From: Adam Back <aba@dcs.ex.ac.uk>
Date: Tue, 13 Jan 1998 11:19:07 +0800
To: thomas.womack@merton.oxford.ac.uk
Subject: Re: local vs remote eternity servers (Re: (eternity) Traffic Analysis)
In-Reply-To: <01bd1fad$24885680$409001a3@mc64.merton.ox.ac.uk>
Message-ID: <199801130215.CAA00351@server.eternity.org>
MIME-Version: 1.0
Content-Type: text/plain




Thomas Womack <thomas.womack@merton.oxford.ac.uk> writes:
> >Thomas Womack <thomas.womack@merton.oxford.ac.uk> writes:
> >> I can imagine *use* of
> >> the service becoming a felony; you're therefore committing a felony
> >> merely by connecting to http://www.eternity.to, and acquiring
> >> evidence for that is a trivial matter of logging connections from a
> >> given user.
> >
> >One solution is to run eternity on a web server with SSL turned on,
> >and which serves lots of other data too.
> 
> It's not completely clear that such an object would exist; in legal terms,
> it would seem to be the same as a large and well-respected department store
> which happens to possess and tolerate a fence for stolen property. That is,
> it's an object which handles stolen property and can be shouted at loudly,
> legally, and with very large sticks.

Yes, but merely being seen going into this department store is you
hope not grounds for prosecution.  

ie The flow of the discussion being that you said "you're therefore
committing a felony by connecting to www.eternity.to" .. my reply
being that if we can arrange that there are any number of reasons for
connecting to www.eternity.to, any of which are protected by an SSL
connection, that this lessens the risks of being seen connecting to
said server.  We can easily arrange this by offering interesting free
services.

Certainly turning on SSL does not protect the server operator.  There
server operator in your analogy was the department store owner.  But
we were discussing the client (the shopper)'s risks.

> >The general problem with the remote server approach is that you have
> >to trust the server.  You could alternatively use a local eternity
> >server, which is easy to do if you have a local unix machine.
> 
> The operating system is immaterial here!

Ah, not if you are talking about my eternity prototype, because it 
only works on the unix platform.  Same for Ryan at present I think.
The overloading of "eternity service" is not helping here.

My point was that talking about my eternity prototype using USENET as
a distribution medium, where the `eternity server' is just a
convenient way to present an apparently persistent view of transient
USENET articles, using a local eternity server reduces the risk of
traffic analysis attack.  Now all you are doing is reading news.  If
you already have a full USENET feed, you have no new externally
observable traffic.

This process would be better termed a `local eternity proxy', in that
it would effectively be acting as a local web proxy process, where the
eternity virtual web pages were being fetched from a local news spool
by the local web proxy.

> >Ideally you would like a local news feed also, so that your local
> >eternity servers NNTP traffic or file system accesses to read news are
> >not available to the attacker.
> 
> That nearly makes sense - but 'running a news feed including the eternal.*
> groups' can be phrased such that any sane jury takes it as 'using/running an
> eternity server'.

Cross-post, and / or post to random newsgroups, threshold secret split
your posts so that only N of M are required to reconstruct.  If you
get shouted at for SPAM, steganographically encode the eternity
traffic.  Pornographic images in alt.binaries.* would be suitable
because there are lots of those already.  Because this is a publically
readable message an attacker (such as Ryan's system admin he mentioned
at MIT) might recognize the message based on successful stego
decoding, and purge it from the news feed.  We can counter this move
by encrypting the original posting, and posting the decryption key a
day or two later to ensure we get the full feed before anti-eternity
crusaders get to work purging the eternity traffic masquerading as
images.

USENET carries all sorts of materials which could potentially get you
in trouble.  I don't know what your news feed is like, but the one at
Exeter last time I looked had a healthy selection of dodgy gifs in
alt.binaries.*

> >Depending on your available resources, you can either operate from a
> >local news feed (people are less likely to be prosecuted for the
> >contents of a normal full newsfeed IMO), or have SSL access to a
> >remote ISPs NNTP server.
> 
> I suspect that, had anyone the least intention of arresting certain of my
> acquaintances on a trumped-up charge, they could persuade a jury that a
> 'normal' full newsfeed is sanitised, and that a newsfeed containing *warez*
> or *erotica* is clearly an Evil Perversion of the Natural Law.

We can't do much about the idiotic juries, and corrupt judicial
systems ... `they'd indict a ham sandwich if I told them to' -- some
US judge.  You're probably right too.  But I think we need to keep a
sense of proportion about opening ourselves to having technical
actions misconstrued to a clueless jury: there are easier ways to
frame someone once they have decided they don't like you.

To truly retain plausible deniability you need to maintain excellent
plausible deniability, you have to be squeaky clean: you need to
appear to be a model citizen, to not post politically incorrect
opinions to non-government approved fora, etc.  You must be below the
radar belt, you must be essentially invisible to the government, the
spooks dossier on you must read Mr Average and be entirely wholesome.
Then you must have one or more alter-egos, for your real interests.

> >> How can you defend against the felonisation of 'operating an Eternity
> >> Server'?
> >
> >Operate closed eternity servers for small group only, or a local
> >server for yourself or local users only.
> 
> But wasn't the point of the eternity service that it was massively
> distributed; if you're running a server for a small group consisting of
> forty-nine hackers and the deputy director of the NSA going incognito,
> you'll suddenly discover that all your servers have been seized, and that
> men with intimidating glasses want to ask you a number of searching
> questions.

The surest way is to run the eternity server for yourself only.  The
distribution medium is massively distributed, as the distribution
medium is USENET.  USENET is a broadcast medium.  Possibly the most
secure way to create one way anonymous communications is to broadcast
the messages.  Tim May's BlackNet uses this approach.  Eternity is
doing the same thing.

Adam