Concealed data aggregation in wireless sensor networks: A comprehensive survey

The objectives of concealed data aggregation are end-to-end privacy preservation and en route aggregation of reverse multicast traffic in wireless sensor networks. Privacy homomorphism has been used to realize these objectives together. Although privacy homomorphism helps in achieving conflicting objectives, namely, privacy and data aggregation, it negatively affects other security objectives such as integrity and freshness. Privacy homomorphism, which protects sensor readings from passive adversaries, makes sensor readings vulnerable against active adversaries whose aim is to modify or to inject malicious data packets in the network. In this article, we present a comprehensive survey of the state-of-the-art concealed data aggregation protocols in wireless sensor networks. We investigate the need for en route aggregation, encrypted data processing, en route and end-to-end integrity verification, and replay protection. We discuss the challenges and their proposed solutions that achieve the conflicting objectives, such as in-network aggregation, privacy, integrity, and replay protection, together. We comparatively evaluate the performance of concealed data aggregation protocols to measure their respective strengths and weaknesses. In addition, we provide a detailed insight into the open research issues in concealed data aggregation and conclude with possible future research directions.