Trade-off between Resiliency and Connectivity for WSN by Unbalanced Key Predistribution

Sensors in wireless sensor networks (WSNs) may collect data and transmit them to backend databases for information storage, analysis, and retrieval. Because sensor nodes are very much vulnerable to various attacks, security in WSN is critical. Key predistribution (KP) is frequently used to establish pairwise keys for secure communication. To enhance the resiliency of node capture attack (NCA), in which attackers capture and compromise nodes to collect keys for eavesdropping communications among other uncompromised nodes, the hash chain based KP (HKP) schemes were accordingly proposed. In the paper, we adopt the unbalanced key predistribution on KP and HKP to realize the unbalanced KP (UKP) and the unbalanced HKP (UHKP). By adjusting the number of nodes with different key ring sizes, we balance the trade-off between the NCA resiliency and the probability of connectivity in WSN. Simulation results demonstrate that our unbalanced key assignment is effective and efficient. Furthermore, we also propose adaptive UKP and UHKP to achieve more flexibility in key predistribution.