Formal Modeling and Verification of ERC Smart Contracts: Application to NFT

Blockchain-based applications are basically built on smart contracts, which are widely different in regards of the encoded logic and the used standards. When talking about Ethereum standards, ERC-721 is a well-known standard interface developed for Non-Fungible Tokens. Even though it is standard-based contracts that are more and more exploited, prior work on smart contracts verification mostly investigates efforts in regards of specific vulnerabilities. To address this gap, this paper introduces a formal modeling and verification approach for Ethereum smart contracts including the standard-based ones. We propose a model checking framework that, according to a Solidity smart contract provided as an input, uses ERC guidelines as a standard template to extract the related security properties. Another added benefit of our proposal consists on modeling ERC contracts using the extended finite state machine formalism. As a proof of concept, we illustrate our model checking approach through an NFT contract.