SAR-based Rights Models Conceptual Access Rights Models

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6.1.1 SAR-based Rights Models

The abstract term subject is used to refer to entities like users, agents, services, processes etc. The characteristic property of subject entities is that they initialize interactions with the resources of the system. The resources of the system are e.g. members of classes like computer, service, file or feature and usually need to be protected. Each of these resource classes defines a number of operations and by calling these operations subjects can perform certain actions on the resources of the system. The central characteristic of Subject-Action-Resource-based rights models short: SAR- based rights models is that rights are modeled by a ternary relation as shown in Figure 2. Hence from a conceptual perspective a right in a SAR-based model is a subject-id i , action-id j , resource-id k tupel and describes an allowed or a denied - in case of an open world assumption action of a specific subject on a specific abstract resource. Subject authorized Action Resource Subject-Id Resource-Id Action-Id L M N Figure 2: Conceptual design of a SAR-based rights model During the evaluation of SAR-based rights the access control system has to determine the resources that are affected by the intended interaction. After the corresponding resource- id values have been identified, the access control system has to check if the interacting subject represented by its subject-id is allowed to perform the intended action represented by an action-id value on these resources. This checking is realized by searching for matching entries in the set of defined subject-id, action-id, resource-id tupels. In case the administrators used abstractions of the existing subjects, actions and resources for their right definitions e.g. subject-id = ”adult” or resource-id = “building-within- germany”, the access control systems additionally needs to verify if the subject, the action and the involved resources are members of one of the abstractions used in the right definitions. Every conceptual SAR-based model can usually be mapped to different logical models. Popular logical SAR-based rights models are access control tables, access control lists and capability lists.

6.1.2 View-based Rights Models