Blockchain Papers

Lynette Louise Berger

No abstract is available for this record.

Pasquale Forte, Diego Romano, Giovanni Schmid

No abstract is available for this record.

Geoffroy Couteau, Thomas Peters, David Pointcheval

Committing integers and proving relations between them is an essential ingredient in many cryptographic protocols. Among them, range proofs have shown to be fundamental. They consist in proving that a committed integer lies in a public interval, which can be seen as a particular case of the more general Diophantine relations: for the committed vector of integers x, there exists a vector of integers w such that P (x,w) = 0, where P is a polynomial. In this paper, we revisit the security strength of the statistically hiding commitment scheme over the integers due to Damgard-Fujisaki, and the zero-knowledge proofs of knowledge of openings. Our first main contribution shows how to remove the Strong RSA assumption and replace it by the standard RSA assumption in the security proofs. This improvement naturally extends to generalized commitments and more complex proofs without modifying the original protocols. As a second contribution, we design an interactive technique turning commitment scheme over the integers into commitment scheme modulo a prime p. Still under the RSA assumption, this results in more efficient proofs of relations between committed values. Our methods thus improve upon existing proof systems for Diophantine relations both in terms of performance and security. We illustrate that with more efficient range proofs under the sole RSA assumption.

Rebecca Haw Allensworth

INTRODUCTIONAt its heart, antitrust law believes it is exceptional. Unlike most areas of regulation where rules must trade off costs and benefits different in kind, antitrust claims to pursue one single goal: competition.1 Courts often endorse the idea that the values traded off in regulation-the procompetitive effects and the anticompetitive effects-are commensurate. For example, courts frequently characterize Sherman Act § 1 as condemning restraints on trade having a net anticompetitive effect, and condoning those whose effects sum to a neutral or procompetitive effect. This supposedly unitary goal of antitrust-to facilitate competition-allows the law to appear to avoid the murky, value-laden compromises struck by other areas of regulation.But antitrust law is not exceptional. Even within the nowdominant paradigm that antitrust pursues only economic goals,2 value judgments are unavoidable. What are typically offered in antitrust cases as procompetitive and anticompetitive effects are rarely two sides of the same coin, and there is no such monolithic thing as competition that is furthered or impeded by competitor conduct. In fact, competition-whether defined as a process or as a set of outcomes associated with competitive markets-is multifaceted. Antitrust law often must trade off one kind of for another, or one salutary effect of (such as price, quality or innovation) for another. And in so doing, antitrust courts must make judgments between different and incommensurate values.The incommensurability problem is not entirely unrecognized in antitrust discourse, but it is downplayed in a manner harmful to policy and doctrine.3 Antitrust scholars acknowledge-and sometimes even highlight-the incomparability of the effects they measure.4 Judicial opinions occasionally, although less often, contain explicit discussions of the disparate competitive values at stake.5 But more often, these judgments are implicit.The absence of attention to the fact that procompetitive and anticompetitive effects, as they are presented in an antirust suit, are usually incommensurate, and the absence of debate about how to trade them off means that antitrust law is under-theorized. Rhetoric of commensurability in antitrust has made it unpopular for judges to acknowledge the use of value judgments in deciding antitrust cases.6 This has pushed important debates about those values into the subtext of antitrust opinions rather than allowing for the full and open discussion that they merit. It has also led to a set of doctrines that courts use to avoid the appearance of judgment, which distort antitrust litigation usually in favor of defendants. These evasive maneuvers have made a mess out of questions such as when the burden of production shifts from plaintiff to defendant, which arguments require empirical proof or a rigorously defined market, and what kinds of procompetitive justifications are categorically illegitimate.This Article uses Sherman Act § 1 liability to illustrate the incommensurability of most pro- and anticompetitive effects in antitrust litigation. Although the problem pervades antitrust law and policy, § 1 doctrine nicely illustrates the (false) exceptionalism of antitrust. The rhetoric of the Rule of Reason7 (the dominant mode of §1 analysis) exemplifies the problem: it claims to protect agreements that enhance and condemn those that destroy it,8 as if competition referred to one single value that antitrust must promote. But below the surface, the cases and rules actually do struggle with how to trade off very different benefits and costs of agreements among competitors. Examples include trading off quantitative for qualitative measures of consumer welfare, balancing present and future competitive effects, and trading off competitive effects on different classes of consumers. These latent debates play out in cases considering restraints that suppress intrabrand while stimulating interbrand competition,9 that trade a free market with failures for a self-regulated market with suppressed rivalry,10 and that create a new product by otherwise restricting competition. …

Andrew Miller

The past several years have seen the surprising and rapid rise of Bitcoin and other “cryptocurrencies.” These are decentralized peer-to-peer networks that allow users to transmit money, tocompose financial instruments, and to enforce contracts between mutually distrusting peers, andthat show great promise as a foundation for financial infrastructure that is more robust, efficientand equitable than ours today. However, it is difficult to reason about the security of cryptocurrencies. Bitcoin is a complex system, comprising many intricate and subtly-interacting protocol layers. At each layer it features design innovations that (prior to our work) have not undergone any rigorous analysis. Compounding the challenge, Bitcoin is but one of hundreds of competing cryptocurrencies in an ecosystem that is constantly evolving. The goal of this thesis is to formally reason about the security of cryptocurrencies, reining in their complexity, and providing well-defined and justified statements of their guarantees. We provide a formal specification and construction for each layer of an abstract cryptocurrency protocol, and prove that our constructions satisfy their specifications. The contributions of this thesis are centered around two new abstractions: “scratch-off puzzles,” and the “blockchain functionality” model. Scratch-off puzzles are a generalization of the Bitcoin “mining” algorithm, its most iconic and novel design feature. We show how to provide secure upgrades to a cryptocurrency by instantiating the protocol with alternative puzzle schemes. We construct secure puzzles that address important and well-known challenges facing Bitcoin today, including wasted energy and dangerous coalitions. The blockchain functionality is a general-purpose model of a cryptocurrency rooted in the “Universal Composability” cryptography theory. We use this model to express a wide range of applications, including transparent “smart contracts” (like those featured in Bitcoin and Ethereum), and also privacy-preserving applications like sealed-bid auctions. We also construct a new protocol compiler, called Hawk, which translates user-provided specifications into privacy-preserving protocols based on zero-knowledge proofs.

Dr Craig S Wright

Bitcoin scripts currently do not enable loops. Therefore, they are commonly considered to be not Turing Complete. This limits the types of algorithms the Bitcoin scripts can execute to linear or tree-like instructions. This white paper describes the invention of an Oracle module that: • Continuously monitors the state of Blockchain. • Makes decisions based on the current state. • Generates the next set of transactions to be written onto the Blockchain. The above processes is executed continuously by the Oracle in parallel to the Blockchain network. It therefore implements looping constructs that makes the combined Oracle and Blockchain system Turing Complete. As old blocks cannot be erased from the Blockchain, but new blocks can be added, the Oracle and the Blockchain will work as a non-erasable Turing Machine as described in Minsky et al. (1967). We will discuss the use of the Oracle in applications including: • Distributed data storage • Distributed computing • The control of drones. We will also describe how metadata storage and digital signature authorization on the Blockchain can be useful features for implementing these applications.

Sidharth Quamara, Awadhesh Kumar Singh

Bitcoins have opened a new chapter in the arena of electronic financial transactions. Due to their decentralized nature and independence from the need of a third party for authorizing transactions, they are seen as an alternative choice for payments by many firms and financial institutions. But like all other prevalent financial transaction technologies, they are also having their securities issues of their own kind. The current article discusses the security issues associated with the bitcoins based financial transaction processing system and various proposed research endeavors to combat them in recent years.

Şahnaz Koçoğlu, Yasin Erdem ÇEVİK, Cihan Tanrıöven

Bitcoin is a virtual money and a new payment system which is not regulated by a central authority. Bitcoin became popular quickly and gained the ability of affecting the real economy. Being used extensively and seen as an investment tool, Bitcoin created its own market, users and investors. This study aims to shed light on Bitcoin market. To understand what Bitcoin is, the history of Bitcoin was summarized firstly and the Bitcoin system and how the protocol works was explained. Then Efficiency, Liquidity and Volatility of the Bitcoin Markets were analyzed. We concluded that the pricing of Bitcoin is too complicated; and the Bitcoin market is still vulnerable to many risks and speculation.

Alin Tomescu, Srinivas Devadas

No abstract is available for this record.

Markus C. Arnold, Florian Elsinger, Frederick W. Rankin

No abstract is available for this record.

Jean‐Baptiste Harguindéguy, Emilio Rodríguez López

The 2008 crisis has had serious political consequences on the process of devolution in Spain. The rise of public deficit and debt drove the Spanish cabinet to adopt a series of austerity measures. Such decisions have considerably re-centralized the process of territorial decision-making. This paper aims to adopt the hypothesis of convergence among autonomies by comparing the different secondary effects exerted by the crisis on the autonomous communities between 2010 and 2014. Four indicators were used to depict Spanish decentralization in times of crisis: the profile of intergovernmental conflicts, the discourse of regional elites, the legitimacy of the current model of territorial organization, and the evolution of nationalist feelings of belonging. We conclude that the State of Autonomies will survive, but that it faces considerable internal tensions.

Zhiqiang Zhu, Ma Kexin, Lei Sun

No abstract is available for this record.

Nils Fleischhacker, Johannes Krupp, Giulio Malavolta, Jonas Schneider · 6 authors

A sanitizable signature scheme is a malleable signature scheme where a designated third party has the permission to modify certain parts of the message and adapt the signature accordingly. This primitive was introduced by Ateniese et al . (ESORICS 2005) and Brzuska et al . (PKC 2009) formalized the initially suggested five security properties. In the subsequent year, Brzuska et al . (PKC 2010) introduced a notion called unlinkability where the basic idea is that linking message‐signature pairs of the same document should be infeasible. Brzuska et al . formalized this notion and suggested a generic instantiation based on group signatures with a special structure. Unfortunately, the most efficient instantiations of group signatures do not have this property. In this work, we present the first efficient construction of unlinkable sanitizable signatures based on a novel type of signature schemes with re‐randomizable keys. This property allows one to re‐randomize both the signing and the verification key separately but consistently. Given a signature scheme with re‐randomizable keys, we obtain a sanitizable signature scheme by signing the message with a re‐randomized key and proving in zero‐knowledge that the derived key originates from either the signer or the sanitizer. To obtain an efficient instantiation, we instantiate this generic idea with Schnorr signatures and efficient ‐protocols that we turn into a non‐interactive zero‐knowledge proof via the Fiat‐Shamir transformation. In this work, we present an optimized version that is more efficient than the construction we suggested in the extended abstract of this work at PKC 2016.

Dorota Kamrowska‐Załuska

In last thirty years Poland has gone a long way toward democracy and decentralization. Role of public participation in planning is increasing rapidly and recently many new instruments of empowering the community is being introduced, participatory budgeting is one of the most important. On the other hand, urban regeneration is one of the most important challenges of polish cities are facing. Technical and transport infrastructure investments are, in most cases, financed by public sphere. We can also observe increasing role of NGO's in neighbourhood regeneration process but their scope of actions is mostly limited to soft projects. The paper tries to answer the question whether participatory budget can fill this gap and be a source of financing local community needs. This paper shows the creation and evolution of participatory budgets in Poland as well as the process of their implementation including examples of projects financed from participatory budget in Polish cities. It consists of analyses of participatory budgets’ expenditures structure and influence of the projects on the neighbourhood and the city. It also assesses long term influence and identify barriers, challenges and opportunities of using this instrument in urban regeneration process.

A.I. Soeparwata

The research aims to contribute to the understanding of institutional autonomy in higher education systems. Recent years demonstrated a growing emphasis on New Public Management oriented policies as a response to the increasing demands for autonomy, accountability and legitimacy as well as to the lack of trust in decentralized units. The research focuses on faculty competences of the traditionally centrally regulated areas of finance and human resource management and utilizes the principal-agent theory as a normative approach on policy reform. On the basis of the theoretical background, it is hypothesized that the actual level of autonomy does not necessarily resemble the same level of autonomy formally granted. Therefore, exemplified by the case of North Rhine-Westphalia, the formal and real autonomy is assessed by analyzing laws and policy documents at the federal and institutional level and by conducting semi-open expert interviews with university personnel in leading positions, respectively. In order to test the hypothesis, the findings of formal and real institutional autonomy were compared. The research found evidence that indicate a divergence between formal and real autonomy in the areas of financial and human resource management at the decentralized level.

Paulo Nicolás Carrillo, Pe ntilde a Clara I., de La Rosa Josep Ll.

With the popularization of online games and social networks, the virtual currencies have acquired a boom growing as solution of alternative payment and best adapted to the particular needs of the exchange of goods or virtual services offering faster, more secure and low cost transactions of value. This work proposes a case study to create the Eurakos Next cryptocurrency based on a virtual currency named Eurakos which currently works using digital contracts. The idea is to allow agreements to be signed by two peers and validated by other peers in a mobile social community network using Smart Contracts through the Ethereum framework to take advantage of the Blockchain technology.

Kaido Künnapas

No abstract is available for this record.

Christopher Marks

No abstract is available for this record.

Claire Ingram, Marcel Morisse

Studies of legitimacy have typically looked at the creation and maintenance of legitimacy by both established and new organisations. This paper looks at how a set of entrepreneurs use the legitimacy of one, Alternative, community as a scaffold to build legitimacy in a more Mainstream one, despite the fact that norms between the two were often contradictory. Studying Bitcoin entrepreneurs in Europe, we find that the distributed, digital community of Bitcoin operates as a kind of MNC: the larger decentralised (and Alternative) community acts as the headquarters, while the local entrepreneurs seeking Mainstream legitimacy behave like subsidiaries. This allow them to rely on the legitimacy of the community at large, while simultaneously distinguishing themselves from the broader Bitcoin community as they seek legitimacy.

Joseph R. Creighton

Since World War II, many of America's largest corporations have decentralized. Some, like General Dynamics, have joined several independent businesses under one corporate roof ; others, like General Electric, have made separate, semi-autonomous divisions out of an existing centralized business. Smaller companies have followed similar paths until today corporate divisions which have their own autonomous management are widespread. The corporate law department has come of age during this same period. The advantage of a closer relationship between management and its lawyers sparked this movement.1 It was accelerated by recognition that better knowledge of the company's business, its problems and its managers would enable the lawyers to give more pertinent and therefore more useful legal advice. Now, as company decision-making on major business matters has been delegated to divisional management, many companies have correspondingly delegated legal responsibility to divisional counsel. Thereby they have sought to retain and enhance the inherent benefits of corporate counsel. Law department decentralization, like that of the business itself, has created a host of new relationships, with both benefits and problems. For example, should the division counsel report to the division manager or to the corporate General Counsel or to both? To what extent should patent, tax, labor, anti-trust and such specialized legal matters be dealt with on a decentralized basis? Can the need fo* easy availability of legal counsel best be met if lawyers are assigned to geographic regions or plants, rather than according to the company's business organization?

Olivier Blazy, David Derler, Daniel Slamanig, Raphael Spreitzer

No abstract is available for this record.

Michel Avital, Roman Beck, John Leslie King, Matti Rossi · 5 authors

The panel focuses on blockchain, the technology behind Bitcoin and Ethereum. The topic has drawn much attention recently in both business and academic circles. The blockchain is a distributed, immutable digital record system that is shared among many independent parties and can be updated only by their consensus. If unbiased and incorruptible blockchain-based information systems become prevalent repositories of our records, trusting other humans with<br/>constructing and maintaining key records to define the resources at our disposal could become unnecessary. In principle, blockchain could provide a decentralized information infrastructure that no one fully controls, thereby no one has absolute power and no one can distort past or current records. The full potential let alone implications of blockchain is still unknown. The panel explores blockchain challenges and opportunities from the IS research perspective.

Jarunee Wonglimpiyarat

This paper discusses whether Bitcoin could revolutionise our payment system and replace our cash-based society. The analysis, in an attempt to understand the process of technological change, is based on the technology S-curve. This paper discusses the problems that hinder Bitcoin’s achieving wide adoption, as it has not been well received by international government central banks. Interestingly, the swing of S-curves is not strong enough to cause a paradigm shift. The results have shown parallel S-curve trajectories of electronic money innovations, signifying a move from a cash-based economy toward a less cash-based society. The paper provides useful information to support the diffusion of Bitcoin innovation.

Shravanthi, R Pooja, Bhagya Shree J

Bitcoin is a crypto currency with several advantages over approaches. Transactions are confirmed and stored by a peer-to-peer network in a blockchain. Therefore, all transactions are public and soon solutions where designed to increase privacy in Bitcoin. Many come with downsides, like requiring a trusted third-party or requiring modifications to Bitcoin. In this paper, we compare these approaches according to several criteria. Based on survey, coin Join emerges as the best approach for anonymizing Bitcoins today.