Combinatorial Design Based Key Pre-distribution Scheme with High Scalability and Minimal Storage for Wireless Sensor Networks

Given the sensitivity of applications and the sensor node's resource constraints, key management is an important security concern in Wireless Sensor Networks (WSNs). Combinatorial Design based schemes are used to propose key pre-distribution in WSNs as they have patterns that can be mapped to the WSNs. We employ Combinatorial Designs to pre-distribute the keys to the sensor nodes. The deployment area is divided into equal-sized regions called cells. The network comprises two types of sensor nodes: ordinary sensor nodes and cell masters. The ordinary sensor nodes within a cell can communicate with each other directly. The inter-cell communication is through the cell masters, which have higher resource capabilities than the ordinary sensor nodes. To take into account the Radio Frequency range of cell masters, we use Lee sphere region around each cell (Ruj in ACM Transactions on Sensor Networks (TOSN) 6:4, 2009, Rui Key predistribution using partially balanced designs in wireless sensor networks, 2007). The proposed key pre-distribution scheme for cell masters provides high network scalability with low key storage overhead compared to other schemes. The model's performance is measured in terms of key storage overhead and the number of sensor nodes supported. A detailed analysis of resiliency in terms of fractions of links disrupted is also presented. Also, the proposed scheme achieved better resiliency and requires much less number of keys to be stored in sensor nodes than the existing schemes.