[freehaven-dev] Differences between Tarzan and freedom.net

[Roger Dingledine <arma@mit.edu>]

* Cost: we want to provide an anonymizing network which is free to use,
so people don't have to deal with paying US currency for the service.

* Free: not all of the code from Freedom is available for use in any
environment, or easy extension and redistribution.

* Ease of understanding/extension: we want to make sure that the design
-- and the code -- are simple, so people can understand what's going
on and can easily add experimental extensions (e.g., micropayment or
reputation protocols).

* Freedom has more reliable paths, nodes, and performance, because
they have a small number of highly reliable nodes (commercially run).
Tarzan has a large number of unreliable nodes, so it's much trickier to
ensure high quality service. Thus Tarzan's success is based much more
on getting the above extensions to work 'well enough'.

* User experience emphasis: Freedom is designed to be useful to ``normal
people'' so ZKS can make money -- a lot of the emphasis is on transparent
integration into the user-side. Tarzan, on the other hand, focuses on
building a back-end infrastructure. Other people might write front-ends
down the road, for *applications* that are layered on top of Tarzan.

* Speed: Tarzan is meant to be an experimental network, so reliable,
consistently good performance isn't as relevant yet. Further, since
Freedom works at the kernel tcp stack level, it will be faster and more
efficient. Similarly, Freedom distributes routing tables to its nodes,
so they only connect to nodes which are ``close'' to them in the network
(this is a standard networking thing). We trade this speed for simplicity
and decentralized design.

* Different levels of user-behavior-based anonymity: if you use Freedom,
it tunnels all your IP packets through the anonymized network. Tarzan
only anonymizes one specific tcp stream (per connection), meaning you
have to be aware of how your connections and applications are behaving
lest you accidentally reveal (hints about) your identity.

* Two-way anonymized connections: while Freedom is designed to be one-way,
Tarzan is designed to support two-way anonymization (via meeting places).
That is, Tarzan can handle pseudonymous ``servers'', even when they're
behind NATs and firewalls.

* Tarzan has no centralized control (ZKS can cancel your nyms). Conspiracy
theorists might like this, but I think it's not very relevant in the
big picture. Also, centralized control means that ZKS has a realistic
mechanism in place to handle abuse issues, whereas we currently ignore
them. (Note: ignoring them is a bad idea long-term.)

Any others I've missed?
--Roger