Encrypting Controller using Fully Homomorphic Encryption for Security of Cyber-Physical Systems

作     者：Kim, Junsoo Lee, Chanhwa Shim, Hyungbo Cheon, Jung Hee Kim, Andrey Kim, Miran Song, Yongsoo 

作者机构：ASRI Dep. of Electrical and Computer Engineering Seoul National University Seoul Korea Republic of Dep. of Mathematical Sciences Seoul National Univ. Seoul Korea Republic of 

出 版 物：《IFAC-PapersOnLine》 

年 卷 期：2016年第49卷第22期

页      面：175-180页

核心收录：

主　　题：Cryptography Controllers Cyber Physical System Embedded systems Water tanks Arithmetic operations Conventional controllers Finite lifespan Fully homomorphic encryption Ho momorphic encryptions MAtrix multiplication Multiple controllers Security 

摘      要：In order to enhance security of cyber-physical systems, it is important to protect the signals from sensors to the controller, and from the controller to the actuator, because the attackers often steal and compromise those signals. One immediate solution could be encrypting the signals, but in order to perform computation in the controller, they should be decrypted before computation and encrypted again after computation. For this, the controller keeps the secret key, which in turn increases vulnerability from the attacker. In this paper, we introduce the fully homomorphic encryption (FHE), which is an advanced cryptography that has enabled arithmetic operations directly on the encrypted variables without decryption. However, this also introduces several new issues that have not been studied for conventional controllers. Most of all, an encrypted variable has a finite lifespan, which decreases as an arithmetic operation is performed on it. Our solution is to run multiple controllers, and orchestrate them systematically. Also, in order to slow down the decrease of the lifespan, a tree-based computation of sequential matrix multiplication is introduced. We finally demonstrate the effectiveness of the proposed algorithm with quadruple water tank example. © 2016