A methodology for extracting and decoding smart contracts data

Blockchain technology has been widely adopted to enhance the security and the decentralisation of smart applications in large-scale pervasive systems. In such a context, data extraction is crucial as it provides a better understanding of the system's behaviours. However, several challenges arise in automatically extracting data, due to the variety of data sources, such as transactions, events, contract storage, and the complexity of the blockchain structure. In particular, retrieving smart contract state changes remains unexplored despite its potential usage for discovering unexpected behaviour. For such reasons, in this work, we propose a novel methodology and a supporting application for extracting smart contract state changes and other execution-related data. The obtained data is then decoded and offered in a standard format to be easily reused. The methodology provides additional functionalities such as transaction filtering and capabilities for querying over extracted data. The effectiveness and the performance of the methodology were evaluated on three real-world projects from different EVM-based blockchains.