Blockchain Papers

А. В. Смирнов, Nikolay Teslya

No abstract is available for this record.

Aditya Pradana, Goh Ong, Yogan Jaya, Ali A. Mohammed

In Malaysia, a new regulation of traffic offences demerit points has been over a debate. Therefore, a blockchain model is formulated to solve this issue. It serves a purpose to be a Proof of Work (PoW) of a blockchain system. This model contains application layer and blockchain layer with smart contract inside. The smart contracts act as a conditional filter which follows the regulation rules. It contains three contracts starting from the declaration of each offence’s demerit points and fines until the penalties when a certain amount of demerit points is collected, including revocation of driver license. The contracts will be automatically executed when such conditions are fulfilled. A transaction schema is also designed to match the schema of a traffic offence system. This model is deployed in online environment with two servers synced to each other to prove the decentralized characteristic of blockchain. It is developed using NodeJS while preserving JSON format for transaction between server and client. A user interface is also provided as a simulation media where a traffic officer can input offences and send it to blockchain server while public users or the driver itself can check the status of the driver license recorded on the blockchain. Government officer can monitor the records through a dashboard analytics provided which contains graphs and charts based on the records. This interface is used as media to do evaluation which produces satisfying results. The evaluation shows that the smart contracts are executed properly as compared to real regulations.

Jakub J. Szczerbowski

Smart contracts are computer programs executed on virtual machines, which are used to regulate relationships between the subjects of law. They allow parties to foresee, with a high degree of certainty, how will the contractual relationship develop and by the use of blockchain technology they provide a high degree of certainty. It has been conjured that smart contracts will offer significantly lower transaction costs in relation to traditional contracts. The paper analyzes this proposition and finds that not only are the gains doubtful, but also that in some cases transaction costs may be significantly higher.

Gaby G. Dagher, Praneeth Babu Marella, Matea Milojkovic, Jordan Mohler

Voting is a fundamental part of democratic systems; it gives individuals in a community the faculty to voice their opinion. In recent years, voter turnout has diminished while concerns regarding integrity, security, and accessibility of current voting systems have escalated. E-voting was introduced to address those concerns; however, it is not cost-effective and still requires full supervision by a central authority. The blockchain is an emerging, decentralized, and distributed technology that promises to enhance different aspects of many industries. Expanding e-voting into blockchain technology could be the solution to alleviate the present concerns in e-voting. In this paper, we propose a blockchain-based voting system, named BroncoVote, that preserves voter privacy and increases accessibility, while keeping the voting system transparent, secure, and cost-effective. BroncoVote implements a university-scaled voting framework that utilizes Ethereum’s blockchain and smart contracts to achieve voter administration and auditable voting records. In addition, BroncoVote utilizes a few cryptographic techniques, including homomorphic encryption, to promote voter privacy. Our implementation was deployed on Ethereum’s Testnet to demonstrate usability, scalability, and efficiency.

Kristian Lauslahti, Juri Mattila, Taneli Hukkinen, Timo Seppälä

Platform businesses are born global, with instant access to global markets. Thanks to the algorithmic, self-executing and self-enforcing computer programmes known as smart contracts, platform businesses now also have instant access to global capital markets from birth. However, the legal status of these smart-contract-enabled funding mechanisms and smart contracts in general is not well defined. In this article, we analyse how well the formation mechanisms of the general principles of Finnish contract law can be applied to the technological framework of smart contracts. We find that depending on the case, smart contracts can create legally binding rights and obligations to their parties. We also observe that contracts have not been formerly perceived as technical boundary resources in the sense that platform ecosystems could foster broader network effects by opening their application contracting interfaces to third parties.

Haya R. Hasan, Khaled Salah

With the widespread of E-commerce, the need of a trusted system to ensure the delivery of traded items is crucial. Current proof of delivery (PoD) systems lacks transparency, traceability, and credibility. These systems are mostly centralized and rely on trusted third parties (TTPs) to complete the delivery between sellers and buyers. TTPs can be costly, a single point of failure, and subject to hacking, privacy evasion, and compromise. The blockchain is an immutable, trusted, and decentralized ledger with logs and events that can be used for transparency, traceability, and tracking. In this paper, we present a solution and a general framework using the popular permissionless Ethereum blockchain to create a trusted, decentralized PoD system that ensures accountability, auditability, and integrity. The solution uses Ethereum smart contracts to prove the delivery of a shipped item between a seller and a buyer irrespective of the number of intermediate transporters needed. In our proposed solution, all participating entities are incentivized to act honestly by using a double deposit collateral. Automated payment in ether is an integral part of a solution to ensure that every entity gets its intended share of ether upon successful delivery. An arbitration mechanism is also incorporated if a dispute arises during the shipping process. In this paper, we show how we implemented, verified, and tested the proper functionality of our PoD solution. We also provide security analysis and give estimates of the cost consumption in ether gas. We made the full code of the Ethereum smart contracts publicly available at Github.

Nikos Fotiou, Vasilios A. Siris, George C. Polyzos

Despite technological advances, most smart objects in the Internet of Things (IoT) cannot be accessed using technologies designed and developed for interacting with powerful Internet servers. IoT use cases involve devices that not only have limited resources, but also they are not always connected to the Internet and are physically exposed to tampering. In this paper, we describe the design, development, and evaluation of a smart contract-based solution that allows end-users to securely interact with smart devices. Our approach enables access control, Thing authentication, and payments in a fully decentralized setting, taking at the same time into consideration the limitations and constraints imposed by both blockchain technologies and the IoT paradigm. Our prototype implementation is based on existing technologies, i.e., Ethereum smart contracts, which makes it realistic and fundamentally secure.

Seth Oranburg, Liya Palagashvili

No abstract is available for this record.

José Carlos Severino Cardoso

O Blockchain é uma tecnologia emergente recentemente generalizada para muitas áreas de atividade. O seu modo de operação descentralizado enquadra-se perfeitamente em vários cenários onde o principal desafio reside na melhoria da comunicação máquina-máquina e na possibilidade de realizar transferências seguras com serviços de valor acrescentado. As redes IoT são uma das áreas possíveis de aplicação da tecnologia Blockchain, uma vez que, para poder satisfazer os requisitos da indústria, a arquitetura atual das redes IoT tem limitações, que podem ser superadas através da melhoria das comunicações entre dispositivos e do acesso a formas evoluídas de agregação e consumo dos dados recolhidos. Este trabalho procura avaliar a combinação desses dois paradigmas - IoT e Blockchain -, procurando entender como o IoT pode beneficiar das funcionalidades que o Blockchain oferece: um sistema de armazenamento mais económico, descentralização e verdadeira redundância, confiança sem autoridade central - privacidade - e segurança reforçada. Por outro lado, o Blockchain como infraestrutura financeira para o IoT é também um aspeto fundamental desse trabalho. Na prova de conceito construída, este cenário é implementado, pois os dados de um sensor podem ser transacionados com uma entidade que os solicite. São igualmente realizadas análises estatísticas e de desempenho relativamente à arquitetura implementada, sendo também apontados alguns pontos de melhoria para alavancar o uso do sistema em situações reais.

Yu Zhuang, Lincoln Sheets, Zon‐Yin Shae, Jeffrey J. P. Tsai · 5 authors

"Blockchain" is a distributed ledger technology originally applied in the financial sector. This technology ensures the integrity of transactions without third-party validation. Its functions of decentralized transaction validation, data provenance, data sharing, and data integration are a good fit for the needs of health information exchange and clinical trials. We investigated the current workflow of Health Information Exchange and clinical trials; conducted design thinking processes with clinicians, trial managers, informaticians, and blockchain professionals; and implemented a private blockchain model to tackle known issues. We used coded Smart Contract regulations to simulate several scenarios in healthcare processes. This proof-of-concept work provides a feasible simulation for potential solutions to monitor clinical trials across different census regions persistently. Various levels of data access privileges have been designed to utilize a suite of customized Smart Contract settings. These settings emulate the workflow protocols for the monitoring entities, trial sponsors, clinical sponsors and participating subjects. Keywords: Blockchain, Smart Contract, Health Information Exchange, Clinical Trial, Persistent Monitoring.

Massimiliano Vatiero

No abstract is available for this record.

Bhavya Bhandari

No abstract is available for this record.

K. Boogaard

Blockchain technology has provided a platform for the decentralized execution of smart contracts. A smart contract is an agreement that is automatically executed when certain conditions have been met. The immutability, decentral nature, and consensus mechanisms that are characteristic to blockchain technology make the smart contract and its development cycle a new field of study in software engineering. A novel economic and defensive thinking is needed to develop workable, secure smart contracts. Motivated by the need for a novel approach to development, this thesis proposes a model-driven approach to smart contract development.\nModel-Driven Engineering (MDE) is an approach to information system development in which models and model technologies are applied to raise the level of abstraction at which developers create and evolve software, with the goal of both simplifying and formalizing the various activities and tasks that comprise the Software Development Life Cycle (SDLC). Model-Driven Architecture (MDA) is a framework for this approach. This thesis aims to apply this framework to create a method which describes the development phase from domain knowledge to smart contract foundation.\nThe creation of a method has two main aims, namely (i) to bridge the semantic gap between domain knowledge and smart contract by lowering the threshold for domain experts, and (ii) support developers in creating less vulnerable smart contracts that accurately represent the problem domain. This is done by constructing a model-driven method based on existing research that applies MDE to smart contract development. A literature study into this field yields the requirements and techniques for the method, which is consequently constructed based on these requirements and techniques.\nThe method is evaluated in twofold. First, the value is assessed through a case study, which shows that the developer benefits from a structured approach and the reduction of manual programming. Second, by an experiment which shows that people are better able to comprehend and communicate about models containing functional aspects of the smart contract if a computational independent model is included. By doing so it fulfills the aim of lowering the threshold for domain experts to participate in the smart contract development cycle.

Jelena Madir

No abstract is available for this record.

Kuo‐Hui Yeh, Chunhua Su, Jia-Li Hou, Wayne Chiu · 5 authors

Recently, the popularity and universality of smart-devices has led to rapid advancement in the development of applications for mobile commerce around the world. Novel mobile payment schemes, such as Apple pay, Android pay, and Samsung pay are becoming an increasingly popular ways to conduct online transactions, no matter what type of smart devices are used. Due to the attendant growth in the importance of security, significant attention has been devoted to the challenge of designing and implementing a robust mobile payment scheme for securing online transactions. In this paper, we demonstrate a robust mobile payment scheme based on sturdy certificateless signatures with bilinear pairing. We elegantly refine the proposed mobile payment scheme to make it suitable for computation-constrained mobile devices. The practicability of the proposed mobile payment scheme is then certified via a rigorous security analysis and thorough performance evaluation using the Raspberry PI as the implementation platform for our proposed scheme. Furthermore, we implement a transaction repository with the aid of smart contract technology. The simulation results, based on Ethereum, demonstrate the feasibility of employing the smart contract technology to secure mobile payments.

Sttphane Blemus

No abstract is available for this record.

Sina Rafati Niya, Florian Schüpfer, Thomas Bocek, Burkhard Stiller

Abstract This work introduces the design and implementation of an Android-based Peer-to-peer Purchase and Rental Application termed PuRSCA, which leverages Smart Contracts (SC) and the Ethereum public blockchain (BC). As a Device-to-device (D2D) communication protocol, WiFi-Direct is chosen to enable the P2P data transmission between two parties. This work results in a cost-efficient, secure, SC-based, P2P, and Decentralized application (Dapp). Evaluations on performance of this Dapp is specified in terms of its D2D deployment, transaction costs, scalability, security, and privacy.

Shaun Azzopardi, Gordon J. Pace, Fernando Schapachnik

Smart contracts have been proposed as executable implementations enforcing real-life contracts. Unfortunately, the semantic gap between these allows for the smart contract to diverge from its intended deontic behaviour. In this paper we show how a deontic contract can be used for real-time monitoring of smart contracts specifically and request-based interactive systems in general, allowing for the identification of any violations. The deontic logic of actions we present takes into account the possibility of action failure (which we can observe in smart contracts), allowing us to consider novel monitorable semantics for deontic norms. For example, taking a rights-based view of permissions allows us to detect the violation of a permission when a permitted action is not allowed to succeed. A case study is presented showing this approach in action for Ethereum smart contracts.

Emilien Bai, Kåre Synnes

This paper discusses supporting collaborative care of elderly through a reward system based on distributed ledger technologies. The design and implementation of such a reward system that connect elderly and volunteers by mutual agreements involve technologies such as smart contracts and blockchains. The work is motivated by the demographic change, where an aging population consequently increases the need for care. This causes a great tension in our society, as care resources become increasingly constrained, both regarding costs and availability of care staff. Much of the daily care of the elderly is today done by family members (spouses, children) and friends, often on a voluntarily basis, which adds to the tension. The core idea of this work is to help broaden the involvement of people in caring for our elderly, enabled by a system for collaborative care. The proposed system benefits from recent advances in distributed ledger technologies, which similarly to digital currencies, are build on the ability for mutual agreements between people who do not know each other. The system also benefits from recent gamification techniques to motivate people to collaborate on a larger scale through performing simple daily tasks. The proposed system benefits from inherent distributed ledger technologies advantages, such as a high level of decentralization, thus a high availability, and strong data consistency. These advantages make it interesting to develop the possible links between blockchains and the outside world to allow for a higher level of automation and distribution of services such as collaborative care. New models for distributed ledger technologies, such as Iota tangles or the Swirld platform, may however scale and perform better than blockchains. These should thus be considered for a full implementation and test of the system. In summary, this paper presents a novel framework and prototype implementation of a reward system supporting collaborative care of elderly, that is based on distributed ledger technologies.

Massimo Bartoletti, Roberto Zunino

A landmark security property of smart contracts is liquidity: in a non-liquid contract, it may happen that some funds remain frozen. The relevance of this issue is witnessed by a recent liquidity attack to the Ethereum Parity Wallet, which has frozen $${\sim }160M$$ USD within the contract, making this sum unredeemable by any user. We address the problem of verifying liquidity of Bitcoin contracts. Focussing on BitML, a contracts DSL with a computationally sound compiler to Bitcoin, we study various notions of liquidity. Our main result is that liquidity of BitML contracts is decidable, in all the proposed variants. To prove this, we first transform the infinite-state semantics of BitML into a finite-state one, which focusses on the behaviour of any given set of contracts, abstracting the context moves. With respect to the chosen contracts, this abstraction is sound and complete. Our decision procedure for liquidity is then based on model-checking the finite space of states of the abstraction.

Christopher D. Clack, Gabriel Vanca

Implementing smart contracts to automate the performance of high-value over-the-counter (OTC) financial derivatives is a formidable challenge. Due to the regulatory framework and the scale of financial risk if a contract were to go wrong, the performance of these contracts must be enforceable in law and there is an absolute requirement that the smart contract will be faithful to the intentions of the parties as expressed in the original legal documentation. Formal methods provide an attractive route for validation and assurance, and here we present early results from an investigation of the semantics of industry-standard legal documentation for OTC derivatives. We explain the need for a formal representation that combines temporal, deontic and operational aspects, and focus on the requirements for the temporal aspects as derived from the legal text. The relevance of this work extends beyond OTC derivatives and is applicable to understanding the temporal semantics of a wide range of legal documentation.

Atin Angrish, Benjamin Craver, Mahmud Hasan, Binil Starly

With product customization an emerging business opportunity, organizations must find ways to collaborate and enable sharing of information in an inherently trust-less network. In this paper, we propose – “FabRec”: a decentralized approach to handle manufacturing information generated by various organizations using blockchain technology. We propose a system in which a decentralized network of manufacturing machines and computing nodes can enable automated transparency of an organization’s capability, third party verification of such capability through a trail of past historic events and automated mechanisms to drive paperless contracts between participants using ‘smart contracts’. Our system decentralizes critical information about the manufacturer and makes it available on a peer-to-peer network composed of fiduciary nodes to ensure transparency and data provenance through a verifiable audit trail. We present a testbed platform through a combination of manufacturing machines, system-on-chip platforms and computing nodes to demonstrate mechanisms through which a consortium of disparate organizations can communicate through a decentralized network. Our prototype testbed demonstrates the value of computer code residing on a decentralized network for verification of information on the blockchain and ways in which actions can be autonomously initiated in the physical world. This paper intends to expose system elements in preparation for much larger field tests through the working prototype and discusses the future potential of blockchain for manufacturing IT.

Krishnendu Chatterjee, Amir Kafshdar Goharshady, Yaron Velner

Smart contracts are computer programs that are executed by a network of mutually distrusting agents, without the need of an external trusted authority. Smart contracts handle and transfer assets of considerable value (in the form of crypto-currency like Bitcoin). Hence, it is crucial that their implementation is bug-free. We identify the utility (or expected payoff) of interacting with such smart contracts as the basic and canonical quantitative property for such contracts. We present a framework for such quantitative analysis of smart contracts. Such a formal framework poses new and novel research challenges in programming languages, as it requires modeling of game-theoretic aspects to analyze incentives for deviation from honest behavior and modeling utilities which are not specified as standard temporal properties such as safety and termination. While game-theoretic incentives have been analyzed in the security community, their analysis has been restricted to the very special case of stateless games. However, to analyze smart contracts, stateful analysis is required as it must account for the different program states of the protocol. Our main contributions are as follows: we present (i)~a simplified programming language for smart contracts; (ii)~an automatic translation of the programs to state-based games; (iii)~an abstraction-refinement approach to solve such games; and (iv)~experimental results on real-world-inspired smart contracts.

Zheng Yang, Hang Lei

In recent publications, we presented a novel formal symbolic process virtual machine (FSPVM) framework that combined higher-order theorem proving and symbolic execution for verifying the reliability and security of smart contracts developed in the Ethereum blockchain system without suffering the standard issues surrounding reusability, consistency, and automation. A specific FSPVM, denoted as FSPVM-E, was developed in Coq based on a general, extensible, and reusable formal memory (GERM) framework, an extensible and universal formal intermediate programming language, denoted as Lolisa, which is a large subset of the Solidity programming language that uses generalized algebraic datatypes, and a corresponding formally verified interpreter for Lolisa, denoted as FEther, which serves as a crucial component of FSPVM-E. However, our past work has demonstrated that the execution efficiency of the standard development of FEther is extremely low. As a result, FSPVM-E fails to achieve its expected verification effect. The present work addresses this issue by first identifying three root causes of the low execution efficiency of formal interpreters. We then build abstract models of these causes, and present respective optimization schemes for rectifying the identified conditions. Finally, we apply these optimization schemes to FEther, and demonstrate that its execution efficiency has been improved significantly.