[11797] in cryptography@c2.net mail archive
Re: Optical analog computing?
daemon@ATHENA.MIT.EDU (Steven M. Bellovin)
Wed Oct 2 15:14:49 2002
From: "Steven M. Bellovin" <smb@research.att.com>
To: Greg Rose <ggr@qualcomm.com>
Cc: "John S. Denker" <jsd@monmouth.com>,
"R. A. Hettinga" <rah@shipwright.com>,
Digital Bearer Settlement List <dbs@philodox.com>,
cryptography@wasabisystems.com
Date: Wed, 02 Oct 2002 14:58:56 -0400
In message <5.1.0.14.2.20021003031603.0409fea8@203.30.171.11>, Greg Rose writes
:
>At 01:30 AM 10/2/2002 -0400, John S. Denker wrote:
>>"R. A. Hettinga" wrote:
>>...
>> > "the first computer to crack enigma was optical"
>>1) Bletchley Park used optical sensors, which were (and
>>still are) the best way to read paper tape at high speed.
>>You can read about it in the standard accounts, e.g.
>> http://www.picotech.com/applications/colossus.html
>
>But Colossus was not for Enigma. The bombes used for Enigma were
>electro-mechanical. I'm not aware of any application of optical techniques
>to Enigma, unless they were done in the US and are still classified. And
>clearly, the first bulk breaks of Enigma were done by the bombes, so I
>guess it depends whether you count bombes as computers or not, whether this
>statement has any credibility at all.
>
If memory serves (my references are at home), the Bletchley Park crew
used holes punch in large grids. They'd overlap many sheets and see
where the light made it through; that would be a good key (or candidate
key).
I don't know if you'd call that a "computer", but it was an interesting
optical device. I'm sure there have been many later applications of
similar principles -- see Shamir's TWINKLE, for example, which relied on
detecting aggregate brightness over many LEDs.
--Steve Bellovin, http://www.research.att.com/~smb (me)
http://www.wilyhacker.com ("Firewalls" book)
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