Lattice-based forward and backward secure group signature with selective linkability for VANETs

Abstract

Vehicular Ad Hoc Networks (VANETs) is more and more important in improving transportation efficiency, preventing traffic accidents, and enhancing the comfort of drivers. Group signatures (GS) have been widely studied in VANETs. However, current group signature schemes rarely mention backward security in the event of key leakage, and they lack fine-grained functionalities: selective linkability. Undoubtedly, this is of great importance in VANETs. Based on above issues, this paper proposes a lattice-based forward and backward secure group signature with selective linkability (FBS-LSLGS). We have adopted the Bonsai tree structure to construct a key evolution scheme, which allows users to update keys regularly. Compared to other group signature schemes, our scheme not only provides forward security but also backward security. At the same time, we have restructured the linkability tags in the group signatures so that only specific judgers can determine the linkability between two signatures. Our scheme is based on the Short Integer Solution (SIS) and Learning With Errors (LWE) assumptions, demonstrating good quantum resistance. We conducted the performance analysis on the proposed scheme. And our scheme has been proven to satisfy correctness, full anonymity, forward and backward security, full traceability and selective linkability.