From: smb@research.att.com
Date: Mon, 2 May 94 09:07:49 PDT
To: perry@imsi.com
Subject: Re: So, what are we going to do?
Message-ID: <9405021607.AA26531@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


	 
	 "Jim Sewell" says:
	 >   A friend of mine that repaired computers said he ran across an
	 >   old disk drive that was used in WWII.

	 There were no disk drives in WWII. There were barely computers. Hell,
	 there was barely magnetic audio storage -- on steel wire!

I sent the same reply privately.  But disks were used in a WWII voice
security system -- phonograph disks...

I just learned about this system a few weeks ago.  As anyone who has
read Kahn knows, the early secure voice systems weren't secure; trained
listeners could even understand the scrambled system.  Some folks at
Bell Labs were asked to design one that would work.

The eventual system -- known as SIGSALY, or as Project X (and the
end units were called X terminals, which is probably the only time
that phrase was ever used for something that is secure...) -- utilized
a vocoder and a one-time pad.  The one-time pad was recorded on two
high-quality phonograph records, each of which held 15 minutes of
keying information.

SIGSALY terminals were quite large -- they took up 30 seven-foot bays.
And they needed a *lot* of air conditioning.  But the system did work,
even over transoceanic radio links.  Churchill had one in his underground
office in London, in fact.

References are ``Secret Telephony as a Historical Example of Spread-
Spectrum Communication'', William R. Bennett, IEEE Trans. on Communications,
Vol 31, No. 1, Jan '83, and ``A History of Engineering and Science in
the Bell System:  National Service in War and Peace (1925-1975)''.