Topics in Cryptology – CT-RSA 2005

Abstract

Recently, a first step toward establishing foundations for group signatures was taken [5], with a treatment of the case where the group is static. However the bulk of existing practical schemes and ap- plications are for dynamic groups, and these involve important new el- ements and security issues. This paper treats this case, providing foun- dations for dynamic group signatures, in the form of a model, strong formal definitions of security, and a construction proven secure under general assumptions. We believe this is an important and useful step because it helps bridge the gap between [5] and the previous practical work, and delivers a basis on which existing practical schemes may in future be evaluated or proven secure.