Blockchain Papers

Khamis Hamed Al‐Yahyaee, Walid Mensi, Seong‐Min Yoon

No abstract is available for this record.

Khaled Guesmi, Samir Saadi, Ilyes Abid, Zied Ftiti

No abstract is available for this record.

İrem Önder, Horst Treiblmaier

No abstract is available for this record.

Paweł Szałachowski

Bitcoin provides freshness properties by forming a blockchain where each block is associated with its timestamp and the previous block. Due to these properties, the Bitcoin protocol is being used as a decentralized, trusted, and secure timestamping service. Although Bitcoin participants which create new blocks cannot modify their order, they can manipulate timestamps almost undetected. This undermines the Bitcoin protocol as a reliable timestamping service. In particular, a newcomer that synchronizes the entire blockchain has a little guarantee about timestamps of all blocks. In this paper, we present a simple yet powerful mechanism that increases the reliability of Bitcoin timestamps. Our protocol can provide evidence that a block was created within a certain time range. The protocol is efficient, backward compatible, and surprisingly, currently deployed SSL/TLS servers can act as reference time sources. The protocol has many applications and can be used for detecting various attacks against the Bitcoin protocol.

Mehdi Jafarı, Amin Habibirad, Arefeh Pourtaleb, Mohammad Hossein Salarianzadeh

BACKGROUND: Since the early 1990s, Iran has initiated structural and decentralization reforms in the hospital system. This policy led to the formation of a Board of Trustees (BOTs) for the governing of public educational hospitals and making important modifications in hospitals' financing. This study was conducted to identify the barriers in implementing this policy. METHODS: All the Iranian Medical Sciences Universities and hospitals involved in the policy implementation were included in this qualitative study. The data were analyzed by using content analysis. RESULTS: In total, 403 problems were divided into 9 classes including problems related to implementing regulation, financial problems in policy implementation, problems related to faculty members, ambiguity in executive regulation, problems related to the BOTs, authority level, hospital structure, the quality and quantity of hospital human resources, and fee for services. CONCLUSION: It appears that "implementing regulation" and "financial problems" embrace over 50% of the barriers. Apparently, the new approach to hospitals' autonomy has not achieved the desired goals. Considering the contextual factor, the evidence and identification of the clear role of various stakeholders should be essential determinants. Partial implementation of this policy without paying attention to the other aspects would end in failure. The results showed insufficient budget to be the most influential factor that posed a dilemma in implementing the BOTs' policy. However, BOTs in Iranian health system need to strive toward a higher level of performance that will improve effectiveness and efficiency now more than ever.

Paweł Szałachowski

Bitcoin provides freshness properties by forming a blockchain where each block is associated with its timestamp and the previous block. Due to these properties, the Bitcoin protocol is being used as a decentralized, trusted, and secure timestamping service. Although Bitcoin participants which create new blocks cannot modify their order, they can manipulate timestamps almost undetected. This undermines the Bitcoin protocol as a reliable timestamping service. In particular, a newcomer that synchronizes the entire blockchain has a little guarantee about timestamps of all blocks. In this paper, we present a simple yet powerful mechanism that increases the reliability of Bitcoin timestamps. Our protocol can provide evidence that a block was created within a certain time range. The protocol is efficient, backward compatible, and surprisingly, currently deployed SSL/TLS servers can act as reference time sources. The protocol has many applications and can be used for detecting various attacks against the Bitcoin protocol.

Zhiyuan Jiang, Bhaskar Krishnamachari, Sheng Zhou, Zhisheng Niu

The blockchain technology has achieved tremendous success in open (permissionless) decentralized consensus by employing proof-of-work (PoW) or its variants, whereby unauthorized nodes cannot gain disproportionate impact on consensus beyond their computational power. However, PoW-based systems incur a high delay and low throughput, making them ineffective in dealing with real-time applications. On the other hand, byzantine fault-tolerant (BFT) consensus algorithms with better delay and throughput performance have been employed in closed (permissioned) settings to avoid Sybil attacks. In this paper, we present Sybil-proof wirelEss Network coordinAte based byzanTine consEnsus (SENATE), which is based on the conventional BFT consensus framework yet works in open systems of wireless devices where faulty nodes may launch Sybil attacks. As in a Senate in the legislature where the quota of senators per state (district) is a constant irrespective with the population of the state, "senators" in SENATE are selected from participating distributed nodes based on their wireless network coordinates (WNC) with a fixed number of nodes per district in the WNC space. Elected senators then participate in the subsequent consensus reaching process and broadcast the result. Thereby, SENATE is proof against Sybil attacks since pseudonyms of a faulty node are likely to be adjacent in the WNC space and hence fail to be elected.

Yoshiaki Kawase

No abstract is available for this record.

William J. Magnuson

The recent decade has witnessed an extraordinary degree of innovation in the financial sector. Developments in financial technology, computing power, and networking theory have allowed decentralized online platforms such as Bitcoin to fundamentally change the way that financial services are provided. While these innovations have been applauded by many as bringing a welcome degree of competition to a sector long dominated by powerful incumbents, they also create a set of challenges for current financial regulation. How do fiduciary standards apply to algorithms? How does online finance affect the behavior of investors? And more generally, how can regulators monitor and constrain the financial industry when it is increasingly run by autonomous, dispersed computer networks? This Article argues that current financial regulation is inadequate to address the unique problems presented by the rise of Bitcoin and other fintech industries. In particular, these innovations raise concerns about the ability of financial regulation to promote three inter-related financial goals: the efficient allocation of capital, the protection of consumers, and the prevention of systemic risk. These goals, at the core of current approaches to financial regulation, are all challenged by fintech’s defining feature: its reliance on disembodied institutions and complex algorithms for its functioning. These traits render the traditional tools used by regulators to discipline markets—substantive behavioral obligations, the threat of sanctions, and the constraining effect of reputation—largely ineffective. The Article concludes by proposing a set of principles to guide lawmakers in designing a more effective financial regulatory structure for the Bitcoin era.

Sébastien Forestier, Damir Vodenicarevic, Adrien Laversanne-Finot

Decentralized crypto-currencies based on the blockchain architecture\nunder-utilize available network bandwidth, making them unable to scale to\nthousands of transactions per second. We define the Blockclique architecture,\nthat addresses this limitation by sharding transactions in a block graph with a\nfixed number of threads. The architecture allows the creation of intrinsically\ncompatible blocks in parallel, where each block references one previous block\nof each thread. The consistency of the Blockclique protocol is formally\nestablished in presence of attackers. An experimental evaluation of the\narchitecture's performance in large realistic networks demonstrates an\nefficient use of available bandwidth and a throughput of thousands of\ntransactions per second.\n

Chi‐Wei Su, Zhengzheng Li, Ran Tao, Deng-Kui Si

No abstract is available for this record.

Marek A Cyran

Blockchain technology has the potential to transform healthcare delivery by facilitating data sharing between providers and electronic health record (EHR) systems. However, significant roadblocks stand in the way of widespread implementation of this technology across the healthcare industry. Our blockchainbased data-sharing solution addresses two of the most critical challenges associated with using blockchain for health data sharing: protecting sensitive health information and deploying and installing blockchain software across diverse hospital environments. Since transparency is a fundamental feature of blockchain, we enabled user- and group-based secret sharing by adding purpose-built software that leverages a collection of well-established cryptographic algorithms. To streamline deployment, we built a containerized solution that guarantees portability, simplifies installation, and reduces overhead maintenance costs associated with administration. To ensure ease of implementation in a hospital system, we designed our blockchain solution using a distributed microservices architecture that allows us to encapsulate core functions of our system into isolated services that can be scaled independently based on the requirements of a particular hospital system deployment. As part of this architecture, we built core components for securely handling cryptographic secrets, interacting with blockchain nodes, facilitating large file sharing, enabling secondary-index based lookups, and integrating external business logic that governs how users interact with Smart Contracts. The innovative design of our blockchain solution, which addresses critical data security, deployment, and installation challenges, provides the healthcare community with a unique approach that has the power to connect providers while protecting sensitive data. Keywords: Blockchain, Data Sharing, Data Exchange, EHR,electronic health record, Ethereum, interplanetary file system, IPFS

Kevin A. Clauson, Elizabeth A. Breeden, Cameron Davidson, Tim K. Mackey

Background: Effective supply chain management is a challenge in every sector, but in healthcare there is added complexity and risk as a compromised supply chain in healthcare can directly impact patient safety and health outcomes. One potential solution for improving security, integrity, data provenance, and functionality of the health supply chain is blockchain technology. Objectives: Provide an overview of the opportunities and challenges associated with blockchain adoption and deployment for the health supply chain, with a focus on the pharmaceutical supply, medical device and supplies, Internet of Healthy Things (IoHT), and public health sectors. Methods: A narrative review was conducted of the academic literature, grey literature, and industry publications, in addition to identifying and characterizing select stakeholders engaged in exploring blockchain solutions for the health supply chain. Results: Critical challenges in protecting the integrity of the health supply chain appear well suited for adoption of blockchain technology. Use cases are emerging, including using blockchain to combat counterfeit medicines, securing medical devices, optimizing functionality of IoHT, and improving the public health supply chain. Despite these clear opportunities, most blockchain initiatives remain in proof-of-concept or pilot phase. Conclusion: Blockchain technology has the unrealized promise to help improve the health supply chain, but further study, evaluation and alignment with policy mechanisms is needed. Keywords: Blockchain, Distributed Ledger, Pharmacy, Pharmaceutical, Supply chain

Olivia Choudhury, Hillol Sarker, Nolan Rudolph, Morgan A. Foreman · 9 authors

Recent changes to the Common Rule, which govern Institutional Review Boards (IRB), require implementing new policies to strengthen research protocols involving human subjects. A major challenge in implementing such policies is an inability to automatically and consistently meet these ethical rules while securing sensitive information collected during the study. In this paper, we propose a novel framework, based on blockchain technology, to enforce IRB regulations on data collection. We demonstrate how to design smart contracts and a ledger to meet the requirements of an IRB protocol, including subject recruitment, informed consent management, secondary data sharing, monitoring risks, and generating automated assessments for continuous review. Furthermore, we show how we can employ the immutable transaction log in the blockchain to embed security in research activities by detecting malicious activities and robustly tracking subject involvement. We evaluate our approach by assessing its ability to enforce IRB guidelines in different types of human subjects studies, including a genomic study, a drug trial, and a wearable sensor monitoring study. Keywords: Blockchain, Data Sharing, Data Exchange, EHR, electronic health record, Ethereum, interplanetary filesystem, IPFS

Dimitrios Koutmos

No abstract is available for this record.

Ron Ribitzky, J. Clair, David Houlding, Chrissa McFarlane · 9 authors

Background: Blockchain and distributed ledger technology is a disruptive force in healthcare. Methods: This article provides a globally relevant, interdisciplinary perspective intended to aid disparate group of actors, participants, and users that represent the diverse stakeholders of an increasingly complex and technologically reliant healthcare system. Domain expertise reinforced by literature published via industry, technical, and academic venues was used to inform these perspectives. Results: Key characteristics of blockchain and distributed ledger technology are highlighted and framed for a readership ranging from healthcare executive to policy makers to researchers. Antecedent application of blockchain in the financial sector is explored followed by the technical, security, and interoperability considerations specific to healthcare. Conclusion: Blockchain remains an emerging technology both fraught with unanticipated challenges and the promise of unrealized potential in healthcare. Keywords: Blockchain, Healthcare, Innovation, Adoption, Global, Interoperability

Authors unavailable

Headline INTERNATIONAL: NSA surveillance may undermine bitcoin

Roberto Casado‐Vara, Juan M. Corch ado

No abstract is available for this record.

Elie Bouri, Rangan Gupta, Amine Lahiani, Muhammad Shahbaz

No abstract is available for this record.

Angelos Dassios, Luting Li

We introduce a new diffusion process Xt to describe asset prices within an economic bubble cycle. The main feature of the process, which differs from existing models, is the drift term where a mean-reversion is taken based on an exponential decay of the scaled price. Our study shows the scaling factor on Xt is crucial for modelling economic bubbles as it mitigates the dependence structure between the price and parameters in the model. We prove both the process and its first passage time are well-defined. An efficient calibration scheme, together with the probability density function for the process are given. Moreover, by employing the perturbation technique, we deduce the closed-form density for the downward first passage time, which therefore can be used in estimating the burst time of an economic bubble. The object of this study is to understand the asset price dynamics when a financial bubble is believed to form, and correspondingly provide estimates to the bubble crash time. Calibration examples on the US dot-com bubble and the 2007 Chinese stock market crash verify the effectiveness of the model itself. The example on BitCoin prediction confirms that we can provide meaningful estimate on the downward probability for asset prices.

Jean-Maxime Rivière

The blockchain, as underlying technology of Bitcoins, has implications that reach far beyond the original intent as virtual currency. In this paper, we investigate how blockchain technology can be encompassed in the innovation process and bring huge benefits to the patent system as well as copyrights, trade secrecy, defensive publications, and open innovation. We further explore the institutional support for the technology necessary for a successful implementation, in form of legislations and governmental projects. We find out that numerous authorities have started voting favorable legislations and recognizing the technology as a valid public ledger. Ultimately, we confirm our findings by interviewing three actors involved in the innovation process. Keywords: Bitcoin, Blockchain, Intellectual property, Legislation, Innovation

Peter Rohner, Lewin Boehnke, Hans-Joachim Voth

Die Bitcoin-Blase ist geplatzt. Doch wie geht es jetzt weiter? Zwei Experten legen die Argumente für und gegen die Kryptowährung dar.

Percival Lucena, Alécio Pedro Delazari Binotto, Fernanda da Silva Momo, Henry Kim

One of the key processes in Agriculture is quality measurement throughout the transportation of grains along its complex supply chain. This procedure is suitable for failures, such as delays to final destinations, poor monitoring, and frauds. To address the grain quality measurement challenge through the transportation chain, novel technologies, such as Distributed Ledger and Blockchain, can bring more efficiency and resilience to the process. Particularly, Blockchain is a new type of distributed database in which transactions are securely appended using cryptography and hashed pointers. Those transactions can be generated and ruled by special network-embedded software -- known as smart contracts -- that may be public to all nodes of the network or may be private to a specific set of peer nodes. This paper analyses the implementation of Blockchain technology targeting grain quality assurance tracking in a real scenario. Preliminary results support a potential demand for a Blockchain-based certification that would lead to an added valuation of around 15% for GM-free soy in the scope of a Grain Exporter Business Network in Brazil.

Alexander Chepurnoy, Mayank Rathee

Inspired by the success of Bitcoin, many clients for the Bitcoin protocol as well as for alternative blockchain protocols have been implemented. However, implementations may contain errors, and the cost of an error in the case of a cryptocurrency can be extremely high. We propose to tackle this problem with a suite of abstract property tests that check whether a blockchain system satisfies laws that most blockchain and blockchain-like systems should satisfy. To test a new blockchain system, its developers need to instantiate generators of random objects to be used by the tests. The test suite then checks the satisfaction of the laws over many random cases. We provide examples of laws in the paper.