Cryptanalysis of Two Fully Anonymous Attribute-Based Group Signature Schemes with Verifier-Local Revocation from Lattices

摘要

Attribute-based group signature (ABGS) is a new variant of group signature, and it allows any group member with certain specific attributes to sign a message on behalf of the whole group anonymously, without revealing the member's identity or attributes information; once a dispute arises, an opening authority (OA) can effectively reveal the anonymity and track the real identity and attributes of the signer. In order to support for membership revocation and resist against quantum computers, Perera et al. (NSS 2019, WISA 2019) recently proposed two (traceable or not) fully anonymous ABGS schemes with verifier-local revocation (VLR) from lattices. Unfortunately, in this paper we show that their two constructions do not satisfy the full-anonymity and present an improved scheme which obtains the strongest security, full-anonymity, in a relatively simple manner.