Developing Safe Smart Contracts.

Blockchain is a shared, distributed ledger on which transactions are digitally recorded and linked together. Smart Contracts are programs running on Blockchain and are used to perform transactions in a distributed environment without need for any trusted third party. Since smart contracts are used to transfer assets between contractual parties, their safety and security are crucial and badly written and insecure contracts may result in catastrophe. Actor-based programming is known to solve several problems in building distributed software systems. Moreover, formal verification is a solid technique for developing dependable systems. In this paper, we show how the actor model can be used for modeling, analysis and synthesis of smart contracts. We propose Smart Rebeca as an extension of the actor-based language Rebeca, and use the model checking toolset Afra for verification of smart contracts. We implement a synthesizer to synthesize Solidity programs that run on the Ethereum platform from Smart Rebeca models. We examine the challenges and opportunities of our approach in modeling, formal verification, and synthesis of smart contracts using actors.