Security: Role-based access control (RBAC) fundamentals

An Extended RBAC Profile of XACML
Diala Abi Haidar 1,2, Nora Cuppens-Boulahia 1, Frederic Cuppens 1, Herve Debar 2
1 ENST Bretagne, 2 rue de la Chˆataigneraie, 35512 Cesson-S´evign´e Cedex, France
2 France Telecom R&D Caen, 42 rue des Coutures BP 6243, 14066 Caen, France

SWS’06, Novem ber 3, 2006, Alex andria, Virginia, USA.
Copyright 2006 ACM 1-59593-546-0/06/0011...$5.00.

The basic concept of the RBAC model is that users are assigned to roles, permissions are assigned to roles and users acquire permissions by being members of roles. The user-role
assignment can be a many-to-many relation in the sense that a user can be assigned to many roles and a role can have many users. Similarly, the permission-role assignment is also a many-to-many relation. The RBAC model is organized in four levels [24] each including the requirements of the basic RBAC: the flat (or core) RBAC, the hierarchical RBAC that adds requirements for supporting role hierarchies and the constrained RBAC that adds constraints on the hierarchical RBAC. The constraints may be associated with the user-role assignment (for static separation of duty) or with the activation of roles within user sessions (for dynamic separation of duty). The last level is the symmetric RBAC (also called consolidated) that adds a requirement for permission-role review. This is essential in any authorization management to identify and review the permissions assignment, i.e. the relation between permissions and roles.

The main benefit of this model is the ease of administration of security policies and its scalability. When a user moves inside an organization and has another function, the only thing the administrator needs to do is to revoke the existing user-role assignment and assign her a new role. There is no need to revoke the authorizations she had before and she will be granted new authorizations assigned to her new role. Adding to that, the role hierarchy defined in this model, where a given role can include all the permissions of another role, is a way of having a well structured access control that is the mirror of the organization structure. Finally the RBAC model supports the delegation of access permissions between roles. A role can delegate its role or
part of its role to another role [12].
[pages 14-15]

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