PG: Byzantine Fault-Tolerant and Privacy-Preserving Sensor Fusion with Guaranteed Output Delivery

We design and implement PG, a Byzantine fault-tolerant and privacy-preserving multi-sensor fusion system. PG is flexible and extensible, supporting a variety of fusion algorithms and application scenarios. On the theoretical side, PG develops and unifies techniques from dependable distributed systems and modern cryptography. PG can provably protect the privacy of individual sensor inputs and fusion results. In contrast to prior works, PG can provably defend against pollution attacks and guarantee output delivery, even in the presence of malicious sensors that may lie about their inputs, contribute ill-formed inputs, and provide no inputs at all to sway the final result, and in the presence of malicious servers serving as aggregators. On the practical side, we implement PG in the client-server-sensor setting. Moreover, we deploy PG in a cloud-based system with 261 sensors and a cyber-physical system with 19 resource-constrained sensors. In both settings, we show that PG is efficient and scalable in both failure-free and failure scenarios.