Impact of key pool size with secret key encryption on the lifetime of wireless sensor networks

In Wireless Sensor Networks (WSN) system design, maximizing the network lifetime is one of the most important goals. Optimizing each node's lifetime does not result to the optimal network lifetime, network must be optimized altogether. The lifetime of wireless sensor networks is optimized if the traffic within the network is adjusted in a way that all nodes dissipate their energies in a balanced fashion. To balance the energy dissipation, nodes split their flows and these flows are forwarded to different nodes acting as relays. Security of wireless sensor networks is another important issue in system design. It is important to secure communication of the network against eavesdroppers, node capture attacks, etc. Secure data flow is provided with secret key distribution which enables hop-by-hop security and allows addition and deletion of nodes or keys. A Mixed Integer Programming (MIP) framework is constructed to characterize the impact of key distributions on the lifetime. The results show that the lifetime depends on the probability of sharing at least one key of two nodes due to key ring size and key pool size.