Hang With Your Buddies to Resist Intersection Attacks
David Isaac Wolinsky, Ewa Syta, Bryan Ford · 2013
Some anonymity schemes, such as DC-nets and MIX cas-cades, can guarantee anonymity even against traffic analysis— provided messages are independent and unlinkable. Users in practice often desire pseudonymity—sending messages inten-tionally linkable to each other but not to the sender—but pseudonymity in dynamic networks exposes users to inter-section attacks. We present Buddies, the first systematic at-tempt to offer intersection attack resistant pseudonyms in practical anonymity systems. Buddies groups users dynam-ically into buddy sets, controlling message transmission to make buddies within a set behaviorally indistinguishable to a traffic-monitoring adversary. Intersection attack resistance does not come “for free, ” of course, and Buddies offers users control over the inevitable tradeoffs between anonymity, la-tency, and the useful lifetime of a pseudonym.