From: Jon Callas <jon@pgp.com>
Date: Sat, 18 Oct 1997 02:34:27 +0800
To: Bill Stewart <cypherpunks@cyberpass.net
Subject: Re: consensus on pgp? can we consolidate for action?
In-Reply-To: <19971016.032545.attila@hun.org>
Message-ID: <3.0.3.32.19971017111721.00b53d40@mail.pgp.com>
MIME-Version: 1.0
Content-Type: text/plain



At 01:18 AM 10/17/97 -0700, Bill Stewart wrote:
   At 08:40 AM 10/16/1997 +0000, Attila T. Hun wrote:
   >    I have not seen any further discussion on my suggestion to
   >    create a sendmail type daemon which implements DH between
   >    mail clients. this, of course, is on the presumption that DH 
   >    is a wrapper for an already encrypted packet, 
   
   DH between mail clients and servers is a really fine idea if you're
   starting from scratch, but sendmail is such a wretched hive of
   crime, corruption, and villainy that nobody in their right mind
   really wants to mess with it.  You could implement it as a sendmail
   extension using the EHLO stuff, but you'd have to go get people
   to adopt it widely once you'd done it; I suppose if you could talk
   Netscape and Eudora into adding DH exchange to their client code
   and get it into a few popular servers, you'd have a large fraction 
   of the Internet's email encrypted, which would be a Good Thing.
   It'd still have some major traffic analysis issues,
   and if you want to deal with the Man In The Middle problem,
   you need a key distribution infrastructure, which is much harder.
   
   An alternative approach is to encrypt everything using IPSEC,
   and you don't have to mess with Sendmail, but there are
   performance issues, and there's a lot of work getting it deployed also.

There's another solution too -- make your mail servers talk with TLS
(Transport Level Security, a.k.a. SSL).

This solves some problems and not others. If your SMTP path includes any
hops, then the message is in plaintext on that machine. Complicating it
further, you cannot reliably enforce what the hops will be. 

This is one of the reasons that email keys are sometimes considered comm
keys and sometimes storage keys. 

	Jon



-----
Jon Callas                                  jon@pgp.com
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