Identity and Pairing-based Secure Key Management Scheme for Heterogeneous Sensor Networks Sk. Md. Mizanur Rahman Department of Computing and Information Science, University of Guelph, Guelph, Ontario, N1G, Canada srahman@uoguelph.ca Nidal Nasser Department of Computing and Information Science, University of Guelph, Guelph, Ontario, N1G, Canada nasser@cis.uoguelph.ca Kassem Saleh Department of Information Science College for women Kuwait University 13060 Safat, Kuwait k.saleh@cfw.kuniv.edu Abstract���Key management poses a main concern for security operation in sensor network. Most existing key management schemes try to establish shared keys for all pairs of neighbor sensors, no matter whether these nodes communicate with each other or not, and causes large overhead. Recent trend of research mainly consider homogeneous sensor network and a few consider heterogeneous sensor network for key management. In this paper, we consider heterogeneous sensor network (HSN) as a model for our proposed novel key agreement protocol based on pairing identity based encryption (IBE). The proposed scheme reduces the key spaces of the nodes, in fact nodes do not need to store any key of the other nodes rather it computes secret sharing key by using pairing and IBE properties. Security analysis shows, it also robust against different attacks such as replay attack, masquerade attack, and integrity attack. Keywords- Key management, Heterogenous sensor netwoek, Pairing-based cryptograpgy. I. INTRODUCTION Recent progresses of research in key agreement protocol for sensor networks consider mainly homogeneous sensor networks, where all sensor nodes have the same capabilities. However, a homogeneous ad hoc network suffers from poor performance. Research has demonstrated its performance bottleneck both theoretically [1], [2] and through simulation experiments and test bed measurements [3]. Some recent work (e.g., [4], [5], and [6]) has studied Heterogeneous Sensor Networks (HSNs), where sensor nodes have different capabilities in terms of communication, computation, energy supply, storage space, reliability and other aspects. Security is critical to sensor networks deployed in hostile environments, such as military battlefield and security monitoring. The paper by Du et al. [8] has studied the security issues in sensor networks, and it mainly proposed a key management scheme for a heterogeneous network. Key management is an essential cryptographic primitive upon which other security primitives are built. Due to resource constraints, achieving such key agreement in wireless sensor networks is non-trivial. In [6], Eschenauer and Gligor present a key management scheme based on probabilistic key pre- distribution for sensor networks. Several other key pre- distribution schemes have been proposed (e.g., [7]). Probabilistic key pre-distribution is a promising scheme for key management in sensor networks. To guarantee that such schemes work properly, the probability that each sensor shares at least one key with a neighbor sensor (referred to as key- sharing probability) should be high. For the key pre- distribution scheme in [6], each sensor randomly selects its key ring from a key pool of size P. When the key pool size is large, each sensor needs to pre-load a large number of keys to achieve a high key-sharing probability. For example, when P is 10,000, each sensor needs to pre-load more than 150 keys [8] for a key-sharing probability of 0.9 [6]. If the key length is 256 bits, then 150 keys require a storage space of 4,800 bytes. Such a storage requirement is too large for many sensor nodes. For example, a smart dust sensor [9] has only 8K bytes of program memory and 512 bytes of data memory. The above discussion shows that many existing key management schemes require a large storage space for key pre-distribution and are not suitable for small sensor nodes. In [8], heterogeneous sensor network (HSN) key management scheme is discussed, based on elliptic curve public/ private key sharing. But it still needs to preload 2 or more public/ private key pair depending on the leaf nodes either they know their root nodes or not at the bootstrap of the network, which is inconvenient for deployment. In addition, nodes of the network need to know the tree structure of the network before deployment. In this paper, we present an efficient key management scheme where the nodes need to know only its own secret part of a secret key based on identity based encryption (IBE) and pairing-based cryptography. Hence, this scheme reduces key space and communication overhead comparing to the existing protocol. For efficient key management in sensor networks, key management scheme only needs to set up shared keys for each sensor and its communication neighbors, i.e., it does not need to set up shared with all of its neighbor sensors. The new scheme can significantly reduce the overhead of key establishment in sensor networks by establishing secret key between the communication neighbor nodes either between leaf node to leaf node or between leaf nodes to cluster head node. Thus, secret key established in a hierarchical fashion among the nodes in the network. Therefore, the new scheme can significantly reduce communication and computation overheads, and hence reduce sensor energy consumption. IEEE International Conference on Wireless & Mobile Computing, Networking & Communication 978-0-7695-3393-3/08 $25.00 �� 2008 IEEE DOI 10.1109/WiMob.2008.79 423