Blockchain Papers

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Financing Agreement (Decentralized Service Delivery Program II Project) between the Republic of Sierra Leone and the International Development Association (with schedules, appendix and International Development Association General Conditions for Credits and Grants, dated 31 July 2010). Washington, 14 February 2012

Siti Zulaikha, Sari Rusmita

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Andrey A. Gusev, 49 Leningradsky Prospect, Moscow, 125993, Russia

Many fintech start-ups participant companies and cryptocurrencies have experienced phenomenal growth in value during the past several years.Many specialists would like to know the reasons for such success.In this article we investigate the predictive power of public opinions.This is one of the few works that using quantitative analysis connects social media and internet users' activities with cryptocurrency valuations.

Dominique Hurley

Session Description: Privacy laws like GDPR and California Consumer Privacy Act (CCPA) have created a much more regulated environment in which enterprises need to operate in regards to consumer data permissions. Built on hyperledger fabric, HealthVerity Consent is an enterprise-level platform that allows organizations to aggregate and manage all existing touchpoints across the organization in one central location to comply with evolving privacy requirements. In this session we'll review what it took to deliver an enterprise blockchain installation where we drove business process change across departments and companies to better manage rights to data access and use. We’ll cover: • 5 key lessons learned you can apply to future blockchain implementations • How to integrate into a non-blockchain ecosystem • What challenges were faced in order to drive business process change with blockchain • How to manage existing barriers when migrating from legacy systems and business process to distributed ledger technology

A.V. Bogucharskov, I.E. Pokamestov, Karine Adamova, Zh. N. Tropina

The complexity of trade finance instruments associated with need for many accompanying documents, constant coordination are problems of this process.Successful development of trade finance instruments depend on improvement of software and implement blockchain solutions that enable companies to unite and through partnerships and process automation to accelerate cash flow and documentation throughout supply chain.The paper aims to examine areas and ways of blockchain application in trade finance and to identify key aspects of improving transactions process.We present possible interaction of participants with digital letters of credit and factoring with blockchain application and display its effect on key trade finance instruments.Moreover, we identifies a number of problems, implementation solutions of which will lead to further more efficient application of technology in supply chain finance.The achieving these goals will lead to further more effective application of blockchain in financing of supply chain.Blockchain with a high level of functionality and security in trade finance processes reduces processing time for documents, transaction costs, expanding number of participants and increases level of transparency.

Weijie Zhao

Abstract It has been more than 10 years since Satoshi Nakamoto published his famous paper entitled ‘Bitcoin: a peer-to-peer electronic cash system’, which set the foundation of blockchain technology. Accompanied by the price volatility of bitcoins from 2017 to 2018, blockchain has been a hot word on the internet, and particularly hot in China. Blockchain offers a distributed and secure system for data storage and value transactions. Its applications are springing up in multiple fields. The Chinese government is considering these trends with great caution. Initial coin offering has been banned in China since September 2017. By contrast, an official white paper on China's blockchain technology, which was released in May 2018, said that blockchain technology will be widely applied in the real economy of China within 3 years. In a recent panel discussion held by National Science Review, experts talked about related topics. Their opinions may provide a quick view of the future development of blockchain in China and abroad. Jing Chen Assistant Professor of Computer Science Department, Stony Brook University and Chief Scientist at Algorand LLC, USA Xiaotie Deng Professor of School of Electronics Engineering and Computer Science, Peking University, China Guohua Gan Vice President of Beijing Tai Cloud Technology Corp., China Xiaoyun Wang Professor of Institute of Advanced Study, Tsinghua University, China Zhiming Zheng Professor of School of Mathematics and Systems Science, Beihang University, China Lei Guo (Chair) Professor of Academy of Mathematics and Systems Science, Chinese Academy of Sciences, China

Vibhaalakshmi Sivaraman, Shaileshh Bojja Venkatakrishnan, Mohammad Alizadeh, Giulia Fanti · 5 authors

With the growing usage of Bitcoin and other cryptocurrencies, many scalability challenges have emerged. A promising scaling solution, exemplified by the Lightning Network, uses a network of bidirectional payment channels that allows fast transactions between two parties. However, routing payments on these networks efficiently is non-trivial, since payments require finding paths with sufficient funds, and channels can become unidirectional over time blocking further transactions through them. Today's payment channel networks exacerbate these problems by attempting to deliver all payments atomically.

Bing Jia, Tao Zhou, Wuyungerile Li, Zhenchang Liu · 5 authors

Crowd sensing is a perception mode that recruits mobile device users to complete tasks such as data collection and cloud computing. For the cloud computing platform, crowd sensing can not only enable users to collaborate to complete large-scale awareness tasks but also provide users for types, social attributes, and other information for the cloud platform. In order to improve the effectiveness of crowd sensing, many incentive mechanisms have been proposed. Common incentives are monetary reward, entertainment & gamification, social relation, and virtual credit. However, there are rare incentives based on privacy protection basically. In this paper, we proposed a mixed incentive mechanism which combined privacy protection and virtual credit called a blockchain-based location privacy protection incentive mechanism in crowd sensing networks. Its network structure can be divided into three parts which are intelligence crowd sensing networks, confusion mechanism, and blockchain. We conducted the experiments in the campus environment and the results shows that the incentive mechanism proposed in this paper has the efficacious effect in stimulating user participation.

С. В. Криворучко, Владислав Понаморенко, Anatoly Nebera

: Private cryptocurrencies became an integral part of the financial market. Central banks expressed various positions with respect to cryptocurrency from strong denial to non-intervention. We found out a common and dominating trend in the central bank’s policy to lead the further development of crypto-currency by restrictions, robust surveillance and licensing. The first section contains common information about central banks’s approach to regulation cryprocurrencies. Next section summarizes the treatment of cryptocurrency by central bankers, also it cointains 2 tables devoted to typology of cryptocurrency legality by countries and recognition of cryptocurrency by countries. Section 3 is devoted to the impact of global crisis on the dissemination of digital cryptocurrencies and contains 5 tables with information about banknotes and coins in circulation and a tables with top-10 cryptocurrencies. Section 4 describes the typology of warning signals sent by central banks to general public, investors, and market players. Section 5 concludes the material.

Ryosuke Abe, Shigeya Suzuki, Jun Murai

A type of Bitcoin node called "Full Node" has to hold the entire of historical transaction data called "Blockchain" to verify that new transactions are correct or not. To operate nodes as Full Nodes, the required storage size will be too large for resource-constrained devices. In this paper, to mitigate storage size, we propose a storage load balancing scheme by distributed storage based on Distributed Hash Table (DHT). By our scheme, nodes in a DHT cluster can behave like Full Nodes without holding the entire of the blockchain.

Karine Adamova, I.E. Pokamestov

Over the past 30 years financial markets have moved from a highly centralized to a globalized system that includes all the world's stock exchanges and other financial institutions. The global stock architecture has united the world market. Traditionally, trading in financial instruments took place between stock brokers and traders who made personal transactions on trading platforms. At that time, stock brokers were monopolists of the market, only their information, their recommendations were the only source of information for investors. This was before the dotcom revolution, when communication became simple and accessible to everyone. Trade has been transformed from physical to electronic form, today you can buy securities, currencies and any derivatives in any quantity, at any time and from anywhere in the world. Development of blockchain technologies is integrated into financial transactions. Financial intermediaries are forced to follow the market and actively introduce new technologies in their processes. This article will consider the possibility of using the technology of the distributed ledger by institutions of custodian infrastructure. Today, a number of Russian financial institutions are developing their own projects using blockchain.

Aniruddh Rao Kabbinale, Emmanouil Dimogerontakis, Mennan Selimi, Anwaar Ali · 7 authors

Summary Decentralization, in the form of mesh networking and blockchain, two promising technologies, is coming to the telecommunications industry. Mesh networking allows wider low‐cost Internet access with infrastructures built from routers contributed by diverse owners, whereas blockchain enables transparency and accountability for investments, revenue, or other forms of economic compensations from sharing of network traffic, content, and services. Crowdsourcing network coverage, combined with crowdfunding costs, can create economically sustainable yet decentralized Internet access. This means that every participant can invest in resources and pay or be paid for usage to recover the costs of network devices and maintenance. While mesh networks and mesh routing protocols enable self‐organized networks that expand organically, cryptocurrencies and smart contracts enable the economic coordination among network providers and consumers. We explore and evaluate two existing blockchain software stacks, Hyperledger Fabric (HLF) and Ethereum geth with Proof of Authority (PoA) intended as a local lightweight distributed ledger, deployed in a real city‐wide production mesh network and in laboratory network. We quantify the performance and bottlenecks and identify the current limitations and opportunities for improvement to serve locally the needs of wireless mesh networks, without the privacy and economic cost of relying on public blockchains.

Zijian Bao, Bin Wang, Yongxin Zhang, Qinghao Wang · 5 authors

We propose Lockcoin, a secure and privacy-preserving mix service for bitcoin anonymity. We introduce mix servers to provide mix service for user to prevent attackers linking the input address with output address by using blind signature shceme, multisignature scheme. Lockcoin provides anonymity, scalability, bitcoin compatibillity, theft impossibility and accountability. We have proposed a prototype of Lockcoin based on bitcoin test network, experimental results show that our solution is efficient. Lockcoin's source codes are released on github.com/Northeastern-University-Blockchain/Lockcoin.

Amiangshu Bosu, Anindya Iqbal, Rifat Shahriyar, Partha Chakraborty

The blockchain technology has potential applications in various areas such as smart-contracts, Internet of Things (IoT), land registry, supply chain management, storing medical data, and identity management. Although the Github currently hosts more than six thousand active Blockchain software (BCS) projects, few software engineering research has investigated these projects and its' contributors. Although the number of BCS projects is growing rapidly, the motivations, challenges, and needs of BCS developers remain a puzzle. Therefore, the primary objective of this study is to understand the motivations, challenges, and needs of BCS developers and analyze the differences between BCS and non-BCS development. On this goal, we sent an online survey to 1,604 active BCS developers identified via mining the Github repositories of 145 popular BCS projects. The survey received 156 responses that met our criteria for analysis. The results suggest that the majority of the BCS developers are experienced in non-BCS development and are primarily motivated by the ideology of creating a decentralized financial system. Although most of the BCS projects are Open Source Software (OSS) projects by nature, more than 93% of our respondents found BCS development somewhat different from a non-BCS development as BCS projects have higher emphasis on security and reliability than most of the non-BCS projects. Other differences include: higher costs of defects, decentralized and hostile environment, technological complexity, and difficulty in upgrading the software after release. Software development tools that are tuned for non-BCS development are inadequate for BCS and the ecosystem needs an array of new or improved tools, such as: customized IDE for BCS development tasks, debuggers for smart-contracts, testing support, easily deployable simulators, and BCS domain specific design notations.

Sue-Chen Hsueh, Jia-He Zeng

No abstract is available for this record.

Nathaniel Mason, Charles O. Oyaya, Julia Boulenouar

Abstract Motivation Across the Global South, unclear institutional frameworks undermine progress in improving services. Often, ongoing decentralization reforms reduce clarity further. Policy professionals working on institutional reform lack comparative models. Purpose To identify key challenges for the institutional arrangements for urban sanitation in decentralizing contexts, in Kenya and elsewhere, and to propose possible responses. Approach and methods We use key informant interviews and literature review in a problem‐driven analysis, drawing from three comparative case studies: South Africa, Indonesia and Tamil Nadu State. The analysis builds upon research on institutional effectiveness—co‐operation, collaboration and co‐ordination—rooted in game theory and elaborated in the 2017 World Development Report. Findings Three key problems in Kenya are identified: overlaps and competition around sector leadership at national and devolved levels; weak incentives for county governments to commit policy attention and finance, despite devolution; and limited regulatory oversight. Policy implications We identify a range of options for urban sanitation policy‐makers: (a) to engage non‐sectoral authorities in co‐ordinating multi‐sectoral issues across all levels of government; (b) to encourage political commitment to pro‐poor sanitation services at decentralized levels; and (c) to use incentive‐based and risk‐based approaches to regulate decentralized entities and strengthen local capacity for monitoring and enforcement.

Lars Kaiser

No abstract is available for this record.

Dehua Shen, Andrew Urquhart, Pengfei Wang

No abstract is available for this record.

Jianbo Gao, Han Liu, Chao Liu, Qingshan Li · 6 authors

While Ethereum smart contracts enabled a wide range of blockchain applications, they are extremely vulnerable to different forms of security attacks. Due to the fact that transactions to smart contracts commonly involve cryptocurrency transfer, any successful attacks can lead to money loss or even financial disorder. In this paper, we focus on the overflow attacks in Ethereum, mainly because they widely rooted in many smart contracts and comparatively easy to exploit. We have developed EASYFLOW, an overflow detector at Ethereum Virtual Machine level. The key insight behind EASYFLOW is a taint analysis based tracking technique to analyze the propagation of involved taints. Specifically, EASYFLOW can not only divide smart contracts into safe contracts, manifested overflows, well-protected overflows and potential overflows, but also automatically generate transactions to trigger potential overflows. In our preliminary evaluation, EASYFLOW managed to find potentially vulnerable Ethereum contracts with little runtime overhead. A demo video of EASYFLOW is at https://youtu.be/QbUJkQI0L6o.

Yin Cao

No abstract is available for this record.

Álvaro García-Pérez, Alexey Gotsman

Some of the recent blockchain proposals, such as Stellar and Ripple, use quorum-like structures typical for Byzantine consensus while allowing for open membership. This is achieved by constructing quorums in a decentralised way: each participant independently chooses whom to trust, and quorums arise from these individual decisions. Unfortunately, the theoretical foundations underlying such blockchains have not been thoroughly investigated. To close this gap, in this paper we study decentralised quorum construction by means of federated Byzantine quorum systems, used by Stellar. We rigorously prove the correctness of basic broadcast abstractions over federated quorum systems and establish their relationship to the classical Byzantine quorum systems. In particular, we prove correctness in the realistic setting where Byzantine nodes may lie about their trust choices. We show that this setting leads to a novel variant of Byzantine quorum systems where different nodes may have different understanding of what constitutes a quorum.

Sourav Das, Vinay J. Ribeiro, Abhijeet Anand

One major shortcoming of permissionless blockchains such as Bitcoin and Ethereum is that they are unsuitable for running Computationally Intensive smart Contracts (CICs). This prevents such blockchains from running Machine Learning algorithms, Zero-Knowledge proofs, etc. which may need non-trivial computation. In this paper, we present YODA, which is to the best of our knowledge the first solution for efficient computation of CICs in permissionless blockchains with guarantees for a threat model with both Byzantine and selfish nodes. YODA selects one or more execution sets (ES) via Sortition to execute a particular CIC off-chain. One key innovation is the MultI-Round Adaptive Consensus using Likelihood Estimation (MIRACLE) algorithm based on sequential hypothesis testing. M I RACLE allows the execution sets to be small thus making YODA efficient while ensuring correct CIC execution with high probability. It adapts the number of ES sets automatically depending on the concentration of Byzantine nodes in the system and is optimal in terms of the expected number of ES sets used in certain scenarios. Through a suite of economic incentives and technical mechanisms such as the novel Randomness Inserted Contract Execution (RICE) algorithm, we force selfish nodes to behave honestly. We also prove that the honest behavior of selfish nodes is an approximate Nash Equilibrium. We present the system design and details of YODA and prove the security properties of MIRACLE and RICE. Our prototype implementation built on top of Ethereum demonstrates the ability of YODA to run CICs with orders of magnitude higher gas per unit time as well as total gas requirements than Ethereum currently supports. It also demonstrates the low overheads of RICE.

Mariana Makarova

Introduction. Bitcoin is a digital, decentralized, partially anonymous currency, not supported by any government or legal entity and not provided with gold or other goods. It relies on a peer-to-peer network and cryptography to maintain its integrity. The proponents claim that Bitcoin has many properties that could make it an ideal currency for consumers and merchants in a modern digital economy. Aim and tasks. The purpose of article was to determine and analyze impact of Bitcoin ecosystem on global digital economy. The research objectives were as follows: to specify the concept of Bitcoin ecosystem; to study the trends and prospects of cryptocurrencies development; to determine the role of Bitcoin as an alternative mean of preserving capital for investors – «gold bugs»; to compare the influence of gold and Bitcoin on development of a world financial system; to study the importance of Bitcoin and gold as financial assets of digital economy and the role of Bitcoin as a financial instrument inherent in this economy. Research results. The concept of Bitcoin ecosystem, its main components, factors and risks of development in historical and logical aspects are considered. The tendencies and prospects of cryptocurrencies development, particullary Bitcoin, their influence on traditional E-commerce, conduction of micro-payments, calculations in a field of virtual games are investigated. The role of Bitcoin as an alternative mean of capital preservation for a certain type of investors is determined. The comparative analysis of an influence of gold and Bitcoin on development of world financial system in historical aspect has been carried out. The conclusions are made about role of cryptocurrency (bitcoin) and gold as financial assets of digital economy. The role of Bitcoin as a financial tool corresponding to service requirements of actors of digital economy is determined. Conclusion. In last few years in many countries the large-scale Bitcoin-ecosystem and economy has developed with tens of millions of Bitcoins which daily change owners in electronic transactions. These funds still have a small amount relative to the rest of world's trading assets and economy. Today, while the digital currencies work in the semi-legal field in most countries, they may be a danger to national securities laws, be an instrument for tax evasion, illegal banking, money laundering, illicit drug trafficking, etc. This ability should be considered as one of the most unsafe risks of the functioning for Bitcoin ecosystem. But this is just the beginning of transformations for globalized system, since both society, economy and finance will become fully digital. The problem now is how to find right application for cryptocurrency, so that it becomes a paradigm of financial trust for humanity, as was previously with gold.

Jingwei Liu, Xiaolu Li, Lin Ye, Hongli Zhang · 6 authors

Electronic medical record (EMR) is a crucial form of healthcare data, currently drawing a lot of attention. Sharing health data is considered to be a critical approach to improve the quality of healthcare service and reduce medical costs. However, EMRs are fragmented across decentralized hospitals, which hinders data sharing and puts patients' privacy at risks. To address these issues, we propose a blockchain based privacy-preserving data sharing for EMRs, called BPDS. In BPDS, the original EMRs are stored securely in the cloud and the indexes are reserved in a tamper-proof consortium blockchain. By this means, the risk of the medical data leakage could be greatly reduced, and at the same time, the indexes in blockchain ensure that the EMRs can not be modified arbitrarily. Secure data sharing can be accomplished automatically according to the predefined access permissions of patients through the smart contracts of blockchain. Besides, the joint-design of the CP-ABE-based access control mechanism and the content extraction signature scheme provides strong privacy preservation in data sharing. Security analysis shows that BPDS is a secure and effective way to realize data sharing for EMRs.