Visualising the Structure of an IC-card Security Architecture

The standard way of visualising protocols using pictures with boxes and arrows is insufficient to study the protocols in detail. The problem is that the structuring of the protocols relies on elements not explicit in the standard visual rendering. To solve the problem one should visualise not only the operations and the messages but also the state and the security. Using an object oriented data flow model makes it possible to explicitly render the security and the state manipulations of the protocols. The required combination of data flow and object orientedness is provided by the Prograph language. This language has been used to build a prototype of some of the protocols in the load purse transaction of the CEN inter-sector electronic purse draft standard. The resulting conformant prototype provides abstract and concrete views on the system at all levels. The prototype supports animation of the standard, giving the protocol designer feedback on design decisions.