Supporting parameterised roles with object-based access control

The per-method access control lists of standard Internet technologies allow only simple forms of access control to be expressed and enforced. They also fail to enforce a strict need-to-know view of persistent data. Real applications require more flexible security constraints including parameter restrictions, logging of accesses and state-dependent access constraints. In particular, the concept of parameterised roles, central to a fine-grained specification of access rules and compliance with privacy laws, should be supported in a natural way. In this paper, we demonstrate how an object-based approach using the mechanism of bracket capabilities can be used to enforce various kinds of access constraints including discretionary, mandatory and parameterised role-based access control. We give examples from a health information system incorporating secure patient access and secure access by appropriate medical and administrative personnel.