Improved one-pass IP Multimedia Subsystem authentication for UMTS

As defined in the 3rd Generation Partnership Project specifications, a Universal Mobile Telecommunications System (UMTS) user device has to carry out two authentication steps to access multimedia services in IP Multimedia Subsystem (IMS). The first authentication step is used to gain UMTS General Packet Radio Service (GPRS) network admission. The second authentication step is the IMS authentication. The authentication steps utilize Authentication and Key Agreement (AKA) and many of the authentication steps are similar. This paper proposed a simplified authentication process known as Improved AKA (I-AKA) which reduced the two authentication steps used to access the UMTS GPRS network and IMS services to one authentication step. Simulation results showed the I-AKA protocol could significantly reduce the authentication delay and improve overall efficiency.