Re: [tor-talk] NSA supercomputer

[Gregory Maxwell <gmaxwell@xxxxxxxxx>]

On Fri, Apr 5, 2013 at 6:51 AM, Andrew F <andrewfriedman101@xxxxxxxxx> wrote:
> I would love to see an analysis of a 128 bit AES encryption VS a 10 exoflop
> computer. How long to crack it?  Anyone got the math on this?
[...]
> So what does this mean?   Any article that suggest that brute forcing
> present day encryption is not possible should be taken with a grain of
> salt.  While the article may be correct today, come September 2012, Utah
[...]
> I would love to see an analysis of a 128 bit AES encryption VS a 10 exoflop
> computer. How long to crack it?  Anyone got the math on this?

You really should take just a _moment_ to do a little figuring before
posting to a public list and consuming the time of hundreds or
thousands of people.

Lets assume that decrypting with a key and checking the result is one
"Floating point operation" (since you're asking us to reason about
apples and oranges, I'll just grant you that one apple stands for all
the required oranges).

To search a 128 bit keyspace on a classical computer you would expect
that on average the solution will be found in 2^127 operations.

2^127 'flops' / 10 exaflop/s =  2^127 flops / 10*10^18 flops/second =
17014118346046923173 seconds = 539,152,256,819 years.

...Or, about 39x the currently believed age of the universe.

Surely with a lot of computing power there are many very interesting
attacksâ particularly in the domain of traffic analysis, weak user
provided keys, discovering new faster than brute force attacks, etc.
But to suggest that they're going to classically brute force a 128 bit
block cipher is laughable, even with very generous thinking.
Honestly, these other things are arguably far more worrisome but
they're all just handwaving... which is all any of this discussion
is...
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