24 research outputs found
Conscript Your Friends into Larger Anonymity Sets with JavaScript
We present the design and prototype implementation of ConScript, a framework
for using JavaScript to allow casual Web users to participate in an anonymous
communication system. When a Web user visits a cooperative Web site, the site
serves a JavaScript application that instructs the browser to create and submit
"dummy" messages into the anonymity system. Users who want to send non-dummy
messages through the anonymity system use a browser plug-in to replace these
dummy messages with real messages. Creating such conscripted anonymity sets can
increase the anonymity set size available to users of remailer, e-voting, and
verifiable shuffle-style anonymity systems. We outline ConScript's
architecture, we address a number of potential attacks against ConScript, and
we discuss the ethical issues related to deploying such a system. Our
implementation results demonstrate the practicality of ConScript: a workstation
running our ConScript prototype JavaScript client generates a dummy message for
a mix-net in 81 milliseconds and it generates a dummy message for a
DoS-resistant DC-net in 156 milliseconds.Comment: An abbreviated version of this paper will appear at the WPES 2013
worksho
TASP: Towards anonymity sets that persist
Anonymous communication systems are vulnerable to long term passive "intersection attacks". Not all users of an anonymous communication system will be online at the same time, this leaks some information about who is talking to who. A global passive adversary observing all communications can learn the set of potential recipients of a message with more and more confidence over time. Nearly all deployed anonymous communication tools offer no protection against such attacks. In this work, we introduce TASP, a protocol used by an anonymous communication system that mitigates intersection attacks by intelligently grouping clients together into anonymity sets. We find that with a bandwidth overhead of just 8% we can dramatically extend the time necessary to perform a successful intersection attack
Hang With Your Buddies to Resist Intersection Attacks
Some anonymity schemes might in principle protect users from pervasive
network surveillance - but only if all messages are independent and unlinkable.
Users in practice often need pseudonymity - sending messages intentionally
linkable to each other but not to the sender - but pseudonymity in dynamic
networks exposes users to intersection attacks. We present Buddies, the first
systematic design for intersection attack resistance in practical anonymity
systems. Buddies groups users dynamically into buddy sets, controlling message
transmission to make buddies within a set behaviorally indistinguishable under
traffic analysis. To manage the inevitable tradeoffs between anonymity
guarantees and communication responsiveness, Buddies enables users to select
independent attack mitigation policies for each pseudonym. Using trace-based
simulations and a working prototype, we find that Buddies can guarantee
non-trivial anonymity set sizes in realistic chat/microblogging scenarios, for
both short-lived and long-lived pseudonyms.Comment: 15 pages, 8 figure