Volume 5, No. 4, April 2014 (Special Issue) International Journal of Advanced Research in Computer Science RESEARCH PAPER Available Online at www.ijarcs.info © 2010-14, IJARCS All Rights Reserved 74 ISSN No. 0976-5697 CONFERENCE PAPER Two day National Conference on Innovation and Advancement in Computing Organized by: Department of IT, GITAM UNIVERSITY Hyderabad (A.P.) India Schedule: 28-29 March 2014 Enhancing the Key Pre-Distribution on Wireless Sensor Networks by Reducing Storage Overhead Manoj R 1 1, Assistant Professor, GITAM University, Hyderabad Campus/IT Dept, Hyderabad, India manojr11@gmail.com,manojr11@gitam.edu, Tripti C 2 2 Assistant Professor,Rajagiri School of Engineering & Technology/CSE Dept, Cochin, Kerala, India tripti84_05@rediffmail.com Y.Md.Riyazuddin 3 3 Assistant Professor, GITAM University, Hyderabad Campus/IT Dept, Hyderabad, India riyazymd@gmail.com. G.Victor Daniel 4 4 Assistant Professor, GITAM University, Hyderabad Campus/IT Dept, Hyderabad, India victordaniel.gera@gitam.edu Abstract: Wireless Sensor Networks (WSNs) are characterized by resource constraints and large scalability. Many applications of WSNs require secure communication, a crucial component especially in hostile environments. However, the low computational capability and small storage budget within sensors render many popular public-key-based cryptographic systems impractical. Symmetric key cryptography, on the other hand, is attractive due to its efficiency. Nevertheless, establishing a shared key for communicating parties is a challenging problem.. Key management is challenging since sensors can land anywhere after deployment. Earlier approaches on key management mostly focus on key pre- distribution where a small number of keys are placed in sensors before deployment. Several symmetric-key pre-distribution protocols have been investigated recently to establish secure links between sensor nodes, but most of them are not scalable due to their linearly increased communication and key storage overheads. To address these limitations, in this paper, different key distribution mechanisms for wireless sensor networks with fixed key storage overhead, full network connectivity, and low communication overhead are proposed. Keywords-Pre-distribution, Deployment, Symmetric key, Storage Overhead I. INTRODUCTION A wireless sensor network (WSN) consists of potentially hundreds of sensor nodes and is deployed in an ad hoc manner for collecting data from a region of interest over a period of time. Typically, a wireless sensor network is composed of a large number of sensors nodes; each sensor node is small, inexpensive wireless device with limited battery power, memory storage, data processing capacity and short radio transmission range. Depending on the equipped sensing units, wireless sensor nodes can measure various physical characteristics, such as sound, temperature, pressure, etc. A number of wireless sensor nodes can be organized into clusters to track a particular object or monitor the surrounding environment in an interested area for encryption in WSNs, keys must be shared between communicating nodes. There is an excessive number of works done on key management in WSNs. The proposed techniques can be grouped into two: symmetric key management schemes, and asymmetric key management schemes. Asymmetric key management schemes are studied in is based on RSA cryptosystem. Elliptic curve cryptography (ECC) is computationally feasible on sensor are asymmetric schemes for sensor networks. Currently, the memory overhead of the public-key cryptography techniques is a barrier to secure most of the WSN applications. As a result, most WSNs use symmetric key schemes since these schemes require less computation time and space than their asymmetric counters do. Symmetric keys are required to be distributed for symmetric key cryptography and key pre distribution has emerged as a promising solution. Random key pre distribution schemes have been proposed for large- scale WSNs. Two straightforward strategies exist to pre-load symmetric keys into sensors. The first one is called master- key approach, in which all the sensors are pre-loaded a unique symmetric key in its memory [6]. After the deployment, every two nodes in the network use the same symmetric key to encrypt/decrypt the exchanged data between them. This approach is extremely efficient since there is no communication overhead for key establishment and only one key is required to be stored in sensors, but it cannot provide sufficient security for wireless sensor networks. In master-key approach [6], even one single node’s capture could compromise the entire network, which is unacceptable for large-scale wireless sensor networks. Another method is pairwise-key based approach. In this approach, a set of symmetric keys are preloaded into each sensor node to make sure any two nodes have a unique key between them. This approach can provide sufficient security since any node’s capture cannot compromise the secure communication between non-captured nodes, but it is not scalable due to its extremely large key storage overhead. For a network composed of n nodes, this approach requires each node stores at least (n-1) keys to ensure any two sensors can establish a secure link. The limited memory size of wireless sensors makes these approaches infeasible for real deployments. Above two straightforward approaches show that key pre- distribution schemes have a tradeoff between the security and the key storage overhead. To achieve sufficient security, a certain number of keys should be pre- loaded in each node; but the limited memory size of tiny sensors, on the other hand, decides that sensors cannot store