Blockchain Papers

Jacob Hamburger

No abstract is available for this record.

Cara R. Baros

Over the past few years, virtual money has emerged via the Internet. Although currently unregulated, Internal Revenue System Notice 2014-21 will most likely cause virtual money to lose its mass appeal in the United States. Historically, other means of tax avoidance, including barter transactions and bearer bonds, have suffered the same fate. Virtual money will likely have more success as a technology than as a means of value.

Kim Brander

No abstract is available for this record.

C. Coughlan, W. Ledger, Q. Wang, Fenghua Liu · 10 authors

No abstract is available for this record.

Pablo Canóvas Vaca

No abstract is available for this record.

Cristina Pérez Solà, Jordi Herrera‐Joancomartí

Este trabajo esta parcialmente financiado por el Ministerio de Educacion, a traves de los proyectos TIN2011-27076-C03-02 CO-PRIVACY, TIN2010-15764 N-KHRONOUS, CONSOLIDER INGENIO 2010 CSD2007-0004 ARES, y de la beca FPU-AP2010-0078.

Matthew J. Allan

This paper will show the effect of cryptocurrencies, specifically Bitcoin and Litecoin, on a diversified portfolio of traditional and alternative assets. By using weekly closing price of these data, I use a single-index model to find betas, Sharpe ratios, and asset correlations. Then using the Markowitz Portfolio Optimization model to find optimal weights both with and without percentage restrictions. To date there is little academic research into cryptocurrency portfolio management. This paper expands upon a similar study done in the summer of 20131 through the Université Libre de Bruxelles. However, their data was from before a major spike in Bitcoin demand in November that same year, and did not include Litecoin. This paper fills the gap.

Łukasz Dopierała, Adam Borodo

No abstract is available for this record.

Sascha Böhme

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2014.

Antonio Escoda Viladomiu

No abstract is available for this record.

Georg Erber

No abstract is available for this record.

Kazuki Yoneyama

Almost all existing password-based authenticated key exchange (PAKE) schemes achieve concurrent security in the standard model by relying on the common reference string (CRS) model. A drawback of the CRS model is to require a centralized trusted authority in the setup phase; thus, passwords of parties may be revealed if the authority ill-uses trapdoor information of the CRS. There are a few secure PAKE schemes in the plain model, but, these are not achievable in a constant round (i.e., containing a linear number of rounds). In this paper, we discuss how to relax the setup assumption for (constant round) PAKE schemes. We focus on the multi-string (MS) model that allows a number of authorities (including malicious one) to provide some reference strings independently. The MS model is a more relaxed setup assumption than the CRS model because we do not trust any single authority (i.e., just assuming that a majority of authorities honestly generate their reference strings). Though the MS model is slightly restrictive than the plain model, it is very reasonable assumption because it is very easy to implement. We construct a (concurrently secure) three-move PAKE scheme in the MS model (justly without random oracles) based on the Groce-Katz PAKE scheme. The main ingredient of our scheme is the multi-string simulation-extractable non-interactive zero-knowledge proof that provides both the simulation-extractability and the extraction zero-knowledge property even if minority authorities are malicious. This work can be seen as a milestone toward constant round PAKE schemes in the plain model.

Vesna Harasic

IntroductionThe Internet revolutionized the world like nothing before. It allowed for various forms of communication and connectivity, yet produced a number of social, legal, and economic challenges. Evidently, scholars began to theorize that the Internet would lead to the development of new forms of digital currency.1 And, they were right.This Note focuses on the regulatory status of a digital called Bitcoin.2 Specifically, it explores whether Bitcoin may be regulated as a security under various domestic securities laws. Part II summarizes the unique characteristics of Bitcoin and its current regulatory classification. Part III analyzes the securities laws of the United States, the United Kingdom (U.K.), Brazil, and Japan- four regional leaders in financial regulation. Part III also applies these laws to Bitcoin, arguing that Bitcoin does not fit squarely within the securities definitions of any country. Lastly, Part IV suggests a possible solution to regulating Bitcoin in the United States under a quasi-security framework. It recommends that the Securities and Exchange Commission (SEC) define Bitcoin as a quasisecurity and pass regulations aimed solely at Bitcoin regulation, rather than trying to incorporate it into existing legislation. By promulgating new rules, the SEC can effectively spearhead the effort towards global Bitcoin regulation.I.Bitcoin's Unique Characteristics and Current Regulatory ClassificationThis Section explains what Bitcoin is and how it works. It discusses the unique characteristics of Bitcoin, and gives a brief overview of its varying legal status around the world.A.Entering the Bitcoin MarketBitcoin is the first digital currency that allows two parties to directly exchange single monetary units without going through a central payment system.3 The Bitcoin system is regulated entirely by computer software.4 It awards bitcoins to users through a program that solves various mathematical proofs and takes increasing amounts of computational power.5 Once users take time to download this program and use their computers to generate solutions, new bitcoins are issued.6 However, as the number of users in the system increases, the mathematical proofs become more difficult, which eventually slows down the production of bitcoins over time.7 Today, due to Bitcoin's popularity, few users acquire bitcoins through the mining process; rather, they acquire bitcoins in exchange for goods and services,8 or they purchase them directly through online exchanges.9B.Bitcoin TransfersOnce a user enters the Bitcoin market, he or she may choose to engage in Bitcoin transfers. Transfers occur through a network operated by thousands of computers, similar to a music-sharing system like iTunes or Spotify.10 Bitcoins are sent from one computer to another through individual messages. Each message has a personal identifier called an address,12 and each address has an associated pair of public and private keys, consisting of a string of numbers and letters.13 When an individual transfers bitcoins to a recipient, the recipient sends his or her address to the transferor.14 The transferor then adds the address and the amount of bitcoins to the transfer message.15 Finally, the transferor signs the message with his or her private key, and announces the public key to the recipient for signature verification.16In addition, the Bitcoin system provides a built-in mechanism to prevent individuals from copying and pasting the same digital addresses over and over again-a process that is often referred to as double spending.17 The traditional answer to the double-spending problem was a central clearinghouse, such as a bank, to keep a database of all transfers made in an account. However, Bitcoin found a way to alter this approach.18 After a transfer is completed, the system automatically broadcasts the time of the transfer and adds it to the Bitcoin block chain. …

Anastasia Michailaki

No abstract is available for this record.

Naya Nagy, Marius Nagy

No abstract is available for this record.

Michel Abdalla⋆, Roberto De Prisco

No abstract is available for this record.

Bashir Jumare

Local governments in Nigeria are saddled with the responsibility of providing social services to local people. The surest development of rural areas has been constitutionally placed on Local Governments. In order to achieve these statutory functions, 20% of revenue from Federation Accounts has been distributed to Local Government Councils since 1991 fiscal year. Despite enhanced revenue during the review period, there are reoccurring questions as to how and whether Local Governments have fully utilized revenues earmarked for socio-economic services. There are arguments that low tax structure and fluctuations in Local Government revenues have impacted negatively on the provision of socio-economic services. Many other researchers and political analysts have attributed the poor performance of Local Government Councils in the provision of social service as a result of lopsidedness of 1999 Constitution, in particular section 164 where the autonomy of the Local Government Councils was eroded. Others attributed the problems from endemic corruption and lack of fiscal accountability at local government level. This paper has examined revenue allocations for social service provision at local government level. Secondary data from Central Bank of Nigeria (CBN) annual and financial statements of accounts (19972011) were used. Both descriptive and regress analytical statistics were applied. The results of statistics indicate that the Nigerian Fiscal system has gone through rapid decentralization. This decentralization was driven primarily by changes in the revenue sharing arrangement from shares of Federation Account (FA) allocations introduced since 1981. This has led to rapid spending by the Local Government Councils. Rapid expenditure decentralization has created both new opportunities and challenges for public service in Nigeria. Given that sub-national governments are mainly responsible for financing basic public services such as primary health and education, decentralization creates the potential for further improvements in the financing of these primary sectors. The paper therefore recommended for upward review of capital spending by 70% and should come from share of Federation Account. The paper also recommended that recurrent expenditure in particular personnel cost should be met through local government’s internal revenue generation efforts. This would increase Local Governments fiscal autonomy and made them more prudent in their public expenditure management.

Shashank Agrawal, Shweta Agrawal, Shweta Agrawal, Shweta Agrawal · 5 authors

We provide a new framework of cryptographic agents that unifies various modern “cryp- tographic objects” — identity-based encryption, fully-homomorphic encryption, functional encryption, and various forms of obfuscation – similar to how the Universal Composition framework unifies various multi-party computation tasks like commitment, coin-tossing and zero-knowledge proofs. These cryptographic objects can all be cleanly modeled as “schemata” in our framework. Highlights of our framework include the following: • We use a new indistinguishability preserving (IND-PRE) definition of security that in- terpolates indistinguishability and simulation style definitions, which (often) sidesteps the known impossibilities for the latter. IND-PRE-security is parameterized by the choice of the “test” family, such that by choosing different test families, one can obtain different levels of security for the same primitive (including various standard definitions in the literature). • We present a notion of reduction from one schema to another and a powerful composition theorem with respect to IND-PRE security. We show that obfuscation is a “complete” schema under this notion, under standard cryptographic assumptions. We also provide a stricter notion of reduction (∆-reduction) that composes even when security is only with respect to certain restricted test families of importance. • Last but not the least, our framework can be used to model abstractions like the generic group model and the random oracle model, letting one translate a general class of constructions in these heuristic models to constructions based on standard model assumptions. We also illustrate how our framework can be applied to specific primitives like obfus- cation and functional encryption. We relate our definitions to existing definitions and also give new constructions and reductions between different primitives. ∗University of Illinois, Urbana-Champaign. Email: sagrawl2@illinois.edu. †Indian Institute of Technology, Delhi. Email: shweta.a@gmail.com. ‡University of Illinois, Urbana-Champaign. Email: mmp@illinois.edu.

Handan Kılınç, Alptekın Küpçü

Secure two-party computation cannot be fair against malicious adversaries, unless a trusted third party (TTP) or a gradual-release type super-constant round protocol is employed. Existing optimistic fair two-party computation protocols with constant rounds are either too costly to arbitrate (e.g., the TTP may need to re-do almost the whole computation), or require the use of electronic payments. Furthermore, most of the existing solutions were proven secure and fair via a partial simulation, which, we show, may lead to insecurity overall. We propose a new framework for fair and secure two-party computation that can be applied on top of any secure two party computation protocol based on Yao’s garbled circuits and zero-knowledge proofs. We show that our fairness overhead is minimal, compared to all known existing work. Furthermore, our protocol is fair even in terms of the work performed by Alice and Bob. We also prove our protocol is fair and secure simultaneously, through one simulator, which guarantees that our fairness extensions do not leak any private information. Lastly, we ensure that the TTP never learns the inputs or outputs of the computation. Therefore, even if the TTP becomes malicious and causes unfairness by colluding with one party, the security of the underlying protocol is still preserved.

Muthuramakrishnan Venkitasubramaniam

No abstract is available for this record.

Cristian Dogar, Codruța Mare

European Social Fund has to be accurately implemented by Members’ States authorities through projects developed by public and private national entities, according also to the principle of “sound financial management”, described as the expression of the appropriate mix of economy of assigned resources, efficient allocation of resources toward indicators and effectiveness of financed operations. As long as ESF funding is trusted for implementation through a decentralized management mechanism to the Members’ State Authorities, those have to comply with reporting objectives to the EC, as set into the European Regulations, including compliance to the “sound financial management” principle whose three components are specific, measurable, achievable, realistic and timely (SMART). Identifying the most appropriate quantitative methods that could be applied to the measurable elements may be seen as a first step in assisting both: management's decision towards implementation and reporting over the EC objectives. Our study tends to appropriate some quantitative models to the ESF implementation mechanisms, enhancing connections among ESF specific variables: project's budgets and number of individuals receiving labor market related services (also called project's indicators). Conclusions lead us to a series of quantitative models that may be practically used for assisting management's decision and reporting towards a sound ESF implementation in Romania.

Jean Paul Simon

An upheaval is taking place in media circles globally. There are new programme services, new distribution vehicles and new devices; at the same time, financing sources are being eroded, with a growing competition for advertising revenues. The companies must deal with changing expectations of the viewers, especially younger viewers. The legacy models, formerly based on geographic boundaries and scarcity of certain kinds of resources (i.e. spectrum) are under pressure; new services (server-based distribution of content) are location-agnostic (customers can access, for instance, YouTube or DailyMotion from any location). The ubiquity and rise of the Internet are turning upside down the legacy media logic (Busson and Pham, 2010). Media and telecommunication networks were hierarchical and had centralized architectures; the Internet has a decentralized architecture, open and flexible, allowing interaction at both ends (the receiver can become the transmitter), forging a major schism from that model. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Brigitte Le Normand

"The devastation of World War II left the Yugoslavian capital of Belgrade in ruins. Communist Party leader Josip Broz Tito saw this as a golden opportunity to recreate the city through his own vision of socialism. In Designing Tito's Capital, Brigitte Le Normand analyzes the unprecedented planning process called for by the new leader, and the determination of planners to create an urban environment that would benefit all citizens. Led first by architect Nikola Dobrovic and later by Miloš Somborski, planners blended the predominant school of European modernism and the socialist principles of efficient construction and space usage to produce a model for housing, green space, and working environments for the masses. A major influence was modernist Le Corbusier and his Athens Charter published in 1943, which called for the total reconstruction of European cities, transforming them into compact and verdant vertical cities unfettered by slumlords, private interests, and traffic congestion. As Yugoslavia transitioned toward self-management and market socialism, the functionalist district of New Belgrade and its modern living were lauded as the model city of socialist man. The glow of the utopian ideal would fade by the 1960s, when market socialism had raised expectations for living standards and the government was eager for inhabitants to finance their own housing. By 1972, a new master plan emerged under Aleksandar Đordevic, fashioned with the assistance of American experts. Espousing current theories about systems and rational process planning and using cutting edge computer technology, the new plan left behind the dream for a functionalist Belgrade and instead focused on managing growth trends. While the public resisted aspects of the new planning approach that seemed contrary to socialist values, it embraced the idea of a decentralized city connected by mass transit. Through extensive archival research and personal in

Ashley Lee

The article focuses on a Chapter 15 filing by MtGox, a Japanese Bitcoin exchange, for U.S. recognition of its local restructure in March 2014. Topics discussed include the impact of this filing on how U.S. courts deal with cryptocurrency enterprises, and recent court decisions which have called into question foreign debtors' use of Chapter 15 if they do not have U.S. asset.