MAC aggregation protocols resilient to DoS attacks

In smart grid, sensor measurements are often sent to a control node over a hop–by–hop network of sensors themselves. To prevent en route accidental and malicious data corruption, each message is authenticated with a MAC, keyed with a symmetric key known to the generating sensor and the control node. MACs represent a significant overhead: a typical 128–bit MAC may often authenticate a 10–bit temperature reading. To mitigate these overheads, MAC aggregation methods were proposed. However, previously proposed MAC aggregation schemes are not resilient to Denial–of–Service (DoS) attacks, where a rogue node or a man–in–the–middle attacker can easily disrupt the entire set of MACs, and hence prevent using any of the transmitted data. In this work we propose a new way of MAC aggregation, which will allow the relay sensors to greatly reduce transmission overhead due to MACs, while achieving full unforgeability, and, simultaneously, much stronger resilience to DoS attacks.