Paper 2017/1128

Forward Secure Efficient Group Signature in Dynamic Setting using Lattices

Meenakshi Kansal, Ratna Dutta, and Sourav Mukhopadhyay

Abstract

Secret key exposure is at high risk in the computing infrastructure due to the increase in use of harmful devices. As a result, achieving forward secrecy is a preferable feature for any cryptosystem where the lifetime of a user is divided into discrete time periods. Forward secrecy preserves the security of past periods even if the secret key is exposed. In this work, we introduce the first lattice based forward secure dynamic group signature scheme. The existing forward secure group signature schemes are secure in the bilinear setting, and becomes insecure in the quantum computer period. We employ a complete binary tree whose leaves are associated with discrete time periods and label the nodes in a unique way that enables each node of the same depth to have different hamming weight. This helps the group manager to produce distinct certificates to distinct users. Our scheme withstand framing attacks, mis-identification attack and preserves anonymity under the learning with errors (LWE) and short integer solution (SIS) assumptions.