Abstract
Blockchain based smart contracts arc computer programs that encode an agreement between non-trusting participants. Smart contracts are executed on a blockchain system if specified conditions are met, without the need of a trusted third party. Blockchains and smart contracts have received increasing and booming attention in recent years, also in academic circles. We carry out a systematic mapping study of all peer-reviewed technology-oriented research in smart contracts. Our interest is twofold, namely to provide a survey of the scientific literature and to identify academic research trends and uptake. We only focus on peer-reviewed scientific publications, in order to identify how academic researchers have taken up smart contract technologies and established scientific outputs. We obtained all research papers from the main scientific databases, and using the systematic mapping method arrived at 188 relevant papers. We classified these papers into six categories, namely, security, privacy, software engineering, application, performance & scalability and other smart contract related topics. We found that the majority of the papers falls into the applications (about 64%) and software engineering (21%) categories. Compared to our 2017 survey [lb we observe that the number of relevant articles has increased about eightfold and shifted considerably towards applications of smart contracts.