An improved statistical disclosure attack

Abstract

Statistical disclosure attack (SDA) is known to be an effective long-term intersection attack against mix-based anonymising systems, in which an attacker observes a large volume of the incoming and outgoing traffic of a system and correlates its senders with receivers that they often send messages to. In this paper, we further strengthen the effectiveness of this attack. We show, by both an example and a proof, that by employing a weighted mean of the observed relative receiver popularity, the attacker can determine more accurately the set of receivers that a user sends messages to, than by using the existing arithmetic mean-based technique.