Sender cover traffic to counter an improved Statistical Disclosure Attack

Abstract

The statistical disclosure attack (SDA) is quite an effective method for attackers to go against an anonymity system and to reveal the information behind it. It targets at a particular anonymity system user, tries to find its sending/receiving relationship with others after a long term observation. In this thesis, we first make an improvement for SDA, using weighted mean instead of the orginal arithmetic mean to calculate the cumulative observed receiver popularity in order to get a more precise value of the attack result. Second, we present an analysis for the effectiveness of the sender generated cover traffic, showing that employing this kind of cover traffic helps little on protecting anonymity system users against a sophisticated attacker. The analysis also validates an earlier empirical result of the ineffectiveness of sender generated cover traffic.