Research On Policy-based Session And Media Authorization In IP Video Phone Systems

The IP Video Phone service is a greatly developing service, it transfer the audio and video signals through the IP networks. Compared with the PSTN, the IP networks have two characteristics: the first one is that IP networks cannot ensure quality of services because its'best efforts'nature; the other is the IP networks are insecure network and are more easily to be attacked. IP Video Phone needs to use more bandwidth than normal phone, and the IP Video Phone systems should ensure certain quality of services. At the same time, the systems should prevent the bandwidth being illegally used. In the IP Video Phone Systems, each session has diverse privileges and the network statuses are different, so it needs to set up security mechanism aiming at each session. Before assigning one session bandwidth it requests, the systems should authenticate and authorize its request and limit its bandwidth within certain bound according to the session's privilege.However, the existing authentication and authorization technologies are design for authenticating users'ID, they can only perform simple authorization work so they are not fit for the session and media authorization in IP Video Phone systems. Some existing authorization schemes in VoIP systems are too complex and inconvenient to be used to handily manage the systems, so it needs a new session and media authorization model in IP Video Phone Systems.In this thesis, we describe a Policy-based Session and Media Authorization Model in IP Video Phone Systems. In this model, various entities in the network can exchange authorization information through the authorization tokens and can manage the session and media effectively. This model reduces the times of message exchanging and can authorize the session and media when the session is set up. At the same time, the pre-established trust relationship between the elements in the network are greatly reduced, this characteristic makes the network more open and more extensible. In this model, the policy server in the caller network create an authorization token and transfer this token to called network with SIP message. The policy server in called network validates the token and authorizes this session. The authorization token include authorization information and this thesis design...