[2979] in cryptography@c2.net mail archive
Re: Turing Bombe story
daemon@ATHENA.MIT.EDU (Scott G. Kelly)
Thu Jul 16 19:12:29 1998
Date: Thu, 16 Jul 1998 15:26:08 -0700
From: "Scott G. Kelly" <skelly@redcreek.com>
To: Carl Ellison <cme@acm.org>
CC: Steve Reid <sreid@alpha.sea-to-sky.net>,
Marcus Leech <Marcus.Leech.mleech@nt.com>, cryptography@c2.net
Carl Ellison wrote:
<trimmed...>
> At 12:03 PM 7/16/98 -0700, Steve Reid wrote:
> >Are these figures accurate?
> >
> >I thought the Enigma had a much smaller number of combinations, around
> >10^5, give or take a digit...?
>
<trimmed...>
> The brilliance of the Bombe was that it needed to test only for
> the non-plugboard elements: (26^3)*P(5,3) = 1054560 possibilities,
> or half that to the expected break. This comes out to about an hour
> and a half, for a single Bombe, if it runs at 10 msec per rotor
> position. [Don't quote me on that speed -- it's from a distant
> memory of something I read.]
>
> As for a modern Pentium beating the Bombe, maybe -- but the Bombe did an
> incredible number of LIPS. It was testing for logical contradictions and if
> you were to do the Bombe in Prolog, it could bog down a modern processor....
So, just out of curiosity, could someone build a similar (specialized)
machine for DES... or skipjack?
