An Event-B Based Approach for Formal Modelling and Verification of Smart Contracts

Abstract

While smart contracts are becoming widely recognized as the most successful application of the blockchain technology that could be applied into various industries and for different purposes such as e-commerce, energy tradings, assets management, and healthcare services, their implementation has posed several challenges insofar that they could handle large amount of money and digital assets in addition to their ability to manipulate critical data and transactions related information which makes them attractive targets of security threats and attacks that could lead to significant problems like money losses, privacy leakage and data breach. To better deal with such issues, reasoning about the correctness, the safety and the functional accuracy of smart contracts before their deployment on the blockchain network is critical and no important than ever. In this context model checking tools are well adopted for the formal verification of smart contracts in order to assure their execution as parties' willingness as well as their reliable and secure interaction with users. In this direction, this paper uses Event-B formal verification method to formally model solidity written smart contracts in order to verify and validate their safety, correctness and functional accuracy in addition to their compliance with their specification for given behaviors. The verification is conducted using a model checking tool along which expected safety properties are formalized, validated and judged to be satisfied or unsatisfied. To illustrate the proposed approach, its application to a realistic industrial use case is described.

Formalising a Gateway-based Blockchain Interoperability Solution with Event-B

“…They applied the tool in a public Honeypot smart contract and proved its functional correctness and safety properties. Finally, Lahbib et al [17] used Event-B as a formal method to verify smart contracts written in solidity. In particular, they manually modelled a smart contract to verify their safety, correctness, functional accuracy, and compliance with the requirements specification.…”

“…Fur-thermore, the Event-B method has not been used to formalise interoperability solutions, although it enables verification of safety properties and verification of functional correctness of a system according to a specification [15]. In addition, the Event-B method provides capabilities to verify smart contract correctness and safety properties [16], [17], which makes it suitable for the gateway-based approach, as it relies on smart contracts. Taking this into account, this study selected the gateway proposed by Pandolfi et al [8] as a case study to evaluate the suitability of the Event-B method to formalise the gateway-based approach and give insights to answer the following research question: How can the gateway-based approach be formalised with Event-B?…”

Introduction of Formal Methods in Blockchain Consensus Mechanism and Its Associated Protocols

“…The objective is to verify and validate the safety, correctness and functional accuracy of smart contracts with their specified behavior. In [76], Lahbib et.al. translated smart contract into event-B models, later the model is verified by using RODIN platform.…”

The Use of Formal Approach and Techniques Applied to Understand and Improve the Blockchain

“…That research analyzed the steps that went into making the system [28Please provide official verification of the Event-B smart contract's legitimacy. The point is to make sure the smart contracts everyone uses are safe, correct, and carry out their intended functions as programmed [29], Once the smart contract had been translated into Event-B models, it was validated on the RODIN platform. The TLAC framework may be used to verify the integrity of the cryptographic protocols and consensus mechanisms utilized by a blockchain [30].…”