Adding Generic Role- and Process-based Behaviors to Smart Contracts using Dynamic Condition Response Graphs.

Smart contracts executed on blockchains are interactive programs where external actors generate events that trigger function invocations. Events can be emitted by participants asynchronously. However, some functionalities should be restricted to participants inhabiting specific roles in the system, which might be dynamically adjusted while the system evolves. We argue that current smart contract languages adopting imperative programming paradigms require additional complicated access control code. Furthermore, smart contracts are often developed independently and cannot share a joint access control policy. We propose to use Dynamic Condition Response Graphs for role-based and declarative access control for smart contracts. We show that they allow to capture and visualize a form of dynamic access control where access rights evolve as the contract state progresses. Their use supports straight-forward declaration of access control rights, improved code auditing, programming error reduction and improves users' understanding of smart contracts.