176 Int. J. Communication Networks and Distributed Systems, Vol. 10, No. 2, 2013 Copyright © 2013 Inderscience Enterprises Ltd. ESF: an efficient security framework for wireless sensor network Somanath Tripathy Department of Computer Science and Engineering, Indian Institute of Technology Patna, Pataliputra Colony, Patna, Bihar, India E-mail: som@iitp.ac.in Abstract: A wireless sensor network (WSN) consists of a large number of resource constrained sensor nodes, usually deployed in hostile environments, where they face a variety of malicious attacks. To address the security vulnerabilities in WSN, this paper proposes an efficient security framework (ESF), which comprises of two security building blocks. The first one security building block is to establish key between the sending and receiving nodes while other component provides confidentiality and integrity of data. Owing to the limited resources available with the sensor nodes, ESF avoids intensive computations like public key cryptography and encryption mechanisms. Analysis of ESF shows that the framework provides a secure environment and resistant against the wireless threats using simple bit-wise operations and cryptographic hash functions. Keywords: wireless sensor network; WSN; security; authentication; cellular automata; CA. Reference to this paper should be made as follows: Tripathy, S. (2013) ‘ESF: an efficient security framework for wireless sensor network’, Int. J. Communication Networks and Distributed Systems, Vol. 10, No. 2, pp.176–194. Biographical notes: Somanath Tripathy received his PhD in Computer Science and Engineering from the Indian Institute of Technology Guwahati in 2007. At present, he is an Assistant Professor at the Indian Institute of Technology Patna. His research interest includes lightweight cryptography, network security, and security issues in resource constrained devices (RFID, sensor networks). He has published more than 20 research papers in journals and conferences. 1 Introduction Wireless sensor network (WSN) (Akyildiz et al., 2002) is a popular technology that plays a vital role in sensing, gathering and disseminating information about environmental phenomena. WSN can be used for a variety of applications (Arora et al., 2004; Burne et al., 2001; Szewezyk et al., 2004) include target tracking in the battle field, habitat monitoring, etc. For different applications there are different technical issues arise. A common WSN comprises of a large number of resource restrained sensor nodes and a powerful base station (BS). The sensor nodes are resource constrained in terms of computational capability, storage capacity and energy, as these are battery powered.