A key management architecture and protocols for secure smart grid communications

Providing encrypted communications among power grid components is expected to be a basic requirement of smart grid systems in the future. Here, we propose a key management architecture and associated protocols tailored to support encrypted smart grid communications. The architecture consists of two levels structured around the grid control system hierarchy. At the top level, which consist of control centers and regional coordinators, a bottom-up key structure is adopted using hash chaining and a logical key hierarchy. The lower level of the architecture consists of the regional coordinators (i.e., substations and distribution systems) and remote ends (e.g., meters and pole-top sensors) and utilizes a top-down key management approach built on an inverse element method. The proposed key management schema supports the hierarchical structure of the smart grid control mechanisms, and it takes the resource and electronic/physical security differences of the control levels into account. We define a set of protocols utilizing the architecture to provide secure unicast, multicast, and broadcast communications. Furthermore, we illustrate how the architecture is flexible enough to easily handle power grid nodes joining and leaving the system at the different levels. Lastly, we compare the proposed schema with existing ones and show that our architecture can achieve efficient key management to provide secure communications. Copyright © 2016 John Wiley & Sons, Ltd