A Case Study in Access Control Requirements for a Health Information System

We present a detailed examination of the access constraints for a small real-world Health Information System with the aim of achieving minimal access rights for each of the involved principals. We show that, even for such a relatively simple system, the resulting constraints are very complex and cannot be expressed easily or clearly using the static per-method access control lists generally supported by component-based software. We derive general requirements for the expressiveness of access constraints and propose criteria for a more suitable access control mechanism in the context of component-based systems. We describe a two-level mechanism which can fulfil these criteria.