Just an interesting cost estimate

cullip@radonc.unc.edu
Wed, 28 May 97 14:31:29 -0400


I apologize if I'm rehashing already covered ground.

Has anyone considered the aggregate cost of cracking this key?
How about we ignore everything except the electrical cost (yeah,
I tend to look at things from very odd perspectives).

We have 2^56 = 7.2 x 10^16 possible keys.

Let's assume the average computer is able to test say
10^6 keys/sec and burns 100 watts while running (make the
naive assumption that the computer would be off if it wasn't
working on this problem - the most unrealistic of my assumptions).
Finally assume the average electrical cost is 5 cents/kilowatt*hr
(is that anywhere near reasonable?).

7.2 x10^16 keys / 10^6 keys/sec = 7.2 x 10^10 seconds

7.2 x 10^10 seconds / 3600 sec/hr = 2.0 * 10^7 hours

2.0 * 10^7 hours * 0.100 kilowatts = 2.0 * 10^6 kwatt*hrs

2.0 * 10^6 kwatt*hours * $0.05/kwatt*hr = $100,000.

So it will cost the world $100,000 of electricity to solve
this problem.

I'm not saying this is good or bad (actually it looks like
a rather trivial cost), just an interesting but probably
useless observation.

Tim Cullip
cullip@radonc.unc.edu