Action Control by Term Rewriting

Abstract

We address the problem of defining access control policies that may be used in the evaluation of requests made by client actors, in the course of e-trading, to perform actions on the resources maintained by an e-collective. An e-collective is a group of agents that may act individually or in conjunction with other agents to satisfy a client's request to act. Our principal contribution to this key problem is to define formally an access control model in terms of which policies may be specified for helping to ensure that only legitimate forms of client actions are performed in the course of engaging in e-trading. We call this model the action control model . In action control, the notion of intentional, empowered, authorized actions, that may be performed individually or jointly with other agents and in a manner that is consistent with a group ethos, is the basis for specifying a set of permissives . A permissive is a generalization of the notion of permission (as the latter term is usually interpreted in access control). We define our action control model as a term rewrite system and we give examples of access policy representation.