Efficient multi-server password authenticated key agreement using smart cards

Remote user authentication and key agreement scheme using smart cards is a very practical solution to validate the eligibility of a remote user and provide secure communication later. Also, due to fast progress of networks and information technology, most of provided services are in multi-server environments. In this paper, we propose a novel user authentication and key agreement scheme using smart cards for multi-server environments with much less computational cost and more functionality. The major merits include: (1) users only need to register at the registration centre once and can use permitted services in eligible servers; (2) the scheme does not need a verification table: (3) users can freely choose their passwords; (4) the computation and communication cost is very low; (5) servers and users can authenticate each other; (6) it generates a session key agreed by the user and the server; and (7) it is a nonce-bayed scheme which does not have a serious time-synchronization problem.