Dr. Fei Hu { Department of Electrical and Computer Engineering University of Alabama Tuscaloosa, Alabama Introduction to CPS Security 1

Motivation "Cyber-Physical Systems (CPS) is a critical part of the national cyber infrastructure. Security threats to CPS pose significant risk to the health and safety of human lives, threaten severe damage to the environment, and could impose an adverse impact on the U.S. economy." "Cyber-Physical Systems (CPS) is a critical part of the national cyber infrastructure. Security threats to CPS pose significant risk to the health and safety of human lives, threaten severe damage to the environment, and could impose an adverse impact on the U.S. economy." - Homeland Security, Dr. Nabil Adam,

CPS Security: What? 3

CPS Security: Why? Cannot simply use conventional, general cyber security schemes to achieve all CPS protections. Cannot simply use conventional, general cyber security schemes to achieve all CPS protections. This is because most CPS security solutions need to be closely integrated with the underlying physical process control features. This is because most CPS security solutions need to be closely integrated with the underlying physical process control features. 4

CPS Security: Example IMD Wireless Powering security IMD Wireless Powering security 5 - It is meaningless to use conventional cryptographies to encrypt the power charge waves - Energy transfer is entirely different from data transfer

Motivation “It is estimated that as much as 10% of all high-tech products sold globally are counterfeit which leads to a conservative estimate of $100 billion of revenue loss.” “It is estimated that as much as 10% of all high-tech products sold globally are counterfeit which leads to a conservative estimate of $100 billion of revenue loss.” [Guajardo et al, 2008] [Guajardo et al, 2008] Several invasive and semi-invasive physical Several invasive and semi-invasive physical tampering methods have been developed, tampering methods have been developed, which made it possible to learn the ROM- which made it possible to learn the ROM- based keys through attacks and compromise based keys through attacks and compromise systems by using counterfeit copies of the systems by using counterfeit copies of the secret information. secret information.

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Layered Architecture and Modularized Design 9

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A Holistic Viewpoint 11

A Possible Solution: Defense ‐ in ‐ Depth 12

13 A Data Mining Approach to CPS Security

Use Historical Data for Anomaly Detection 14

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CPS Smart grid Interactions e e a a c c b b d d e e a a c c b b d d e e At this IEM, information obtained from the observable physical event yields information about the cyber command (b) SST PHEV Load PV DGI SST PHEV Load Wind DGI SST Battery Load PV DGI a a b b c c d d Read state of Physical system a a Issue command to make a setting b b Message exchange including partial state information c c Power draw or contribution on the shared power bus d d e e Event due to physical flow on the shared power bus e e IEM 1 IEM 2 IEM 3

Information flow usecase of a CPS

Information Flow Security aims at guaranteeing that no high level (confidential) information is revealed to users at a low level, even in the presence of any possible cyber/physical process Potential information flow models for CPSs: – Non-Interference: Information does not flow from high to low if the high behavior has no effect on what low level observer can observe – Non-Inference: leaves a low level observer in doubt about high level events. – Non-deducibility: Given a set of low-level outputs, no low-level subject should be able to deduce anything about the high-level inputs [Sutherland]. – Composition of deducibly secure systems: not composable [McCullough] – McCullough`s Generalized noninterference-secure property considers non- determinism of real systems

PUFs Physical Unclonable Functions(PUFs) -a function which is an innovative circuit primitive that exploits the unique intrinsic uncontrollable physical features which are introduced by manufacturing process variations. -a function which is an innovative circuit primitive that exploits the unique intrinsic uncontrollable physical features which are introduced by manufacturing process variations. Physical Objects Process Variations Unpredictable Behavior Easy to Evaluate Hard to Clone PUFPUF Anti-counterfeiting marks for ICs

Thank you! Questions? Questions? 21