The Security Of VoIP Sstem Based On SIP Pprotocol

Session Initiation Protocol (SIP) proposed by IETF is an application layer, control/signaling protocol for creating, communicating, and terminating multimedia session with one or more participants. It has now become the extensively–used session establishment protocol of VoIP and further been adopted to be the core protocol of session control for the Next Generation Network (NGN) due to its characteristic advantages of simplicity, preferable expansibility, and toilless realization. However, it suffers from many safe leaks which feature a great threat to the users'privacy and communications security. Therefore, it is imperative to investigate the security of SIP.In this thesis, the operation principle of VoIP and the related different critical techniques were firstly summarized. The functions and operation mechanisms were also analyzed and discussed.Secondly, all kinds of information styles of SIP as well as the functions and their relations between the SIP protocols were analyzed and investigated comprehensively. Due to the characteristic vulnerabilities of SIP, the securities of SIP information are emphasized for future discussions.At last, an improved proposal based on HTTP summary authentication scheme is brought forward to ensure bidirectional authentications and its securities. Besides the traditional advantages of HTTP authentication, this system not only expends the authentication head realms of SIP but also achieves higher quality of transmission and data transmission speed by applying message digest algorithms MD5 to the plaintext so as to obtain a brief message digest H, applying RSA algorithms to achieve digital signature of the brief message digest H to producing a signed message digest D(H) which is further applied to encrypt the plaintext M, followed by utilizing AES algorithms to encrypt the plaintext and the message digest of D(H). The effectiveness of the scheme is experimentally verified.