List of English Publication

@inproceedings{LeeKimShim20,

title = {Zero-Dynamics Attack on Homomorphically Encrypted Control System},

author = {Joowon Lee and Junsoo Kim and Hyungbo Shim},

doi = {https://doi.org/10.23919/ICCAS50221.2020.9268374},

isbn = {978-89-93215-20-5},

year  = {2020},

date = {2020-10-14},

urldate = {2020-10-14},

booktitle = {Proc. of 20th International Conference on Control, Automation and Systems (ICCAS)},

pages = {385-390},

publisher = {IEEE},

address = {Busan, Korea},

abstract = {Against recent cyber-attack strategies on networked control systems which commonly utilize information of control data, the notion of encrypted control system has been introduced, to protect private data in the network layer by encryption. However, even though the adversary cannot learn the information from the encrypted control signals or parameters, it is known that their values can be manipulated by the adversaries, based on homomorphic property of the cryptosystem. In this paper, we demonstrate that the injection of zero-dynamics attack is possible even for encrypted control systems. By injecting an attack signal, generated with knowledge of the plant model, directly on the encrypted controller output being transmitted to the actuator, we show that it disrupts the plant state while it is undetectable from the input and output of the controller. Simulation results are presented to demonstrate the effectiveness of the proposed attack.},

keywords = {Controller encryption, Cyber-physical systems, Homomorphic encryption, Zero-dynamics},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{HaShim19,

title = {Study on Realizable Generalized Hold Functions As a Countermeasure against Zero Dynamics Attack },

author = {Jongsoo Ha and Hyungbo Shim},

doi = {https://doi.org/10.1109/CDC40024.2019.9029726},

year  = {2019},

date = {2019-12-12},

booktitle = {Proc. of 2019 IEEE 58th Conference on Decision and Control},

pages = {5362-5367},

publisher = {IEEE},

address = {Nice, France},

abstract = {Zero dynamics attacks are known to be lethal in the sense that they are stealthy in principle and are not detected from output measurements. Therefore, instead of detecting the zero dynamics attacks, an idea to mitigate the effect of the zero dynamics attack has been proposed recently, which is to enforce the zeros to become stable by changing the zero-order hold to a generalized hold in the sampled data framework. Once all the zeros become stable, then even if the zero dynamics attack is engaged, its effect on the plant is negligible. However, it was observed that the amplitude of the generalized hold becomes unrealistically large in some cases, which leads to a large input to the physical plant. This paper studies this phenomenon at a deeper level and figures out that changing the intrinsic zeros requires an excessively large amplitude of the generalized hold while changing the sampling zeros can be done with a reasonable amplitude.},

keywords = {Generalized hold, Zero-dynamics},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{ParkLeeShim18,

title = {On Stealthiness of Zero-dynamics Attacks against Uncertain Nonlinear Systems: A Case Study with Quadruple-tank Process},

author = {Gyunghoon Park and Chanhwa Lee and Hyungbo Shim},

url = {http://mtns2018.ust.hk/media/files/0224.pdf},

year  = {2018},

date = {2018-06-17},

booktitle = {Proc. of 23rd International Symposium on Mathematical Theory of Networks and Systems},

pages = {10-17},

address = {Hong Kong},

abstract = {This paper studies the problem of constructing a zero-dynamics attack on “nonlinear and uncertain” cyberphysical systems being of non-minimum phase, particularly for the case of the quadruple-tank rocess. In most of the previous works, the zero-dynamics attack is usually designed by linearizing the nonlinear system at an operating point. As a consequence, the stealthiness of the attack may be easily

violated whenever the plant has even small model uncertainty or the state trajectory under the attack moves too far from the operating point (so that the linearization is not accurate enough). Without relying on the linearization of the plant at all, in this paper we propose a nonlinear zero-dynamics attack based on the Byrnes-Isidori normal form representation. In particular, it is shown via the Lyapunov analysis that the proposed attack for the quadruple-tank process always remains stealthy until some of the tanks become empty or overflow even in the presence of small parametric uncertainty, which cannot be ensured by the existing methods. Simulation results are presented to verify the performance of the proposed attack.},

keywords = {Zero-dynamics},

pubstate = {published},

tppubtype = {inproceedings}

}