Execution Of Smart Contracts Research Articles

Ethereum smart contracts: Analysis and statistics of their source code and opcodes

Smart contracts are programs that are used for verifying and enforcing the terms of an agreement. Ethereum is an extensively used platform that can be used to execute smart contracts. These can be defined by using high-level languages such as Solidity, Vyper and Bamboo that are compiled into low-level machine instructions, i.e., bytecode. These instructions define a Turing complete language and are often represented by using a readable format that is referred to as opcodes. Here, we present a novel, more comprehensive, study that aims at gaining a precise understanding on how programmers use the linguistic instructions supported by Ethereum. More precisely, the contracts’ source code has been also analysed, in order to understand the high-level control structures and core instructions that are used for smart contract definitions, and how they are reflected on the opcode level. We have gathered ten of thousands of verified Ethereum smart contracts that have been written by using the Solidity language. This study can lay the groundwork for defining new formalisms and new domain specific languages (DSL). These can support the users in the development of decentralised applications (DAPPs).

Peer-to-Peer Energy Trading in Virtual Power Plant Based on Blockchain Smart Contracts

A novel Peer-to-peer (P2P) energy trading scheme for a Virtual Power Plant (VPP) is proposed by using Smart Contracts on Ethereum Blockchain Platform. The P2P energy trading is the recent trend the power society is keen to adopt carrying out several trial projects as it eases to generate and share the renewable energy sources in a distributed manner inside local community. Blockchain and smart contracts are the up-and-coming phenomena in the scene of the information technology used to be considered as the cutting-edge research topics in power systems. Earlier works on P2P energy trading including and excluding blockchain technology were focused mainly on the optimization algorithm, Information and Communication Technology, and Internet of Things. Therefore, the financial aspects of P2P trading in a VPP framework is focused and in that regard a P2P energy trading mechanism and bidding platform are developed. The proposed scheme is based on public blockchain network and auction is operated by smart contract addressing both cost and security concerns. The smart contract implementation and execution in a VPP framework including bidding, withdrawal, and control modules developments are the salient feature of this work. The proposed architecture is validated using realistic data with the Ethereum Virtual Machine (EVM) environment of Ropsten Test Network.

Dynamic Autonomous Cross Consortium Chain Mechanism in e-Healthcare.

Safe and scalable dynamic autonomous data interaction between medical institutions can increase the number of clinical trial records, which is of great significance for improving the level of medical trial collaboration, especially for clinical decision-making with regard to rare diseases. Through a preset authorization access and consensus mechanism, consortium chain provides integrity and traceability management for medical clinical data. However, how to enable users have ownership of their own medical data and share their medical data safely and dynamically between different medical institutions remains an area of particular concern. To achieve dynamic communication between medical consortium chains, this paper proposes (i) a cross-chain communication mechanism by simplifying the heterogeneous node communication topology and (ii) the construction rules of the node identity credibility path-proof to carry out dynamic construction and verification of the path-proof for cross-chain transactions. In addition, the consensus of the cross-chain transaction is modeled as a threshold digital signature process with multiple privileged subgroups; thus, the intra-chain consortium consensus based on the verification node list is extended to the cross-chain consensus. A smart contract deployment and execution scheme based on rational node value transfer mechanism is proposed by analyzing the value transfer game between nodes. Experimental results showed that the proposed scheme can not only enable patients to share their records safely and autonomously in an authorized medical consortium chain within milliseconds but also realize dynamic adaptive interaction among heterogeneous consortium chains.

Secure Modular Smart Contract Platform for Multi-Tenant 5G Applications

Trusted decentralized applications based on distributed ledger technologies provide many potential opportunities to 5G applications and verticals, as well as in fifth generation mobile network (5G) enabling technologies, systems, and services. Apart from the tamper-proof exchange of transactions, distributed ledgers can provide a software environment for the trusted execution of smart contracts. In this article, we explore the security aspects of decentralized applications and, in particular, the security of smart contracts. Distributed ledger characteristics impose distinct requirements on smart contract design, implementation, deployment, and management. We briefly present the approach to the development of secure smart contracts, and highlight key smart contract vulnerabilities and the developer tools supporting smart contract security. We developed a secure, upgradeable modular multi-contract platform. It combines per-contract Smart Contract Tunnels and per-user-based access control to minimize vulnerabilities. The smart contract platform is comprised of service-agnostic, auxiliary, and service-specific smart contracts. It can be therefore easily adapted to different 5G application verticals. For illustration and evaluation, we elaborated on the proposed solution on a case of smart electric charging. During the design and development, state-of-the-art code analysis was applied. Finally, we propose an architecture for the integration of the secure multi-contract platform into a 5G architecture. The integration proposal utilizes hybrid private-public blockchain networks for possible security, scalability, performance, and transaction cost optimization.

A Novel Smart Healthcare Design, Simulation, and Implementation Using Healthcare 4.0 Processes

Blockchain technology is found to have its applicability in almost every domain because of its advantages such as crypto-security, transparency, immutability, decentralized data network. In present times, a smart healthcare system with a blockchain data network and healthcare 4.0 processes provides transparency, easy and faster accessibility, security, efficiency, etc. Healthcare 4.0 trends include industry 4.0 processes such as the internet of things (IoT), industrial IoT (IIoT), cognitive computing, artificial intelligence, cloud computing, fog computing, edge computing, etc. The goal of this work is to design a smart healthcare system and it is found to be possible through integration and interoperability of Blockchain 3.0 and Healthcare 4.0 in consideration with healthcare ground-realities. Here, healthcare 4.0 processes used for data accessibility are targeted to be validated through statistical simulation-optimization methods and algorithms. The blockchain is implemented in the Ethereum network, and with associated programming languages, tools, and techniques such as solidity, web3.js, Athena, etc. Further, this work prepares a comparative and comprehensive survey of state-of-the-art blockchain-based smart healthcare systems. The comprehensive survey includes methodology, applications, requirements, outcomes, future directions, etc. A list of groups, organizations, and enterprises are prepared that are working in electronic health records (EHR), electronic medical records (EMR) or electronic personal records (EPR) mainly, and a comparative analysis is drawn concerning adopting the blockchain technology in their processes. This work has explored optimization algorithms applicable to Healthcare 4.0 trends and improves the performance of blockchain-based decentralized applications for the smart healthcare system. Further, smart contracts and their designs are prepared for the proposed system to expedite the trust-building and payment systems. This work has considered simulation and implementation to validate the proposed approach. Simulation results show that the Gas value required (indicating block size and expenditure) lies within current Etherum network Gas limits. The proposed system is active because block utilization lies above 80%. Automated smart contract execution is below 20 seconds. A good number (average 3 per simulation time) is generated in the network that indicates a health competition. Although there is error observed in simulation and implementation that lies between 0.55% and 4.24%, these errors are not affecting overall system performance because simulated and actual (taken in state-of-the-art) data variations are negligible.

Smart Contract: The Concept, Legal Nature, Features of Conclusion and Execution

Introduction: the paper is devoted to a new phenomenon in business activity in the conditions of IT development that contribute to the creation of secure contractual relations on the Internet on the basis of transactions executed through smart contracts. The author notes that the need for amendments that could fill the loopholes in the current legislation is obvious. And, first of all, it concerns Blockchain technology – the algorithm that mediates the safe development, conclusion and execution of smart contracts. Blockchain technology is considered in the paper as one of the safest means for concluding and executing smart contracts. The author argues that the study of the concept, legal nature and essence of smart contracts is relevant in the light of spreading their share in the total array of transactions in the world economy in conjunction with the changing domestic legislation governing the relevant sphere, as well as the international integration processes affecting the intensification of foreign economic activity of the Russian Federation. The smart contract concepts formulated by the Russian legislator in the process of upgrading the array of statutory regulation under conditions of economy digitalization are studied and compared. The features of conclusion and protection of the smart contract in the civil legislation of the Russian Federation are analyzed. In order to fully articulate the concept of the smart contract, reflecting its essence, functional purpose and legal nature, it is proposed to create a special law that would focus on the conclusion and implementation of “the smart contract” and the specification of the general norms of the civil code. At the same time, the norms of other special laws would supplement and correct the provisions fixed by this act depending on the sphere of managing and the legal regulation branch. The concept of the smart contract is formulated; its value for economic and contractual activity, and also the advantages and disadvantages of its application are established. The possible classifications of smart contracts are given.

Research on Smart Contract Optimization Method on Blockchain

The smart contract on the blockchain allows credible transactions without a third party. These transactions are traceable and irreversible. The deployment and implementation of smart contracts in Ethernet will consume some gas, which will directly affect the cost of smart contracts. In order to reduce the consumption of gas during the execution of smart contracts, this article proposes an optimization algorithm for generating business process smart contracts. First, business process modeling notation (BPMN) models are extended to Petri nets. Second, Petri nets are simplified to find nodes in BPMN models that can be considered fusion tasks. Using new mapping rules from the BPMN model to solidity language, BPMN model is generated into Ethereum Smart contract model. In the BPMN models with multilayer fusion task, experimental results show that the proposed algorithm can save 15% gas on average for business processes with multiple fusion tasks.

Formal Models of Bitcoin Contracts: A Survey

Although Bitcoin is mostly used as a decentralized application to transfer cryptocurrency, over the last ten years there have been several studies on how to exploit Bitcoin to execute smart contracts. These are computer protocols which allow users to exchange bitcoins according to complex pre-agreed rules. Some of these studies introduce formal models of Bitcoin contracts, which specify their behaviour in non-ambiguous terms, in some cases providing tools to automatically verify relevant contract properties. In this paper we survey the formal models proposed in the scientific literature, comparing their expressiveness and applicability in the wild.

Enabling the Internet of Mobile Crowdsourcing Health Things: A Mobile Fog Computing, Blockchain and IoT Based Continuous Glucose Monitoring System for Diabetes Mellitus Research and Care.

Diabetes patients suffer from abnormal blood glucose levels, which can cause diverse health disorders that affect their kidneys, heart and vision. Due to these conditions, diabetes patients have traditionally checked blood glucose levels through Self-Monitoring of Blood Glucose (SMBG) techniques, like pricking their fingers multiple times per day. Such techniques involve a number of drawbacks that can be solved by using a device called Continuous Glucose Monitor (CGM), which can measure blood glucose levels continuously throughout the day without having to prick the patient when carrying out every measurement. This article details the design and implementation of a system that enhances commercial CGMs by adding Internet of Things (IoT) capabilities to them that allow for monitoring patients remotely and, thus, warning them about potentially dangerous situations. The proposed system makes use of smartphones to collect blood glucose values from CGMs and then sends them either to a remote cloud or to distributed fog computing nodes. Moreover, in order to exchange reliable, trustworthy and cybersecure data with medical scientists, doctors and caretakers, the system includes the deployment of a decentralized storage system that receives, processes and stores the collected data. Furthermore, in order to motivate users to add new data to the system, an incentive system based on a digital cryptocurrency named GlucoCoin was devised. Such a system makes use of a blockchain that is able to execute smart contracts in order to automate CGM sensor purchases or to reward the users that contribute to the system by providing their own data. Thanks to all the previously mentioned technologies, the proposed system enables patient data crowdsourcing and the development of novel mobile health (mHealth) applications for diagnosing, monitoring, studying and taking public health actions that can help to advance in the control of the disease and raise global awareness on the increasing prevalence of diabetes.

Adding concurrency to smart contracts

Modern cryptocurrency systems, such as the Ethereum project, permit complex financial transactions through scripts called smart contracts. These smart contracts are executed many, many times, always without real concurrency. First, all smart contracts are serially executed by miners before appending them to the blockchain. Later, those contracts are serially re-executed by validators to verify that the smart contracts were executed correctly by miners. Serial execution limits system throughput and fails to exploit today’s concurrent multicore and cluster architectures. Nevertheless, serial execution appears to be required: contracts share state, and contract programming languages have a serial semantics. This paper presents a novel way to permit miners and validators to execute smart contracts in parallel, based on techniques adapted from software transactional memory. Miners execute smart contracts speculatively in parallel, allowing non-conflicting contracts to proceed concurrently, and “discovering” a serializable concurrent schedule for a block’s transactions, This schedule is captured and encoded as a deterministic fork-join program used by validators to re-execute the miner’s parallel schedule deterministically but concurrently. We have proved that the validator’s execution is equivalent to miner’s execution. Smart contract benchmarks run on a JVM with ScalaSTM show that a speedup of 1.39$$\times $$ can be obtained for miners and 1.59$$\times $$ for validators with just three concurrent threads.

Blockchain-oriented dynamic modelling of smart contract design and execution in the supply chain

Recently, the applications of Blockchain technology have begun to revolutionise different aspects of supply chain (SC) management. Among others, Blockchain is a platform to execute the smart contracts in the SC as transactions. We develop and test a new model for smart contract design in the SC with multiple logistics service providers and show that this problem can be presented as a multi-processor flexible flow shop scheduling. A distinctive feature of our approach is that the execution of physical operations is modelled inside the start and completion of cyber information services. We name this modelling concept ‘virtual operation’. The constructed model and the developed experimental environment constitute an event-driven dynamic approach to task and service composition when designing the smart contract. Our approach is also of value when considering the contract execution stage. The use of state control variables in our model allows for operations status updates in the Blockchain that in turn, feeds automated information feedbacks, disruption detection and control of contract execution. The latter launches the re-scheduling procedure, comprehensively combining planning and adaptation decisions within a unified methodological framework of dynamic control theory. The modelling complex developed can be used to design and control smart contracts in the SC.

Approaching the Communication Constraints of Ethereum-Based Decentralized Applications.

Those working on Blockchain technologies have described several new innovative directions and novel services in the Internet of things (IoT), including decentralized trust, trusted and verifiable execution of smart contracts, and machine-to-machine communications and automation that reach beyond the mere exchange of data. However, applying blockchain principles in the IoT is a challenge due to the constraints of the end devices. Because of fierce cost pressure, the hardware resources in these devices are usually reduced to the minimum necessary for operation. To achieve the high coverage needed, low bitrate mobile or wireless technologies are frequently applied, so the communication is often constrained, too. These constraints make the implementation of blockchain nodes for IoT as standalone end-devices impractical or even impossible. We therefore investigated possible design approaches to decentralized applications based on the Ethereum blockchain for the IoT. We proposed and evaluated three application architectures differing in communication, computation, storage, and security requirements. In a pilot setup we measured and analyzed the data traffic needed to run the blockchain clients and their applications. We found out that with the appropriate designs and the remote server architecture we can strongly reduce the storage and communication requirements imposed on devices, with predictable security implications. Periodic device traffic is reduced to 2400 B/s (HTTP) and 170 B/s (Websocket) from about 18 kB/s in the standalone-device full client architecture. A notification about a captured blockchain event and the corresponding verification resulted in about 2000 B of data. A transaction sent from the application to the client resulted in an about 500 B (HTTP) and 300 B message (Websocket). The key store location, which affects the serialization of a transaction, only had a small influence on the transaction-related data. Raw transaction messages were 45 B larger than when passing the JSON transaction objects. These findings provide directions for fog/cloud IoT application designers to avoid unrealistic expectations imposed upon their IoT devices and blockchain technologies, and enable them to select the appropriate system design according to the intended use case and system constraints. However, for very low bit-rate communication networks, new communication protocols for device to blockchain-client need to be considered.

A Secure Charging Scheme for Electric Vehicles With Smart Communities in Energy Blockchain

The smart community (SC), as an important part of the Internet of Energy (IoE), can facilitate integration of distributed renewable energy sources and electric vehicles (EVs) in the smart grid. However, due to the potential security and privacy issues caused by untrusted and opaque energy markets, it becomes a great challenge to optimally schedule the charging behaviors of EVs with distinct energy consumption preferences in SC. In this paper, we propose a contract-based energy blockchain for secure EV charging in SC. First, a permissioned energy blockchain system is introduced to implement secure charging services for EVs with the execution of smart contracts. Second, a reputation-based delegated Byzantine fault tolerance consensus algorithm is proposed to efficiently achieve the consensus in the permissioned blockchain. Third, based on the contract theory, the optimal contracts are analyzed and designed to satisfy EVs’ individual needs for energy sources while maximizing the operator’s utility. Furthermore, a novel energy allocation mechanism is proposed to allocate the limited renewable energy for EVs. Finally, extensive numerical results are carried out to evaluate and demonstrate the effectiveness and efficiency of the proposed scheme through comparison with other conventional schemes.

Non‐blocking two‐phase commit using blockchain

SummaryThe two‐phase commit (2PC) protocol has long been known to have a provably inevitable vulnerability to blocking or non‐progress amidst server crashes, even when the distributed database system guarantees the most demanding timing‐related or “synchrony” requirements. Our aim here is to eliminate this vulnerability by using a blockchain for coordinating 2PC execution. We present the impossibilities, the possibilities, the cost, and the trade‐offs in this blockchain‐based approach to blocking‐free management of distributed transactions. We prove that a non‐blocking and blockchain‐coordinated 2PC protocol can exist only if both the blockchain and distributed database systems meet synchrony requirements; otherwise, although blocking remains eliminated, transactions can unnecessarily abort. We present a blockchain‐coordinated 2PC protocol and provide rigorous arguments for its correctness under the synchrony requirements. We then implement this protocol on the Ethereum Testnet and demonstrate, through our experiments, that the monetary cost of executing smart contracts is quite small, that the protocol performance slows down when using a public blockchain like Ethereum, and that even major violations of synchrony requirements lead only to relatively small increases in unnecessary aborts. We thus identify a trade‐off between improving protocol performance and admitting a risk that transactions could occasionally abort unnecessarily.

A blockchain based approach for the definition of auditable Access Control systems

This work proposes to exploit blockchain technology to define Access Control systems that guarantee the auditability of access control policies evaluation. The key idea of our proposal is to codify attribute-based Access Control policies as smart contracts and deploy them on a blockchain, hence transforming the policy evaluation process into a completely distributed smart contract execution. Not only the policies, but also the attributes required for their evaluation are managed by smart contracts deployed on the blockchain. The auditability property derives from the immutability and transparency properties of blockchain technology. This paper not only presents the proposed Access Control system in general, but also its application to the innovative reference scenario where the resources to be protected are themselves smart contracts. To prove the feasibility of our approach, we present a reference implementation exploiting XACML policies and Solidity written smart contracts deployed on the Ethereum blockchain. Finally, we evaluate the system performances through a set of experimental results, and we discuss the advantages and drawbacks of our proposal.

Smart Contract Security: A Software Lifecycle Perspective

Smart contract security is an emerging research area that deals with security issues arising from the execution of smart contracts in a blockchain system. Generally, a smart contract is a piece of executable code that automatically runs on the blockchain to enforce an agreement preset between parties involved in the transaction. As an innovative technology, smart contracts have been applied in various business areas, such as digital asset exchange, supply chains, crowdfunding, and intellectual property. Unfortunately, many security issues in smart contracts have been reported in the media, often leading to substantial financial losses. These security issues pose new challenges to security research because the execution environment of smart contracts is based on blockchain computing and its decentralized nature of execution. Thus far, many partial solutions have been proposed to address specific aspects of these security issues, and the trend is to develop new methods and tools to automatically detect common security vulnerabilities. However, smart contract security is systematic engineering that should be explored from a global perspective, and a comprehensive study of issues in smart contract security is urgently needed. To this end, we conduct a literature review of smart contract security from a software lifecycle perspective. We first analyze the key features of blockchain that can cause security issues in smart contracts and then summarize the common security vulnerabilities of smart contracts. To address these vulnerabilities, we examine recent advances in smart contract security spanning four development phases: 1) security design; 2) security implementation; 3) testing before deployment; and 4) monitoring and analysis. Finally, we outline emerging challenges and opportunities in smart contract security for blockchain engineers and researchers.

Blockchain technology and the governance of foreign aid

AbstractBlockchain technology has been considered a vehicle to foster development in poor countries by promoting applications such as secure delivery of humanitarian aid, digital identity services, and proof of provenance. This article examines whether (and if so, how) blockchain technology can enhance the effectiveness and efficiency of foreign aid governance, thereby moving beyond completely anonymous contexts. Foreign aid governance is plagued by lack of credible commitments among states, which are further exacerbated by information asymmetries and which often undermine aid effectiveness. In this context, blockchain technology holds two promises. First, through the guaranteed execution of smart contracts, it can strengthen the credibility of state commitments, for example collective burden-sharing rules among a group of donors or recipient country compliance with policy conditionality in return for aid. Second, through leveraging prediction markets, blockchain technology can allay information problems related to the verification of real-world events along the entire aid delivery chain.

Блокчейн у системі охорони здоров’я: проблеми правового забезпечення

Блокчейн у системі охорони здоров’я: проблеми правового забезпечення

ПРАВОВЕ РЕГУЛЮВАННЯ СМАРТ-КОНТРАКТІВ У ЕПОХУ ЦИФРОВОЇ ЕКОНОМІКИ

The article considers the legal framework for the use of smart contracts in Ukraine to assess the prospects for their use in contract law in the context of the digital transformation of the economy. A study of scientific views on the legal nature of a smart contract is presented. The features of blockchain technology, which predetermine the features of smart contracts and the specifics of their application, are considered. The definition of the place of a smart contract in the system of contracts is proposed. The analysis of Ukrainian and foreign legislation in the field of application of digital technologies and smart contracts in the economy was carried out. It has been determined that smart contracts are currently not regulated in the current legislation of Ukraine. Legislation regulating relations related to the use of information technology is just beginning to take shape. It is noted that the lack of internationally coordinated efforts to recognize the legitimacy of smart contracts can be a serious problem. It is concluded that a smart contract is an agreement that can be automated and enforced. This analysis will lead to a critical examination of whether the functionality of traditional contracts has been superseded by the emergence of smart contracts. It is noted that a smart contract is a combination of technological and legal aspects. As a result of the study, problems were identified, the solution of which at the legislative level will allow the introduction of smart contracts in various areas of economic activity. An important characteristic of these contracts is emphasized - automaticity and the possibility of enforcement. The imperfection of legal instruments for regulating the conclusion and execution of smart contracts is noted. It is concluded that a smart contract, taking into account its features, is a contractual structure and that the successful development of smart contracts requires legislative consolidation of the legal status of smart contracts, the parties to smart contracts, the procedure for organizing the protection of the interests of each side of the smart contract.

What Is the Blockchain?

Blockchain is a new technology, based on hashing, which is at the foundation of the platforms for trading cryptocurrencies and executing smart contracts. This article reviews the basic ideas of this technology and provides a sample minimalist implementation in Python.