关键词: 隐私保护, 匿名通信, Tor, 网站指纹, 防御

Abstract: Tor is an anonymity system that protects users’ online privacy. However, website fingerprinting (WF) attacks can deanonymize users’ privacy and thus destroy their anonymity protected by Tor. In response, the Tor community has deployed a WF defense framework, called Circuit Padding Framework (CPF) in the Tor network. However, the defense techniques of the CPF framework cannot effectively prevent the most advanced website fingerprinting attack algorithm, TikTok. In this paper, we propose a novel WF defense called BreakPad. Based on BreakPad, we implemented two padding machines called August and October. August is a oneway padding machine, and October is a twoway padding machine. Our results show that, compared to the best padding machine RBB, August, with 18% less bandwidth overhead, further reduces TikTok’s TPR by 2.4%, and October, with 11% less bandwidth overhead, further reduces TikTok’s TPR by 11.3%. The results show that BreakPad is effective against TikTok and outperforms CPF.

Key words: privacy, anonymity system, Tor, website fingerprinting, defense