**3. Privacy**

Smart grids are a promising technology describing electrical power infrastructure for transmission and distribution with integrated information and communications technologies [40]. The purpose of a smart grid is to bill the customers accurately and manage and distribute electrical energy in an efficient way. In a smart grid, an SM is the key entity. When an SM is deployed, the concern regarding meter tempering and consumer privacy is raised. There is a need for legislation of SMs. In compliance with privacy requirements, certain properties ensuring the privacy are confidentiality, integrity, authenticity, and availability [24,41]. An SM is prone to data tempering where an adversary can invade the SM. If an SM is compromised, it is then easy to access a cryptographic key. By exploiting a common vulnerability, a large number of SMs can be compromised and can result in manipulating real-time consumption. Therefore, a scalable access control is needed to prevent meter compromises and make sure that any stored information is used for the purpose of billing operations and other value-added services [42]. The major benefit of an SM is accurate billing, but the frequent sharing of consumption information with the utility might leak some private information. In order to protect billing information techniques—e.g., battery management—a zero knowledge homomorphic encryption technique is proposed in [43].
