Language features for access control

The properties of a capability-based protection mechanism to be incorporated in a language for concurrent programming are presented. The protection mechanism is first abstractly characterized in terms of a protection model; the components of the protection mechanism, that is, the objects, subjects, and protection rules which govern the accessing to the objects by the subjects, are defined. The paper then concentrates on appropriate programming language features to specify how the protection mechanism may be embedded in an object-oriented programming language which allows an abstract data-type definition. In particular, it is shown how the protection rules can be implemented in the language so that a completely static access control to objects is obtained.