1993-10-23 - Re: Warning about exposing anon id

Header Data

From: Matt Blaze <mab@crypto.com>
To: hfinney@shell.portal.com (Hal Finney)
Message Hash: 53aeeb10a3d1e6b5ed5b4613bd2cc3747fbacade8dd4e26b38698164ad21d983
Message ID: <9310231826.AA08908@crypto.com>
Reply To: <9310231752.AA11323@jobe.shell.portal.com>
UTC Datetime: 1993-10-23 18:43:06 UTC
Raw Date: Sat, 23 Oct 93 11:43:06 PDT

Raw message

From: Matt Blaze <mab@crypto.com>
Date: Sat, 23 Oct 93 11:43:06 PDT
To: hfinney@shell.portal.com (Hal Finney)
Subject: Re: Warning about exposing anon id
In-Reply-To: <9310231752.AA11323@jobe.shell.portal.com>
Message-ID: <9310231826.AA08908@crypto.com>
MIME-Version: 1.0
Content-Type: text/plain

It seems that an anonymous remailer can operate in one of three ways -
it can reveal your psuedonym, it can reveal your identity, or it can
reveal nothing and simply give you a generaic "anonymous" identity.
Unfortunately each mode of operation is inapproprate as a default behavior:

- If it reveals your psuedonym, you could inadvertently expose map your
name to your psuedonym if you reply to a remailed message and include your
real identity.

- If it reveals your real identity, this could lead all sorts of obvious
problems with people who don't expect this behavior.

- If it simply strips out all identifying information and calls you some
generic anonymous name, this could lead to problems for people who expect
a reply to their messages.

I think the best solution is to require any message sent through a remailer
to include explicit instructions as to how it should be handled.  For example,
require something like an "X-Identify:" field that would be used to select the
return address behavior, with options like "real-id", "psuedonym", or
"anonymous".  Messages that don't include the field should bounce, probably
with some instructions as to how to fix the message to make it go through