Isabelle/Solidity: A Tool for the Verification of Solidity Smart Contracts

Smart contracts are an important innovation in Blockchain which allow to automate financial transactions. Every day, hundreds of thousands of new contracts are deployed managing millions of dollars' worth of transactions. Thus, bugs in smart contracts may lead to high financial losses and it is important to get them right before deploying them to the Blockchain. To address this problem we developed Isabelle/Solidity, a tool for the verification of smart contracts in Isabelle. The tool is implemented as a definitional extension for the Isabelle proof assistant and thus complements existing tools in this area which are mostly based on axiomatic approaches. In this paper we describe Isabelle/Solidity and demonstrate it by verifying a casino contract from the VerifyThis long term verification challenge.