From: ph@netcom.com (Peter Hendrickson)
Date: Sat, 16 Nov 1996 13:29:56 -0800 (PST)
To: Adam Back <aba@dcs.ex.ac.uk>
Subject: Re: Remailer Abuse Solutions
Message-ID: <v02140b03aeb3dd600b95@[192.0.2.1]>
MIME-Version: 1.0
Content-Type: text/plain


At 1:38 PM 11/15/1996, Adam Back wrote:
>Peter Hendrickson <ph@netcom.com> writes:
>> However, if you restrict postings to an approved group of people, perhaps
>> everybody on the mailing list, you can eliminate spam.  How, then, do we
>> allow anonymous postings to come through?  Individual people on the list
>> can receive the proposed post and forward it to the list if it is
>> appropriate.  They could even charge a fee for doing it.  That's easy to
>> do if there is a "paying" remailer which will handle the money for them.

> Not necessarily a good idea.  The post may be a hot potatoe, and the
> forwarder may find themselves in legal trouble.  (Say RC4 & RC2 source
> code, NSA handbook, the results of the Mykotronic's dumpster diving
> spree, etc).  Exercising `editorial control' has landed some ISPs in
> trouble, to the extent that some are specifically avoiding it for that
> legal reason alone.  Being _paid_ for forwarding the message may make
> that even worse.

Yes, this is the part of my proposal with which I felt least comfortable.
Actually, not to flog a dead horse or anything, this is a perfect
application for semi-anonymous authentication.  Anybody on the list
could forward the mail, but nobody need know exactly who sent it.

> Howabout someone liberates skipjack and forwards it to you via
> remailers with $50 for your trouble.  Do you bite?  I thought not, NSA
> interviews, ITAR violation, etc.

Well, there are ways to do this.  For instance, you can send it
to a bunch of other people anonymously at, say, a dollar each.
It will get around quickly, albeit at greater inconvenience and
a higher cost.  But, for something this important that would be
acceptable.

> Ecash for email works better to stop spam sent directly to email
> addresses where you don't cash the money as a curtesy, and your
> software junks if it doesn't have valid ecash.  Email spam itself is
> getting mildly annoying lately, I get a couple a day average at the
> moment.

Except most people don't have e-cash accounts, software that handles
e-cash, or the interest in keeping a site which is secure enough
to handle e-cash.  This is the feature of having the remailer operator
deal with it.  The technology can be introduced to the existing
system with minimal hassle and cost.  All you need is one remailer
operator to do it.

Incidentally, a similar idea can be used to handle flooding attacks
on remailers.  A bad person could take down a remailer by directing
many encrypted packets to it that did not contain any payment.  This
is hard to solve, of course, because the mail all comes from other
remailers.

The solution is for the remailer itself to not accept mail from
other machines that do not pay.  The other remailers in the network
make a payment themselves (out of money they already received)
to make it worthwhile for the remailer to look inside the message
and see if there is even more business.

Does anybody know if military communications systems ever
take this approach?  I know that a highly redundant network is
used when any part of it can be taken out.  What is awkward about
this is that everybody wants to send messages at the very same
time the bandwidth is attenuated; i.e., during battle.

I'm guessing that in practice everybody in the network - all of
whom are basically trusted and identifiable - is ordered to send
only urgent traffic.

But, it would be neat if there was a way to budget bandwidth for
every unit, just like we do for ammunition.

Peter