Research On Dynamic Access Control Model In Cooperative Environment

With the coming of the network age, the Computer Supported Collaborative Work(CSCW) system is greatly emphasized. As a new research field, however, there are many problems remain unresolved, one of which is security issue. The thesis focuses on access control in Cooperative environment.the access control issues in Cooperative systems involve in how to incorporate access control model into Cooperative runtime context, in a simple and appropriate way.Based on the analyse of access control security requirements of Cooperative system, this thesis brought forward and designed a new kind of security model.The main work is as follow:To begin with, several classical access control models are compared with analyzing the possibility and drawback when applying them to Cooperative environments. Then a dynamic access control model( DT-RBAC) is presented to fulfill the requirement of Cooperative environments. The DT-RBAC model is formally defined and then some important security axioms and security theorems of the model are presented. On the base of those definitions,axioms and theorems,security rules of DT-RBAC are designed.A method that utilizing Pertri-Net to model task process for the newly designed DT-RBAC model is proposed,utilizing Pertri-Net to model task process with task patterns.Then,combining reachability and liveness to define a task structure correctness validation method and validate task process.Taking a example to analyse modeling.Introduce user credit tag in DT-RBAC model, a hierarchy fuzzy quality evaluation method is proposed in task environment.AHP method has been applied to determine the right of all factors of in task quality evaluation and the fuzzy comprehensive evaluation is utilized to make the evaluation system more accurate.Taking a example to calculate.Using the task based DT-RBAC security model,the prototype design of Cooperative access control platform (CACP) is presented. The level that theplatform placed in,the structure of the platform and the main function of each module of the platform are described.At last we research in key point of design.