The Study Of Authentication And Encryption Mechanism Of VoIP Based On SIP

With the development of telecommunication and computer science, the operation of telecommunication becomes diversified. The traditional operation of telecommunication can not meet the requirement of the clients. Transferring the multimedia, like voice and video over the TCP/IP in the packet switching network has become the mainstream of the world. The new technology is called VoIP. On the contrary to the traditional PSTN network, VoIP has many advantages, for example, it is economical, diversified, efficient and expansible. There is a trend that transforming from PSTN to VoIP. But they will coexist for a period of time. There are two significant standards of VoIP. One is H.323 which is proposed by the ITU-T, and the other is SIP(Session Initiation Protocol) which is proposed by the IETF. Although now VoIP based on H.323 has been widely used over the world, it has a lot of disadvantages compared with SIP. And SIP has been more and more widely used during the past few years.At first, this paper analyzes the infrastructure of VoIP system based on SIP. With the study of SIP's functions, SIP protocol stack, network infrastructure, SIP message, call process, we get the idea of SIP and figure out the advantages of it. Then we research the security threats of SIP, and we know the importance of authentication and encryption mechanism in securing VoIP system.Secondly, we study the authentication and encryption mechanisms for...