An Enhanced interoperability Framework for Smart Grids Analyzing Vulnerabilities and Designing Secured Collaboration
- 주제(키워드) security
- 발행기관 고려대학교 대학원
- 지도교수 김황남
- 발행년도 2012
- 학위수여년월 2012. 2
- 학위구분 석사
- 학과 일반대학원 전기전자전파공학과
- 원문페이지 45 p
- 실제URI http://www.dcollection.net/handler/korea/000000033762
- 본문언어 영어
- 제출원본 000045696969
초록/요약
Chapter 1 Introduction Smart Grid is the new power grid whose adaptive control capability is accelerated and enhanced by communication networks since the networks enable interactive communications between power generators and customers. The Smart Grid is a huge combination of networks and domains. Fig. 1.1 shows a whole design of the potential Smart Grid. As shown in the figure, the Smart Grid consists of seven domains: Bulk Generation, transmission, Distribution, Market, Service Provider, Operation, and Customers [1]. The Customer domain can be further classified into home, building and industrial sub-domain [1-3]. Each domain can have its own network infrastructure; for instance, as for transmission domain, there is the networking infrastructure for Supervisory Control and Data Acquisition (SCADA); as for distribution, there is a network for distribution automation (DA); as for residential customer, there is a home area network. Those domains are interconnected with each other via allocated private networks or public networks such as Internet. Especially, the interaction between the Customer domain and other domains is realized through Advanced Metering Infrastructure (AMI). The AMI system is a primary component of realizing bi-directional information com- munication in the Smart Grid. As above mentioned, all the componens of the Smart Grid can be interconnected to each other, and consequently one point that is vulnerable to security at 3 Figure 1.1: The 6 domains are connected via various communication networks. tacks may cause the whole system to be susceptible to the attacks. Therefore the Smart Grid is supposed to address possible security attacks with various security schemes; a privacy (confidentiality) scheme between communicating peers, an integrity scheme for protecting command and data from malicious modifications and changes, an authentication scheme for identifying communication parties, and a non-repudiation scheme for addressing the denial of information or services. It is very important to examine various domains and actors in the Smart Grid, identify the security issues and challenges that are unique in the Smart Grid, and then explain possible solutions that can be used to address each discovered security issue. In order to construct the intra-domain networks and inter-domain networks, the Smart Grid can employ various communication infrastructures such as wireless mesh networks (WMN), virtual private networks (VPN), WiFi hot-spots, public switched telephone network (PSTN), sensor networks, and nation-wide cellular/data networks, such as WiMAX-based or LTE-4 based networks [4]. Even though those networks are also available for the AMI system, IEEE 802.11-based wireless mesh networks (WMN) draw much attention in the community because of its flexibility and robustness [5]. In the Smart Grid, various types of facilities over the end-to-end power supplying path, such as power generation, transmission, and consump- tion are monitored, controlled and managed. Based on delivered and aggregated data, such as DR (Demand Response) signal, through the communication networks, the central system , such as usually the Control Center in Operation or Service Provider domain, controls power generation, distributes generated power, decides energy price with interaction among power generators, service providers, and consumers in the power market, and collects power usage again. Smart Grid makes all the power grid system automated. and it enables bidirectional communication between central systems and customers. This leads customers to active participation in Smart Grid. For example, customers can trade own generated power in electricity market, choose adaptive and cost-effective power price corresponding to a time slot in real time. Energy management system (EMS) is supposed to be built in inside/outside of smart meters, control points of operation and market, or the front-end system of power service providers at each domain. The EMS offers an interface which helps every domain to communicate each other, manages trading of distributed generated power, and deals with the pricing signal and various power data. In particular, the EMS in the Customer domain monitors, controls and manages all home appliances via a Home Area Network (HAN), and it communicates with not only the Control Center but also other domains via the smart meter connected to the AMI system. The smart meter in the Customer domain measures the power consumption, and reports the power usage data to the Control Center in Operation or Service Provider. Also the smart meter obtains the current power pricing information and/or the control/maintenance information from the Control Center. Based on the information, the corresponding EMS controls, manages and schedules the usage of home appliances in addition to presenting the obtained information to customers via various types of home displaying devices. The power 5Figure 1.2: Decentralized power consumption consumption which is controled by the data from EMS makes power demands decentralized. Fig. 1.2 shows the decentralized power demands. The previous power consumption is concentrated at 2:00 pm. This results in operation of expensive power generator such as water power generation and natural gas. However, Smart Grid achieves decentralized power con- sumption and avoid such a high-priced operation. Note that the control of EMS over home appliances is also implemented with aforementioned HAN. the EMS is able to reduce some extreme case of each individual customer's dynamic power usage by summing them into aggregate power usage. For example, as for office building customers, it usually supports multiple individual offices with a single EMS in cooperation with its building management system for providing energy-efficient power services. There-fore, we can save more power consumption if we enable a single common EMS to cover two or more customers even though they are not building customers. With this extended EMS, the customers who is under the control of the common EMS collaborate on power sharing in the manner that they purchase a common service plan from a power service provider and share it according to the dynamic situation of each customers power consumption. The ad- vantages of this power sharing are three-folds: (i) power service provider or customers can save the initial investment to deploy the EMS system; (ii) even though each customer can save the expenditure for power consumption by choosing the most suitable power service plan, some customers may have residual power while other customers may pay more money than their contract due to the penalty when they overuse the power more than the contract specifies; therefore, it would be cost-effective if several customers are combined to cooper- atively purchase a service plan from a service provider and share the purchased power; (iii) the collaboration on the power-sharing imposes less overload on the Smart Grid. than when each customer uses the power service individually since the fluctuation of each customers power usage can be smoothed by combining multiple customers [1]. Note that the reduc-tion on power is one of main objectives that the Smart Grid should achieve. We use the terminology of 'collaborative customer' for the customers who join together to collaborate on power service purchase and sharing, which is seen as a single customer to their power service provider. The basic concept of the collaborative customer is presented in Fig. 1.1. In the figure, two industrial customers share the power consumption under the same EMS, and thus, if one of them does not need to fully exploit its allocated share, it can transfer the right on its residual power to the other industrial that needs more electric power than usual. The other industrial should compensate the transferred right with the reward that guarantees the more power allocation later (to the industrial that transfers the right) and can be traded in the market. However, when a fraction of members in the collaborative customers behaves self-ishly or maliciously, some customers may not take the advantages of such the collaboration; for example, if any malicious or selfish member counterfeits the right, overuses the power, or breaks the agreement on power sharing, the overall collaboration in collaborative customer is failed, and consequently the ultimate goal of the Smart Grid, which is to save the overall power consumption and to stabilize the dynamics of power consumption, is disrupted. There- fore, we need to promote the collaboration among members in a collaborative customer, and the power-sharing among customers needs to be protected against any counterfeit, forgery, repudiation, and discarding attack. In this paper, we propose a secure collaboration scheme for sharing power usage among members of a collaborative customer, which promotes the power sharing among members with a certificate and protects the certificate from various security attacks, such as forgery, counterfeit, replay, and the illegal exposure of private infor- mation. The certificate is called voucher, and the scheme is the voucher scheme. We formally construct the security model for the voucher scheme, and we prove that the scheme is secure against aforementioned security attacks in the random oracle model. Then we investigate the monetary benefit of the proposed scheme and its security robustness. The results indicate that the proposed voucher scheme promotes a power trading for the collaborative customer and protects the trading from malicious and/or selfish behaviors. The rest of the paper is organized as follows. In section II, we give a succinct summary about related work and also explain preliminaries that are used to develop the security model of the voucher scheme. In section III, we explain the general security attack model. In section IV,we describe the security model for the voucher scheme. and In section V, we show that it is secure against possible security attacks using mathematical method. In section VI, we present the effectiveness of the proposed voucher scheme. In section VII, we propose the application of voucher. Finally we conclude this paper with section VIII.
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Contents
1 Introduction 3
2 Related Work 9
3 Security attack Model 12
3.1 Confidentiality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2 Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.4 Non-repudiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Collaborative Customers Based on Voucher 15
4.1 Collaborative Customer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2 Structure and Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5 Securities 21
5.1 The proof of confidentiality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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5.2 The proof of non-forgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6 Performance Evaluation 28
6.1 Monetary Advantage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.2 Thwarting Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.2.1 Confidentiality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.2.2 Forgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2.3 Replay Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2.4 Discarding Voucher . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2.5 Discarding request . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2.6 Repudiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.3 Computational Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7 Applications of Voucher 37
8 Conclusion 38
