Paper 2015/020

Simpler Efficient Group Signatures from Lattices

Phong Q. Nguyen, Jiang Zhang, and Zhenfeng Zhang

Abstract

A group signature allows a group member to anonymously sign messages on behalf of the group. In the past few years, new group signatures based on lattice problems have appeared: the most efficient lattice-based constructions are due to Laguillaumie {\it et al.} (Asiacrypt '13) and Langlois {\it et al.} (PKC '14). Both have at least $O(n^2\log^2 n \log N)$-bit group public key and $O(n\log^3 n\log N)$-bit signature, where $n$ is the security parameter and $N$ is the maximum number of group members. In this paper, we present a simpler lattice-based group signature, which is more efficient by a $O(\log N)$ factor in both the group public key and the signature size. We achieve this by using a new non-interactive zero-knowledge (NIZK) proof corresponding to a simple identity-encoding function. The security of our group signature can be reduced to the hardness of SIS and LWE in the random oracle model.

Note: This is the full version of the paper published in PKC 2015.