From: Hal <hfinney@shell.portal.com>
Date: Wed, 13 Apr 94 23:36:39 PDT
To: cypherpunks@toad.com
Subject: Remailer reply addresses
Message-ID: <199404140637.XAA24792@jobe.shell.portal.com>
MIME-Version: 1.0
Content-Type: text/plain


Graham's suggestion about automatic remailer reply chains reminded me of
a simpler system which I would like to see.

Suppose one site, somewhere, would create new mail addresses upon request,
and map them to encrypted remailer chain blocks.  (These are nested remailer
requests, where the outer layer is encrypted for the first remailer and tells
it where to send the message, the next layer is encrypted for the 2nd remailer
and tells it where to send, and so on.  No remailer sees anything more than
where it is sending the message and where it received it from.)  A new account
is created which maps, say, to a file which has one of these "anonymous return
addresses" in it.  Any mail incoming for that address simply gets sent to the
remailer in the file, with the ARA stuck in front of it.

This is not complicated software.  I wrote a Bourne/Korn shell script which
does the whole thing in a dozen lines.  What is needed is a sendmail hack to
allow mail to addresses in a specified form (say anxxxxx) to be piped to this
script.  I don't have a machine where I can do this.

If such a site were running, then I could create an ARA block and send it to
that site (via a remailer, of course).  The site would make me a new address
and return it via the ARA.  That new address would be my pseudonym.

Now, when I want to send something pseudonymously, I just stick a "Reply-To"
into the outgoing headers of the message as it leaves the last remailer.  The
remailer-chain-creation script can easily be modified to do this.  The
Reply-To points at the address I got back from the pseudonym server site.

With this software I could do something which cannot be done today.  I could
send mail to which someone could hit "r" to reply, and receive that reply,
without any one person knowing my pseudonym.  This is not that much to ask
for!  I'd say it is the bare minimum for the use of pseudonyms on the net,
yet we don't have it, after all this time.  And look how close we are to
being able to do it.

With this basic system in place, some of Graham's ideas about time-limited
or use-limited pseudonyms could be applied as well.  Other extensions people
have suggested would have the pseudonym server hold messages in inboxes until
people trigger a dump to a freshly created anonymous address.  A lot of things
are possible.

But we should walk before we run.  Right now I don't feel that we are even
crawling yet.

Hal