Re: Remailers and ecash

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Bill Stewart wrote:
>Latency is essential to security, though high volume reduces the
>latency that's needed to get a given level of security.

Latency may be a means to get security in the current remailer design,
but it is a means to the end and not the end itself.  This doesn't
mean we shouldn't use latency to get security, but it is undesirable,
like using cinderblocks for construction.  The reason I point this out
is that it is important to separate design choices to achieve a goal
from the goal itself.

If we had a remailer network in which each customer had a constant
bandwidth connection to one or more remailers, you could have zero
latency mail. (Actually, this would be nice to use with those Comsec
phones.)

It is my understanding that serious naval vessels like aircraft
carriers use constant bandwidth channels to defeat traffic analysis.
That is, to every place they might wish to communicate, they
continuously broadcast encrypted information.  Most of the time the
channel is empty, of course, but nobody outside can tell when.

Monty Cantsin
Editor in Chief
Smile Magazine
http://www.neoism.org/squares/smile_index.html
http://www.neoism.org/squares/cantsin_10.html

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At 2:03 AM -0700 10/1/97, Robert A. Costner wrote:

>Let me get this straight.  You are suggesting that anyone who wishes to be
>anonymous should send a continuous 24 hour stream of low bandwidth data to
>a central point in an effort to help keep anyone from knowing that they
>wish to be anonymous.

He was describing how a constant-traffic pipe defeats "sudden burst of
activity" types of traffic analysis. (As, for example, when nightime
activity in the White House is signalled by deliveries of lots of pizzas.)

In fact, this constant traffic approach is the basis of PipeNet, proposed
and described by Wei Dai, and, I think, being implemented.

Obviously not everyone will want this, or want to pay for it, etc. Nothing
surprising there. But some may. In particular, it makes more economic
sense for sites already full-time on the Net, e.g., remailers not on
dial-up lines. (And even on dial-up lines, a call every hour, with a packet
of traffic, can implement this cover traffic scheme, albeit in a different
form.(

>
>While this may help correct the latency problem, how do you think this will
>effect anonymity?  Do you think that by sending a continuos stream of data
>to the remailer, the sender will be less identifiable?

Again, _latency_ per se is not important, _mixing_ is.

As I understand your example above, the sender becomes less identifiable
because he can always be counted on to send some packets; an attacker
cannot see a message after a long period of no messages and correlate it to
a similar sudden increase of activity at a possible recipient machine.

Traffic analysis is something you should look at. And think about.

--Tim May


The Feds have shown their hand: they want a ban on domestic cryptography
---------:---------:---------:---------:---------:---------:---------:----
Timothy C. May              | Crypto Anarchy: encryption, digital money,
ComSec 3DES:   408-728-0152 | anonymous networks, digital pseudonyms, zero
W.A.S.T.E.: Corralitos, CA  | knowledge, reputations, information markets,
Higher Power: 2^2,976,221   | black markets, collapse of governments.
"National borders aren't even speed bumps on the information superhighway."

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In <v03102803b05829bdf10b@[207.167.93.63]>, on 10/01/97 
   at 09, Tim May <tcmay@got.net> said:

>At 2:03 AM -0700 10/1/97, Robert A. Costner wrote:

>>Let me get this straight.  You are suggesting that anyone who wishes to be
>>anonymous should send a continuous 24 hour stream of low bandwidth data to
>>a central point in an effort to help keep anyone from knowing that they
>>wish to be anonymous.

>He was describing how a constant-traffic pipe defeats "sudden burst of
>activity" types of traffic analysis. (As, for example, when nightime
>activity in the White House is signalled by deliveries of lots of
>pizzas.)

In Ian Slater's book Showdown such "burst activity" was put to use. In
order to find where the rebel headquarters was located rummors were spread
that the rebel leader was dead. Soon afterwards there was an increase in
radio trafic from the headquarters in an attempt to kill the rummors
thereby giving away their location as the "sudden burst of activity" stood
out like a sore thumb over the normal radio traffic.

- -- 
- ---------------------------------------------------------------
William H. Geiger III  http://www.amaranth.com/~whgiii
Geiger Consulting    Cooking With Warp 4.0

Author of E-Secure - PGP Front End for MR/2 Ice
PGP & MR/2 the only way for secure e-mail.
OS/2 PGP 2.6.3a at: http://www.amaranth.com/~whgiii/pgpmr2.html                        
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At 09:59 AM 10/1/97 +0200, Anonymous (Monty Cantsin) wrote:
>It is my understanding that serious naval vessels like aircraft
>carriers use constant bandwidth channels to defeat traffic analysis.
>That is, to every place they might wish to communicate, they
>continuously broadcast encrypted information.  Most of the time the
>channel is empty, of course, but nobody outside can tell when.
>
>If we had a remailer network in which each customer had a constant
>bandwidth connection to one or more remailers, you could have zero
>latency mail.

Let me get this straight.  You are suggesting that anyone who wishes to be
anonymous should send a continuous 24 hour stream of low bandwidth data to
a central point in an effort to help keep anyone from knowing that they
wish to be anonymous.  

While this may help correct the latency problem, how do you think this will
effect anonymity?  Do you think that by sending a continuos stream of data
to the remailer, the sender will be less identifiable?


  -- Robert Costner                  Phone: (770) 512-8746
     Electronic Frontiers Georgia    mailto:pooh@efga.org  
     http://www.efga.org/            run PGP 5.0 for my public key