| 1. |
- Abdalmoaty, Mohamed, 1986-, et al.
(författare)
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Privacy and Security in Network Controlled Systems via Dynamic Masking
- 2023
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Ingår i: IFAC-PapersOnLine. - : Elsevier. - 2405-8963. ; 56:2, s. 991-996
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a new architecture to enhance the privacy and security of networked control systems against malicious adversaries. We consider an adversary which first learns the system using system identification techniques (privacy), and then performs a data injection attack (security). In particular, we consider an adversary conducting zero-dynamics attacks (ZDA) which maximizes the performance cost of the system whilst staying undetected. Using the proposed architecture, we show that it is possible to (i) introduce significant bias in the system estimates obtained by the adversary: thus providing privacy, and (ii) efficiently detect attacks when the adversary performs a ZDA using the identified system: thus providing security. Through numerical simulations, we illustrate the efficacy of the proposed architecture
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| 2. |
- Coimbatore Anand, Sribalaji, et al.
(författare)
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Joint controller and detector design against data injection attacks on actuators
- 2020
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Ingår i: IFAC PapersOnline. - : Elsevier BV. - 2405-8963. ; , s. 7439-7445
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Konferensbidrag (refereegranskat)abstract
- This paper addresses the issue of data injection attacks on actuators in control systems. Considering attacks that aim at maximizing impact while remaining undetected, the paper revisits the recently proposed output-to-output gain, which is compared to classical sensitivity metrics such as H-infinity and H_. In its original formulation, the output-to-output gain is unbounded for strictly proper systems. This limitation is further investigated and addressed by modifying the performance output of the system and ensuring that the system from attack signal to performance output is also strictly proper. With this system description, and by using the theory of dissipative systems, a Bi-linear Matrix Inequality (BMI) is formulated for system design. Using this BMI, a design algorithm is proposed based on the heuristic of alternating minimization. Through numerical simulations of the proposed algorithm, it is found that the output-to-output gain presents advantages over the other metrics: the effect of the attack is reduced in the performance output and increased in the detection output in a relatively large spectrum of frequencies.
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| 3. |
- Coimbatore Anand, Sribalaji, et al.
(författare)
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Optimal tracking strategies for uncertain ensembles of thermostatically controlled loads
- 2020
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Ingår i: 2020 IEEE 16th International Conference on Control & Automation (ICCA). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 901-906
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Konferensbidrag (refereegranskat)abstract
- Demand side energy management (DSEM) promises to regulate ensembles of loads to track desired power levels, in response to grid events (demand peaks, emergencies, variable renewable power generation, etc). A large fraction of such loads are Thermostatically Controlled Loads (TCLs) such as refrigerators, electric water heaters, and air conditioners. Such loads exhibit parametric uncertainty and heterogeneity which make power tracking difficult. Adaptive control strategies are explored in this work as a way to achieve power tracking. Effectiveness of such strategies are studied via numerical simulations.
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| 4. |
- Coimbatore Anand, Sribalaji, et al.
(författare)
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Risk assessment and optimal allocation of security measures under stealthy false data injection attacks
- 2022
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Ingår i: 2022 IEEE Conference on Control Technology and Applications (CCTA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665473392 - 9781665473385 ; , s. 1347-1353
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Konferensbidrag (refereegranskat)abstract
- This paper firstly addresses the problem of risk assessment under false data injection attacks on uncertain control systems. We consider an adversary with complete system knowledge, injecting stealthy false data into an uncertain control system. We then use the Value-at-Risk to characterize the risk associated with the attack impact caused by the adversary. The worst-case attack impact is characterized by the recently proposed output-to-output gain. We observe that the risk assessment problem corresponds to an infinite non-convex robust optimization problem. To this end, we use dissipative system theory and the scenario approach to approximate the risk-assessment problem into a convex problem and also provide probabilistic certificates on approximation. Secondly, we con-sider the problem of security measure allocation. We consider an operator with a constraint on the security budget. Under this constraint, we propose an algorithm to optimally allocate the security measures using the calculated risk such that the resulting Value-at-risk is minimized. Finally, we illustrate the results through a numerical example. The numerical example also illustrates that the security allocation using the Value-at-risk, and the impact on the nominal system may have different outcomes: thereby depicting the benefit of using risk metrics.
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| 5. |
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| 6. |
- Coimbatore Anand, Sribalaji, et al.
(författare)
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Risk-averse controller design against data injection attacks on actuators for uncertain control systems
- 2022
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Ingår i: 2022 AMERICAN CONTROL CONFERENCE (ACC). - : IEEE. - 9781665451963 ; , s. 5037-5042
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Konferensbidrag (refereegranskat)abstract
- In this paper, we consider the optimal controller design problem against data injection attacks on actuators for an uncertain control system. We consider attacks that aim at maximizing the attack impact while remaining stealthy in the finite horizon. To this end, we use the Conditional Value-at-Risk to characterize the risk associated with the impact of attacks. The worst-case attack impact is characterized using the recently proposed output-to-output l(2)-gain (OOG). We formulate the design problem and observe that it is non-convex and hard to solve. Using the framework of scenariobased optimization and a convex proxy for the OOG, we propose a convex optimization problem that approximately solves the design problem with probabilistic certificates. Finally, we illustrate the results through a numerical example.
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| 7. |
- Coimbatore Anand, Sribalaji, 1994-
(författare)
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Risk-Based Analysis and Design of Secure Control Systems
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Networked Control Systems (NCSs) are integral to many critical infrastructures such as power grids, transportation, and production systems. The resilient operation of such NCS against cyber-attacks is essential for society, and risk management presents an effective framework for addressing these security challenges. The risk management framework encompasses two steps: risk assessment and risk mitigation. The risk assessment step aims to quantify the risk, whereas the risk mitigation step focuses on designing mitigation strategies. This thesis leverages the risk management framework to analyze and design NCSs that are resilient to cyber-attacks. In particular, this thesis aims to address the following research challenges. Firstly, we aim to assess the risk of attack scenarios that are realistic (risk assessment step). In particular, we consider adversaries and operators with different levels of knowledge about the NCS. For instance, an adversary or operator may possess complete knowledge of the system dynamics or have only partial knowledge with varying degrees of uncertainty. Hence, we describe a systematic approach to assess the risk considering the interplay between the knowledge levels of adversaries and operators.Secondly, we aim to design the NCS to minimize the risk of attacks (risk mitigation step). We explore three different strategies to minimize the risk: (a) controller/detector design, (b) security measure allocation, and (c) system architecture design. In the first strategy, we design the controller and detector gains to minimize the risk of attacks. Here, risk is characterized by the performance loss caused by stealthy attacks on the NCS. In the second strategy, we consider a distributed NCS where certain distributed devices can be secured from attacks by deploying secure sensors and actuators. Then, we aim to strategically determine the devices to secure and mitigate the risk of attacks effectively. Finally, inspired by digital watermarking, we explore the idea of introducing watermarks in NCS to detect attacks efficiently. Throughout the thesis, we provide various numerical examples to depict the efficacy of risk assessment and risk mitigation algorithms. We also provide numerous discussions and avenues for future research directions.
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| 8. |
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| 9. |
- Coimbatore Anand, Sribalaji, et al.
(författare)
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Stealthy Cyber-Attack Design Using Dynamic Programming
- 2021
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Ingår i: 2021 60th IEEE Conference On Decision And Control (CDC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665436595 ; , s. 3474-3479
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Konferensbidrag (refereegranskat)abstract
- This paper addresses the issue of data injection attacks on control systems. We consider attacks which aim at maximizing system disruption while staying undetected in the finite horizon. The maximum possible disruption caused by such attacks is formulated as a non-convex optimization problem whose dual problem is a convex semi-definite program. We show that the duality gap is zero using S-lemma. To determine the optimal attack vector, we formulate a soft-constrained optimization problem using the Lagrangian dual function. The framework of dynamic programming for indefinite cost functions is used to solve the soft-constrained optimization problem and determine the attack vector. Using the Karush-Kuhn-Tucker conditions, we also provide necessary and sufficient conditions under which the obtained attack vector is optimal to the primal problem. Finally, we illustrate the results through numerical examples.
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| 10. |
- Gallo, Alexander J., et al.
(författare)
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Design of multiplicative watermarking against covert attacks
- 2021
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Ingår i: 2021 60th IEEE CConference On Decision And Control (CDC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665436595 ; , s. 4176-4181
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Konferensbidrag (refereegranskat)abstract
- This paper addresses the design of an active cyber-attack detection architecture based on multiplicative watermarking, allowing for detection of covert attacks. We propose an optimal design problem, relying on the so-called output-to-output l(2)-gain, which characterizes the maximum gain between the residual output of a detection scheme and some performance output. Although optimal, this control problem is non-convex. Hence, we propose an algorithm to design the watermarking filters by solving the problem suboptimally via LMIs. We show that, against covert attacks, the output-to-output l(2)-gain is unbounded without watermarking, and we provide a sufficient condition for boundedness in the presence of watermarks.
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