An SM2-based Traceable Ring Signature Scheme for Smart Grid Privacy Protection

A smart grid can dynamically adjust the amount of electricity supply by smart meters' personalized needs, reducing energy waste and protecting the environment. However, because the uploaded data could reveal users' sensitive information, and internal adversaries could poison the power statistics, privacy preservation and security supervision in smart grid systems need to be concerned. To solve these, we propose a traceable ring signature scheme based on SM2 with strong security and anonymity, in addition to utilizing this scheme to build a four-layer smart grid model, separating the duty of statistics and regulations. Specifically, the scheme integrates the advantages of a key-insulated linkable ring signature (LRS) for Monero and an SM2-based ring signature: a key derivation mechanism to make the key more secure and a simple SM2-based ring structure. A trapdoor has been introduced in the "key image" of the signature, which is often used in LRS for linkability, but in our signature, it's used for traceability. This allows authorized participants to open signatures and reveal the identity of the real signer when exceptions occur. Besides the security and privacy analyses, we also implement the proposed scheme and give some experiments to evaluate the time and space performance. The results show that our new scheme with space of kilobyte level size and time of linear or constant cost can be effectively adapted to the functional requirement of our smart grid model. In addition, the signature can be ported to wireless mobile devices for privacy protection and security management.