An efficient key management scheme in hierarchical wireless sensor networks

In this paper, a secure efficient hierarchical key management scheme (SEHKM) for wireless sensor networks is proposed. It satisfies several requirements of WSN. The design of the scheme is motivated by the constraints of sensor networks and high resources cost in traditional key management techniques. The key management scheme supports the establishment of three types of keys to encrypt messages sent among sensor nodes. They are network key, group key and pairwise key. Network key encrypts broadcast messages and authenticates new nodes. Group key is shared by all nodes in the same cluster. Pairwise key is shared with a specific pair of nodes. In hierarchical WSN, cluster heads are very important due to the structure of the network. In order to improve security strength and reduce resource cost and risk after cluster head compromise, an assistant node is introduced in the scheme. SHEKM includes key establishment, key transportation, mechanisms after node operation and dynamical freshness of keys. The evaluation of SEHKM is presented as well as the comparison with some existing key management schemes. The performance analysis and simulation show that SEHKM is very efficient in computation, communication, and storage while the security strength is high.