Trust Score-based Zero Trust Architecture for Advanced Metering Infrastructure Security

The traditional electrical grid is evolving into a Smart Grid (SG) to improve efficiency, reliability, and sustainability in electricity generation and distribution. The Advanced Metering Infrastructure (AMI), a key component of the SG, facilitates communication between utility companies and consumers. However, this communication layer is vulnerable to various cyber-physical attacks. To combat these vulnerabilities, this paper proposes a Zero Trust Architecture (ZTA) based on trust scores for securing the AMI. The ZTA model developed in this research assigns trust scores to various attributes of the smart grid network and grants access based on dynamic policies that evaluate these scores. We define a comprehensive list of trust attributes corresponding to the components of the AMI, the user, the devices used by the user, etc., which are crucial for evaluating the trustworthiness of the entities within the network. Our proposed model ensures that access to the network is granted only when the total trust score exceeds a predetermined threshold, and more than half of the attributes meet their individual threshold scores. A case study is presented to demonstrate the model's efficacy, showing its effectiveness in securing the communication in an AMI system. This approach enhances the security and reliability of smart grid communications by preventing unauthorized access and maintaining data integrity.