Blockchain Papers

Zvika Brakerski, Nico Döttling

No abstract is available for this record.

Pavel Hubáček, Alon Rosen, Margarita Vald

We present an unconditional transformation from any honest-verifier statistical zero-knowledge (HVSZK) protocol to standard SZK that preserves round complexity and efficiency of both the verifier and the prover. This improves over currently known transformations, which either rely on some computational assumptions or introduce significant computational overhead. Our main conceptual contribution is the introduction of instance-dependent SZK proofs for NP, which serve as a building block in our transformation. Instance-dependent SZK for NP can be constructed unconditionally based on instance-dependent commitment schemes of Ong and Vadhan (TCC’08).

Kang Li, Rupeng Yang, Man Ho Au, Qiuliang Xu

No abstract is available for this record.

Craig Calcaterra, Wulf A. Kaal, Gopinath Sivalingam

No abstract is available for this record.

Венелин Терзиев, Stefcho Bankov, Мarin Georgiev

In its jurisprudence the Court of Justice of the European Union (CJEU) has changed its approach towards the purely internal situation rule applicable in the context of the market freedoms. From the 1990s onwards the Court has showed a greater leniency in accepting that certain cases fall within the scope of Union law, as compared to in the years before. This has been done in various ways, depending on the specific fundamental freedom at stake in the case, but always resulted in a relaxing of the fulfilment of the test used for determining whether a case falls within the scope of a market freedom - the linking factor test. More specifically, the Court seems to be accepting that hypothetical future scenarios are sufficient to bring a case within the scope of EU law even though the underlying facts of the case do not satisfy the test, or even to rule in cases which clearly do not fulfil some of the conditions of the test. The overall change of approach towards the purely internal rule can also be seen in an issue of jurisdiction, and not scope, which is still however relevant. This is the fact that the Court has begun issuing preliminary reference rulings in purely internal cases whereby the question referred is in reality hypothetical. It will be claimed that the CJEU does so without requiring sufficient proof by the domestic court that an EU law interpretation is required.

Anna Marchuk

Introduction.The objective reason for the existence of an institution of local budgets is an increase in the efficiency of the provision of public services guaranteed by the state due to the proximity of such services to the immediate consumer. This process is based on the principle of subsidiarity, requires a sufficient level of financial security of local budgets and demonstrates the basic idea of the concept of fiscal decentralization. The decentralization reform is systematic and involves structural changes in various spheres of public life. The object of research of this article is the impact of changes in tax and budget laws aimed at decentralization on structure and dynamics of income and expenditures of local budgets. Purpose.The purpose of the article is to identify trends, priorities and unresolved issues in financing local budget expenditures, compare dynamics of expenditures with dynamics and structural changes in local budget revenues. Results. In the course of the research, the expenditures and revenues of local budgets of Ternopil region during 2004-2017 were analysed, comparison with trends in Ukraine was made. It has been established that due to slowed down economic growth and a systematic decrease in the share of own revenues in recent years, the amount of funding for institutions and activities in the social and cultural sphere has been reduced and the transfer of important functions to the local level was not accompanied by the transfer of sufficient amount of financial resources. Conclusions.The strategic goal of decentralization is to ensure the availability and proper quality of public services for all categories of the population. The decentralized budget system should function on the basis of a coordinated, unified national cooperation policy for many independent institutions, each of which has a legislatively defined sphere of autonomy. Since tax revenues form the main volume of own revenues of local budgets, the issue of improving the efficiency of tax administration comes to the forefront in the context of decentralization changes. Therefore, on the way to ensuring the increase of tax revenues, the strategic goal of local authorities should be to promote economic development of regions.

Dmitry Fedorov

No abstract is available for this record.

Jérémy Charlier, Radu State, Jean Hilger

Background: Past few months have seen the rise of blockchain and cryptocurrencies. In this context, the Ethereum platform, an open-source blockchain-based platform using Ether cryptocurrency, has been designed to use smart contracts programs. These are self-executing blockchain contracts. Due to their high volume of transactions, analyzing their behavior is very challenging. We address this challenge in our paper. Methods: We develop for this purpose an innovative approach based on the non-negative tensor decomposition Paratuck2 combined with long short-term memory. The objective is to assess if predictive analysis can forecast smart contracts activities over time. Three statistical tests are performed on the predictive analytics, the mean absolute percentage error, the mean directional accuracy and the Jaccard distance. Results: Among dozens of GB of transactions, the Paratuck2 tensor decomposition allows asymmetric modeling of the smart contracts. Furthermore, it highlights time dependent latent groups. The latent activities are modeled by the long short term memory network for predictive analytics. The highly accurate predictions underline the accuracy of the method and show that blockchain activities are not pure randomness. Conclusion: Herein, we are able to detect the most active contracts, and predict their behavior. In the context of future regulations, our approach opens new perspective for monitoring blockchain activities.

Jesús Fernández‐Villaverde

Abstract This article reviews what cryptocurrencies are, and it frames them within the context of historical monetary experiences and contemporary monetary economics. The article argues that, as pure fiduciary private money, cryptocurrencies are a bubble without a fundamental value and they will not provide, in general, optimal amounts of money or deliver price stability. Nevertheless, cryptocurrencies can play a role in improving the current means of payments and in disciplining central banks into providing better government‐run fiduciary monies.

Jesús Fernández‐Villaverde

Advocates of cryptocurrencies such as Bitcoin believe that having currency competition will help achieve the economic objective of price stability. This Issue Brief summarizes research that explores whether competition among privately issued fiat currencies can actually produce price stability. The research finds that in most cases, a system of private monies does not deliver price stability. And even when it does, it always is subject to self-fulfilling inflationary episodes, and it supplies a suboptimal amount of money. Although there is no economic reason to curb the use of cryptocurrencies at the moment, it is important to review key regulatory issues that policymakers need to consider now, before the use of cryptocurrencies becomes even more widespread.

Stafford C. Baum

No abstract is available for this record.

Seok-Jun Bu, Sung-Bae Cho

No abstract is available for this record.

Engin Iyidogan

No abstract is available for this record.

Yanqi Zhao, Yannan Li, Qilin Mu, Bo Yang · 5 authors

The cyber physical system (CPS) has gained considerable success in large-scale distributed integration environment. In such systems, the sensor devices collect data which would be disseminated via reliable manner to all interested co-operant entities from the physical world. However, highly unreliable environment of CPS, for example, a number of limitations of existing network middle wares, makes secure and reliable data distribution services a challenge issue. In this paper, we propose a new architecture called secure pub-sub (SPS) without middle ware, i.e., blockchain-based fair payment with reputation. In SPS, publishers publish a topic on the blockchain and subscribers specify an interest message by making a deposit to subscribing the topic. Then, if the interest message matches the topic, the publisher transmits the encrypted content of the topic to the blockchain such that the subscribers can decrypt the ciphertext to obtain the content, and mark the publisher as its reputation. Finally, the publisher receives the payment from the subscriber. The new proposal provides confidentiality and reliability of data, anonymity of subscribers and payment fairness between the publishers and subscribers. Different from the traditional pub-sub services, no trusted third party is involved in our system due to employing blockchain technique. The security of the proposed SPS is analyzed as well. The implementation of the protocol on Ethereum of smart contract demonstrates the validity of SPS.

Ioannis Antoniadis, Nikolaos Sariannidis, Stamatis Kontsas

No abstract is available for this record.

Bikramaditya Singhal, Gautam Dhameja, Priyansu Sekhar Panda

The former Soviet Union used to be the largest country in the world, with its territory occupying about one-sixth of the entire Earth’s land surface and controlling about half of Europe (all the modern Eastern European countries). As we can see today, most subjects of the “Evil Empire” were not joined voluntarily. Therefore, the communists also had to have the biggest army in the world to be able to watch over such a vast territory. So, they had a draft, a mandatory enrollment into the armed forces, when every young man (well, almost everyone) had to spend two or three years (depending on the military branch they were drafted into) at the most dangerous place you can even imagine.

Hengyu Zhou, Yukun Niu, Jianqing Liu, Chi Zhang · 6 authors

No abstract is available for this record.

Sergey Avdoshin, Vladimir A. Lazarenko

Bitcoin is the most popular cryptocurrency on the planet. It relies on strong cryptography and peer-to-peer network. Bitcoin is gaining more and more popularity in criminal society. That is why Bitcoin is often used as money laundering tool or payment method for illegal products and services. In this paper we explore various methods for Bitcoin users deanonimization, which is an important task in anti-money laundering process and cybercrime investigation.

Danni Wang, Juntao Gao, Haiyong Yu, Xuelian Li

No abstract is available for this record.

Stefano Colucci

No abstract is available for this record.

Duc-Hiep Nguyen, Dinh-Nghia Nguyen-Duc, Nguyen Huynh Tuong, Hoang-Anh Pham

By using a decentralized peer-to-peer network together with public and distributed ledger to decentralize the central authority, Blockchain has shown its great potential with the success of Bitcoin. However, the blockchain technology can go beyond financial transactions. In this paper, we propose an approach that utilizes the blockchain technology to issue immutable digital certificates and improve the current limitations of the existing certificate verifying systems such as faster, more trusted, and independent of the central authority. Our prototype has been successfully deployed for several short-term courses at the Center of Computer Engineering, HCMC University of Technology, Vietnam. This result indicates that our proposed system is an appropriate solution adopting ICT for e-government, especially in certificate and diploma management.

Sandi Rahmadika, Kyung-Hyune Rhee

The personal health information (PHI) is an activity among the health-care providers and the patients in terms of managing the data which is sensitive to the parties. The PHI data have been maintained by multiple health-care providers, thus resulting in separated data. Moreover, the PHI data are stored in the provider’s database, hence the patients have no authority to manage their own information. Therefore, in this article, we propose a conceptual model for managing the PHI data which is derived from several health-care providers by relying on the blockchain technology in the peer-to-peer overlay network. In addition, we elaborate the security analysis that might be occurring in the proposed model. By leveraging on our model, it allows the patients and the providers to collect effectively the PHI data onto a single view as well guarantee of data integrity. The blockchain offers an immutable of the data record without having to trust a third party. The experimental results show that the proposed approach is promising to be developed due to the high success rate in terms of data dissemination.

Gilbert Fridgen, Sven Radszuwill, Nils Urbach, Lena Utz

Bringing Blockchain technology and business process management together, we follow the Design Science Research approach and design, implement, and evaluate a Blockchain prototype for cross-organizational workflow management together with a German bank. For the use case of a documentary letter of credit we describe the status quo of the process, identify areas of improvement, implement a Blockchain solution, and compare both workflows. The prototype illustrates that the process, as of today paper-based and with high manual effort, can be significantly improved. Our research reveals that a tamper-proof process history for improved auditability, automation of manual process steps and the decentralized nature of the system can be major advantages of a Blockchain solution for cross-organizational workflow management. Further, our research provides insights how Blockchain technology can be used for business process management in general.

Yunru Zhang, Debiao He, Kim‐Kwang Raymond Choo

Internet of Things (IoT) and cloud computing are increasingly integrated, in the sense that data collected from IoT devices (generally with limited computational and storage resources) are being sent to the cloud for processing, etc., in order to inform decision making and facilitate other operational and business activities. However, the cloud may not be a fully trusted entity, like leaking user data or compromising user privacy. Thus, we propose a privacy‐preserving and user‐controlled data sharing architecture with fine‐grained access control, based on the blockchain model and attribute‐based cryptosystem. Also, the consensus algorithm in our system is the Byzantine fault tolerance mechanism, rather than Proof of Work.