An efficient unlinkable secret handshake protocol without ROM

A secret handshake scheme with unlinkable reusable credentials secure in the standard model has remained to be an open problem until Ateniese and Blanton use an identity-based encryption scheme to construct a secret handshake. However, the scheme is less efficient and its security reduction is also looser. In this paper we propose a new unlinkable secret handshake scheme with reusable credentials. Our scheme is not only much more efficient, but our scheme uses fewer public parameters and its security reduction is tighter.