Certificate-Based IP Multimedia Subsystem Authentication and Key Agreement

While more and more mobile devices making requests to get access to the IP multimedia subsystem (IMS), authenticating these devices leads to heavy load on the IMS entities. So, how to shorten the IMS authentication procedure is an important issue. This paper proposes a certificate-based IMS authentication and key agreement scheme, abbreviated as C-IMS AKA. We modify the E-UTRAN attach procedure to obtain the certificate of a UE, and enable the home subscriber server (HSS) and serving call session control function (S-CSCF) to authenticate the UE by verifying the certificate as certification authority (CA) in the registration procedure. Therefore, the UE can be authenticated without the challenge-response procedure; moreover, the number of message exchanges will be reduced. In addition, we analyze and compare the C-IMS AKA with other existing schemes in terms of message propagation delay and queuing delay. Analytical results show that the proposed scheme could make the IMS registration more efficient than current alternatives.