From: Johnathan Corgan <jcorgan@aeinet.com>
Date: Mon, 6 Feb 95 14:09:54 PST
To: eric@remailer.net>
Subject: Re: "encrypt tcp connections" hacks
Message-ID: <Chameleon.4.01.950206140937.jcorgan@comet.aeinet.com>
MIME-Version: 1.0
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>It's certain that IP security will greatly increase the overall
>security of the Internet.  I'm not advocating its removal but rather
>the acknowledgement that higher (and lower) level abstractions will
>require their own cryptography.

This resolves to a layered quality-of-service issue.  Encryption and
authentication at the network layer provides an excellent base for
improving security, and in and of itself solves a lot of problems like
packet payload sniffing, session stealing, etc.

But as you so aptly point out, trust boundaries do not coincide with
network boundaries.  Applications that "ride" on top of TCP and UDP may
have their own, very different, threat models.  And sniffing the
physical layer provides most of what you need for traffic analysis
unless some sort of sophisticated packet laundering is used.

You pointed this out to me at the last cpunks meeting--each layer in the
network model needs to be able to ask for and use security facilities in
the lower layer, as well as advertise its security features to the next
layer up. 

Of course, it is perfectly reasonable for me to expect to write an
email, encrypt it with PGP and send it via an encrypted SMTP protocol to
my mail gateway.  On its way, it will ride on top of an encrypted TCP
session to port 25, with the physical T1 link between my site and the
internet encrypted as well.  This is an example of security features
present at most of the layers between 1 and 7 of the OSI model.  These
should remain independent.

==
Johnathan Corgan       "Violence is the last refuge of the incompetent."
jcorgan@aeinet.com                    -Isaac Asimov
WWW:                    http://ftp.netcom.com/pub/jc/jcorgan/home.html

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