An Efficient Anonymous Credential System

Abstract. This paper presents an efficient anonymous credential system that in-cludes two variants. One is a system that lacks a credential revoking protocol, but provides perfect anonymity-unlinkability and computational unforgeability under the strong Diffie-Hellman assumption. It is more efficient than existing creden-tial systems with no revocation. The other is a system that provides revocation as well as computational anonymity-unlinkability and unforgeability under the strong Diffie-Hellman and decision linear Diffie-Hellman assumptions. This sys-tem provides two types of revocation simultaneously: one is to blacklist a user who acted wrong so that he can no longer use his credential, and the other is identifying a user who acted wrong from his usage of credential. Both systems are provably secure under the above-mentioned assumptions in the standard model