Towards Analyzing the Complexity Landscape of Solidity Based Ethereum Smart Contracts

The blockchain based decentralized cryptocurrency platforms are one of the hottest topics in tech at the moment. Though most of the interest is generated by cryptocurrency related activities, it is becoming apparent that a much wider spectrum of applications can leverage the blockchain technology. The primary concepts enabling such general use of the blockchain are the so-called smart contracts, which are special programs that run on the blockchain. One of the most popular blockchain platforms that supports smart contracts are Ethereum. As smart contracts typically handle money, ensuring their low number of faults and vulnerabilities are essential. To aid smart contract developers and help maturing the technology, we need analysis tools and studies for smart contracts. As an initiative for this, we propose the adoption of some well-known OO metrics for Solidity smart contracts. Furthermore, we analyze more than 10,000 smart contracts with our prototype tool. The results suggest that smart contract programs are short, not overly complex and either quite well-commented or not commented at all. Moreover, smart contracts could benefit from an external library and dependency management mechanism, as more than 80% of the defined libraries in Solidity files code the same functionalities.