Effectively and Efficiently Defending Shadowsocks against Website Fingerprinting Attacks

Shadowsocks is one of the most popular encryption proxies. It is designed with few defense methods against website fingerprinting attack (WFP). WFP can identify user accessed websites by analyzing Shadowsocks traffic. Existing studies defending Shadowsocks against WFP generally pad or insert packets to minimize statistical differences between accesses to different websites. They can achieve promising denfense effects, yet at the cost of large time delay and bandwidth overhead. Therefore, it is necessary to design an effective and efficient algorithm to defend Shadowsocks against WFP. In this paper, we propose two algorithms, namely, PadS and PadI, which are based on the size and the true distribution of time series of traffic data packets, respectively. The results show that PadI and PadS can substantially degrade the attack performance while reducing bandwidth consumption to 34% and 32%, respectively, and the combination of the two algorithms outperforms existing defense algorithms.