Research And Application Of An Improved SIP Protocol Security Authentication Mechanism

With the rapid development of the Internet, the multimedia communications that data, video and audio services merged with each other are required higher demand. Vo IP technology as the main support technology of the data merging had been widely used. However, the SIP protocol can’t provide a enough high security in terms of authentication mechanism, the further work need to be done with the identity authentication mechanism.The SIP protocol needs to authenticate the user’s identity before establishing a session, requiring the user to have legal identity. The authentication mechanism of SIP protocol includes the HTTP(Hypertext Transfer Protocol) digest authentication mechanism, TLS,but they all have shortcomings. Nowadays, the academic focus of SIP authentication mechanism is mainly the HTTP digest and PKI(Public Key Infrastructure) authentication mechanism, which the PKI authentication mechanism has the problem of costing too much, too long time of decryption, difficult of the actual deployment. Therefore, the paper is to improve the deficiencies of the HTTP digest authentication, using the security authentication mechanism to the concrete realization of the system. The mainly work of the paper is as follows:(1) The authentication mechanism of dynamic password based on a chaotic equation is proposed. Firstly, the existing disadvantage of SIP security identity authentication(HTTP digest authentication) is analyzed. Then, according to the chaotic sequence produced by chaotic equation, we can optimize the production of dynamic password in the process of the HTTP digest authentication. The SIP security authentication mechanism based on chaotic equation is proposed, expending the header fields of SIP protocol based on the structural analysis of the SIP header fileds.(2) Design and implement a building digital video intercom system based on SIP protocol. After analyzing the framework structure, performance and header structure of the SIP protocol, a Vo IP system including an outdoor machine, an indoor machine, the system service terminal and the management platform of web center is designed. The Vo IP system uses the TCP(or UDP) protocol to provide the reliable(or unreliable) business for SIP protocol layers, uses SDP protocol to provide enough session information for called users, uses g711 series of protocol, h263/h264 protocol to compress audio and video streams, and uses RTP protocol to realize the real-time transmission of audio and video streams. These methods realized the basic functionality of the system in a large extent, such as audio and video calls, a key monitoring, recording and camera, pushing messages.(3)An improved secure authentication scheme was applied to a video intercom system. The chaos signal generator of the Single Chip Computer was designed based on the chaos equation. Then the SIP registration process was improved and the improved secure authentication scheme was applied to the system. The testing report showed that all the designed functions of the system with improved SIP authentication was achieved.