摘要

Many key management schemes were proposed for protecting wireless sensor networks (WSNs). While applying key management to the network, it is important to ensure that the efficiency of the network is not greatly affected by key connectivity. Poor connectivity might lead to many messages forwarding. Consequently, a large amount of energy of the involved nodes would be consumed during message forwarding, which is not suitable for the resources-constraint sensor nodes. In this work, we analyze the impact of key connectivity on the efficiency of communication. Then, a novel key generation method based on system of equations is proposed to improve key connectivity of key management. The involved equations are applied to establish secret keys and each node uses these keys for protecting their communication. The system of equations is constructed to have one and only one solution so that the unique solution can also be used to establish a shared hidden key for enhancing the association among nodes. As a result, neighbors can directly communicate with each other through the shared hidden key even though they do not have common keys. To differentiate from normal keys, keys generated by the proposed method are called associated-keys. According to the analyses, we recommend that systems of linear equations (linear systems) instead of systems of polynomial equations are used to realize the proposed method with respect to the computation complexity. Furthermore, we illustrate that linear systems of two variables are sufficient to generate keys for large scale of networks. The Exclusion Basis System (EBS) is used as a instance to illustrate the implementation of key management with associated-keys. The theoretical analyses and simulation results show that key management schemes with associated-keys have better key connectivity than the corresponding schemes with normal keys. Meanwhile, other performance metrics are unaffected.