A Survey on Security Verification of Blockchain Smart Contracts

A smart contract is an agreement between two or more parties, which is executed by the computer code. The code does the execution without giving either party the ability to back out, so it ensures the trustless execution. The smart contract is one of the most important features in blockchain applications, which implements trusted transactions without third parties. However, with the rapid development, blockchain smart contracts have also exposed many security problems, and some attacks caused by contract vulnerabilities have led to terrible losses. In order to better deal with such dilemma, making a comprehensive survey about the security verification of blockchain smart contracts from major scientific databases is quite indispensable. Even though the significance of studying security verification of blockchain smart contracts is evident, it is really fresh yet. The major contributions of our survey work come from three aspects. First, after retrieving all-sided research studies, we select 53 most related papers to show the state-of-the art of this topic, where 20 papers focus on dealing with security assurance of blockchain smart contracts, and 33 papers focus on the correctness verification of blockchain smart contracts. Second, we propose a taxonomy toward the topic of security verification of blockchain smart contracts and discuss the pros and cons of each category of related studies. Third, through in-depth analysis of these studies, we come to know that the correctness verification of smart contracts based on the formal method has already become the more significant and more effective method to validate whether a smart contract is credible and accurate. So, we further present representative studies of formal verification of smart contracts in detail to demonstrate that using a formal method to validate blockchain smart contracts must have a promising and meritorious future.