From: nelson@crynwr.com (Russell Nelson)
Date: Fri, 6 Jan 95 20:03:52 PST
To: cypherpunks@toad.com
Subject: Can someone verify this conjecture for me?
Message-ID: <m0rQSSj-0008ZFC@crynwr.crynwr.com>
MIME-Version: 1.0
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I'd like to make sure I understand how a digital mix works.  I've read
Chaum's paper on it, but hey, there's a reason why I don't have a Phd
in spite of having all the coursework done.

It seems like it solves two separate problems: 1) foiling traffic
analysis, and 2) foiling a cheater remailer.  The problems are
separate, really, because if you really, really trust the remailer (as
many people do Julf), then 2) isn't a problem.  All you need to do is
solve 1.  Or, you can solve 1) by using a single remailer.  A
necessary but not sufficient step to foil traffic analysis is to strip
headers.

If you trust any one remailer, then you needn't bother using any other
ones (assuming that remailer has enough traffic, delay, mixing, etc to
foil traffic analysis).  There's no real difference between using a
set (N>1) of trusted remailers and using only one, because you can
consider the set of remailers to be a single remailer from the point
of view of traffic analysis.

But to be sure, at least one of your remailers MUST attempt to foil
traffic analysis, otherwise you're effectively mistrusting the
remailer operators but trusting the NSA (or FBI).  As I said a month
or two ago, you MUST assume that the spooks are watching all the
remailers.  It's cheap and easy, therefore it's being done.

Sorry for the Crypto 101, but I figure that there are other people out
there who don't understand it.

-- 
-russ <nelson@crynwr.com>    http://www.crynwr.com/crynwr/nelson.html
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