Group Signature Scheme Based on Lattice

Abstract

An attack is mounted on a group signature scheme based on lattice posted in Asia Crypt 2010.It shows the group signature scheme is vulnerable to trap attacks and a dishonest group manager can get all group members′ signing keys and then forge all group members′ valid signatures.Meanwhile,the scheme can′t increase or delete group members flexibly and efficiently which is not applicable to dynamic groups.Every time a new member joins,the system has to update the public key and all group members′ signing keys which are of huge calculation and low efficiency.Also,the scheme doesn′t provide an effective method to revoke group members.Using statistical zero-knowledge proofs and time parameters,an improved scheme based on the hardness of the closest vector problem is proposed.The improved scheme is anti-trap attacks and can dynamic increase or deletes group members more efficiently and applicably.