Nowadays, blockchain technology and industry has developed rapidly all over the world, which is inseparable from continuous innovation and improvement on smart contract technology. Therefore, by summarizing the working principle and application research status of blockchain smart contract, this paper analyzes the development and challenges of smart contract. Firstly, we introduce the model and operation principle of blockchain smart contract for the overall architecture, analyze the deployment process of smart contract with Ethereum, Hyperledger Fabric and EOSIO, and make a comparative analysis from the technical level. And taking Byteball, InterValue and IOTA platforms as examples, we introduce the deployment process and application potential for DAG-based blockchain smart contract. Additionally, we also summarize the application research of smart contract for international and Blockchain Oracle, and discuss its innovative application and development trend in the future. Secondly, we introduce the application status of smart contract with Ethereum and Hyperledger Fabric platforms from the aspects of financial transactions, Internet of things, medical applications, and supply chain, and further discuss EOS (enterprise operation system), Blockchain Oracle and other application fields. Furthermore, we introduce the application advantages and challenges to smart contract for industrial Internet from the fields of manufacturing, food industry, industrial Internet of things and industry 4.0. Finally, we discuss the challenges faced by smart contract with technical issues, analyzes the impact on large-scale applications and mining system on the sustainable development of smart contract, and looks forward to the future research direction of blockchain smart contract. 

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A survey of application research based on blockchain smart contract

Blockchain has evolved into a platform for decentralized applications, with beneficial properties like high integrity, transparency, and resilience against censorship and tampering. However, blockchains are closed-world systems which do not have access to external state. To overcome this limitation, oracles have been introduced in various forms and for different purposes. However so far common oracle best practices have not been dissected, classified, and studied in their fundamental aspects. In this paper, we address this gap by studying foundational blockchain oracle patterns in two foundational dimensions characterising the oracles: (i) the data flow direction, i.e., inbound and outbound data flow, from the viewpoint of the blockchain; and (ii) the initiator of the data flow, i.e., whether it is push or pull-based communication. We provide a structured description of the four patterns in detail, and discuss an implementation of these patterns based on use cases. On this basis we conduct a quantitative analysis, which results in the insight that the four different patterns are characterized by distinct performance and costs profiles.

Foundational Oracle Patterns: Connecting Blockchain to the Off-chain World

Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World

The InterPlanetary File System (IPFS) is a novel decentralised storage architecture, which attempts to provide decentralised cloud storage by building on founding principles of P2P networking and content addressing. IPFS is used by more than 230k peers per week and serves tens of millions of requests per day, which makes it an interesting large-scale operational network to study. While it is used as a building block in several projects and studies, its inner workings, properties, and implications have only been marginally explored in research. Thus, we provide an overview of the IPFS design and its core features, along with the opportunities that it opens as well as the challenges that it faces because of its properties. Overall, IPFS presents an interesting set of characteristics and offers lessons which can help building decentralised systems of the future.

Towards Decentralised Cloud Storage with IPFS: Opportunities, Challenges, and Future Directions

With the fast growth of networked devices, the shared data volume keeps increasing over time, i.e., the Internet of Things (IoT) devices may generate zettabytes of data in the coming few years. According to the recent version of General Data Protection Regulation (GDPR), users have the right to fully control their personal data. Many web service providers also provide some options for users to control the data. However, it is still a challenge to investigate how they enforce these actions. There is a need to deploy additional measures to secure the data access. Focused on this challenge, in this work, we design a scheme that uses smart contract and blockchain to provide a secure data sharing and access environment. In our scheme, there are three major parties and each of them has its own key pair for encrypting and signing the data. We also develop four main smart contracts for different parties, and discuss what kinds of data should be immutable and placed on-chain. In the evaluation, we explore the performance of our scheme under different platforms such as Ethereum with EtHash, Ethereum with Clique, and Hyperledger. With the analysis of several potential attacks, our results indicate the viability and effectiveness of our scheme.

My data, my control: A secure data sharing and access scheme over blockchain

Distributing data in a tamper-proof and traceable way is a necessity in many Internet of Things (IoT) scenarios. Blockchain technologies are frequently named as an approach to provide such functionality. Despite this, there is a lack of concrete solutions which integrate the IoT with the blockchain for data distribution purposes.

Simon Krejci

Papers

Blockchain- and IPFS-Based Data Distribution for the Internet of Things