Obligation Constraints in Access Control

We introduce the notion of obligation constraints in the context of access control systems. Such constraints requires that in order to have all permissions necessary to complete a sensitive task, the cooperation of at least a certain number of users is required. In this paper, we formally define the notion of obligation constraints, strict obligation constraints, and introduce the obligation satisfy checking problem (OSCP), which asks whether an access control state satisfies a given obligation constraint, and show that it is intractable (NP-complete). We present an improvement algorithm for OSCP, the algorithm uses preprocessing and static pruning techniques that reduce the number of users that need to be considered. Furthermore, we design and evaluate an improvement algorithm for solving OSCP.