Florentin Rochet

Florentin Rochet, Olivier Bonaventure, Olivier Pereira

Internet technologies have been designed from guidelines like the robustness principle also known as Postel's law. Jon Postel's law is described as: "Be conservative in what you do, be liberal in what you accept from others." Fundamentally, it advises protocol designs to be tolerant with what they accept from the other peers. We propose to take a step back and wonder how the robustness principle could be revisited to support security requirements as well as unifying flexibility from specifications, protocol design and software implementations. Our goal would be to define a software architecture that offers the benefits of the robustness principle (i.e., efficient network services despite the presence of various software versions), while also guaranteeing that this robustness cannot be exploited by making sure that it is only used to support authentic evolution of the protocol specification.

Florentin Rochet, Olivier Pereira

We present the Waterfilling circuit selection method, which we designed in order to mitigate the risks of a successful end-to-end traffic correlation attack. Waterfilling proceeds by balancing the Tor network load as evenly as possible on endpoints of user paths. We simulate the use of Waterfilling thanks to the TorPS and Shadow tools. Applying several security metrics, we show that the adoption of Waterfilling considerably increases the number of nodes that an adversary needs to control in order to be able to mount a successful attack, while somewhat decreasing the minimum amount of bandwidth required to do so. Moreover, we evaluate Waterfilling into Shadow and show that it does not impact significantly the performance of the network. Furthermore, Waterfilling reduces the benefits that an attacker could obtain by hacking into a top bandwidth Tor relay, hence limiting the risks raised by such relays.