Energy Efficient Secure Communication in Wireless Sensor Networks

A Wireless Sensor Network (WSN) consists of sensor nodes which communicate with each other using wireless only, and it is usually deployed over inaccessible regions to collect information from the environment. Today WSNs have many applications, but sensor nodes of WSNs are resource constraint devices, in particular, energy constraint devices. Hence, it is required to minimize the energy consumption of sensor nodes as far as possible. Security in WSNs is also an important requirement since WSNs cannot meet their objectives without having security. Besides, solutions to security problems in WSNs have to meet not only the security goals of WSNs but also consume as minimum energy as possible. Both symmetric key cryptography and public key cryptography have been used to provide solutions to security problems in WSNs. Public key cryptography consumes more energy compared to symmetric key cryptography, but public key cryptography can provide unique identity to each sensor node besides fulfilling other security requirements. In contrast, symmetric key cryptography like encryption and MAC computation is vulnerable to cryptanalysis, and therefore, keys need to be renewed frequently. In this paper, we propose a scheme for energy efficient secure communication between pairs of sensor nodes essentially using symmetric key cryptography ensuring authenticity and integrity of messages. We have used ECC-based public key cryptography only to identify each node uniquely, and to establish initial symmetric keys between pairs of sensor nodes. In the proposed scheme, we make use of a key generation technique to reduce the frequency of key renewals and symmetric key-based Diffie-Hellman key renewal scheme to reduce the energy consumed during key renewals. The proposed scheme has been compared with basic secure communication scheme which uses ECC-based public key cryptography for key renewal. We have carried out the simulation study of the proposed scheme using Cooja simulator for Contiki 3.x operating system, and the simulation results show that the proposed scheme consumes less energy than the basic secure communication scheme