Optimization of Trust Node Assignment for Securing Routes in Smart Grid SCADA Networks

The move toward a smart power grid has widened the range of cyber vulnerabilities in supervisory control and data acquisition (SCADA) systems. Specialized security hardening devices, such as the trust systems, are being developed to protect energy SCADA networks from possible cyberattacks. The trust systems are network security resources that monitor and act on malicious packets. A node is said to be a trust node when it is equipped with a trust system. This paper investigates the optimal security deployment problem in resource-constrained SCADA networks. It proposes two deployment schemes for inline security devices: 1) link coverage maximization; and 2) minimal path tolerance (MPT). The first scheme focuses on the overall monitoring coverage. It is formulated as a quadratic assignment problem. The second scheme focuses on the hop distance between consecutive trust nodes. It uses a heuristic approach that deploys trust nodes in a distributive manner. The proposed schemes are evaluated considering the IEEE test case topologies under various scenarios. Numerical results demonstrate that the proposed schemes are capable of achieving their primary goals. They also reveal a performance tradeoff between the proposed schemes in the highly resource-constrained scenarios where MPT offers a better distributiveness.