Efficient three-party key exchange using smart cards

In this paper, we propose a novel three-party key exchange scheme using smart cards. The main merits of our scheme include: (1) there is no need for verification, passwords or shared keys table in the trusted server; (2) users can freely choose and change their own passwords, (3) the communication and computation cost is very low; (4) two users can authenticate each other by the trusted server; (5) it generates a session key agreed between two users; (6) it is a nonce-based scheme which does not have a serious time-synchronization problem.