24 A Constrained Workflow Access Control Method Based on RBAC Model

In this paper, we propose a workflow access control model based on role and task. In our model, roles and permissions do not bound directly, but bound through workflow tasks. We assigned every user a suitable role through which the user gets the tasks he has access to. And then user gets the access right to an object during executing some task instances. Comparing with other researches, our method achieves more facilitate access granularity control and management. Moreover, we add time constraints in the workflow model to restrict a task finishing in a period of time. In workflow implementation process, the system will save an authorized base, namely the historical task to perform information, according to these historic executive information find qualified perform tasks users set, so as to realize dynamic duties separation.