Blockchain Papers

Stefan Hubrich

No abstract is available for this record.

Octavian Nica, Karolina Piotrowska, Klaus Reiner Schenk–Hoppé

Since the creation of Bitcoin in 2009, hundreds of cryptocurrencies have emerged, thus becoming a common fixture of financial news bulletins. With a market capitalization of the five highest-valued cryptocurrencies exceeding $140 billion at the time of writing, these alternative currencies have caught the attention of both financial institutions and central banks with their innovative technological foundations and their potential to disrupt current financial institutional structures. We provide a non-technical overview of the concept and current market structure of cryptocurrencies for researchers in economics, finance, mathematics and computer science.

Gerard H. Th. Bruijl

No abstract is available for this record.

Authors unavailable

Bitcoin transaction fee is an important kind of transaction costs that can be observed. In this paper, we address that the long-term effects of the demand are greater than that of the supply through empirical analyses of the influence degree of computational power, the number of transactions and the price of bitcoin. Based on the theory of supply and demand, there is a trend upward for bitcoin transaction fee in the future.

Nashirah Abu Bakar

Bitcoin is the first decentralized peer-to-peer payment network that is powered by its users with no central authority or middlemen. The objective of this study is to evaluate the normality of data distribution for exchange rate of Bitcoin. The method implemented in this study is Shapiro-Wilk normality test including graphical approach namely box plot .Results show the data distribution of exchange rate for Bitcoin follows non-normal distribution. Therefore, the normality transformation is important to make sure the distribution of data follows normal distribution. The normal distribution is very crucial as one of the requirement for validity of statistical test.Normality tests are used to determine if a data set is well-modeled by a normal distribution and to compute how likely it is for a random variable underlying the data set to be normally distributed.This study implemented two-stages of outliers detection and deletion process.The final results shows the distribution of Bitcoin exchange rate with first difference is follow normal distribution with probability of 0.722.Result concluded the distribution of data after second stages of outlies deletion treatment shows high normal distribution characteristics. This finding concludes that Bitcoin data is highly volatile with existence of many outliers. The transformation process is highly important to make sure the Bitcoin data follows normal distribution that underlying critical assumption for statistical tests.

David Vitt

No abstract is available for this record.

Tina Ehrke-Rabel, Iris Eisenberger, Elisabeth HHdl, Lily Zechner

German Abstract: Distribuierte Systeme, wie die Bitcoin-Blockchain, stellen das Recht vor neue Herausforderungen. Das disruptive Potential liegt unter anderem im Fehlen einer zentralen, verantwortlichen Kontrollinstanz, an die das Recht traditionell anknüpft, und im Verschwimmen der Rollen von „ProduzentInnen“ und „KonsumentInnen“ innerhalb des Systems. Die Erzeugung von Kryptowährungen, wie Bitcoin, mittels „Proof of Work“ und die gleichzeitige Validierung von Transaktionen zwischen NetzwerknutzerInnen (sog „Mining“) ist ein Beispiel dafür, dass die rechtlich etablierten Kategorien heute für eine effiziente Rechtsdurchsetzung unzureichend sind. „Mining“ kann rechtlich zwar als Glücksspiel iSd österreichischen GSpG eingeordnet werden. Konsequenz dieser Einordnung sind allerdings Probleme beim Vollzug des anwendbaren Ordnungs-, Abgaben- und Strafrechts. Regulierung von „Peer-to-Peer“-Systemen erfordert neue Lösungsansätze, um staatliche Steuerungsfunktionen zu erhalten. English Abstract: Distributed ledgers, such as the Bitcoin blockchain, create new challenges for authorities and legislators alike. The technology is considered disruptive due to the lack of a responsible legal entity and because the lines are blurred between the “producers” and “consumers” operating within it. The creation of cryptocurrencies, like Bitcoin, through “proof of work” and the simultaneous validation of transactions between users of the network (so called “mining”) perfectly illustrate how established legal categories are insufficient to achieve effective law enforcement at present. This paper shows that according to Austrian law, “mining” qualifies as a gamble. In that case, the applicable provisions of Austrian regulatory, tax and criminal law are, however, hardly enforceable. It follows that the regulation of “peer to peer”-systems requires an innovative approach, in order for the state to remain a key player in managing society.

Jochen Kasper

Bitcoin volatility is known to be high, as is shown by comparing Bitcoin volatility to several currencies and to assets like stock, gold etc. This work attempts to extend this work by comparing Bitcoin volatility to volatility of currencies of least developed countries and other cryptocurrencies. Exchange rate and return data drawn from Bloomberg and covering March 2014 to March 2017 was analysed. It was found that Bitcoin volatility is still considerably higher than volatilities of currencies of least developed countries. Only five currencies were more volatile for more than 10% of the time span analysed.

Thomas F Heston

Blockchain technology is a system of creating an immutable, secure, distributed database of transactions. Blockchains were initially created to provide a distributed ledger of financial transactions that did not rely upon a central bank, credit company, or other financial institution. The technological breakthrough, however, has been extended to transactions involving legal matters, medical records, insurance billing, and smart contracts. One primary way that blockchain technology is important to healthcare professionals in that it can revolutionize medical database interoperability. This greater interoperability can help improve access to medical records, imaging archives, prescription databases. Given that a patient’s medical history is a primary cornerstone of good medicine, blockchain technology has the potential to dramatically improve medical care.

Usman W. Chohan

No abstract is available for this record.

Felipe de Oliveira Simoyama, Ian Grigg, Ricardo Luiz Pereira Bueno, Ludmila Cavarzere De Oliveira

Legislation generally requires public agencies to account for their activity to the public. Among the many duties imposed by legislatures around the world are requirements for transparency in procurement of services, budgeting and presentation of accounts. However, agencies in countries with high corruption problems have trouble complying with the legislation, especially in smaller agencies. Moreover, it is typically infeasible for national auditors to audit all the accounts rendered, and instead, they select a small sample for audit based on their level of risk. Another problem is that the presentation of accounts occurs once a year for all agencies, leading to a seasonal demand with significant lag time between auditing and accounting period. In this study, we present a non-technical framework based on the emerging technology of blockchain that could be a solution to all these concerns. We apply it within the context of Brazilian legislation and the Federal Court of Accounts of Brazil (TCU), although the proposal is applicable across a wide range of countries facing severe corruption.

Tao Su

In the last decades, we have witnessed an exploding growth of the Internet. The massive adoption of distributed systems on the Internet allows users to offload their computing intensive work to remote servers, e.g. cloud. In this context, distributed systems are pervasively used in a number of difference scenarios, such as web-based services that receive and process data, cloud nodes where company data and processes are executed, and softwarised networks that process packets. In these systems, all the computing entities need to trust each other and co-operate in order to work properly. While the communication channels can be well protected by protocols like TLS or IPsec, the problem lies in the expected behaviour of the remote computing platforms, because they are not under the direct control of end users and do not offer any guarantee that they will behave as agreed. For example, the remote party may use non-legitimate services for its own convenience (e.g. illegally storing received data and routed packets), or the remote system may misbehave due to an attack (e.g. changing deployed services). This is especially important because most of these computing entities need to expose interfaces towards the Internet, which makes them easier to be attacked. Hence, software-based security solutions alone are insufficient to deal with the current scenario of distributed systems. They must be coupled with stronger means such as hardware-assisted protection. In order to allow the nodes in distributed system to trust each other, their integrity must be presented and assessed to predict their behaviour. The remote attestation technique of trusted computing was proposed to specifically deal with the integrity issue of remote entities, e.g. whether the platform is compromised with bootkit attacks or cracked kernel and services. This technique relies on a hardware chip called Trusted Platform Module (TPM), which is available in most business class laptops, desktops and servers. The TPM plays as the hardware root of trust, which provides a special set of capabilities that allows a physical platform to present its integrity state. With a TPM equipped in the motherboard, the remote attestation is the procedure that a physical node provides hardware-based proof of the software components loaded in this platform, which can be evaluated by other entities to conclude its integrity state. Thanks to the hardware TPM, the remote attestation procedure is resistant to software attacks. However, even though the availability of this chip is high, its actual usage is low. The major reason is that trusted computing has very little flexibility, since its goal is to provide strong integrity guarantees. For instance, remote attestation result is positive if and only if the software components loaded in the platform are expected and loaded in a specific order, which limits its applicability in real-world scenarios. For such reasons, this technique is especially hard to be applied on software services running in application layer, that are loaded in random order and constantly updated. Because of this, current remote attestation techniques provide incomplete solution. They only focus on the boot phase of physical platforms but not on the services, not to mention the services running in virtual instances. This work first proposes a new remote attestation framework with the capability of presenting and evaluating the integrity state not only of the boot phase of physical platforms but also of software services at load time, e.g. whether the software is legitimate or not. The framework allows users to know and understand the integrity state of the whole life cycle of the services they are interacting with, thus the users can make informed decision whether to send their data or trust the received results. Second, based on the remote attestation framework this thesis proposes a method to bind the identity of secure channel endpoint to a specific physical platform and its integrity state. Secure channels are extensively adopted in distributed systems to protect data transmitted from one platform to another. However, they do not convey any information about the integrity state of the platform or the service that generates and receives this data, which leaves ample space for various attacks. With the binding of the secure channel endpoint and the hardware TPM, users are protected from relay attacks (with hardware-based identity) and malicious or cracked platform and software (with remote attestation). Third, with the help of the remote attestation framework, this thesis introduces a new method to include the integrity state of software services running in virtual containers in the evidence generated by the hardware TPM. This solution is especially important for softwarised network environments. Softwarised network was proposed to provide dynamic and flexible network deployment which is an ever complex task nowadays. Its main idea is to switch hardware appliances to softwarised network functions running inside virtual instances, that are full-fledged computational systems and accessible from the Internet, thus their integrity is at stake. Unfortunately, currently remote attestation work is not able to provide hardware-based integrity evidence for software services running inside virtual instances, because the direct link between the internal of virtual instances and hardware root of trust is missing. With the solution proposed in this thesis, the integrity state of the softwarised network functions running in virtual containers can be presented and evaluated with hardware-based evidence, implying the integrity of the whole softwarised network. The proposed remote attestation framework, trusted channel and trusted softwarised network are implemented in separate working prototypes. Their performance was evaluated and proved to be excellent, allowing them to be applied in real-world scenarios. Moreover, the implementation also exposes various APIs to simplify future integration with different management platforms, such as OpenStack and OpenMANO.

Pedro Bonillo Bueno, Emilio Aragon Fortes, Konstantinos Vlachoski

No abstract is available for this record.

Dr Craig S Wright

No abstract is available for this record.

Anna Piotrowska, Dariusz Piotrowski

Bitcoin is a system created to service micro-payments in e-commerce, as well as the digital unit of value functioning in the system's environment. When analysed, the behaviour of market participants indicates that the introduction of investment applications of the cryptocurrency, in parallel with its original payment application, had a tremendous impact on the larger-scale functioning of the system. This was aided by the functioning of many trading platforms allowing for exchange into traditional currencies and a high volatility of quotations. Without doubt, bitcoin may be branded a ground-breaking financial innovation or a work of genius. However, the growing, and even global use of bitcoin has brought some of the system's imperfections to light. As the system developed, bitcoin users started to have a better view of the threats to the correct functioning of the system arising from its construction. The paper aims to indicate the main barriers limiting the functioning of the bitcoin system, and its use in payments in particular. The work has adopted the following research hypothesis: In the early stages of bitcoin functioning, users had little awareness of the technological flaws of the system. The study analyses the literature on the subject and the results of a survey carried out among Polish bitcoin users. The analysis confirms of the research hypothesis, as it shows that in the system's first several years, users identified the following threats to the system's functioning: the speculative nature of bitcoin, the lack of adequate awareness in society which would allow for a widespread use of the innovation, potential too strict regulation of the cryptocurrencies market or its banning. The authors also present threats to the functioning of the system which in their opinion are of greatest importance at the moment. These relate to the existence of intermediaries, the lack of systemic incentives addressed to bitcoin merchants, growing costs and payment processing time. The authors intend to indicate those aspects of bitcoin's functioning in order to make the use of cryptocurrencies more conscious and contribute to limiting financial risk of system users.

Chinelle van der Westhuizen

Virtual and digital crypto-currencies, specifically Bitcoin, were developed by an anonymous pseudonym ‘Satoshi Nakamoto’ in 2009 and have become a developing form of payment system used by businesses and consumers. Unlike traditional payment systems, Bitcoin is a peer-to-peer network with unique characteristics. Bitcoin is a private, anonymous and decentralised network that is intended to work independently from a government or banking authority. Bitcoin is therefore a network dependent upon mathematical algorithms between two users and managed through a process called ‘mining’, which is then stored within a user’s private ‘wallet’. This innovative technology offers numerous opportunities as a payment system; however, the legal challenges and risks it creates can be detrimental to consumers and businesses that use Bitcoin as an alternative payment system. The legal challenges of Bitcoin cause uncertainty for governments, businesses and consumers on the treatment of Bitcoin as an acceptable means of payment in Australia. Therefore, the purpose of this thesis is to determine whether Bitcoin is a form of ‘money’ and as such ought to be accepted as legal tender by the Australian Government under specific legislative instruments. Furthermore, this thesis will examine how Bitcoin is used to facilitate money laundering activities. Moreover, this thesis considers the treatment of tax within Bitcoin transactions and how unregulated Bitcoin transactions can be used to avoid tax. In addressing these legal issues and concerns, consideration is given to the possible regulation of virtual and digital currencies like Bitcoin in Australia. This thesis considers Australian banking, money laundering and taxation legislation and examines whether these regulatory frameworks are suitable to include Bitcoin as a payment system in order to limit money laundering and tax evasion activities within Bitcoin payment systems. Additionally, this thesis examines regulatory approaches to virtual and digital currencies in foreign jurisdictions, namely the United States, Canada and the European Union in order to gain some insight into how other countries are regulating Bitcoin as a payment system. This thesis arrives at a number of conclusions relevant to the possible regulation of Bitcoin in Australia. Firstly, it identifies Bitcoin as money and a form of payment system, but not legal tender and therefore not an accepted legal currency in Australia, which considers self-regulation of Bitcoin as a payment system a possibility. Secondly, it recognises that existing money laundering legislation can be amended to include Bitcoin as a payment system through which money laundering can take place and where Bitcoin exchange platforms are required to implement a ‘know-your-customer’ policy or ‘know-your-user’ policy. Thirdly, this thesis identifies that Bitcoin is recognised as a commodity for tax purposes and that suitable guidelines can be introduced on how to deal with tax activities and tax evasion within Bitcoin payments. Lastly, it is also recommended that international organisations such the Financial Action Task Force and International Monetary Fund could provide clarity on the treatment of virtual and digital currencies, specifically Bitcoin, as a payment system and legal currency, given that Bitcoin in global and borderless. Therefore, this research contributes towards how the Bitcoin network operates, its legal challenges and regulation in order to further research in this area of law.

Liam Lander, Nichola Cooper

No abstract is available for this record.

Lei Xu, Lin Chen, Nolan Shah, Zhimin Gao · 6 authors

Since Internet based applications have become the norm for most users, security has become a bigger concern than ever before, especially for applications like social networking and cloud based storage. Access control is one of the key techniques that can mitigate security concerns for web based applications. However, most existing access control mechanisms require a trusted party, which are vulnerable to many threats including malicious insiders and single point failure. In response to these challenges, we propose DL-BAC, a novel access control system based on the distributed ledger. DL-BAC robustly enforces access control policies without depending on a single trusted party. We also provide an extension of DL-BAC that is privacy respecting and evaluate the performance of DL-BAC to show its practicability.

Christian Pfister

In spite of a still very low volume at the global level, in comparison with the main reserve currencies, digital currencies attract a lot of attention. The paper reminds that it is above all the exchange mechanism incorporated in digital currencies (the distributed ledger technology) which should contribute to their success. It is shown that a widespread use of these currencies is likely to materialize only under conditions that woulDeessentially leave unchanged the capacity of the central bank to pursue the same inflation target using the same instruments as today, by setting an interest rate level. However, some adjustments may have to be made to the definition of monetary aggregates and possibly also to the base and/or the ratios of reserve requirements. Even in the most extreme and unlikely scenario, where the central bank would issue CBDC the public would have access to and massively adopt, banks role in distributing credit would likely not be seriously impaired. Banks might rather have less direct information on their clients. They would possibly also become more dependent on central bank refinancing, which would call for a clear and pre-announced lending of last resort policy in order to limit moral hazard considerations.

Mark Fenwick, Wulf A. Kaal, Erik P. M. Vermeulen

No abstract is available for this record.

Gorjan Alagic, Yfke Dulek, Christian Schaffner, Florian Speelman

Fully-homomorphic encryption (FHE) enables computation on encrypted data while maintaining secrecy. Recent research has shown that such schemes exist even for quantum computation. Given the numerous applications of classical FHE (zero-knowledge proofs, secure two-party computation, obfuscation, etc.) it is reasonable to hope that quantum FHE (or QFHE) will lead to many new results in the quantum setting. However, a crucial ingredient in almost all applications of FHE is circuit verification. Classically, verification is performed by checking a transcript of the homomorphic computation. Quantumly, this strategy is impossible due to no-cloning. This leads to an important open question: can quantum computations be delegated and verified in a non-interactive manner? In this work, we answer this question in the affirmative, by constructing a scheme for QFHE with verification (vQFHE). Our scheme provides authenticated encryption, and enables arbitrary polynomial-time quantum computations without the need of interaction between client and server. Verification is almost entirely classical; for computations that start and end with classical states, it is completely classical. As a first application, we show how to construct quantum one-time programs from classical one-time programs and vQFHE.

Rishab Goyal, Vipul Goyal

Blockchain technology has the potential to disrupt how cryptography is done. In this work, we propose to view blockchains as an “enabler”, much like indistinguishability obfuscation [5, 23, 46] or one-way functions, for building a variety of cryptographic systems. Our contributions in this work are as follows: 1. A Framework for Proof-of-Stake based Blockchains: We provide an abstract framework for formally analyzing and defining useful security properties for Proof-of-Stake (POS) based blockchain protocols. Interestingly, for some of our applications, POS based protocols are more suitable. We believe our framework and assumptions would be useful in building applications on top of POS based blockchain protocols even in the future. 2. Blockchains as an Alternative to Trusted Setup Assumptions in Cryptography: A trusted setup, such as a common reference string (CRS) has been used to realize numerous systems in cryptography. The paragon example of a primitive requiring trusted setup is a non-interactive zero-knowledge (NIZK) system. We show that already existing blockchains systems including Bitcoin, Ethereum etc. can be used as a foundation (instead of a CRS) to realize NIZK systems. The novel aspect of our work is that it allows for utilizing an already existing (and widely trusted) setup rather than proposing a new one. Our construction does not require any additional functionality from the miners over the already existing ones, nor do we need to modify the underlying blockchain protocol. If an adversary can violate the security of our NIZK, it could potentially also take over billions of dollars worth of coins in the Bitcoin, Ethereum or any such cryptocurrency! We believe that such a “trusted setup” represents significant progress over using CRS published by a central trusted party. Indeed, NIZKs could further serve as a foundation for a variety of other cryptographic applications such as round efficient secure computation [33, 36]. 3. One-time programs and pay-per use programs: Goldwasser et al. [29] introduced the notion of one time program and presented a construction using tamper-proof hardware. As noted by Goldwasser et al. [29], clearly a one-time program cannot be solely software based, as software can always be copied and run again. While there have been a number of follow up works [4, 6, 30], there are indeed no known constructions of one-time programs which do not rely on self destructing tamper-proof hardware (even if one uses trusted setup or random oracles). Somewhat surprisingly, we show that it is possible to base one-time programs on POS based blockchain systems without relying on trusted hardware. Our ideas do not seem to translate over to Proof-of-Work (POW) based blockchains. We also introduce the notion of pay-per-use programs which is simply a contract between two parties — service provider and customer. A service provider supplies a program such that if the customer transfers a specific amount of coins to the provider, it can evaluate the program on any input of its choice once, even if the provider is offline. This is naturally useful in a subscription based model where your payment is based on your usage.

Rowena Cullen

The chapter examines the critical role of good governanceGovernance and robust financial management in building stable democratic states in the Pacific Islands. It explores the role of ICTs in public financial managementPublic financial management (PFM) as a means to this end and identifies some of the factors that lead to the success or failure of e-government initiatives in this core government activity. The chapter outlines the dominant PFM reform agendas in the Pacific, including those of the World BankWorld Bank and the IMF, which have been endorsed by the Pacific Islands ForumPacific Islands Forum Economic Ministers Meeting, and the role of PFM systems and effective audit systems in combating corruptionCorruption . The need for capacity buildingCapacity building and leadershipLeadership in embedding public financial management reforms are discussed and the chapter concludes with a discussion of some issues emerging from the chapter: the value of centralized versus decentralized systems and the tension between development assistance and sovereignty. The chapter argues that ownership of the public financePublic finance reform agenda by Pacific governments and a commitment to good governance is essential for sustainable PFM reforms in the region and for development.

Stephan Meyer, Benedikt Schuppli

Die Blockchain-Technologie ist zurzeit in aller Munde. Der vorliegende Aufsatz widmet sich Smart Contracts und deren Einordnung in das schweizerische Vertragsrecht. Der Fokus liegt dabei auf der Qualifikation möglicher Rechtsverhältnisse zwischen Nutzern, Minern und Blockchain-Entwicklern sowie auf den Rechtsfolgen bei Diskrepanzen zwischen Smart Contracts und Verträgen im rechtlichen Sinne. Im Rahmen eines Ausblicks wird schliesslich die Frage erörtert, welche Bedeutung Verträgen in einer Zukunft mit sicheren, autonomen und pseudonymen Systemen zukommen wird.