Paper 2020/777

Dynamic Universal Accumulator with Batch Update over Bilinear Groups

Giuseppe Vitto and Alex Biryukov

Abstract

We propose a Dynamic Universal Accumulator in the Accumulator Manager setting for bilinear groups which extends Nguyen's positive accumulator and Au et al. and Damgård and Triandopoulos non-membership proof mechanism. The new features include support for batch addition and deletion operations as well as a privacy-friendly decentralized batch witness update protocol, where the witness update information is the same for all users. Together with a non-interactive zero-knowledge protocol, these make the proposed scheme suitable as an efficient and scalable Anonymous Credential System, accessible even by low-resource users. We show security of the proposed protocol under the t-SDH assumption through a proper initialization of the accumulator and we demonstrate its practical relevance by providing and discussing an implementation realized using state-of-the-art libraries.