In this paper, we propose SeGrid, a secure framework for establishing grid keys in low duty cycle sensor networks, for which establishing a common key for each pair of neighboring sensors is unnecessary since most sensors remain in sleep mode at any instant of time. SeGrid intends to compute a shared key for two grids that may be multihop away. This design explores the fact that for most applications, closer grids have higher probability and desire for secure message exchange. SeGrid relies on the availability of a low-cost public cryptosystem. The query and update of the corresponding public shares are controlled by a novel management protocol such that the closer the two grids, the shorter the distance to obtain each other’s public share. We instantiate SeGrid based on Blom’s key establishment to illustrate the computation of a grid key. Copyright © 2006 Xiuzhen Cheng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1.

We develop a cellular automata (CA) based key management scheme for wireless sensor networks termed CAB. Our proposed scheme allows sensors to establish pairwise keys during any stage of the network operation using pre-loaded CAs. Additionally, CAB has the following nice properties: i) it is computationally efficient because operations can be as simple as bitwise OR and XOR; ii) it achieves quasi-perfect resilience against node compromise because the computed pairwise keys are unique with high probability; iii) it is the first scheme that inherently provides rekeying capabilities.

Abstract—In wireless ad hoc and sensor networks, each node is capable of functioning using only its local information about the environment. However, such a node can reach only locally optimal decisions that may prevent the network from ever reaching the global optimum performance for the given application. To avoid this problem, each node needs to cooperate with others to gain knowledge about the overall network and environment properties so that its decision contributes to the network’s global objectives. This paper models the cooperation between nodes by measuring the level of information sharing between the neighbors. If h-cooperation is applied, each node shares its information with all nodes which are at most h hop away from it. As the cooperation level raises, knowledge of each individual node about its environment increases, thus, it can make better decisions in meeting the main objective of the network application. On the other hand, it also brings extra communication cost and increases the network operation complexity. Therefore, these two contradicting aspects of cooperation cause a cost-quality tradeoff. In this paper, we investigate the effects of this tradeoff in three different types of sensor network applications: (i) finding an efficient sleep schedule based on sensing coverage redundancy (ii) routing in a network with failureprone nodes (iii) routing in a network with a mobile sink node. In all of these applications, we simulated different levels of cooperation and showed significant improvements in the overall system quality when the optimal level of cooperation between the network’s nodes is chosen. I.

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