ABSTRACT Key revocation plays an essential role in ensuring the confidentiality of wireless sensor networks following the compromise of one or more of the network nodes. The distributed key revocation protocol presented by Chanet al. has a rapid reaction time and avoids the single‐point failure problem inherent in centralized schemes. However, the scheme is computationally complex, requires a large storage space, and incurs high communication overheads. Accordingly, this paper proposes a novel distributed, scalable, and cost‐effective key revocation scheme based on Blom'st‐secure property. In the proposed approach, any node identified as having a malicious behavior bytor more sensor nodes is categorized as a compromised node, and its keys are immediately revoked from the entire network. The proposed scheme not only satisfies the rigorous definition of a distributed key revocation protocol but also yields a significant improvement over Chan's revocation scheme in terms of a lower storage space requirement, a reduced communication overhead, and a lower computational cost. Copyright © 2013 John Wiley & Sons, Ltd.

As underwater monitoring technology is well-developed, the underwater sensor network plays an important role for the exploration of the oceans. But there exist possible risks of sensor nodes being captured by adversaries and the transmissions in the underwater communication being illegally accessed. As a result, it is vital to take the security issue into account in such an underwater mobile sensor network. In this paper, our goal is to propose a key distribution scheme adequate for underwater mobile sensor networks. We adopt a mobility model to capture the movement of the sensors floating on the sea. Our key distribution scheme is designed to fit the characteristics of the sensors’ movement, and hence the connection and security can be improved in underwater sensor networks. Our scheme can also reduce redundant keys in the key distribution system. We also propose a secure routing method based on the Focused Beam Routing Protocol to adapt to our proposed iterative key distribution scheme. The simulation results show that our scheme possesses better performance, including better local connectivity, availability of path key, resilience and routing results.

Two-layer hierarchy unstructured peer-to-peer (P2P) systems, comprising an upper layer of superpeers and an underlying layer of ordinary peers, are commonly used to improve the performance of large-scale P2P systems. However, the optimal superpeer network design involves several requirements including superpeer degree, network diameter, scalability, load balancing, and flooding performance. A perfect difference graph has desirable properties to satisfy the above design rationale of superpeers overlay network. This paper proposes a two-layer hierarchical unstructured P2P system in which a perfect difference graph (PDG) is used to dynamically construct and maintain the superpeer overlay topology. In addition, the broadcasting performance of the P2P system is enhanced through the use of a PDG-based forwarding algorithm, which ensures that each superpeer receives just one lookup query flooding message. The theoretical results show that the proposed system improves existing superpeer hierarchical unstructured P2P systems in terms of a smaller network diameter, fewer lookup flooding messages, and a reduced average delay, and the experimental results show that the proposed two-layer hierarchy P2P system performs very well in the dynamic network environment.

Peer-to-peer (P2P) content distribution systems based on random linear combination coding schemes outperform traditional block forwarding and source coding systems but have large storage requirements and high computation and communication overheads. To resolve this problem, this paper presents an efficient and scalable P2P content dissemination system based on novel altruistic demand and recoding dissemination mechanisms. In the proposed approach, the shared-content file is segmented and encoded using Reed–Solomon code at a seed. Downstream peers wishing to obtain the file utilize an altruistic demand mechanism to issue demand requests for coded blocks which are useful not only to themselves but also to their neighbors. Upon receiving these requests, the upstream peers utilize a recoding dissemination mechanism to provide the downstream peers with either an existing useful coded block or a new coded block produced using a Lagrange polynomial interpolation method. The two mechanisms rapidly increase the diversity of the coded blocks within the network and therefore provide an effective solution to the missing last block problem. In addition, it is shown that the proposed content distribution system demonstrates a substantial improvement over P2P systems based on random linear combination coding in terms of a lower storage requirement, reduced computation and communication costs, and an improved download efficiency.