CS-BuFLO

Abstract

Website fingerprinting attacks enable an adversary to infer which website a victim is visiting, even if the victim uses an encrypting proxy, such as Tor. Previous work has shown that all proposed defenses against website fingerprinting attacks are ineffective. This paper advances the study of website fingerprinting defenses by first laying out the complete specifications of the CS-BuFlo scheme outlined by Cai, et al. CS-BuFlo, which is based on the BuFlo defense proposed by Dyer, et al., was not fully-specified by Cai, et al, but has nonetheless attracted the attention of the Tor developers. Next, a full working implementation of CS-BuFlo is provided. Finally, a thorough evaluation of CS-BuFlo is performed using empirical data (rather than data from simulations). Our experiments find that CS-BuFlo has high overhead (around 2.3-2.8x) but can get 6times closer to the bandwidth/security trade-off lower bound than Tor or SSH.