[freehaven-cvs] clean up the first page some more.

[arma@xxxxxxxx]

Update of /home/freehaven/cvsroot/doc/alpha-mixing
In directory moria:/home/arma/work/freehaven/doc/alpha-mixing

Modified Files:
	alpha-mixing.tex 
Log Message:
clean up the first page some more.


Index: alpha-mixing.tex
===================================================================
RCS file: /home/freehaven/cvsroot/doc/alpha-mixing/alpha-mixing.tex,v
retrieving revision 1.6
retrieving revision 1.7
diff -u -d -r1.6 -r1.7
--- alpha-mixing.tex	10 Mar 2006 02:03:04 -0000	1.6
+++ alpha-mixing.tex	10 Mar 2006 07:24:05 -0000	1.7
@@ -30,7 +30,7 @@
 
 \begin{document}
 
-\title{Blending different latency traffic with alpha-mixing}
+\title{Blending different latency traffic with $\alpha$-mixing}
 %\title{Alpha-mixing or Getting Personal with the Adversary}
 
 \author{Roger Dingledine\inst{1} \and Andrei Serjantov\inst{2} \and Paul Syverson\inst{3}}
@@ -46,24 +46,49 @@
 %======================================================================
 
 \begin{abstract}
+
+Currently fielded anonymous communication systems either introduce
+too much delay and thus have few users and little security, or have
+many users but too little delay to provide protection against large
+attackers. By combining the user bases, 
+
+$\alpha$-mixing is an approach that can be added to traditional
+batching strategies to let senders specify for each message whether they
+prefer security or speed. Here we describe how to add $\alpha$-mixing
+to various mix designs, and show that mix networks with this feature
+can provide increased anonymity for all participants in the network.
+
 \end{abstract}
 
 
 \section{Introduction}
 \label{sec:intro}
 
-Tor exists with its low latency, but not very good security.
-Mixminion exists with its high latency, but very few users. Here we
-design a hybrid batching strategy that tries to put both user bases
-into the same network but still let them achieve their goals.
+Currently fielded anonymous communication systems don't provide
+much protection against a large attacker. Tor~\cite{tor-design} and
+JAP~\cite{web-mixes} have hundreds of thousands of concurrent users,
+but their low latency and low overhead mean they do not defend against
+an adversary who observes most of the network.  At the other end of the
+spectrum, Mixminion's design~\cite{minion-design} theoretically provides
+strong security against a global attacker by adding high variance
+in latency, but this latency has crippled adoption --- which in turn
+decreases the security that the network can provide, discouraging even
+the users who need high security.~\cite{econymics}
 
-In our scheme, the sender communicates
-an alpha -- a security parameter -- to each mix along the route of the
-message. The time the message spends inside each mix and hence the
-anonymity it accumulates then depends on the size of the security
-parameter, and optionally on a few other key variables such as the
-traffic level in the network, the number of messages inside the mix,
-or a random number chosen by the mix.
+Here we design a hybrid batching strategy for mixes that combines users
+with different anonymity and performance goals into the same network.
+
+In our scheme, each sender communicates
+an $\alpha$ -- a security parameter -- to each mix along the route of her
+message. The time the message spends inside each mix (and hence the
+anonymity it accumulates) then depends on the size of the security
+parameter. Our scheme works with any of the standard mix types
+such as timed mixes, pool mixes, etc.~\cite{batching-taxonomy} to
+give each sender more control over the anonymity/performance tradeoff
+of her message.
+% (Depending on the type of mix used, it can also depend on
+%other variables such as the traffic level in the network, the number of
+%messages inside the mix, or a random number chosen by the mix.)
 
 %Alice gives each message an alpha (number of rounds) delay to each mix
 %in a route. Once a threshold number of messages with alpha 0 enter the
@@ -73,24 +98,25 @@
 %messages that enter with alpha $>0$ get put into the buffer with alpha
 %of that number.
 
-The key observation is that when the attacker knows
-little about the security parameters chosen by the individual users,
-everyone can benefit from the mere possibility of doing so. Further,
-users that desire better anonymity have the opportunity to obtain
-it by increasing alpha.
+Users that desire better anonymity have the opportunity to obtain it
+by increasing $\alpha$. More importantly, there is a network effect:
+when the attacker knows little about the security parameters chosen by
+individual users, all senders will benefit
+% (even those that don't choose a high $\alpha$)
+because of the mere \emph{possibility} that they chose a higher $\alpha$.
 
 %Here we also need to say that the attacker does not have complete
 %knowledge of the alphas in the messages, and this is what we are
 %relying on, see the analysis section.
 
-In this paper we proceed as follows: we start by outlining some simple
+In this paper we start by outlining some simple
 alpha mix designs and analyse what anonymity properties they can
 provide to users with different security preferences. Next we
 look at what strategies users should follow when picking their
 security parameters (recall that one is needed for each mix in the
 route of the message).  Thirdly, we look at the incentives users have
-for increasing their security parameter vs expecting others to do so
-(and hence provide more anonymity to everyone). Then we consider more
+for choosing a high security parameter vs.~expecting others to do so
+(which provides more anonymity to everyone). Last we consider more
 sophisticated alpha mixing strategies which should provide better
 properties but are hard to analyse.
 
@@ -111,7 +137,8 @@
 \section{Deterministic-alpha mix}
 \label{sec:deterministic-alpha-mix}
 
-Perhaps the simplest version of alpha mixing is one in which mixes
+The simplest version of alpha mixing uses \emph{timed mixes}:
+the mixes
 fire at regular intervals. This is also most naturally in keeping with
 the motivation to include traffic for which timeliness matters, since
 this cannot be satisfied for threshold mixes (mixes that fire only
@@ -967,10 +994,7 @@
 %
 %======================================================================
 
-
-
 \bibliographystyle{plain}
 \bibliography{alpha-mixing}
 \end{document}
 
-

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