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In the background of cloud, self-destructing data mainly aims at protecting the data privacy. All the data and its copies will become destructed or unreadable after a user-specified period, without any user intervention. Besides, anyone cannot get the decryption key after timeout, neither the sender nor the receiver. The Washington's Vanish system is a system for selfdestructing data under cloud computing, and it is vulnerable to "hopping attack" and "sniffer attack". We propose a new scheme in this paper, called SafeVanish, to prevent hopping attacks by way of extending the length range of the key shares to increase the attack cost substantially, and do some improvement on the Shamir Secret Sharing algorithm implemented in the Original Vanish system. We present an improved approach against sniffing attacks by using the public key cryptosystem to protectt from sniffing operations. In addition, we evaluate analytically the functionality of the proposed SafeVanish system.

With the integration of the advanced computing and communication technologies, smart grid system is dedicated to enhance the efficiency and the reliability of future power systems greatly through renewable energy resources, as well as distributed communication intelligence and demand response. Along with advanced features of smart grid, the reliability of smart grid communication system emerges to be a critical issue, since millions of smart devices are interconnected through communication networks throughout critical power facilities, which has an immediate and direct impact on the reliability of the entire power infrastructure. In this paper, we present a comprehensive survey of reliability issues posted by the smart grid with a focus on communications in support of neighborhood area networks (NAN). Specifically, we focus on network architecture, reliability requirements and challenges of both communication networks and systems, secure countermeasures, and case studies in smart grid NAN. We aim to provide a deep understanding of reliability challenges and effective solutions toward reliability issues in smart grid NAN.INDEX TERMS Smart grid, neighborhood area network, reliability. • Communication and system reliability of NAN:We focus reliability issues which mainly come from communication networks and systems, we review those reliability challenges, and provide basics for reliability analysis.• Countermeasures and recovery: To efficiently counter-react reliability issues, it is essential to widely deploy prevention, detection, mitigation, and recovery strategies throughout NAN. Therefore, we present some discussions on existing solutions, including network design and system defense countermeasures, by considering applications in smart grid NAN.• Reliability case studies: Several reliability issues in NAN are investigated and we provide a comprehensive analysis for NAN in smart grid, using fault tree analysis on potential system failures and attack countermeasure tree to identify specific detection and mitigation strategies on malicious cyber attacks to communication systems in NAN. We also conduct a simulation study that the self-healing ability of NAN is enhanced through proper topology design. The simulation study evaluates both reliability and networking efficiency of the communication networks in NAN. The rest of this paper is organized as follows. In Section II, we introduce a fundamental architecture of communication networks in smart grid. In Section III, we present basic concepts for reliability analysis. In Section IV, we present the communication reliability issues and challenges for nodes and links. In Section V, we present the reliability issues and challenges from the NAN systems level. In Section VI, we discuss the countermeasure strategies for NAN reliability. We present case studies and discussions in Section VII. We conclude the paper in section VIII. II. COMMUNICATION ARCHITECTUREIn this section, we present a communication architecture in smart grid networks, with a focus on NAN and AMI, foll...

Maintaining a high overall network reliability remains one of the most critical requirements for advanced metering infrastructures (AMIs) in smart grid. Ensuring reliable networks not only determines the robust communications of an AMI, but also guarantees assured information delivery in the access network. To prevent any communication failures, incremental designs based on legacy networks should be carried out in advance to improve the overall redundancy. Current communication architecture of an AMI follows a traditional access network structure with a tree-based topology, which does not always satisfy high robustness and is prone to network failures. To address the challenge, this study conducts a reliability study of the access network in an AMI. Specifically, this study first examines the basic network topology adopted in an AMI access network and its underlying connectivity issues. Secondly, this study proposes two practical solutions as parts of incremental network design to improve the communication robustness of existing communication architectures. Thirdly, mathematical models are formulated to solve network connectivity problems, for maintaining a high overall network reliability, while minimising the communication deployment cost at the same time. Simulation results are provided from the aspects of minimal path sets and minimal cut sets to demonstrate the redundancy analysis.