Blockchain-based Smart Contracts: A Systematic Mapping Study

BLOCKCHAIN-BASED SMART CONTRACTS

A SYSTEMATIC MAPPING STUDY

Maher Alharby1,2 and Aad van Moorsel1

1School of Computing Science, Newcastle University, Newcastle, UK 2College of Computer Science and Engineering, Taibah University,
Medina, KSA

ABSTRACT

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.

KEYWORDS

Blockchain, Smart contracts, Systematic mapping study, Survey

1. INTRODUCTION Transactions between parties in current systems are usually conducted in a centralised form, which requires the involvement of a trusted third party (e.g., a bank). However, this could result in security issues (e.g., single point of failure) and high transaction fees. Blockchain technology has emerged to tackle these issues by allowing untrusted entities to interact with each other in a distributed manner without the involvement of a trusted third party. Blockchain is a distributed database that records all transactions that have ever occurred in a network. Blockchain was originally introduced for Bitcoin (a peer-to-peer digital payment system), but then evolved to be used for developing a wide range of decentralised applications. An appealing application that can be deployed on top of blockchain is smart contracts. A smart contract is executable code that runs on the blockchain to facilitate, execute and enforce the terms of an agreement between untrusted parties. It can be thought of as a system that releases digital assets to all or some of the involved parties once the pre-defined rules have been met [1]. Compared to traditional contracts, smart contracts do not rely on a trusted third party to operate, resulting in low transaction costs. There are different blockchain platforms that can be utilised to develop smart contracts, but Ethereum is the most common one. This is because Ethereum’s language supports Turing-completeness feature that allows creating more advanced and 126 Computer Science & Information Technology (CS & IT)

customised contracts. Smart contracts can be applied to different applications (e.g., smart properties, e-commerce and music rights management). The main aim of this study is to identify the research topics that have been carried out about blockchain-based smart contracts and current challenges that need to be addressed in future studies. To achieve this aim, we selected a systematic mapping study as the methodology for our study. We followed the systematic mapping process presented in [2] to search for relevant papers in scientific databases and to produce a map of current smart contract research. The produced map could help researchers identify gaps for future studies. The focus of our study is to only explore smart contract studies from a technical point of view. The structure of this paper is as follows. Section 2 discusses background information about blockchain and smart contracts technologies. It also discusses several smart contract platforms and potential applications. Section 3 describes the research methodology adopted for our study. Section 4 presents the results of searching and screening for relevant papers and the results of classifying smart contract topics. Section 5 discusses the results and answers the research questions of the study. Section 6 concludes the paper. 2. BACKGROUND This section presents general background information about blockchain and smart contracts technologies. It also discusses some blockchain platforms that support the development of smart contracts. Finally, it provides some potential use cases for smart contracts. 2.1. Blockchain Technology A blockchain is a distributed database that records all transactions that have ever occurred in the blockchain network. This database is replicated and shared among the network’s participants. The main feature of blockchain is that it allows untrust

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