The Ip Phone Encryption System Based On Sip Protocol Design And Implementation

The SIP (Session Initial Protocol) Protocol, as the base protocol of VOIP (Voice over IP),has the benefit of smart organization, easily expand, efficiency transport and maturity IPnetwork. At the same time, expecting the public and complex Internet environment, the lackof safty design causes fatal security problem. The text based SIP protocol will be easilyanalyzed, forged, and tampered.Therefore we should analyze the security problems of VOIP,and design security solution for VOIP.By researching public-key encryption, PKI (Public Key Infrastructure) and Open SSLDevelop Library, this paper design and realize the security subsystem of VOIP. The keycontents are as follows:1. Base on PKI, proposed SIP security subsystem solution. Combining PKI and SIP,realize communication authorization and session key negotiate.2. Base on x509cert and nonsymmetrical encrypt key, realize SIP client and serverbidirectional authorization and SIP clients’ bidirectional authorization.3. Base on symmetric encrypt algrithem and session key negotiation, realize VOIPvoice security transport.4. Base on oSIP SIP stack, write software to realize security design. Preliminary resultsdemonstrate the feasibility of this method.5. Base on Open SSL develop Library, develope the CA system, which could be usedfor other security required network communication.