Concealed data aggregation in wireless sensor networks: A comprehensive survey

The objectives of concealed data aggregation are to provide end-to-end privacy and en route aggregation of reverse multicast traffic in wireless sensor networks. Privacy homomorphism has been used for realizing these objectives together. Although privacy homomorphism achieves the conflicting objectives, such as privacy and data aggregation, it negatively affects other security objectives such as integrity and freshness. Privacy homomorphism that protects sensor readings from passive adversaries makes them susceptible to active adversaries whose aim is to modify or 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 endto-end integrity verification, and replay protection. We discuss the challenges and their proposed solutions for achieving the conflicting goals such as in-network aggregation, privacy, integrity, and replay protection. We comparatively evaluate the performance of concealed data aggregation protocols for measuring 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.