An Efficient Web Traffic Defence Against Timing-Analysis Attacks

Abstract

We introduce a new class of lower overhead tunnel that is resistant to traffic analysis. The tunnel opportunistically reduces the number of dummy packets transmitted during busy times when many flows are simultaneously active while maintaining well-defined privacy properties. We find that the dummy packet overhead is typically less than 20% on lightly loaded links and falls to zero as the traffic load increases i.e. the tunnel is capacity-achieving. The additional latency incurred is less than 100ms. We build an experimental prototype of the tunnel and carry out an extensive performance evaluation that demonstrates its effectiveness under a range of network conditions and real web page fetches.

OpenNym: Privacy preserving recommending via pseudonymous group authentication

“…Of course timing based attacks are not confined to recommender systems and there is, in particular, a growing literature on such attacks against HTTPS traffic and on defenses. Borrowing from this literature, when user traffic can be aggregated, for example by use of a shared VPN, then relatively low amounts of buffering and injection of dummy traffic are sufficient to provably disrupt timing-based attacks 33 and such approaches might usefully be adopted in the present context.…”