Eternity server considerations and musings

I spent some considerable time today thinking about the eternity server
idea proposed, and implemented in alpha stage, by Adam Back.

The main method used by governments around the world so far to attempt to 
censor information has been the use, or proposal of, proxy servers for 
whole countries or jurisdictions.
This method has only thus far been used to censor www connections, and 
has been used to censor specific sites, hence the use of mirroring to 
circumvent government censorship.

To give an overview of the eternity server idea for those who didn`t see 
the original post the idea was that a non existant virtual TLD .eternity 
would be used to access HTML posted to usenet. So to access a site that 
was at say bombmaking.terrorist.com/assasination/killing.html
you would send your browser to:
 
http://bombmaking.terrorist.com.eternity/assasination/killing.html

The assumption being that the distributed nature of usenet would not 
allow censorship.

The proxies idea however can be extended to censor usenet, usenet 
traffic, although pretty huge, is not yet too large to be grep`d for 
keywords (currently around 600mb of traffic a day passes through the 
newsgroups) before being proxied, so a government can run a server which 
first checks to ensure the usenet article is not encrypted (this can be 
done crudely by checking for occurances of common words or by checking 
the redundancy of the text by attempting to compress it) and if it is 
encrypted junks it, if it is plaintext, greps it for keywords like 
"assasination", "anarchy", "porn" etc... then kills the articles that 
have these words in them, the other articles the government does not want 
to censor are put on a main server like news.fourth-reich.de and access 
blocked to all the other news servers.

I know this might seem an unlikely scenario but it is not really when we 
consider the wacky ideas we have seen from governments in recent years, a 
dictatorship like France or Germany might begin implementing this within 
a few years, although the German government has had it`s fingers burnt 
recently with the Radikal fiasco.

What I was considering was the possibility of circumventing proxies 
altogether, this is not an easy question and I could not think of one 
single way to get access, of course one could use and ISP outside of the 
jurisdiction but this incurs internation call charges for dial up users, 
and the gubmint of fascist-regime-N can block telephone access to 
internet POPs outside of their country.

The problem with attempting to prevent censorship of usenet is that we 
cannot mirror it like we can web sites, the web is too huge for a 
government to mirror the whole of the "acceptable" part of it, so 
mirroring sites faster than they can block them is effective, usenet is 
too small to protect in this way, it could be effectively mirrored and 
all other access killed. Of course while we can mirror sites to prevent 
censorship this is almost an academic question, rather than a practical 
one, however, it would be nice to see a more robust system which thwarted 
all attempts to censor without the need for human intervention by 
mirroring sites etc.

I can see no way that a government can censor internal traffic within a 
country, because this need not pass through the proxy, so if we can get a 
copy of a document onto one server within a country all others can access 
it through a virtual URL. However, this is likely to incur the 
displeasure of the authorities in that country and have them knocking at 
the door of the owner of the server holding the document, so we would 
have to have a system for server anonymity. This is all getting very 
complicated ;-)

Anyway, as I have said, I can give no insight here into what is a 
possible solution, I hope that this post might cause someone who does 
have the beginnings of an idea to think about it some more and maybe give 
us a really robust solution to preventing censorship of this kind.
   

        Datacomms Technologies data security
       Paul Bradley, Paul@fatmans.demon.co.uk
  Paul@crypto.uk.eu.org, Paul@cryptography.uk.eu.org    
       Http://www.cryptography.home.ml.org/
      Email for PGP public key, ID: FC76DA85
     "Don`t forget to mount a scratch monkey"

Paul Bradley <paul@fatmans.demon.co.uk> writes:
> The main method used by governments around the world so far to
> attempt to censor information has been the use, or proposal of,
> proxy servers for whole countries or jurisdictions.  This method has
> only thus far been used to censor www connections, and has been used
> to censor specific sites, hence the use of mirroring to circumvent
> government censorship.

One of the main considerations in the design of my eternity server was
the idea that there was information which might get published via
remailers, but would be unlikely to get published on a web page
directly.  Eternity translates the ability of publishing via a
remailer into the ability to publish on the web.

An example is perhaps the NSA handbook, or Mykotronix dumpster diving
results.  These sorts of things tend to arrive via remailer, and then
get mirrored afterwards.

There will also be some class of documents which are too hot to mirror
at all, or where the censor is litigious enough (Scientologists?) to
present a real danger to it's ciritics, and to mirrorers of the
criticisms.

A question then is could a censor systematically block all eternity
search engines effectively.  I think this would be relatively easy,
the design does not really attempt to deal with site blocking
directly.

The URL always includes "eternity" so is easy to block.  You could
perhaps provide an option for a public key encrypted URL.  Or lookup
by the SHA1 of the URL directly.  An SSL session would also help, the
cgi-binary accepts both post and get methods.  However ultimately, the
eternity servers will be advertised, and so the censors just need to
keep track and block all the advertised servers.

However there is another option: all the data is available in USENET
anyway, so anyone can run an eternity search engine for their own use
in a shell account.  To block this is more difficult.

> [blocking USENET, key word searches, recognizing encrypted data]

Use stego solves this (as Bill Frantz observed).  Do a web search on
`texto', it's a nice simple text stego program.

Another interesting fact is that they can't block the traffic unless
they have decrypted it.  As the data can be encrypted with the SHA1 of
the URL, they won't necessarily recognize it as an eternity web page
until it gets accessed or the URL advertised, by which time it is too
late.  The URL can be smuggled in and passed around more readily.

> [a censor can provide a censored USENET feed for their country, they
> can't provide a censored WEB feed because it's too large]

WEB mirroring is useful where the data being mirrored is illegal in
someone else's country and you are trying to stay one step ahead of
the censor.

Eternity means you can publish material which is illegal or
dangerous/unpopular to publish in your own country.  

> [...] it would be nice to see a more robust system which thwarted
> all attempts to censor without the need for human intervention by
> mirroring sites etc.

Sounds like something that could be addressed by building on the
rotating mirror idea William Geiger has been talking about.  Perhaps
you could have an apache module which provided a proxy service which
allows encrypted and steganographically encoded URL passed to it, and
encrypted, stego web pages passed back.  Combine with some unstego
method on the receiving end, and lots of people using apache with this
option turned on, and the censor would have one heck of a problem on
their hands.

Adam
-- 
Have *you* exported RSA today? --> http://www.dcs.ex.ac.uk/~aba/rsa/

print pack"C*",split/\D+/,`echo "16iII*o\U@{$/=$z;[(pop,pop,unpack"H*",<>
)]}\EsMsKsN0[lN*1lK[d2%Sa2/d0<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<J]dsJxp"|dc`

At 10:18 AM -0700 5/13/97, Paul Bradley wrote:
>The proxies idea however can be extended to censor usenet, usenet
>traffic, although pretty huge, is not yet too large to be grep`d for
>keywords (currently around 600mb of traffic a day passes through the
>newsgroups) before being proxied, so a government can run a server which
>first checks to ensure the usenet article is not encrypted (this can be
>done crudely by checking for occurances of common words or by checking
>the redundancy of the text by attempting to compress it) and if it is
>encrypted junks it, if it is plaintext, greps it for keywords like
>"assasination", "anarchy", "porn" etc... then kills the articles that
>have these words in them, the other articles the government does not want
>to censor are put on a main server like news.fourth-reich.de and access
>blocked to all the other news servers.

Obviously you need to stego your message in a post that passes the
automatic censor.  The important question is what is the minimum data
expansion you can get away with?  I see an "arms race" in the making.


-------------------------------------------------------------------------
Bill Frantz       | God could make the world   | Periwinkle -- Consulting
(408)356-8506     | in six days because he did | 16345 Englewood Ave.
frantz@netcom.com | not have an installed base.| Los Gatos, CA 95032, USA