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authorNick Mathewson <nickm@torproject.org>2003-11-03 02:09:31 +0000
committerNick Mathewson <nickm@torproject.org>2003-11-03 02:09:31 +0000
commit3c417a80dc2fefd48061a231f5e622ca9431d68a (patch)
tree19abb097e3a7abf0bf9ef2e41adc292bac96c31e /doc
parent2133ece8e403155e0162b92cb83b7e45bc26e587 (diff)
downloadtor-3c417a80dc2fefd48061a231f5e622ca9431d68a.tar
tor-3c417a80dc2fefd48061a231f5e622ca9431d68a.tar.gz
remove/resolve several comments
svn:r724
Diffstat (limited to 'doc')
-rw-r--r--doc/tor-design.tex55
1 files changed, 14 insertions, 41 deletions
diff --git a/doc/tor-design.tex b/doc/tor-design.tex
index 3adff2d2d..6adb79466 100644
--- a/doc/tor-design.tex
+++ b/doc/tor-design.tex
@@ -191,21 +191,6 @@ circuit building, users can notice failed
nodes while building circuits and route around them. Additionally,
liveness information from directories allows users to avoid
unreliable nodes in the first place.
-%We further provide a
-%simple mechanism that allows connections to be established despite recent
-%node failure or slightly dated information from a directory server. Tor
-%permits onion routers to have \emph{router twins}---nodes that share
-%the same private decryption key. Note that because connections now have
-%perfect forward secrecy, an onion router still cannot read the traffic
-%on a connection established through its twin even while that connection
-%is active. Also, which nodes are twins can change dynamically depending
-%on current circumstances, and twins may or may not be under the same
-%administrative authority.
-%
-%[Commented out; Router twins provide no real increase in robustness
-%to failed nodes. If a non-twinned node goes down, the
-%circuit-builder notices this and routes around it. Circuit-building
-%is offline, so there shouldn't even be a latency hit. -NM]
\item \textbf{Variable exit policies:} Tor provides a consistent
mechanism for
@@ -492,14 +477,6 @@ of network traffic; who can generate, modify, delete, or delay traffic
on the network; who can operate onion routers of its own; and who can
compromise some fraction of the onion routers on the network.
-%Large adversaries will be able to compromise a considerable fraction
-%of the network. (In some circumstances---for example, if the Tor
-%network is running on a hardened network where all operators have
-%had background checks---the number of compromised nodes could be quite
-%small.) Compromised nodes can arbitrarily manipulate the connections that
-%pass through them, as well as creating new connections that pass through
-%themselves. They can observe traffic, and record it for later analysis.
-
In low-latency anonymity systems that use layered encryption, the
adversary's typical goal is to observe both the initiator and the
receiver. Passive attackers can confirm a suspicion that Alice is
@@ -1105,7 +1082,6 @@ simplifying assumption that all participants agree on who the
directory servers are. Second, Mixminion needs to predict node
behavior, whereas Tor only needs a threshold consensus of the current
state of the network.
-% Cite dir-spec or dir-agreement?
Tor directory servers build a consensus directory through a simple
four-round broadcast protocol. In round one, each server dates and
@@ -1126,7 +1102,8 @@ signature is not included on the final directory.
The rebroadcast steps ensure that a directory server is heard by
either all of the other servers or none of them, assuming that any two
-directory servers can talk directly, or via a third directory server (some of the
+directory servers can talk directly, or via a third directory server
+(some of the
links between directory servers may be down). Broadcasts are feasible
because there are relatively few directory servers (currently 3, but we expect
to transition to 9 as the network scales). The actual local algorithm
@@ -1150,8 +1127,6 @@ Thus directory servers are not a performance
bottleneck when we have many users, and do not aid traffic analysis by
forcing clients to periodically announce their existence to any
central point.
-% Mention Hydra as an example of non-clique topologies. -NM, from RD
-
\Section{Rendezvous points: location privacy}
\label{sec:rendezvous}
@@ -1343,18 +1318,15 @@ and its resistance to attacks.
outgoing TCP connections by drop-in libraries such as tsocks.
\item[Flexibility:] Tor's design and implementation is fairly modular,
- so that,
- for example, a scalable P2P replacement for the directory servers
- would not substantially impact other aspects of the system. Tor
- runs on top of TCP, so design options that could not easily do so
- would be difficult to test on the current network. However, most
+ so that, for example, a scalable P2P replacement for the directory
+ servers would not substantially impact other aspects of the system.
+ Tor runs on top of TCP, so design options that could not easily do
+ so would be difficult to test on the current network. However, most
low-latency protocols are designed to run over TCP. We are currently
- discussing with the designers of MorphMix interoperability of the
- two systems, which seems to be relatively straightforward. This will
- allow testing and direct comparison of the two rather different
- designs.
- % Do we want to say this? I don't think we should talk about this
- % kind of discussion till we have more positive results.
+ working with the designers of MorphMix to render our two systems
+ interoperable. So for, this seems to be relatively straightforward.
+ Interoperability will allow testing and direct comparison of the two
+ rather different designs.
\item[Simple design:] Tor opts for practicality when there is no
clear resolution of anonymity tradeoffs or practical means to
@@ -1874,7 +1846,8 @@ a unified deployable system. But there are still several attacks that
work quite well, as well as a number of sustainability and run-time
issues remaining to be ironed out. In particular:
-% Many of these (Scalability, cover traffic) are duplicates from open problems.
+% Many of these (Scalability, cover traffic, morphmix)
+% are duplicates from open problems.
%
\begin{tightlist}
\item \emph{Scalability:} Tor's emphasis on design simplicity and
@@ -1919,10 +1892,10 @@ issues remaining to be ironed out. In particular:
and development where we can start deploying a wider network. Once
we have are ready for actual users, we will doubtlessly be better
able to evaluate some of our design decisions, including our
- robustness/latency tradeoffs, our abuse-prevention mechanisms, and
+ robustness/latency tradeoffs, our performance trade-offs (including
+ cell size), our abuse-prevention mechanisms, and
our overall usability.
% XXX work with morphmix spec
-% XXX small cells vs large cells
\end{tightlist}
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