Debojyoti Bhattacharya

Reliable and secure broadcast communication over resource constrained systems

Compute platforms for wireless sensor networks and Vehicle-to-Vehicle (V2V) communications employ random channel access for message transmission and typically suffer from limited processing capability and on-board memory on a per-application basis because of the multiple processes going on in parallel. Appending digital signatures to transmitted messages in such systems increases information reliability, but requires an intemperate use of scarce resources, more so with an increased security requirement. n nIt thus appears imperative to tradeoff security for network performance to conserve scarce resources for a given resource constrained platform. This requires a good understanding of the communication performance of these systems. We observe that resource constraints in these systems induce complex interaction between the security and MAC layers at a node, obviating the possibility of layer specific optimizations to improve system performance for broadcast applications. For example, reducing the channel access probability at the MAC layer reduces collision probabilities, in turn increasing the verification load on the security layer. There is hence a need to take a holistic approach to dimension such systems to improve performance. In achieving this objective, we provide: n n• an analytical framework to model these systems with or without an impersonation attacker. This analysis also takes into consideration the possibility of multiple digital signatures being attached to a message, so that the receiver has a choice of verifying one of these. n n• a characterization of the stability region of the system. n n• an information-theoretic approach towards reliable communication of application data over these systems. We view the combination of security-MAC-security layers as an erasure channel and provide attainable rates, jointly optimizing on sampling rate and channel transmission rate.