Modeling of control flow and data flow in MLS workflows

A multilevel secure workflow may consist of tasks of different security levels. The needed data items also are assigned different security levels. In a complex business process it can be difficult to detect if a process specification complies with a given multi-level security (MLS) policy. The policy may be too strict and means to relax the policy have to be found. It's necessary to find a way to model the control flow and the needed data items simultaneously for the purpose of analysis. This paper shows how to systematically model the information flow in workflows under a MLS policy. The information flow in a workflow under a MLS policy will be modeled with Colored Petri nets (CP-nets), and the information flow CP-net will be divided into two parts: control flow subnet and data flow subnet. The control flow subnet specifies which tasks need to be executed and in what order. The data flow subnet states how the data items move between the different tasks.