What theoretical results have been established?
Since the 1990s, an extensive body of scholarly work has been published on all aspects of RBAC. As of 2006, more than 6,000 articles on various aspects of RBAC are listed by Google Scholar. Some early results are given below. RBAC MODEL • Ferraiolo and Kuhn (1992) gave a formal definition of roles as sets of permissions, role hierarchies, subject-role activation, subject-object mediation, as well as constraints on user/role membership and role activation. [1] • Nyanchama and Osborn (1994) developed a role graph model for RBAC, providing efficient algorithms for analyzing role relationships. [2] • Ferraiolo, Kuhn, and colleagues developed a prototype RBAC implementation and a 1995 paper further developing the RBAC model with formal definitions of static and dynamic separation of duty. [3] • Sandhu, Coyne, Feinstein, and Youman (1996) introduced a framework of RBAC models, breaking down RBAC into four conceptual models that can be combined to provide a variety of RBAC systems. [5] RELATI
