Intra-cluster Key Distribution In Wireless Sensor Networks

The openness of deployment area and restrictions of sensor resources bring threats to wirelesssensor networks (WSNs). Key management is a basic technique for the security issues of WSNs. Inclustered WSNs, because of the huge imbalance in resource capacity between cluster head (CH) andmembers (CM), different key management schemes should be employed in inter-cluster andintra-cluster tiers. Since the cluster head plays as data&control center of a cluster, the inter-clusterkey management received more attention in the past research, while the intra-cluster problem wasusually ignored. However, the ignorance of intra-cluster key management will cause many networkissues such as source data insecurity and node deployment ineffectiveness because intra-clustercommunications work as connectors between base station and sensor nodes.Intra-cluster key management is a challenging because it requires:1) energy efficient for clustermember,2) strong resistance for cluster head,3) high connectivity,4) independence of thebase-station. Many present key management schemes, however, failed to achieve these requirements.In this dissertation, we mainly focus on the proposal of an efficient intra-cluster key managementsolution. Based on secret sharing, the way of distributed storing keys can establish the CH-CMpairwise key independent of base station. Compared with classic group key management schemesbased on the secret sharing, the methods proposed in this work can not only increase the toleranceagainst invasion but also improve the resilience against node capture attack and energy saving of keyrenewals. The main contributions are listed as follows:(1) Proposed a Secret sharing-based Intra-cluster Key Distribution Framework (SS-IKDFramework) for intra-cluster key management, which has the following properties: first, it is optimalin saving the energy consumption of cluster members; second, it reduces communication overheads asit is independent of stations; third, it improves the resilence against node capture attacks andconnectivity as it applied secrect sharing. Through analysis and simulations the SS-IKD is provedhave the following advantages:1) symmetric cryptography-based,2) high intra-cluster connectivity,3)base-station independence,4) heterogeneous.(2) Proposed key management schemes based on SS-IKD：1) Proposed basic intra-cluster key management scheme (B-IKS(v)) and its extension scheme(M-IKS). The first one achieves the lowest energy consumption for sensor nodes and highest resistanceagainst node capture attack while inherits the advantage of dependency, energy saving, connectivityand security properties of SS-IKD. In the second one we provides parameters u、v to adjust networksconnectivity properties (after captured) and resistant against node capture attacks. 2) Proposed key management scheme based on single cluster head (S-IKS). In this scheme theresistance property against node capture attacks are improved through dividing key into key pieces,thus the attacker can only obtain parts of the keys. Through simulations it is proved full resistanceagainst node capture attack can be achieved with few cluster calculations added.3) Proposed key management scheme based on group deploy model (DM-IKS(d)) and its extension(DM-IKS (u,v)). In these schemes the key storage and negotiation efficiency are improved. Throughsimulations, it is proved that these schemes not only inherit the advantages of connectivity and security,and also improve the efficiency of the key-reconstruction to d times of the B-IKS scheme.In summary, this work studies the key management schemes for intra-clusters in hierarchicalWSNs, the works are theoretical valuable and has application potentials.