EFFICIENT AUTHENTICATION AND KEY AGREEMENT PROCEDURE IN IP MULTIMEDIA SUBSYSTEM FOR UMTS

In a Universal Mobile Telecommunications System (UMTS), a user equipment (UE) can access IP multimedia services through IP Multimedia Subsystems (IMS). In addition to passing IMS authentication, called IMS AKA, this UE also needs to pass General Packet Radio Service (GPRS) authentication, called 3GPP AKA, since the data of the IMS service is transmitted through a GPRS network. Many steps in these two authentication processes are identical and result in inefficiency. Two papers proposed efficient authentication schemes instead of IMS authentication. However, these schemes suffer from security and compatibility problems. In this paper, we design an efficient IMS authentication scheme based on a trust relation between UE and Serving GPRS Support Node (SGSN) established in GPRS authentication. Compared with. the conventional IMS authentication, our scheme can save up to 40% transmission and is analyzed as a secure scheme. Moreover, our scheme does not require any modification in the UE's authentication procedures.