A Survey on Security Verification of Blockchain Smart Contracts <s> 1) BLOCKCHAIN SECURITY <s> An appealing feature of blockchain technology is smart contracts. A smart contract is executable code that runs on top of the blockchain to facilitate, execute and enforce an agreement between untrusted parties without the involvement of a trusted third party. In this paper, we conduct a systematic mapping study to collect all research that is relevant to smart contracts from a technical perspective. The aim of doing so is to identify current research topics and open challenges for future studies in smart contract research. We extract 24 papers from different scientific databases. The results show that about two thirds of the papers focus on identifying and tackling smart contract issues. Four key issues are identified, namely, codifying, security, privacy and performance issues. The rest of the papers focuses on smart contract applications or other smart contract related topics. Research gaps that need to be addressed in future studies are provided. <s> BIB001 </s> A Survey on Security Verification of Blockchain Smart Contracts <s> 1) BLOCKCHAIN SECURITY <s> Since its inception, the blockchain technology has shown promising application prospects. From the initial cryptocurrency to the current smart contract, blockchain has been applied to many fields. Although there are some studies on the security and privacy issues of blockchain, there lacks a systematic examination on the security of blockchain systems. In this paper, we conduct a systematic study on the security threats to blockchain and survey the corresponding real attacks by examining popular blockchain systems. We also review the security enhancement solutions for blockchain, which could be used in the development of various blockchain systems, and suggest some future directions to stir research efforts into this area. <s> BIB002
Several studies summarized common problems in blockchain security and depicted a macro blueprint for building a secure and reliable execution environment. Alharby and Moorsel BIB001 pointed out that the common risks in the blockchain including 51% of computing power, private key protection, criminal activities, double payment, and transaction information disclosure, etc. By analyzing the causes of the problems they provided some existing solutions. Li et al. BIB002 studied the execution process of smart contracts in the blockchain, and proposed two issues of transaction order dependency and timestamp dependency. The transaction was not executed in the correct order or the miner maliciously modified the block timestamp may affect the correctness of the smart contract. Simultaneously they suggested that using the OYENTE tool to detect smart contracts was a perfect solution.