Message pools _are_ in use today!

At 4:37 PM 6/29/96, Hal wrote:
>From: ichudov@algebra.com (Igor Chudov @ home)
>> A nice, albeit quite expensive, way of pretection from traffic analysis
>> is to create a mailing list (or a newsgroup) and forward all messages to
>> all users of that mailing list or newsgroup. Of course, since messages
>> are encrypted, only the recipients will be able to decrypt them.
>
>This was discussed here several years ago, under the name "anonymous
>message pools".  Myron Cuperman, the operator of the extropia remailer
>implemented one, although I don't know if it is still running (I
>haven't gotten any mail from it for years).  It was basically just a
>mailing list specifically for this purpose, that you would use as your
>anonymous return address.  Of course a problem is that there may not be
>enough people signed up to provide much privacy protection.

The newsgroup "alt.anonymous.messages" has existed for a year or two, and
serves to be working reasonably well as a message pool. Check it out.

One will find numerous messages of the sort copied below. Having browsed
some of the less common newsgroups (and trolled, in my my earlier days), I
surmise that messages to nyms like "TheBear" are related to "support and
recovery" sorts of topics. (I mention this because this is a compelling
example of where anonymity is often sought; that people are using remailers
and message pools to communicate is interesting. When Louis Freeh claims
that remailers are only being used by hackers and Russian mafia arms
exporters, this is a counterexample.)

Here's just one such message, of several I saw this morning in
"alt.anonymous.messages". (Note that anonymous message pool sorts of
messages also appear directly from time to time in groups like
"alt.abuse.recovery" and that ilk.)

--begin copied message--

From: nobody@REPLAY.COM (Anonymous)
Newsgroups: alt.anonymous.messages
Subject: TheBear
Date: 15 Jun 1996 14:26:12 +0200
Organization: Replay and Company UnLimited
Lines: 14
Sender: replay@basement.replay.com
Message-ID: <4pua54$gt6@basement.replay.com>
NNTP-Posting-Host: basement.replay.com
X-XS4ALL-Date: Sat, 15 Jun 1996 14:26:17 MET DST
XComm: Replay may or may not approve of the content of this posting
XComm: Report misuse of this automated service to <abuse@REPLAY.COM>


-----BEGIN PGP MESSAGE-----
Version: 2.6.2
Comment: Processed by Mailcrypt 3.4, an Emacs/PGP interface

hIwDrINEDTBBpVEBA/4sKOcgI33fdk6Pz5V27OIX0KiVfb4YDwgNLDpf6Wy0uvix
4oQ9p+vmtsZ32dPBoG4aF7bvh5ejqwZSpvuKOpgt1M8SKbA+Nma+EclMzQ3us3Ey
OX5aFKo3TwB1Ck8tZPhpF8b/fI8gqz5v2FJhnon6NdktjFBVo3SBXya8AdlgUaYA
AABsOTd6WOMH8PWnKHuP7PMCflH2p+halmCDsn9ytmoG6uzrINHH/B8c7aW6c7xw
9nXbB+99xLldhAqyg1M/oKi4pjfJ8cuSonDxMPTP8rr49XTCFaiOuQ7JUe3MEaop
NIppnoBMrBvGRkKOgrYy
=lYbJ
-----END PGP MESSAGE-----

--end copied message--

--Tim May

Boycott "Big Brother Inside" software!
We got computers, we're tapping phone lines, we know that that ain't allowed.
---------:---------:---------:---------:---------:---------:---------:----
Timothy C. May              | Crypto Anarchy: encryption, digital money,
tcmay@got.net  408-728-0152 | anonymous networks, digital pseudonyms, zero
W.A.S.T.E.: Corralitos, CA  | knowledge, reputations, information markets,
Licensed Ontologist         | black markets, collapse of governments.
"National borders aren't even speed bumps on the information superhighway."

In article <adfab86806021004c248@[205.199.118.202]>,
Timothy C. May <tcmay@got.net> wrote:
> The newsgroup "alt.anonymous.messages" has existed for a year or two, and
> serves to be working reasonably well as a message pool. Check it out.

alt.anonymous.messages is not an ideal message pool-- it is a hack.
(Granted, it *is* a really cool, clever, and practically useful hack.)

Ian and I talked about this at some length.  alt.anonymous.messages
has certain unfortunate shortcomings.


Someone sniffing the Berkeley 'net can tell when I receive an
alt.anonymous.messages message by when I download an article from
the NNTP server; they can tell when I send such an article by when
I upload an article to the NNTP server; they can list all the
``subversive'' Berkeley folks who have read alt.anonymous.messages
lately.

The local NNTP server must be trusted.

Furthermore, even if you run a trusted NNTP server on your local
machine, there are still vulnerabilities.  Someone sniffing on your
subnet can tell when you inject a new message onto alt.anonymous.messages,
as can your neighboring NNTP servers.

Then there are all the standard message length and timing threats
from traffic analysis.  And there is no perfect forward secrecy
when using alpha nymservers to redirect email to alt.anonymous.messages.

There are also second-order threats, arising from the fact that
an attacker can selectively and remotely delete messages from some
spools by using cancel messages, without compromising any NNTP servers.


Ian's post detailed a proposal for implementing a message pool with
better security properties: link encryption, constant size messages,
randomized flooding, perfect forward secrecy, etc.

This mechanism is intended to provide recipient anonymity.  Sender
anonymity must still be achieved by standard chaining methods.


If folks have better ideas for how to achieve really good recipient
anonymity, I hope they'll speak up!

Take care,
-- Dave

On 1 Jul 1996, David Wagner wrote:

> Someone sniffing the Berkeley 'net can tell when I receive an
> alt.anonymous.messages message by when I download an article from
> the NNTP server

So, download every message, all the time, and junk posts that don't interest
you offline.

You betray yourself as an Evil Anonymous Communicator, but somehow I think
they might already know. You give no information about which messages you're
actually interested in unless your local workstation is compromised.

> Furthermore, even if you run a trusted NNTP server on your local
> machine, there are still vulnerabilities.  Someone sniffing on your
> subnet can tell when you inject a new message onto alt.anonymous.messages,
> as can your neighboring NNTP servers.

This is true. You'd have to generate white noise, again betraying yourself,
but only in general. "They" would need to track every message. To make it
more interesting, encrypt a bunch of messages for bogus PGP keys created for
the purpose. 

-rich