Anti-eavesdropping communication layer to protect against traffic analysis

Abstract

In this thesis, we present unicast and multicast protocols to resist eavesdropping and traffic profiling of group communications. At the application layer, we propose a secret-sharing approach for the exchange of shared keys. That is, multicast groups use digital signatures to identify a specific secret-sharing rule, so that nodes in the same group can determine their session keys independently. After the initiation phase to establish group memberships and exchange shared key(s), communicating nodes fragment and shuffle messages into unicast or multicast packets to be transported along different paths. We propose two different transport layer primitives for packet delivery. In the breadth-first approach, packets arrying [sic] scattered message pieces are relayed in two stages across group members. For the depth-first approach, group members are configured into multiple rings, each of which is responsible for delivery of one packet to the destination. In both cases, only nodes that have proper keys can decode them. To resist traffic profiling attacks, all nodes keep the inbound and outbound traffic volumes identical via mixed transport of real and decoy packets. Further protection can be added by making the group identifiers secret.