Large scale wireless sensor networks with multi-level dynamic key management scheme

Cyber-Physical Systems (CPSs) have emerged as a promising approach to facilitate the integration of the cyber and physical worlds in highly interconnected and complex ways. CPSs consist of several components, such as sensors, actuators, controllers, etc., and their structures are being complicated, and their scales are increasing day by day. Therefore, the data reliability and security have emerged as critical challenges between physical and virtual components of these systems. Wireless Sensor Networks (WSNs) are accepted as one of the most crucial technologies for building future CPSs. Because of their wireless and dynamic nature, WSNs are more vulnerable to security attacks than wired networks. The main solution for this problem is the usage of signed messages with symmetric or asymmetric key cryptography. Although, asymmetric key cryptography increases network security, it also causes severe computational, memory, and energy overhead for sensor nodes. On the other hand, symmetric key cryptography has the difficulty of providing high-level security and efficient key management scheme; however, it is better in terms of speed and low energy cost. In this paper, it is aimed to build a multi-level dynamic key management system for WSNs with the aid of an Unmanned Aerial Vehicle (UAV), which is a key distribution and coordination center for asymmetric keys. After that, each sensor node constructs different symmetric keys with its neighbors, and communication security is achieved by data encryption and mutual authentication with these keys. Evaluation results show the proposed system is scalable, and its performance is significantly better than asymmetric key management systems.