🚀 go-pugleaf

In article <9112@duke.duke.UUCP>, srt@duke.UUCP (Stephen R. Tate) writes:
> In article <1338@navajo.STANFORD.EDU>, les@navajo.STANFORD.EDU (Lester Earnest) writes:
> > The easiest way to compromise an exclusive-or cryptographic scheme with
> > courier-distributed key is to bribe the courier and make a copy.  This
> > cryptographic scheme is also very inefficient in that you have to
> > transmit the same amount of data via courier as you do over the
> > communication link.
> > 
> 
> Now here's an interesting point.  The exact same amount of information has to
> be transmitted as "key" information as will be transmitted as data.  Now since
> the data is transmitted over an insecure channel, then the key data is the
> valuable information.  So why not just use the secure courier for sending the
> actual data?  I mean, if the courier system can be broken to get the key, the
> data is suddenly rendered readable by anybody who cares.  So what is the

OK, let's assume that we manage to knock out the courier, copy his
key tape, and let the courier wake up without his having noticed anything
happened.  Well, I was sneaky and put the key tape in a plastic bag, and
the bag had an atmosphere that had a little too high Ar40/Ar42 ratio.  
(or some other truly sneaky way to tell that the tape had been possibly
compromised, like a tiny trace of cocaine four hundred feet in on the oxide,
or some other chemical which we can detect in nanogram amounts if we only
know to look.)
	
Now I know someone is attacking my system, and that the tape I now have 
is probably in their hands as well... Fine.  I can send messages over that
channel which are DISinformation, to mislead the enemy.  Meanwhile, I get
another tape by some other courier using a different transport, etc. and
use that for my real data needs.
	
If I'm not interested in active disinformation, I can just not use that
compromised tape and all the enemy has found are a lot of random bits- 
which he can subject to statistical analysis.  If my random-number 
generator was good, he gets nothing but a huge bill for cpu-hours.  
This tells him nothing but that he has to bribe/knock out a courier;
which he knew in the first place.
	
	-Bill Yerazunis