Achieve Revocable Access Control for Fog-Based Smart Grid System

Due to its prodigious advantages, smart grid technology has received considerable attention in recent years. However, security issues are still currently challenging in smart grid. In this paper, aiming at tackle the security issue of power consumption data, we propose a new Ciphertext Policy Attribute-based Encryption (CP-ABE) scheme with revocation for the fog- based smart grid system. Specifically, in order to achieve attribute revocation without requiring users to be always online, we divide users' attributes into attribute groups, assign an attribute group key to each group, and selectively distribute group key update messages. In addition, our scheme uses the DH (Diffie- Hellman) tree to distribute the group key statelessly, which solves the problem of collusion attack. The combination of attribute revocation and user revocation has been used to improve the efficiency of the revocation mechanism. Furthermore, the proposed scheme outsources unnecessary computing operations to fog nodes, so that the computing overhead of users is independent of the number of attributes. Both security analysis and experimental results demonstrate that our proposed scheme can balance the security objectives with the actual efficiency.