DAO attack showed that formal verification of smart contracts is an important issue that should be addressed to prevent irreversible consequences due to design faults activation in Blockchain applications. This paper proposes a modeling method of an Ethereum application based on smart contracts, with the aim of applying a formal method, namely Model-Checking, to verify that the application implementation complies with its specification, formalized by a set of temporal logic propositions. NuSMV tool has been chosen to support this first approach. The proposed model template is shaped by three layers capturing respectively the behavior of Ethereum blockchain, the smart contracts themselves and the execution framework. The approach is illustrated by a case study coming from energy market field.

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Blockchains are a specific type of distributed ledgers structured by a sequence of blocks of transactional data linked to each other. The use of blockchains has increased over time, and several new blockchains are emerging. It is therefore essential to enhance the interoperability between blockchain implementations to allow decentralised trading. One way to achieve this is with Cross-Chain Swap protocols. These protocols are critical systems as they handle assets. Therefore, it must be sure that the system does not contain errors. In this paper, we describe the Cross-Chain Swap problem in a formal way. We define safety and weak-liveness properties that guarantee no correct participant will be worse-off in an asynchronous system. Moreover, we provide a formally proved Byzantine fault-tolerant protocol that satisfies the swap specification. The protocol abstracts the blockchain enough to suit various distributed ledger frameworks aiming to perform a cross-chain swap. In addition, we illustrate how the described abstract protocol can be instantiated in a blockchain system. CCS CONCEPTS• Computing methodologies → Distributed algorithms.