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author | Roger Dingledine <arma@torproject.org> | 2003-11-04 06:54:09 +0000 |
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committer | Roger Dingledine <arma@torproject.org> | 2003-11-04 06:54:09 +0000 |
commit | bcbb0bc0d50bc83e8a5cbdd8172d12191abcfbca (patch) | |
tree | 0038f2d3068e12b48af846a05a7bc59d849a1aa8 /doc/tor-design.tex | |
parent | 44ff60dbaac4a35bea203b7c252ad27ddc20e3fc (diff) | |
download | tor-bcbb0bc0d50bc83e8a5cbdd8172d12191abcfbca.tar.gz tor-bcbb0bc0d50bc83e8a5cbdd8172d12191abcfbca.zip |
rerepatches on sec1-3
svn:r747
Diffstat (limited to 'doc/tor-design.tex')
-rw-r--r-- | doc/tor-design.tex | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/doc/tor-design.tex b/doc/tor-design.tex index 0f20d54e5f..a84491dcb2 100644 --- a/doc/tor-design.tex +++ b/doc/tor-design.tex @@ -96,8 +96,8 @@ Routing design: \item \textbf{Perfect forward secrecy:} The original Onion Routing design was vulnerable to a single hostile node recording traffic and later compromising successive nodes in the circuit and forcing them -% XXX Problem: at this point, readers don't know what an onion is. -to decrypt it. Rather than using a single onion to lay each circuit, +to decrypt it. Rather than using a single multiply encrypted data +structure (an \emph{onion}) to lay each circuit, Tor now uses an incremental or \emph{telescoping} path-building design, where the initiator negotiates session keys with each successive hop in the circuit. Once these keys are deleted, subsequently compromised nodes @@ -106,7 +106,7 @@ 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. -\item \textbf{Separation of protocol cleaning from anonymity:} +\item \textbf{Separation of ``protocol cleaning'' from anonymity:} The original Onion Routing design required a separate ``application proxy'' for each supported application protocol---most of which were never written, so many applications were never supported. Tor uses the @@ -269,7 +269,7 @@ about who is talking to whom. The simplest low-latency designs are single-hop proxies such as the {\bf Anonymizer} \cite{anonymizer}, wherein a single trusted server strips the data's origin before relaying it. These designs are easy to -analyze, but require users to trust the anonymizing proxy. +analyze, but users must trust the anonymizing proxy. Concentrating the traffic to a single point increases the anonymity set (the people a given user is hiding among), but can make traffic analysis easier: an adversary need only eavesdrop on the proxy to observe @@ -314,6 +314,7 @@ encryption, so any node on a circuit can read that circuit's traffic. {\bf Hordes} \cite{hordes-jcs} is based on Crowds but also uses multicast responses to hide the initiator. {\bf Herbivore} \cite{herbivore} and {\bf P5} \cite{p5} go even further, requiring broadcast. +% XXX This should be $P^5$ in bold. How to do it? -RD These systems are designed primarily for communication between peers, although Herbivore users can make external connections by requesting a peer to serve as a proxy. @@ -402,7 +403,7 @@ it is a security requirement \cite{econymics,back01}. Tor should therefore not require modifying applications; should not introduce prohibitive delays; and should require users to make as few configuration decisions -as possible. Finally, Tor should be easily implemented on all commonly +as possible. Finally, Tor should be easily implemented on all common platforms; we cannot require users to change their operating system in order to be anonymous. (The current Tor implementation runs on Windows and assorted Unix clones including Linux, FreeBSD, and MacOS X.) @@ -480,11 +481,9 @@ responder. By observing both ends, passive attackers can confirm a suspicion that Alice is talking to Bob if the timing and volume patterns of the traffic on the connection are distinct enough; active attackers can induce timing -signatures on the traffic to \emph{force} distinct patterns. Tor provides -some defenses against these \emph{traffic confirmation} attacks, for -example by encouraging users to run their own onion routers, but it does -% XXX More P2P issues here. -NM -not provide complete protection. Rather, we aim to prevent \emph{traffic +signatures on the traffic to \emph{force} distinct patterns. Tor +does not address these \emph{traffic confirmation} attacks. +Rather, we aim to prevent \emph{traffic analysis} attacks, where the adversary uses traffic patterns to learn which points in the network he should attack. |