Optical analog computing?

[Steven M. Bellovin]

In message <5.1.0.14.2.20021003031603.0409fea8 at 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)



---------------------------------------------------------------------
The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to majordomo at wasabisystems.com