A new Authentication and Key Agreement protocol for SIP in IMS

IP Multimedia Subsystem (IMS) is widely considered as the main solution for Next Generation Network (NGN). Its signaling plan is based on S IP protocol. However, this protocol is exposed to various security threats. The third Generation Partnership Project (3GPP) proposed an Authentication and Key Agreement protocol called IMS-AKA to address SIP vulnerabilities in IMS network. Although IMS-AKA provides attractive features, several weaknesses were identified both on security (disclosure of identities) and performances (complexity) aspects. In this paper, we propose an improved protocol, called IMS-AKA+ that addresses effectively the obscuring users´ identities by using a key-less cryptography. Furthermore, the protocol preserves performances by reducing the computational cost and the storage space due to the use of Elliptic Curve Cryptography (ECC).