Efficient Universally Composable Password-based Key Exchange

In this article, we propose an improvement on the universally composable password-based key exchange protocol. We replace one-time signature with message authentication codes which reduce the bandwidth consumption. For typical security parameters our improvement saves as much as 12 K bytes of bandwidth in a protocol execution. Our protocol can be efficiently instantiated using either the DDH or the N-Residuosity Assumption. A complete security proof of the proposed protocol is given in the universally composable framework under common reference string model.