Blockchain Papers

A.V. Kochetkov

Аннотация Предмет

Olesia Demianyshyna, Oleksandr Nedbalyuk, N. O. Stanislavchuk

The systemic crisis in the sphere of socio-economic development of territories is a consequence of the lack of a modern management mechanism for the development of territorial communities, which is based on the corresponding development programs.Despite the depth of studying of these scientific studies, the financial aspects of developing programs for the innovative development of territories in the conditions of financial independence of local government bodies require detailed consideration.Focused attention of researchers on the problems of management of territorial development. Attracted attention to the necessity of creating a mechanism for funding work on the development of relevant programs. It is determined that without such mechanism it is impossible to create and effectively implement territorial development programs at all levels of the administrative-territorial system of the country. All elements of the process of territorial development programming that are in need of financing are considered and which should be considered such a separate cost items of the corresponding estimate. On the basis of foreign experience (first of all the USA), it is proposed to create a nation-wide network of state information and consulting (advisory) services that would be the implementers and coordinators of work on the development of territorial development programs. It is determined that the financing of the development of territorial development programs should be carried out precisely through such services, which will ensure the efficiency and transparency of this process in conditions of financial decentralization and creation of united territorial communities in Ukraine. The proposed basic model of the process of programming the innovative development of joint territorial communities will ensure the effectiveness and transparency of this process in the context of financial decentralization.

M. F. Averkynа, Yuliia Shulyk

The article considers the necessity of financial logistic coordination, which involves attracting financial resources in those subsystems of the territories that are most favorable for the rational use of socio-ecological and economic resources, their reproduction, achievement of socio-ecological and economic security and increase in logistics efficiency. It is determined that in order to solve territorial communities’ functioning issues and to ensure their development there is a need to combine local, state and private finances. Effective financial coordination will make it possible to use the resources of the territories efficiently, reduce the use of territories' external resources sub-systems and maximize the provision of their functioning by internal resources. The main resources, revenues and expenditures that provide financial logistics of the territories in Ukraine are estimated. The first results from the implementation of decentralization reform revealed a number of issues: the dependence of Ukraine's local finances on public finances, the social orientation of expenditures etc.. The necessity of completing the process of inter-budgetary relations decentralization and coordination was singled out. The authors identified necessary changes on the state level in order to improve coordination of financial flows and development of the territories. Financial logistics coordination at the local level should solve a number of problems: filling of local budgets with their own financial resources; regulation of prices and tariffs for utilities; increase of communal enterprises and institutions financing; increase of capital expenditures in the spheres of local governments improvement and modernization; investment attraction ; improve the use of local debt securities.

Dong Mo, Qingkai Liang, Xiaozhou Li, Junda Liu

Off-chain scaling techniques allow mutually distrustful parties to execute a contract locally among themselves instead of on the global blockchain. Parties involved in the transaction maintain a multi-signature fraud-proof off-chain replicated state machine, and only resort to on-chain consensus when absolutely necessary (e.g., when two parties disagree on a state). Off-chain scaling is the only way to support fully scale-out decentralized applications ("dApps") with better privacy and no compromise on the trust and decentralization guarantees. It is the inflection point for blockchain mass adoption, and will be the engine behind all scalable dApps. Celer Network is an Internet-scale, trust-free, and privacy-preserving platform where everyone can quickly build, operate, and use highly scalable dApps. It is not a standalone blockchain but a networked system running on top of existing and future blockchains. It provides unprecedented performance and flexibility through innovation in off-chain scaling techniques and incentive-aligned cryptoeconomics. Celer Network embraces a layered architecture with clean abstractions that enable rapid evolution of each individual component, including a generalized state channel and sidechain suite that supports fast and generic off-chain state transitions; a provably optimal value transfer routing mechanism that achieves an order of magnitude higher throughput compared to state-of-the-art solutions; a powerful development framework and runtime for off-chain applications; and a new cryptoeconomic model that provides network effect, stable liquidity, and high availability for the off-chain ecosystem.

Zenovii-Mykhaylo Zadorozhnyi, Volodymyr Muravskyi, Oleg Shevchuk

The need to obtain prompt access to funds through electronic communications, protecting investment after the global financial crisis has led to the emergence of a new type of electronic money — the cryptocurrencies. The modern state and prospects for development of the cryptocurrency as a special kind of electronic money were expounded. Cryptocurrencies gain significant popularity due to the advantages of their use, such as: comfort, independence, accessibility, lack of engagement, confidentiality, no documents, full automation of accounting, and cost optimization for administration. Various scientific positions concerning the accounting and economic positioning of the cryptocurrencies in Ukraine were researched. The proposed order to display in accounting the processes of initial obtaining (mining) with the definition of a cost calculating method and operation of the cryptocurrencies most fully corresponds to the national accounting treatment. It was proposed to resolve to the problems of management accounting of electronic money and cryptocurrencies in Ukraine through the combination of functional capabilities of the blockchain technology, positive qualities of the «Internet Bank» and «Client-Bank» communications, which will enable to create a hybrid system of non-cash payments by the cryptocurrencies, electronic money, funds on accounts in a bank with free conversion of existing funds and possibilities for information exchange with all the participants in settlement operations. The article presents a methodology for collecting accounting information on settlements with the cryptocurrencies and other electronic money without the formation of traditional payment documents and bank statements. Electronic information from the hybrid communication system is the foundation for fully automated documenting, formation of accounting records, informing accountants and management of non-cash transfers. Automation of management accounting of electronic transactions helps to increase the level of internal and external control over execution of money operations due to timely and remote informing sharing about the parameters of payments.

Gokhan Sagirlar, Barbara Carminati, Elena Ferrari

In general, a botnet is a collection of compromised internet computers, controlled by attackers for malicious purposes. To increase attacks' success chance and resilience against defence mechanisms, modern botnets have often a decentralized P2P structure. Here, IoT devices are playing a critical role, becoming one of the major tools for malicious parties to perform attacks. Notable examples are DDoS attacks on Krebs on Security and DYN, which have been performed by IoT devices part of botnets. We take a first step towards detecting P2P botnets in IoT, by proposing AutoBotCatcher, whose design is driven by the consideration that bots of the same botnet frequently communicate with each other and form communities. As such, the purpose of AutoBotCatcher is to dynamically analyze communities of IoT devices, formed according to their network traffic flows, to detect botnets. AutoBotCatcher exploits a permissioned Byzantine Fault Tolerant (BFT) blockchain, as a state transition machine that allows collaboration of a set of pre-identified parties without trust, in order to perform collaborative and dynamic botnet detection by collecting and auditing IoT devices' network traffic flows as blockchain transactions. In this paper, we focus on the design of the AutoBotCatcher by first defining the blockchain structure underlying AutoBotCatcher, then discussing its components.

Songze Li, Mingchao Yu, Chien-Sheng Yang, A. Salman Avestimehr · 6 authors

Today's blockchain designs suffer from a trilemma claiming that no blockchain system can simultaneously achieve decentralization, security, and performance scalability. For current blockchain systems, as more nodes join the network, the efficiency of the system (computation, communication, and storage) stays constant at best. A leading idea for enabling blockchains to scale efficiency is the notion of sharding: different subsets of nodes handle different portions of the blockchain, thereby reducing the load for each individual node. However, existing sharding proposals achieve efficiency scaling by compromising on trust - corrupting the nodes in a given shard will lead to the permanent loss of the corresponding portion of data. In this paper, we settle the trilemma by demonstrating a new protocol for coded storage and computation in blockchains. In particular, we propose PolyShard: ``polynomially coded sharding'' scheme that achieves information-theoretic upper bounds on the efficiency of the storage, system throughput, as well as on trust, thus enabling a truly scalable system. We provide simulation results that numerically demonstrate the performance improvement over state of the arts, and the scalability of the PolyShard system. Finally, we discuss potential enhancements, and highlight practical considerations in building such a system.

R. Iyer Harihara Sudhan, Sowmya Subramaniam

In recent years,the cryptocurrencies have received broader attention and adoption from the investing public. The price appreciation in value of digital currencies has increased to many folds that captivated from individual investors to wall street banks and high frequency traders.An important feature of bitcoin is that they are not backed by any central bank unlike the traditional currencies. The supply of these currencies are limited to a design of protocol (Bouri et al., 2017). The Bitcoin is one of the most popular cryptocurrencies and accounts about 41% of the cryptocurrencies capitalization (Katsiampa,2017).Bitcoin was invented in 2009 by a group of people in the name of Sathoshi Nakamoto (Briere et al., 2015).Since its introduction, bitcoin has grown steeper and sweeping the investors worldwide. The value of Bitcoin grew from US $ 6 billion (Bouri et al.,2017) in 2015 to US $ 167 billion in November 2017(Source: CoinMarketCap) indicating the tremendous growth.

MURAT OSMANOĞLU, Ali Aydın Selçuk

Privacy of blockchains has been a matter of discussion since the inception of Bitcoin. Various techniques with a varying degree of privacy protection and complexity have been proposed over the past decade. In this survey, we present a systematic analysis of these proposals in four categories: (i) identity, (ii) transaction, (iii) consensus, and (iv) smart contract privacy. Each of these categories have privacy requirements of its own, and various solutions have been proposed to meet these requirements. Almost every technique in the literature of privacy enhancing technologies have been applied to blockchains: mix networks, zero-knowledge proofs, blind signatures, ring signatures, secure MPC, homomorphic encryption, to name just a few. We analyze each category separately in the paper. We first define the related privacy issues, and then review the proposed solutions. The limitations of each solution and the attacks discovered are also discussed along with the proposals. For each category, we first define the relevant privacy issues, and then review the proposed solutions along with their features and limitations

Andros Gregoriou

We demonstrate that investors obtain abnormal returns by trading cryptocurrencies daily on the London Stock Exchange from 2014–2017. Excess returns persist once we account for systematic risk, size, value, momentum, profitability and investment. Investor abnormal returns in cryptocurrencies implies inefficiency.

Ahmet Faruk Aysan, Ender Demir, Giray Gözgör, Chi Keung Marco Lau

No abstract is available for this record.

Yackolley Amoussou-Guenou, Antonella del Pozzo, Maria Potop-Butucaru, Sara Tucci-Piergiovanni

In this paper we analyze Tendermint proposed in [7], one of the most popular blockchains based on PBFT Consensus. The current paper dissects Tendermint under various system communication models and Byzantine adversaries. Our methodology consists in identifying the algorithmic principles of Tendermint necessary for a specific combination of communication model-adversary. This methodology allowed to identify bugs [3] in preliminary versions of the protocol ([19], [7]) and to prove its correctness under the most adversarial conditions: an eventually synchronous communication model and asymmetric Byzantine faults.

Ivan Miškulin

Konstantnim povećanjem postotka ljudske populacije u gradovima povećava se i broj automobila u gradovima. S povećanjem broja automobila dolazi do većeg opterećenja prometa te zahtjeva za novim parkirnim mjestima. Kako bi smanjilo opterećenje prometnica i potražnja za parkirnim mjestima potrebno je osmišljavati nove metode. Jedna od tih metoda je i dijeljenje automobila kojoj je cilj smanjiti vrijeme koje vozilo provode na parkirnom mjestu. Za implementaciju takve metode potrebno je kreirati sustav koji će omogućivati iznajmljivanje i dijeljenje automobila te plaćanje usluge. U ovome radu izraditi će se dio aplikacije za dijeljenje automobila koja će funkcionirati na pametnom ugovoru unutar blockchain-a odnosno distribuiranog zapisnika. Postupak izrade te funkcionalnosti aplikacije objašnjene su unutar rada. Aplikacija se fokusira na plaćanje koristeći pametne ugovore te su opisani ostali dijelovi sustava potrebni za implementaciju aplikacije koje nisu unutar okvira ovoga rada.

Marko Matijević

U ovom završnom radu obrađen je pojam hardvera za rudarenje kriptovaluta. Nakon uvoda u prvom poglavlju opisana je prva kriptovaluta "Bitcoin". U drugom poglavlju objašnjen je protokol "Blockchain" na koji Bitcoin funkcionira. U trećem poglavlju opisane su transakcije, te posao rudara u bitcoin mreži. U četvrtom poglavlju je opisana povijest hardvera, te detaljan opis hardvera ovisno o generaciji. U zadnjem poglavlju je opisan suvremeni hardver te najbolje rješenje za Bitcoin i Ethereum, drugu najvrjedniju kriptovalutu.

António Brandão, Henrique São Mamede, Ramiro Gonçalves

No abstract is available for this record.

Лариса Санникова, Yulia S. Kharitonova

No abstract is available for this record.

Yining Hu, Madhusanka Liyanage, Ahsan Manzoor, Kanchana Thilakarathna · 7 authors

In December 2017, CryptoKitties, a game on the Ethereum blockchain became an instant success shortly after its launch. It attracted 180,000 users with over $20 million of spend in Ether, and was at one point taking up 12% of all Ethereum transactions. Technically speaking, CryptoKitties is a smart contract - a piece of code with storage capability that resides on a blockchain. Smart contracts are gaining increasing popularity in recent years. We present a comprehensive review of smart contracts with a focus on existing applications and challenges they face. We have covered the smart contract mechanisms, promising use cases, as well as relevant research work and the open issues.

Dominik Harz, William J. Knottenbelt

With a market capitalisation of over USD 205 billion in just under ten years, public distributed ledgers have experienced significant adoption. Apart from novel consensus mechanisms, their success is also accountable to smart contracts. These programs allow distrusting parties to enter agreements that are executed autonomously. However, implementation issues in smart contracts caused severe losses to the users of such contracts. Significant efforts are taken to improve their security by introducing new programming languages and advance verification methods. We provide a survey of those efforts in two parts. First, we introduce several smart contract languages focussing on security features. To that end, we present an overview concerning paradigm, type, instruction set, semantics, and metering. Second, we examine verification tools and methods for smart contract and distributed ledgers. Accordingly, we introduce their verification approach, level of automation, coverage, and supported languages. Last, we present future research directions including formal semantics, verified compilers, and automated verification.

Yining Hu, Madhusanka Liyanage, Ahsan Mansoor, Kanchana Thilakarathna · 6 authors

A blockchain-based smart contract or a "smart contract" for short, is a computer program intended to digitally facilitate the negotiation or contractual terms directly between users when certain conditions are met. With the advance in blockchain technology, smart contracts are being used to serve a wide range of purposes ranging from self-managed identities on public blockchains to automating business collaboration on permissioned blockchains. In this paper, we present a comprehensive survey of smart contracts with a focus on existing applications and challenges they face.

Lukasz Dykcik, Laurent Chuat, Pawel Szalachowski, Adrian Perrig

This paper describes BlockPKI, a blockchain-based public-key infrastructure that enables an automated, resilient, and transparent issuance of digital certificates. Our goal is to address several shortcomings of the current TLS infrastructure and its proposed extensions. In particular, we aim at reducing the power of individual certification authorities and make their actions publicly visible and accountable, without introducing yet another trusted third party. To demonstrate the benefits and practicality of our system, we present evaluation results and describe our prototype implementation.

Iain Barclay, Alun Preece, Ian Taylor

Organisations are increasingly open to scrutiny, and need to be able to prove that they operate in a fair and ethical way. Accountability should extend to the production and use of the data and knowledge assets used in AI systems, as it would for any raw material or process used in production of physical goods. This paper considers collective intelligence, comprising data and knowledge generated by crowd-sourced workforces, which can be used as core components of AI systems. A proposal is made for the development of a supply chain model for tracking the creation and use of crowdsourced collective intelligence assets, with a blockchain based decentralised architecture identified as an appropriate means of providing validation, accountability and fairness.

Olivier Zephir, Soenke Zehle, Olivier Buchheit

The rise of decentralized ledger (bookkeeping) systems that operate as public transaction archives to store value records (such as payments in a cryptocurrency) and maintain consensus about agreements also seems to promise solutions for the problem of scaling trust-based decision-making processes. Once linked almost exclusively to finance (“cryptocurrencies”), the “blockchain space” has become a terrain of social and technological experimentation. While these changes are likely to substantially transform the way, we organize our collective actions, few digital content creators; artists, designers, and other actors not directly linked to processes of technological innovation are currently involved. In this essay, we describe how such a co-creative approach to such involvement can be developed through the public prototyping of Spectrum, a blockchain-based tool for digital creators. What we found is that such an approach offers opportunities to more fully comprehend value chains, but also highlights need for co-creation approaches that cut across existing audiences and bring in new actors. This matters because blockchain-based strategies for technology design are about to transform the way we create, share, and cooperate. Given the promise and potential stakes of shifting the creation of digital arts-and-cultural assets to infrastructures based on such distributed ledger technologies, it is crucial that artists and other digital creators engage with the design both of these infrastructures and the systems of governance structuring their operation.

Benjamin Hellouin de Ménibus, Ville Salo, Guillaume Theyssier

Abelian cellular automata (CAs) are CAs which are group endomorphisms of the full group shift when endowing the alphabet with an abelian group structure. A CA randomizes an initial probability measure if its iterated images have weak*-convergence towards the uniform Bernoulli measure (the Haar measure in this setting). We are interested in structural phenomena, i.e., randomization for a wide class of initial measures (under some mixing hypotheses). First, we prove that an abelian CA randomizes in Cesàro mean if and only if it has no soliton, i.e., a non-zero finite configuration whose time evolution remains bounded in space. This characterization generalizes previously known sufficient conditions for abelian CAs with scalar or commuting coefficients. Second, we exhibit examples of strong randomizers, i.e., abelian CAs randomizing in simple convergence; this is the first proof of this behaviour to our knowledge. We show, however, that no CA with commuting coefficients can be strongly randomizing. Finally, we show that some abelian CAs achieve partial randomization without being randomizing: the distribution of short finite words tends to the uniform distribution up to some threshold, but this convergence fails for larger words. Again this phenomenon cannot happen for abelian CAs with commuting coefficients.

Nicholas A. Cook

We obtain lower tail estimates for the smallest singular value of random matrices with independent but nonidentically distributed entries. Specifically, we consider $n\times n$ matrices with complex entries of the form \[M=A\circ X+B=(a_{ij}\xi_{ij}+b_{ij}),\] where $X=(\xi_{ij})$ has i.i.d. centered entries of unit variance and $A$ and $B$ are fixed matrices. In our main result, we obtain polynomial bounds on the smallest singular value of $M$ for the case that $A$ has bounded (possibly zero) entries, and $B=Z\sqrt{n}$ where $Z$ is a diagonal matrix with entries bounded away from zero. As a byproduct of our methods we can also handle general perturbations $B$ under additional hypotheses on $A$, which translate to connectivity hypotheses on an associated graph. In particular, we extend a result of Rudelson and Zeitouni for Gaussian matrices to allow for general entry distributions satisfying some moment hypotheses. Our proofs make use of tools which (to our knowledge) were previously unexploited in random matrix theory, in particular Szemerédi’s regularity lemma, and a version of the restricted invertibility theorem due to Spielman and Srivastava.