Smart card based security for fieldbus systems

The provision of security services in fieldbus systems will gain in importance in the coming years. A need for such services is easiest seen in fieldbus systems for building automation as they give ample opportunities for mischievous adversaries to tamper with. Without loss of generality we discuss different ways to integrate security services in fieldbus systems after pointing out possible security deficiencies in three widely used fieldbus systems for building automation. Exemplarily, we show how to integrate security services to the LonWorks system. To do so we introduce a secure smart card and discuss the security services that were implemented, based on some simple but realistic assumptions about a possible security policy.