Abstract
We present two attacks to the authentication protocol that has been proposed in the paper entitled "An approach to secure communication in PCS" (Xu, M. and Upadhyaya, S., Proc. IEEE Vehicular Tech. Conf., 2001). We show that the attacks are feasible and propose a correction that makes the protocol more robust and resistant against the presented attacks. The corrected protocol yields higher security compared to both the original protocol and the GSM authentication protocol. Moreover, the authentication procedures for the different handoff protocols have been presented and discussed. The most appropriate handoff protocol that matches the authentication protocol discussed here is recommended. We also discuss different encryption algorithms and suggest the most suitable one that yields higher throughput and lower delay time to be used in the corrected authentication protocol.