A scalable public key infrastructure for smart grid communications

The public-key cryptography is indispensable for securing the smart grid communications. In this paper, we propose a hierarchical and fully-connected public key infrastructure that considers the smart grid characteristics. In the proposed public key infrastructure, each certificate authority is responsible for managing the public-key certificates for a geo-bounded small area. We also propose a novel format for the certificates that does not only bind a node´s identity to its public key but also to its privileges and permissions. Finally we propose efficient and scalable certificate- renewing scheme that can much reduce the overhead of renewing certificates. Our verifications and evaluations demonstrate that using public key cryptography is essential for securing the smart grid and our proposals are scalable. Moreover, the simulation results demonstrate that the certificate-renewing scheme can significantly reduce the overhead of certificate renewals.