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.
With the rapid development of blockchain technology, blockchain becomes a good platform for execution of smart contracts. However, since smart contracts still have a low performance of transaction processing on blockchain. It can't satisfy real-time requirements in some situations. This paper proposes a parallel smart contract model on blockchain which has a better performance in transaction processing. The challenges with the proposed approach are the implementation of the parallel mode and the solution of synchronization problem of the proposed model. This paper uses multi-thread technology to implement the proposed model where transactions are executed in parallel. Then we propose a transaction splitting algorithm to resolve the synchronization problem. Finally, experimental analysis proves that this parallel model exactly makes a remarkable development of performance in transaction processing.
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.
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.
This article describes the current cryptocurrency regulatory landscape in the United States. It focuses on the following areas: anti-money laundering, securities trading and taxation.
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.
With dramatic developments of blockchain technology, a number of blockchain-based applications emerge rapidly, among which the incorporation of blockchain into Internet of Things is one of the most valued research direction. Such powerful incorporation is a double-sided sword, i.e., it can benefit both individuals and society but has the vulnerability to coin hopping attack that is a new type of pool mining attack and hard to happen in traditional blockchain networks. In this paper, we theoretically prove the feasibility of coin hopping attack, deeply analyze the conditions of attack implementation, and comprehensively investigate the impacts of coin hopping attack. Moreover, some defense strategies are addressed. To our best knowledge, this paper is the first work targeting coin hopping attack.
Rad uspoređuje dvije po konceptu veoma različite blockchain platforme, te na kraju donosi zaključak o uspješnosti platformi na temelju aplikacije za kontrolu ulaza. Platforma Ethereum je primjer prve platforme koja je osmišljena da podržava pametne ugovore, a u mrežu se može ući bez dozvole i čitati sve podatke na blockchainu. Hyperledger Fabric je platforma koja također podržava pametne ugovore, međutim u mrežu se ne može ući bez dozvole i ne mogu se čitati svi podatci već oni za koje čvor ima pristup. U platformi Ethereum se ne mora nikome vjerovati te je osmišljena kao javna mreža, a u Hyperledgeru se mora vjerovati određenim čvorovima i mreža je zamišljena za tvrtke. Krajnja usporedba donosi i zaključke o potrebi blockchaina za kontrolu ulaza naspram konvencionalnih baza podataka.
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
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.
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.
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.
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.
V. Thiruchelvam, Alexandre Shaka Mughisha, Maryam Shahpasand, Mervat Adib Bamiah
Blockchain is a decentralised database, encrypted tamperproof digital ledger technology that allows all network participants to trust each other and interact. This trust is initiated due to the automated verification of the transactions by every node in the network through cryptographic algorithms without any third-party interference. Previous literature identified that traceability, visibility, transparency, and security of operations across the supply chain are challenges to the traditional Coffee Supply Chain (CSC). These challenges raised from inaccuracy regarding manual processes and the involvements of several intermediaries throughout the overall CRC process. Considering these aspects, there is a need for an automated system that enables accurate, secure real-time costeffective supply chain which facilitates a fair CSC trade. Based on the results of the quantitative questioner conducted on all Burundi coffee actors, this study proposed the Technology Acceptance Model (TAM) base Blockchain technology to be deployed in the Burundi Coffee industry.
Gregory Linklater, Christian Smith, Alan Herbert, Barry Irwin
Self-sovereign identity promises prospective users greater control, security, privacy, portability and overall greater convenience; however the immaturity of current distributed key management solutions results in general disregard of security advisories in favour of convenience and accessibility. This research proposes the use of intermediate certificates as a distributed key management solution. Intermediate certificates will be shown to allow multiple keys to authenticate to a single self-sovereign identity. Keys may be freely added to an identity without requiring a distributed ledger, any other third-party service or sharing private keys between devices. This research will also show that key rotation is a superior alternative to existing key recovery and escrow systems in helping users recover when their keys are lost or compromised. These features will allow remote credentials to be used to issuer, present and appraise remote attestations, without relying on a constant Internet connection.
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.
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.