - measure how quickly a specific
> > > computer can match keys. Divide this into the size of the keyspace.
> > > The average time to brute force a key is half that value. AFAIK
> > > this still averages out at enormous numbers of years, even at
> > > insane calculation rates like what RoadRunner can achieve.
> > According to Wikipedia RoadRunner is designed for 1.7 petaflops in
> > peak. Assuming for the sake of simplicity, that decryption can be
> > performed within a single flop:
> > (2^256) / (1.7 * 10^15) / 2 ~= 3.5 * 10^61
> > In years:
> > 3.5 * 10^61 / 3600 / 24 / 356 ~= 10^54
> > Correct me if I'm wrong, but it seems impossible to me, to reduce
> > this get the required amount somewhere near to the life time of a
> > human being
> Even with your ultra-liberal assumptions, it still comes out to:
> times longer than the entire universe is believed to have existed thus
> far (14 billion years). That is an unbelievable stupendously long
> period of time. Yeah, I'd agree that brute force is utterly unfeasible
> as a vector of attack. Not even the almighty NSA could ever pull that
> one off as there simply aren't enough atoms in the universe to make a
> supercomputer big enough.
> Numbers don't lie.
and this is why nobody uses brute force.
There a better ways to crack keys. NSA has tons of experts in mathematics and
cryptoanalysis. Plus very sophisticated hardware. I am sure for most ciphers
they use something much more efficient than stupid brute force.
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