From: Vincent.Cate@FURMINT.NECTAR.CS.CMU.EDU
Date: Tue, 21 Jun 94 18:25:51 PDT
To: cypherpunks@toad.com
Subject: Using "nobody" to camouflage encryption/remailers/commerce
Message-ID: <772247601/vac@FURMINT.NECTAR.CS.CMU.EDU>
MIME-Version: 1.0
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If we use "nobody" as an email address we can hide remailers or make it
seem like there were remailers where there are not, etc.

The convention on the Internet is for mail to "nobody" to go to
"/dev/null".  This is used as a return address when you don't want bounced
mail.

Now remailer operators are clearly more interested in privacy than in
following conventions.  Imagine remailers also had addresses like
"nobody@vox.hacktic.nl", and "nobody@jpunix.com".  Now if someone doing
an internet wire-tap sees mail to "nobody@furmint.nectar.cs.cmu.edu" it
is hard for him to tell if this means:

  a) It will just end up in /dev/null like it does on 99% of the machines
  b) furmint is another remailer
  c) someone on furmint gets mail as "nobody"
  d) furmint acts as a remailer for those with money
  e) furmint is being used for some email based business
  f) etc

So now assume that there was a lot of encrypted mail going to
"nobody@alex.sp.cs.cmu.edu".  That might be because I am also doing
something funny there, or it might be because someone is just sending a
lot of encrypted mail to /dev/null.  By the way, anyone is welcome to send
encrypted mail to this address (via a remailer or not).  Even if there is
no email going out of that machine, it could just be that with my remailer
I collect the mail some period into a file, encrypt the file, move it
off to some other machine (using FTP, NFS, uucp, rcp, http, telnet, etc.),
and mail it from there.  Could be hard to tell.

Remailers named "nobody" will be harder to stop.  So it would be nice
if sites with remailers would set the "nobody" alias to point to their
remailer to start this convention.  Assuming that the remailer will
drop non-encrypted mail (or at least mail that does not have a good
format) this should not cause any problems.

On "furmint" I did the following:

   Changed the "nobody:/dev/null" in /usr/misc/.mmdf/table/aliases 
   to "nobody:vac+pgp@furmint.nectar.cs.cmu.edu". 

   Ran "dbmbuild" to rebuild the "mmdf" database.

I don't know how different this will be on other Unixes.  It may only take
editing "/usr/lib/aliases" on other systems.

So I did give away the puzzle in the second paragraph, if you send mail to
"nobody@furmint.nectar.cs.cmu.edu" it is the same as sending mail to
"vac+pgp@cs.cmu.edu".  So far.  :-)

I doubt that "nobody" was getting a lot of mail, but if so I will modify
my "pgp-receive" script to drop any mail not encrypted for it.

If they ever outlaw sending mail to "nobody" there will be millions of
people who are breaking the law.

If some country outlaws encryption, people (or programs) in other
countries could send encrypted mail to "nobody" at random machines in that
country to act as a cover for the legitimate encrypted mail.

   -- Vince