Re: Latency, bandwidth, and anonymity

[Wei Dai <weidai@eskimo.com>]

On Sat, 7 Jan 1995, Timothy C. May wrote:

> The tradeoffs are best analyzed with an actual mathematical model of
> nodes, traffic rates, clumping of traffic, etc., rather than our
> hand-waving here (hand-waving is OK for broad conceptual points, but
> not in cases like this).

Are there any theoritical tools developed especially for this type 
of analysis?  If so, can anyone provide some references?

> I'll be interested in what others calculate, but I think "conversation
> mixes" are several years off, at best. The upcoming demo of Voice PGP
> by Phil Zimmermann (scheduled to appear at the Demo Day meeting next
> Saturday) may be a step in this direction.

Secrecy will of course have to come before anonymity.  I am eagerly 
awaiting Voice PGP, but unfortuanately can't make the Demo Day meeting.  
Will someone please report the highlights?

> In other words, there are economic as well as technologic reasons I
> doubt we'll see low-latency, high-bandwidth audio or video remailers
> anytime soon. (As we're seeing now: short messages can get through in
> tens of seconds, 

So, the situation: high-latency, low-bandwidth e-mail remailers
the goal: low-latency, high-bandwidth interactive A/V type anonymity, but 
this seems too far away

Perhaps we can tackle the problems of latency and bandwidth seperately.  
That is, develop 2 sets of anonymity tools:
1. low-latency, low-bandwidth, for use in textual interactions such as MUD 
and IRC
2. high-latency, high-bandwidth, for non-interactive A/V use, perhaps 
anonymous TV broadcasting

I'm not too familiar with DC-nets, but they can probably be used as 
tool set #1. (correct me if i'm wrong) How about tool set number 2?

> My suspicion is that Alice and Bob cannot defeat traffic analysis
> while ~10K bits per second are flowing continuously between them
> (audio), at least not until _many_ subnetworks are _much_
> faster. Also, the CPU loads would be great (= costly)). Video is even
> further off. Tricks to reduce bandwidth may help.

Indeed, Vinge makes use of such a trick in True Names.  If I remember 
correctly, the technology in the story includes the ability to compress 
full virtualy reality type interactions down to a few hundred bytes per 
second! (maybe is was thousands, but either way it seems unlikely) 
Vinge seems to be a stronger believer of compression.  There is a
similar technology in A Fire Upon the Deep.