Research Of IMS Network And SIP's Security

With the development of communication industry, the third generation mobile communication standards not only satisfy with the voice and simple data services, but also want to provide rich Internet-like services. SIP protocol was introduced to support multimedia applications and services for carrier in IP multimedia subsystem of 3GAs Internet born to be an unsecured network, The IMS (IP Multimedia Subsystem) network will face the same challenge with IP core network. And how to solve the security issues will be a great problem. So the paper focus on IMS network related security issues. Firstly presents the background of IMS (IP Multimedia Subsystem), and then introduce some important IMS components such as CSCF (Call Session Control Function), HSS (Home Subscriber Server), AS (Application Server). Since SIP protocol is working on the IMS as the signaling, I mention the history about SIP (Session Initiation Protocol). Then discus the SIP messages and network entities. There are some threats to SIP protocol, such as man in the middle attack, intercept and change SIP messages, Deny of Service, monitoring attack. At last presents with what kind of technologies IMS could improve its security. PKI (Public Key infrastructure) could be used for help. So we discus such issues: CA and Certificate, how to Backup and Retrieve of keys, how to Update keys and Certificates, Client Certificates, Cross authenticate, etc. Researching IPSec focus on how AH protocol and ESP protocol work in 2 different modes (Transfer mode and tunnel mode). There are two main tasks for IMS access security. One is Authentication and Authorization for subscribers. The other is building the IPSec SA between UE and P-CSCF (IPSec security association). The last example of registration process reveals how to set up a security System for IMS network. Using those technologies mentioned before, finally make sure the SIP messages are safe in the sending and receiving.The international community for the IMS study, has come to NGN (next generate-on network) and IMS full integration stage. Standard has been relatively mature, major network equipment providers in the world is rich in successful business case, served on a number of pre-commercial and commercial real network. IMS and SIP for the domestic aspects of the ascendant, Huawei, ZTE, Alcatel - Lucent Tech have all development projects about IMS. ZTE and China Mobile cooperation China's own 3G standards: TD-SCDMS.Due to the intern project experiences in IBM CRL and Alcatel-lucent Qingdao R&D, I have the knowledge and intention to write this paper.