Blockchain Papers

Tommy Koens, Erik Poll

No abstract is available for this record.

Benito Arruuada, Luis Garicano

By allowing networks to split, decentralized blockchain platforms protect members against hold up, but hinder coordination, given that adaptation decisions are ultimately decentralized. The current solutions to improve coordination, based on “premining” cryptocoins, taxing members and incentivizing developers, are insufficient. For blockchain to fulfill its promise and out-compete centralized firms, it needs to develop new forms of “soft” decentralized governance (anarchic, aristocratic, democratic, and autocratic) that allow networks to avoid bad equilibria.

Benoît Libert, San Ling, Khoa Nguyen, Huaxiong Wang

No abstract is available for this record.

Riccardo Longo

Cryptography is used to protect data and communications.
\nThe basic tools are cryptographic primitives, whose security and efficiency are widely studied.
\nBut in real-life applications these primitives are not used individually, but combined inside complex protocols.
\nThe aim of this thesis is to analyse various cryptographic protocols and assess their security in a formal way.
\nIn chapter 1 the concept of formal proofs of security is introduced and the main categorisation of attack scenarios and types of adversary are presented, and the protocols analysed in the thesis are briefly introduced with some motivation. 
\nIn chapter 2 are presented the security assumptions used in the proofs of the following chapters, distinguishing between the hardness of algebraic problems and the strength of cryptographic primitives.
\nOnce that the bases are given, the first protocols are analysed in chapter 3, where two Attribute Based Encryption schemes are proven secure.
\nFirst context and motivation are introduced, presenting settings of cloud encryption, alongside the tools used to build ABE schemes.
\nThen the first scheme, that introduces multiple authorities in order to improve privacy, is explained in detail and proven secure.
\nFinally the second scheme is presented as a variation of the first one, with the aim of improving the efficiency performing a round of collaboration between the authorities.
\n
\nThe next protocol analysed is a tokenization algorithm for the protection of credit cards.
\nIn chapter 4 the advantages of tokenization and the regulations required by the banking industry are presented, and a practical algorithm is proposed, and proven secure and compliant with the standard. 
\nIn chapter 5 the focus is on the BIX Protocol, that builds a chain of certificates in order to decentralize the role of certificate authorities.
\nFirst the protocol and the structure of the certificates are introduced, then two attack scenarios are presented and the protocol is proven secure in these settings.
\nFinally a viable attack vector is analysed, and a mitigation approach is discussed.
\nIn chapter 6 is presented an original approach on building a public ledger with end-to-end encryption and a one-time-access property, that make it suitable to store sensitive data. 
\nIts security is studied in a variety of attack scenarios, giving proofs based on standard algebraic assumptions. 
\nThe last protocol presented in chapter 7 uses a proof-of-stake system to maintain the consistency of subchains built on top of the Bitcoin blockchain, using only standard Bitcoin transactions.
\nParticular emphasis is given to the analysis of the refund policies employed, proving that the naive approach is always ineffective whereas the chosen policy discourages attackers whose stake falls below a threshold, that may be adjusted varying the protocol parameters.

Oksana Cheberyаko, Maryna KULISH

Introduction. Local budgets are the most numerous link of the budget system, the financial base of local authorities, which plays a decisive role in implementing regional policy through financing public expenditures and are the key to the emergence of a capable and efficient local government. However, the unsatisfactory results of the local authorities functioning in previous periods have led to the objective need to reform existing structure of local finances through fiscal decentralization. Purpose.To characterize the essence of financial decentralization from the point of view of its necessity for the economy of territorial and administrative units development and to analyze the success and risks of its implementation in Ukraine. Methods. In the course of writing the article, several methods were used. Among them were the method of analysis and synthesis, scientific comparison, formal logic and dialectics. Results. It has been determined that since the beginning of financial decentralization, the share of local budgets in the consolidated budget of Ukraine has doubled. The local budget revenues has increased in 2.8 times. Facts above indicate increasing in financial resources available to local authorities and, accordingly, more equal distribution of powers and opportunities of local and state authorities. The financial capacity of local budgets is evidenced by the balance of funds on accounts, which at the end of 2017 were amounted to 78.1 billion UAH. As a result, due to the accumulated resources of local budgets, more expenditure responsibilities has been given to local authorities. In addition, since the beginning of 2015, the formation of united territorial communities has begun, of which 699 had been formed by the end of 2017, but only 159 of them are fully operational. However, despite of the results achieved, significant financial, administrative and political factors threaten to continue fiscal decentralization. Conclusion. Despite the successful implementation of financial reform for local budgets, neglecting obvious risks can have a significant impact on the budgetary system of Ukraine. Therefore, the state and local authorities should further strengthen the requirements for the quality of community associations, control over their implementation and more objective planning and analysis of the results achieved, as the shortcomings in the reform will tend to be strengthened and may have a synergistic effect.

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.

Alla Petukhina, Simon Trimborn, Wolfgang Karl Härdle, Hermann Elendner

No abstract is available for this record.

Mykola Inshyn, L. V. Mohilevskyi, Oleksii Drozd

As soon as the usage of cryptocurrency in the last few years has been gaining popularity all over the world, and this global trend has affected Ukraine, the purpose of the paper is to examine the essence of cryptocurrency, to identify the issues of its legal regulation in Ukraine, as well as using the analysis of world experience in this sphere, to identify ways of the improvement for relevant domestic legislation. The authors have indicated that the cryptocurrency market (or "virtual" money) operates successfully and provides an opportunity to analyse dynamics of the cost, supply, and demand of about 90-100 different cryptocurrency. Problem's setting. The authors of the paper have emphasized that despite increasing popularity of cryptocurrency in Ukraine and throughout the world, there is no single clear definition of this concept. Therefore, the authors of this article state that cryptocurrency is a digital decentralized currency, a unit of which is a coin cryptographically protected against tampering since it is encrypted information that cannot be copied, while all information about transactions is stored in the blockchain system. Methodology. The study primarily uses comparative methods for the purposes of examination of the approaches taken under different jurisdictions towards cryptocurrency. Additionally, analysis of the body of theoretical literature on the matter was conducted. Results of the study allowed drawing several conclusions on the prospects of further development of the legal framework for cryptocurrencies in Ukraine since nowadays the country is neutral in the issue of using and regulating cryptocurrency and consequently it is losing precious time, because: first, potentially loses money, which could enter the state budget from individuals, who receive income from transactions on cryptocurrency markets; and secondly, the state runs a risk of citizens' rights violation because of no real instruments for their protection. Practical implications of these are proposals to adopt certain amendments to the current legislation in this sphere, including setting up control over brokerage of cryptocurrency, licensing of the industry, and legal definition of the cryptocurrency for the purposes of taxation, etc. Value/originality. The paper represents one of the first comprehensive studies of the current state and prospects of development of the legal framework for the cryptocurrency in Ukraine. Its conclusions provide both proposals for the development of legislation in this sphere and may serve as a basis for the future studies of this topic.

Hanlin Yang

No abstract is available for this record.

Jón Danı́elsson

No abstract is available for this record.

Tiffany L. Minks

No abstract is available for this record.

Yinan Pei, Kazumasa Oida

No abstract is available for this record.

Tatja Kärkkäinen

Following the popularity of Bitcoin trading in recent years, Bitcoin futures were introduced in December 2017 as an effort to provide institutional and retail investors with additional trading tools for Bitcoin. This study analyses the Bitcoin futures mid-quote data from CBOE, and Bitcoin market index applying VAR and VECM process methodologies, Hasbrouck’s information share and the Gonzalo-Granger component share measurement to examine price discovery in Bitcoin markets. Furthermore, the chapter seeks to assess the Bitcoin market microstructure. The results drawn on the intra-day prices show that the futures are leading the price discovery at different frequencies even with comparably low futures trading volumes. This supports the extant literature of futures-spot market price discovery and the role of informed traders in the futures market.

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.

Md. Mehedi Hassan Onik, Mahdi H. Miraz, Chul‐Soo Kim

Application of Information Technology (IT) in the domain of Human Resource Management (HRM) systems is a sine qua non for any organization for successfully adopting and implementing Fourth Industrial Revolution (Industry 4.0). However, these systems are required to ensure non-biased, efficient, transparent and secure environment. Blockchain, a technology based on distributed digital ledgers, can help facilitate the process of successfully effectuating these specifications. A detailed literature review has been conducted to identify the current status of usage of Information Technology in the domain of Human Resource Management and how Blockchain can help achieve a smart, cost-effective, efficient, transparent and secure factory management system. A Blockchain based Recruitment Management System (BcRMS) as well as Blockchain based Human Resource Management System (BcHRMS) algorithm have been proposed. From the analysis of the results obtained through the case study, it is evident that the proposed system holds definite advantages compared to the existing recruitment systems. Future research directions have also been identified and advocated.

Ryan Amsden, Denis Schweizer

No abstract is available for this record.

Jia Kan, Lingyi Zou, Bella Liu, Xin Huang

In recent years, with the rapid development and popularization of BitCoin, the research of blockchain technology has also shown growth. It has gradually become a new generation of distributed, non-centralized and trust-based technology solution. However, the blockchain operation is expensive and transaction is delayed. Take BitCoin as an example. On the one hand, a block is produced every ten minute. On the other hand, once the new block is generated, it takes a certain time to propagate world wide. The slow speed of propagation determines that BitCoin can not use too small block interval time. Ethereum also faces similar problems, so the concept of uncle block was introduced to reduce blockchain forks. This paper introduces a new tree structure based broadcast propagation routing model, providing a novel method to organize network nodes and message propagation mechanism. In oder to avoid the single node failure problem, the tree cluster routing is proposed. The research shows that the tree based routing can accelerate broadcast convergence time and reduce redundant traffic.

Mohammad Hossein Manshaei, Murtuza Jadliwala, Anindya Maiti, Mahdi Fooladgar

Low transaction throughput and poor scalability are significant issues in public blockchain consensus protocols such as Bitcoins. Recent research efforts in this direction have proposed shard-based consensus protocols where the key idea is to split the transactions among multiple committees (or shards), which then process these shards or set of transactions in parallel. Such a parallel processing of disjoint sets of transactions or shards by multiple committees significantly improves the overall scalability and transaction throughout of the system. However, one significant research gap is a lack of understanding of the strategic behavior of rational processors within committees in such shard-based consensus protocols. Such an understanding is critical for designing appropriate incentives that will foster cooperation within committees and prevent free-riding. In this paper, we address this research gap by analyzing the behavior of processors using a game-theoretic model, where each processor aims at maximizing its reward at a minimum cost of participating in the protocol. We first analyze the Nash equilibria in an N-player static game model of the sharding protocol. We show that depending on the reward sharing approach employed, processors can potentially increase their payoff by unilaterally behaving in a defective fashion, thus resulting in a social dilemma. In order to overcome this social dilemma, we propose a novel incentive-compatible reward sharing mechanism to promote cooperation among processors. Our numerical results show that achieving a majority of cooperating processors (required to ensure a healthy state of the blockchain network) is easier to achieve with the proposed incentive-compatible reward sharing mechanism than with other reward sharing mechanisms.

Elisa Gerten, Michael Beckmann, Lutz Bellmann

Abstract This study investigates the impact of information and communication technologies (ICT) on worker autonomy and monitoring using the second wave of the German Linked Personnel Panel, a linked employer-employee data set. From a theoretical point of view, the impact of ICT on workplace organization is ambiguous. On the one hand, the fast diffusion of ICT among employees makes it possible to monitor professional activities, leading to greater centralization. On the other hand, ICT enable employees to work more autonomously, so that workplace organization becomes more decentralized. Based on ordinary least squares and instrumental variable estimates, we find that ICT promotes both centralization and decentralization tendencies. Furthermore, managerial employees are more affected by ICT-induced monitoring and autonomy than their non-managerial counterparts. Finally, the effect of digital ICT on employee autonomy is more pronounced than the corresponding effect on employee monitoring. Again, this does especially hold for managerial employees. All in all, our results support the view that unlike prior technological revolutions digitalization primarily affects the employment prospects and working conditions of employees at medium and higher hierarchical levels.

Kevin McKernan, Yvonne Helbert, Liam T. Kane, Heather Ebling · 14 authors

We describe the use of a Decentralized Autonomous Organization (DAO) to crypto-fund the single molecule sequencing and publication of a Type II Cannabis plant. This resulted in the construction of the most contiguous Cannabis genome assembly to date. The combined use of the Dash cryptocurrency, DAOs, and Pacific Biosciences sequencing delivered a 1.03 Gb genome with a N50 of 665Kb in 77 days from funding to public upload. This represents a 230 fold improvement in the contiguity of the first cannabis assemblies in 2011 and a 4 fold improvement over all cannabis assemblies to date. 34Gb of additional sequencing pushed the assembly to a N50 of 3.8Mb. Hi-C data from Phase Genomics further scaffolded the assembly to 35 contigs at an N50 of 74Mb but requires additional curation. The genome is partially phased and larger than previously reported (2N = 1.33Gb). The CBCA, THCA and CBDA synthase gene clusters have been phased onto respective contigs demonstrating tandem repeat expansions.

Thach Ngoc Nguyen, Christian Servín, Владик Крейнович

Nowadays, most financial transactions are based on a centralized system, when all the transaction records are stored in a central location. This centralization makes the financial system vulnerable to cyber-attacks. A natural way to make the financial system more robust and less vulnerable is to switch to decentralized currencies. Such a transition will also make financial system more transparent. Historically first currency of this type -- bitcoin -- use a large amount of electric energy to mine new coins and is, thus, not scalable to the level of financial system as a whole. A more realistic and less energy-consuming scheme is provided by proof-of-stake currencies, where the right to mint a new coin is assigned to a randomly selected user, with probability depending of the user's stake (e.g., his/her number of coins). What probabilities should we choose? In this paper, we find the probability selection that provides the optimal result -- optimal in the sense that it is the least inductive to cheating.

Bolaji S Aregbeshola

A major challenge to achieve health coverage in Nigeria is expansion of health access to the poor, vulnerable and informal sectors, which constitute over 70% of the population of more than 186 million. Evidence from other countries suggests that it is difficult for contributory insurance schemes to achieve universal health coverage in such conditions, especially with such a large informal sector. In fact, Nigeria's national social health insurance program has provided coverage to less than 5% of the population since its implementation in 2005, private voluntary health insurance has shown poor potential to extend coverage, and community-based health insurance has failed to expand access to poor, vulnerable and informal sector populations as well. Decentralization of health insurance to the states has limited potential to expand health insurance coverage for the poor, vulnerable and those in the informal sector. Furthermore, social health insurance in many developed countries has taken many years to achieve universal health coverage. This paper suggests that policy makers should consider adopting a tax-based, noncontributory, universal health-financing system as the primary funding mechanism to accelerate progress toward universal health coverage. Social health insurance and its decentralization to states for formal sector workers should serve as a supplement, while private voluntary health insurance should cover better-off groups. Simultaneously, it is critical to tackle issues of poor governance structures, mismanagement of funds, corruption, and lack of transparency and accountability within regulatory and implementing agencies, to ensure that monies allocated for expanded health insurance coverage are well managed. Although the proposed universal health coverage reform may take some years to achieve, it is more feasible to collect taxes, improve tax administration and expand the tax base than to enforce payment of contributions from nonsalaried workers and those who cannot afford to pay for health insurance or for services out of pocket.

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.