Blockchain Papers

Benoît Libert, Thomas Peters, Marc Jóye, Moti Yung

No abstract is available for this record.

Phong Q. Nguyễn, Jiang Zhang, Zhenfeng Zhang

No abstract is available for this record.

Michele Ciampi, Giuseppe Persiano, Luisa Siniscalchi, Ivan Visconti

The Fiat-Shamir (FS) transform is a popular technique for obtaining practical zero-knowledge argument systems. The FS transform uses a hash function to generate, without any further over-head, non-interactive zero-knowledge (NIZK) argument systems from public-coin honest-verifier zero-knowledge (public-coin HVZK) proof systems. In the proof of zero knowledge, the hash function is modeled as a programmable random oracle (PRO). In TCC 2015, Lindell embarked on the challenging task of obtaining a similar transform with improved heuristic security. Lindell showed that, for several interesting and practical languages, there exists an efficient transform in the non-programmable random oracle (NPRO) model that also uses a common reference string (CRS). A major contribution of Lindell’s transform is that zero knowledge is proved without random oracles and this is an important step towards achieving efficient NIZK arguments in the CRS model without random oracles. In this work, we analyze the efficiency and generality of Lindell’s transform and notice a significant gap when compared with the FS transform. We then propose a new transform that aims at filling this gap. Indeed our transform is almost as efficient as the FS transform and can be applied to a broad class of public-coin HVZK proof systems. Our transform requires a CRS and an NPRO in the proof of soundness, similarly to Lindell’s transform. 1

Satish Pillarisetti

No abstract is available for this record.

Maria Letizia Perugini, Paolo Dal Checco

Please find the English version of this paper at http://ssrn.com/abstract=2729548 . Italian Abstract: Nel 2008 il protocollo Bitcoin ha introdotto una nuovo modo di trasferire diritti: il modello di Blockchain, uno schema matematico che combina una serie di algoritmi per procedere all'incorporazione di determinati diritti in una stringa digitale trasferibile. Una delle evoluzioni di quel protocollo è rappresentata dagli smart contract, un modello ancora da definire a nei dettagli tecnici e giuridici in cui alcune clausole del contratto vengono tradotte in codice informatico per l'esecuzione automatica in una blockchain derivata dal protocollo Bitcoin. Questo paper propone una prima valutazione dell'argomento basata sulla ricognizione dello stato dell'arte. English Abstract: In 2008 the Bitcoin protocol has introduced a new way to transfer rights: the blockchain model, a method combining mathematical algorithms in order to secure rights in transferrable digital string. One of the implementations of that system is represented by smart contracts, a model that is still to be defined in technical and legal details. The scheme turns specific contractual provisions in executable digital codes, designed for self execution in a Bitcoin derived blockchain system. This paper proposes a preliminary evaluation based on the state of the art.

Yingjie Zhao

In this paper, we concern ourselves with cryptocurrency and how cryptocurrency affects the cryptocurrency market as well as the fiat currency market. The whole topic will be sepreted into two sections: competition among different currencies, as well as competition among exchanges[2]. We aim at figuring out the current circumstance of cryptocurrency which as a casual visitor in the market, and additionaly we will also look at the prospect of cryptocurrency and the currency market. Cryptocurrency with many new features has an uneasy development after entering into the financial market, although it is not yet powerful to compete with fiat currency, the effects of cryptocurrency and cryptocurrency exchange in financial market will still be full of meaning.

Aleksey Bragin

Derivatives are financial instruments whose value depend on the values of other, more basic underlying variables. One of the most common and simple derivatives is a futures contract. This manuscript introduces the new kind of futures contracts called non-linear inverse futures contracts (inverse futures in short) firstly introduced by ICBIT trading platform specifically for Bitcoin trading and later picked up by major bitcoin trading platforms.

Dmitri Kosten

No abstract is available for this record.

Hidalgo Chamba, Teresa de Jesús

Parish Governments, autonomous decentralized, do not have autonomy and decentralization, as well as other Governments autonomous decentralized cantonal and provincial, these rural parish Governments, rely on these Governments in administrative, financial, and political, its autonomy is weak, does not allow them to fulfil effectively their activities to meet the needs of their jurisdiction, which must be met The organic code of Territorial Organization, autonomy and decentralization, in its article 4 purposes of decentralized, in its literal autonomous governments, says: 'The solidarity and equitable development through the strengthening of the process of decentralization and autonomy'; This stated, in respect of the fair, in its application, in the daily exercise of the execution and settlement of this code very difficult is achieved The organic code of Territorial Organization, autonomy and decentralization, in its article 4 purposes of decentralized, in its literal autonomous governments, says: 'The solidarity and equitable development through the strengthening of the process of decentralization and autonomy'; This stated, in respect of the fair, in its application, in the daily exercise of the execution and settlement of this code very difficult is achieved In the same way in the organic code of Territorial Organization, autonomy and decentralization Art.150, manifests itself in relation to the residual powers are that are not assigned in the Constitution or the law in favor of the autonomous governments, and which is not part of the strategic sectors, proprietary or exclusive powers of the central Government. These competencies will be assigned by the National Council's competencies to autonomous governments, decentralized, except for those which by their nature are not susceptible to transfer, following the same procedure laid down in this code. The powers of the parish GAD, are fairly general by which it can be concluded that the economic - financial of the parish is not in charge of this entity and on the other hand, should be held to municipal and provincial plans at the same time that it should act coordinately with the other autonomous governments, implying that it has little independence. Hence, this problem arises since parish autonomous governments lack economic autonomy--financial, which contributes to generate resources and improvement of the quality of life of the inhabitants

Esha Ghosh, Olga Ohrimenko, Roberto Tamassia

We present an efficient method for answering one-dimensional range and closest-point queries in a verifiable and privacy-preserving manner. We consider a model where a data owner outsources a dataset of key-value pairs to a server, who answers range and closest-point queries issued by a client and provides proofs of the answers. The client verifies the correctness of the answers while learning nothing about the dataset besides the answers to the current and previous queries. Our work yields for the first time a zero-knowledge privacy assurance to authenticated range and closest-point queries. Previous work leaked the size of the dataset and used an inefficient proof protocol. Our construction is based on hierarchical identity-based encryption. We prove its security and analyze its efficiency both theoretically and with experiments.

Dan Boneh, Divya Gupta, Ilya Mironov, Amit Sahai

No abstract is available for this record.

David Derler, Henrich C. Pöhls, Kai Samelin, Daniel Slamanig

Abstract. A redactable signature scheme (RSS) allows removing parts of a signed message by any party without invalidating the respective signa-ture. State-of-the-art constructions thereby focus on messages represented by one specific data-structure, e.g., lists, sets or trees, and adjust the secu-rity model accordingly. To overcome the necessity for this myriad of models, we present a general framework covering arbitrary data-structures and even more sophisticated possibilities. For example, we cover fixed elements which must not be redactable and dependencies between elements. Moreover, we introduce the notion of designated redactors, i.e., the signer can give some extra information to selected entities which become redactors. In practice, this often allows to obtain more efficient schemes. We then present two RSSs; one for sets and one for lists, both constructed from any EUF-CMA secure signature scheme and indistinguishable cryptographic accumulators in a black-box way and show how the concept of designated redactors can be used to increase the efficiency of these schemes. Finally, we present a black-box construction of a designated redactor RSS by combining an RSS for sets with non-interactive zero-knowledge proof systems. All the three constructions presented in this paper provide transparency, which is an im-portant property, but quite hard to achieve, as we also conceal the length of the original message and the positions of the redactions. 1

Essam Ghadafi

No abstract is available for this record.

Robert Kurek

No abstract is available for this record.

Kinga Kądziołka

No abstract is available for this record.

Michael B. Abramowicz

No abstract is available for this record.

Jason Paul Cruz, Yuichi Kaji

The role-based access control (RBAC) is a natural and versatile model of the access control principle. In the real world, it is common that an organization provides a service to a user who owns a certain role that was issued by a different organization. However, such a trans-organizational RBAC is not common in a computer network because it is difficult to establish both the security that prohibits malicious impersonation of roles and the flexibility that allows small organizations/individual users to fully control their own roles. This study proposes a system that makes use of Bitcoin technology to realize a trans-organizational RBAC mechanism. Bitcoin, the first decentralized digital currency, is a payment network that has become a platform for innovative ideas. Bitcoin’s technology, including its protocol, cryptography, and open-source nature, has built a good reputation and has been applied in other applications, such as trusted timestamping. The proposed system uses Bitcoin technology as a versatile infrastructure to represent the trust and endorsement relationship that are essential in RBAC and to realize a challenge-response authentication protocol that verifies a user's ownership of roles.

Joshua Elkington

Bitcoin is a decentralized peer-to-peer payment system that has the potential to disrupt the financial industry. In order for the Bitcoin network to function properly, people within the network need to follow the protocol and contribute computing power. However, selfish strategies can be used to disproportionately increase one’s payoff relative to their computational power. Three approaches are used to analyze selfish mining strategies in the Bitcoin network in order to determine when this strategy will dominate.

Stephan Leixnering, Renate E. Meyer

Reform approaches in the public sector led to significant changes in the sector’s design. Especially NPM-inspired reform measures which had largely aimed at organizational disaggregation created pluriform landscapes of public sector organizations (PSOs). Following a core public governance principle, it was the central government’s task to coordinate, steer and control the newly emerged decentralized organizations. This raises questions about the overall design of the public sector at present. Our paper engages with the prevalent public governance phenomenon of fragmentation from a design perspective in order to understand governments’ lacking capability to steer and control PSOs. Therefore, we lift the level of analysis from single organizational entities to the organizational landscape to explore its organizational architecture and to grasp the status of the overall entity. By investigating the structure of the City of Vienna which employs more than 90,000 people, we shed light on the design that structures collective action within the city’s multi-organizational setting. We find that the overall design is rather serendipitous than consciously decided. In more detail, it displays characteristics of a hybrid form of organizing between networks and formal organization: lacking a single center and featuring multiplex and multifaceted relations within the politico-administrative apparatus and between government and PSOs, high fragmentation, local and robust action, but latent structures of significant formal authority and an implicitly shared idea of the overall joint objectives and collective values of ‘the city‘ as a whole. To present our case, we use a twofold strategy of data collection. First, we explored publicly available sources for the architecture of the city’s organizational landscape that provided insights in how structures and relations were formally designed. Second, we interviewed top officials and executives who performed key tasks in the coordination and management of the city’s autonomous units.

Philipp Locher, Rolf Haenni

No abstract is available for this record.

Pyrros Chaidos, Jens Groth

No abstract is available for this record.

Cheng Sh

This paper discusses how to use financial tools to support the national strategy public entrepreneurship and innovation. To implement the strategy public entrepreneurship and and reach the overall goal of building an innovative country, it's needed to conceive of the top-level design of the financial support system for innovation and entrepreneurship, make full use of financial strength, carry out the ideas of innovation and entrepreneurship thoroughly,promote the national strategy by financial guidance. In practice, it's needed to use the decentralization in governing to build a highly-efficient financial market environment for innovation and entrepreneurship, make full use of the function of banking institutions to support innovation and entrepreneurship, actively improve the multi-level capital markets to service innovation and entrepreneurship, strengthen international cooperation to improve the level of financial support to service innovation and entrepreneurship.

CrossBoundary

Mini-grids are viewed as one of the key elements in securing universal energy access in the developing world. However, current levels of investment into renewable decentralized energy are insufficient to reach the development goals identified by initiatives such as the UN’s Sustainable Energy for All. In order to reach such levels of deployment, new models of financing need to be designed. In this report, we provide a conceptual framework for the development of a private sector facility to pool and cross-collateralize diverse capital to support international mini-grid portfolios. We begin by discussing the current status of electrification initiatives in developing countries, and the approaches adopted to access finance for their implementation. We then argue that two key barriers exist to the effective financing of mini-grids. First, mini-grids in emerging markets have a complex risk profile that is difficult to mitigate at the individual project level. Furthermore, individual mini-grid projects are so small that their fixed transaction costs reduce their financial viability.

Yukun Sun

There are three chapters in my dissertation. In chapter one I study the impact of government corruption on tax avoidance by corporations with tax liability in China. I begin by developing a model of a firm's choice of tax avoidance based on the level of corruption in the firm's province. I show that a higher level of government corruption and a higher tax rate are predicted to increase a firm's tax avoidance. My empirical estimates show that a one-standard-deviation increase in government corruption corresponds to a 6% increase in tax avoidance by firms, based on data from nearly 600,000 firms from 1998 to 2007. When I separate the sample by type of ownership of firms, I find that domestic private firms tend to avoid a larger portion of their tax liabilities than foreign or state-owned firms. I also find that tax avoidance increases when the effective tax rate increases. The size of the firm, age of the firm, and whether the firm exports from China also influence tax avoidance. In chapter two, a joint work with Sergey Mityakov, we study the impact of competition on tax avoidance by corporations in Mexico. Using more than 2,000 firm level data, we show that firms tend to avoid more taxes in less competitive markets, that is more concentrated market. A one standard deviation increase in competition leads to a 7.7% increase in tax avoidance. By splitting the sample based on ownership structure, we show that domestic firms avoid more taxes. When we separate the firms according to the plant size, we find that larger firms tend to avoid more taxes. We find robust and consistent results by using different competition measures and other robustness tests. In chapter three, I theoretically demonstrate how fiscal decentralization affects corruption. The theory predicts that fiscal decentralization reduces corruption. This result is then tested using a panel data set of 31 provincial level government from 1998 to 2007 in China. My estimates suggest that fiscal decentralization in government expenditures and government revenue is negatively correlated with corruption. Using leader and location dummy variables, I find that central government leaders can influence the corruption level in China. I also find that more developed regions in China tend to be less corrupt.