Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!agate!ig!uwmcsd1!tut.cis.ohio-state.edu!mailrus!caen!pwallich
From: pwallich@caen.engin.umich.edu (Paul Wallich)
Newsgroups: sci.crypt
Subject: Re: One time pads and spy devices
Message-ID: <661@maize.engin.umich.edu>
Date: 27 Feb 88 20:06:16 GMT
References: <161200004@uiucdcsb>
Distribution: na
Organization: caen
Lines: 17
Summary: Used in WWII

In article <161200004@uiucdcsb>, kadie@uiucdcsb.cs.uiuc.edu writes:
> 
> Could a one time pad be used to make a spy tape recorder or camera?
> 
> It would work like this. At the spy's home base two identical
> (digital?) tapes are make containing random noise. Then the spy goes
> into the field with one tape recording things
> by XORing information onto the tape.
> 
Apparently this was done during WWII using records for secure radio
conversations between allied heads of state: random noise was pressed
onto two phonograph discs and used to modulate the signal carrying
the conversation, then demodulate on the other side. This was analog,
so synchronization was a problem. I expect if it was done then, it's
done now, only more fun.

pw