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give us a real abstract

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Roger Dingledine 2003-11-03 06:29:43 +00:00
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doc/tor-design.tex
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@ -51,16 +51,14 @@
\begin{abstract}
We present Tor, a circuit-based low-latency anonymous communication
system. Tor is the successor to Onion Routing
and addresses various limitations in the original Onion Routing design.
Tor works on the real-world Internet, requires no special
privileges such as root- or kernel-level access,
requires little synchronization or coordination between nodes, and
provides a reasonable trade-off between anonymity, usability, and efficiency.
We include a new, more practical design for rendezvous points, and
close with a list of open problems in anonymous communication systems
today.
% Which other innovations from section 1 should we mention in the abstract?
system. This second-generation Onion Routing system addresses limitations
in the original design. We add perfect forward secrecy, congestion
control, directory servers, integrity checking, variable exit policies,
and a practical design for rendezvous points. Tor works on the real-world
Internet, requires no special privileges or kernel modifications, requires
little synchronization or coordination between nodes, and provides a
reasonable trade-off between anonymity, usability, and efficiency. We
close with a list of open problems in anonymous communication systems.
\end{abstract}
%\begin{center}
@ -109,8 +107,6 @@ As a side benefit, onion replay detection is no longer
necessary, and the process of building circuits is more reliable, since
the initiator knows when a hop fails and can then try extending to a new node.
% Perhaps mention that not all of these are things that we invented. -NM
\item \textbf{Separation of protocol cleaning from anonymity:}
The original Onion Routing design required a separate ``application
proxy'' for each
@ -135,11 +131,12 @@ circuit, to improve efficiency and anonymity.
\item \textbf{Leaky-pipe circuit topology:} Through in-band signalling
within the circuit, Tor initiators can direct traffic to nodes partway
down the circuit. This allows for long-range padding to frustrate traffic
shape and volume attacks at the initiator \cite{defensive-dropping}.
Because circuits are used by more than one application, it also allows
traffic to exit the circuit from the middle---thus frustrating traffic
shape and volume attacks based on observing the end of the circuit.
down the circuit. This novel approach allows both for long-range
padding to frustrate traffic shape and volume attacks at the initiator
\cite{defensive-dropping}, and, because circuits are used by more than one
application, allows traffic to exit the circuit from the middle---thus
frustrating traffic shape and volume attacks based on observing the end
of the circuit.
\item \textbf{No mixing, padding, or traffic shaping:} The original
Onion Routing design called for batching and reordering the cells arriving
@ -216,14 +213,14 @@ long-lived ``reply onions'' that could be used to build virtual circuits
to a hidden server, but these reply onions did not provide forward
security, and would become useless if any node in
the path went down or rotated its keys.
In Tor's current design, clients negotiate {\it
In Tor, clients negotiate {\it
rendezvous points} to connect with hidden servers; reply onions are no
longer required.
\end{tightlist}
We have implemented most of the above features. Our source code is
available under a free license, and is not (as far as we can tell)
encumbered by patents. We have
available under a free license, and we believe it to be
unencumbered by patents. We have
recently begun deploying a widespread alpha network to test
the design in practice, to get more experience with usability and users,
and to provide a research platform for experimenting with new ideas.
@ -242,9 +239,9 @@ work for the Onion Routing project in Section~\ref{sec:conclusion}.
\Section{Related work}
\label{sec:related-work}
Modern anonymity systems date to Chaum's Mix-Net\cite{chaum-mix} design of
1981. Chaum proposed hiding sender-recipient connections by wrapping
messages in layers of public key cryptography, and relaying them
Modern anonymity systems date to Chaum's Mix-Net\cite{chaum-mix}. Chaum
proposed hiding the correspondence between sender and recipient by
wrapping messages in layers of public key cryptography, and relaying them
through a path composed of ``Mixes.'' These mixes in turn decrypt, delay,
and re-order messages, before relaying them along the sender-selected
path towards their destinations.