Xiang Lu

Review and evaluation of security threats on the communication networks in the smart grid

The smart grid, generally referred to as the next-generation power electric system, relies on robust communication networks to provide efficient, secure, and reliable information delivery. Thus, the network security is of critical importance in the smart grid. In this paper, we aim at classifying and evaluating the security threats on the communication networks in the smart grid. Based on a top-down analysis, we categorize the goals of potential attacks against the smart grid communication networks into three types: network availability, data integrity and information privacy. We then qualitatively analyze both the impact and feasibility of the three types of attacks. Moreover, since network availability is the top priority in the security objectives for the smart grid, we use experiments to quantitatively evaluate the impact of denial-of-service (DoS) attacks on a power substation network. Our work provides initial experimental data of DoS attacks against a power network and shows that the network performance degrades dramatically only when the DoS attack intensity approaches to the maximum.

An efficient two-factor user authentication scheme with unlinkability for wireless sensor networks

User authentication with unlinkability is one of the corner stone services for many security and privacy services which are required to secure communications in wireless sensor networks (WSNs). Recently, Xue et al. proposed a temporal-credential-based mutual authentication and key agreement scheme for WSNs, and claimed that their scheme achieves identity and password protection, and the resiliency of stolen smart card attacks. However, we observe that Xue et al.’s scheme is subject to identity guessing attack, tracking attack, privileged insider attack and weak stolen smart card attack. In order to fix the drawbacks, we propose an enhanced authentication scheme with unlinkability. Additionally, the proposed scheme further cuts the computational cost. Therefore, the proposed scheme not only remedies its security flaws but also improves its performance. It is more suitable for practical applications of WSNs than Xue et al.’s scheme.

An Empirical Study of Communication Infrastructures Towards the Smart Grid: Design, Implementation, and Evaluation

The smart grid features ubiquitous interconnections of power equipments to enable two-way flows of electricity and information for various intelligent power management applications, such as accurate relay protection and timely demand response. To fulfill such pervasive equipment interconnects, a full-fledged communication infrastructure is of great importance in the smart grid. There have been extensive works on disparate layouts of communication infrastructures in the smart grid by surveying feasible wired or wireless communication technologies, such as power line communications and cellular networks. Nevertheless, towards an operable, cost-efficient and backward-compatible communication solution, more comprehensive and practical understandings are still urgently needed regarding communication requirements, applicable protocols, and system performance. Through such comprehensive understandings, we are prone to answer a fundamental question, how to design, implement and integrate communication infrastructures with power systems. In this paper, we address this issue in a case study of a smart grid demonstration project, the Future Renewable Electric Energy Delivery and Management (FREEDM) systems. By investigating communication scenarios, we first clarify communication requirements implied in FREEDM use cases. Then, we adopt a predominant protocol framework, Distributed Network Protocol 3.0 over TCP/IP (DNP3 over TCP/IP), to practically establish connections between electric devices for data exchanges in a small-scale FREEDM system setting, Green Hub. Within the real-setting testbed, we measure the message delivery performance of the DNP3-based communication infrastructure. Our results reveal that diverse timing requirements of message deliveries are arguably primary concerns in a way that dominates viabilities of protocols or schemes in the communication infrastructure of the smart grid. Accordingly, although DNP3 over TCP/IP is widely considered as a smart grid communication solution, it cannot satisfy communication requirements in some time-critical scenarios, such as relay protections, which claim a further optimization on the protocol efficiency of DNP3.

A privacy preserving three-factor authentication protocol for e-Health clouds

E-Health clouds are gaining increasing popularity by facilitating the storage and sharing of big data in healthcare. However, such an adoption also brings about a series of challenges, especially, how to ensure the security and privacy of highly sensitive health data. Among them, one of the major issues is authentication, which ensures that sensitive medical data in the cloud are not available to illegal users. Three-factor authentication combining password, smart card and biometrics perfectly matches this requirement by providing high security strength. Recently, Wu et al. proposed a three-factor authentication protocol based on elliptic curve cryptosystem which attempts to fulfill three-factor security and resist various existing attacks, providing many advantages over existing schemes. However, we first show that their scheme is susceptible to user impersonation attack in the registration phase. In addition, their scheme is also vulnerable to offline password guessing attack in the login and password change phase, under the condition that the mobile device is lost or stolen. Furthermore, it fails to provide user revocation when the mobile device is lost or stolen. To remedy these flaws, we put forward a robust three-factor authentication protocol, which not only guards various known attacks, but also provides more desired security properties. We demonstrate that our scheme provides mutual authentication using the Burrows–Abadi–Needham logic.

Robust Chaotic Map-based Authentication and Key Agreement Scheme with Strong Anonymity for Telecare Medicine Information Systems

To ensure only authorized access to medical services, several authentication schemes for telecare medicine information systems (TMIS) have been proposed in the literature. Due to its better performance than traditional cryptography, Hao et al. proposed an authentication scheme for TMIS using chaotic map based cryptography. They claimed that their scheme could resist various attacks, including the smart card stolen attack. However, we identify that their scheme is vulnerable to the stolen smart card attack. The reason causing the stolen smart card attack is that the scheme is designed based on the assumption that the scheme itself achieves user untraceability. Then, we propose a robust authentication and key agreement scheme. Compared with the previous schemes, our scheme not only enjoys more security features, but also has better efficiency. Our analysis indicates that designing a two-factor authentication scheme based on the assumption that privacy protection is achieved in the scheme itself may pose potential security risks. The lesson learned is that, we should avoid this situation in the future design of two-factor authentication schemes.

Achieving privacy preservation in WiFi fingerprint-based localization

WiFi fingerprint-based localization is regarded as one of the most promising techniques for indoor localization. The location of a to-be-localized client is estimated by mapping the measured fingerprint (WiFi signal strengths) against a database owned by the localization service provider. A common concern of this approach that has never been addressed in literature is that it may leak the clients location information or disclose the service providers data privacy. In this paper, we first analyze the privacy issues of WiFi fingerprint-based localization and then propose a Privacy-Preserving WiFi Fingerprint Localization scheme (PriWFL) that can protect both the clients location privacy and the service providers data privacy. To reduce the computational overhead at the client side, we also present a performance enhancement algorithm by exploiting the indoor mobility prediction. Theoretical performance analysis and experimental study are carried out to validate the effectiveness of PriWFL. Our implementation of PriWFL in a typical Android smartphone and experimental results demonstrate the practicality and efficiency of PriWFL in real-world environments.

On Network Performance Evaluation toward the Smart Grid: A Case Study of DNP3 over TCP/IP

The smart grid is the next-generation power system that incorporates power infrastructures with information technologies. In the smart grid, power devices are interconnected to support a variety of intelligent mechanisms, such as relay protection and demand response. To enable such mechanisms, messages must be delivered in a timely manner via network protocols. A cost-efficient and backward-compatible way for smart grid protocol design is to migrate current protocols in supervisory control and data acquisition (SCADA) systems to the smart grid. However, an open question is whether the performance of SCADA protocols can meet the timing requirements of smart grid applications. To address this issue, we establish a micro smart grid, Green Hub, to measure the delay performance of a predominant SCADA protocol, distributed network protocol 3.0 (DNP3) over TCP/IP. Our results show that although DNP3 over TCP/IP is widely considered as a smart grid communication protocol, it cannot be used in applications with delay constraints smaller than 16ms in Green Hub, such as relay protection. In addition, since DNP3 provides reliability mechanisms similar to TCP, we identify that such an overlapped design induces 50%-80% of the processing delay in embedded power devices. Our results indicate that DNP3 over TCP/IP can be further optimized in terms of delay efficiency, and a lightweight communication protocol is essential for time-critical smart grid applications.

Authentication and Integrity in the Smart Grid: An Empirical Study in Substation Automation Systems

The smart grid is an emerging technology that integrates power infrastructures with information technologies to enable intelligent energy managements. As one of the most important facilities of power infrastructures, electrical substations undertake responsibilities of energy transmissions and distributions by operating interconnected electrical devices in a coordinated manner. Accordingly, it imposes a great challenge on information security, since any falsifications may trigger mal-operations, and result in damages to power usage. In this paper, we aim at authentication and integrity protections in substation automation systems (SAS), by an experimental approach on a small scale SAS prototype, in which messages are transmitted with commonly-used data origin authentication schemes, such as RSA, Message Authentication Code, and One-Time Signature. Through experimental results, we find that, current security solutions cannot be applied directly into the SAS due to insufficient performance considerations in response to application constraints, including limited device computation capabilities, stringent timing requirements and high data sampling rates. Moreover, intrinsic limitations of security schemes, such as complicated computations, shorter key valid time and limited key supplies, can easily be hijacked by malicious attackers, to undermine message deliveries, thus becoming security vulnerabilities. Our experimental results demonstrate guidelines in design of novel security schemes for the smart grid.

Development of distributed grid intelligence platform for solid state transformer

This paper introduces the development of a platform intended as a distributed controller for grid intelligence (DGI) system at FREEDM Systems Center. This platform serves as both a hard real-time local converter controller and a communication node for distributed deployment of energy management schemes. One of the converter devices it controls is the solid state transformer (SST), one of the key elements to interface renewable energy sources into distribution system in FREEDM Center. Both the hardware design and software structure for SST control are presented in this paper. For the communication part, the Distributed Network Protocol (DNP) 3.0 is adopted to congregate multiple SSTs to balance local generation and demands in a coordinated manner. Experiment results are presented to show that this distributed platform has good performance.

From security to vulnerability: Data authentication undermines message delivery in smart grid

The smart grid is an emerging technology that integrates the power infrastructure with information technologies to enable real-time monitoring and control of various power equipments. As the most important component in power systems, power substations merge not only many critical equipments, such as transformers and transmission lines, but a large amount of system information to manipulate miscellaneous system events for well-maintained system states. In this paper, we aim at security issues within a substation and try to address the open question, whether existing security mechanisms satisfy both security and performance requirements of applications in Substation Automation Systems (SAS). To this end, we establish a small-scale SAS prototype with commonly-used security mechanisms for message integrity protection, such as RSA and one-time signature (OTS) based schemes, to measure delivery performances of secure SAS messages. Our results reveal that neither of them can be readily adopted by the SAS. Adversely, the limitation of security mechanisms, such as complicated computation, short key valid time and limited key supply, can be easily hijacked by attackers to undermine the SAS message delivery, thereby becoming security vulnerabilities. Our work indicates that message integrity protection in the SAS needs to be addressed urgently before a large-scale deployment of the smart grid.