Moving Tor Circuits Towards Multiple-Path: Anonymity and Performance Considerations

In this paper, we show how multiple-path in the transport layer could be used to increase performance and anonymity of the Tor network. The balance between anonymity and performance when creating circuit is a key to improve the situation regarding the well-known problem of end-to-end traffic correlation attack by relay adversaries. We show that the current Tor path selection algorithm heavily balances towards performance in order to make the Tor network usable. Anonymity is not principally related to the number of nodes being in the network, therefore we provide some metrics that can capture more precisely the anonymity of the Tor network regarding relay adversaries. We show that our multiple-path strategies improve both client performance and anonymity at the cost of a server-side load increase. Finally, we discuss a possible architecture of Tor using Multipath-TCP, a TCP extension allowing multiple-path in the transport layer.