Katiuscia Mannaro, Gavina Baralla, Andrea Pinna, Simona Ibba
The use of teledermatology in primary care has been shown to be reliable, offering the possibility of improving access to dermatological care by using telecommunication technologies to connect several medical centers and enable the exchange of information about skin conditions over long distances. This paper describes the main points of a teledermatology project that we have implemented to promote and facilitate the diagnosis of skin diseases and improve the quality of care for rural and remote areas. Moreover, we present a blockchain-based approach which aims to add new functionalities to an innovative teledermatology platform which we developed and tested in the Sardinian Region (Italy). These functionalities include giving the patient complete access to his/her medical records while maintaining security. Finally, the advantages that this new decentralized system can provide for patients and specialists are presented.
Reasoning about commutativity between data-structure operations is an important problem with applications including parallelizing compilers, optimistic parallelization and, more recently, Ethereum smart contracts. There have been research results on automatic generation of commutativity conditions, yet we are unaware of any fully automated technique to generate conditions that are both sound and effective. We have designed such a technique, driven by an algorithm that iteratively refines a conservative approximation of the commutativity (and non-commutativity) condition for a pair of methods into an increasingly precise version. The algorithm terminates if/when the entire state space has been considered, and can be aborted at any time to obtain a partial yet sound commutativity condition. We have generalized our work to left-/right-movers and proved relative completeness. We describe aspects of our technique that lead to useful commutativity conditions, including how predicates are selected during refinement and heuristics that impact the output shape of the condition. We have implemented our technique in a prototype open-source tool Servois. Our algorithm produces quantifier-free queries that are dispatched to a back-end SMT solver. We evaluate Servois through two case studies: (i) We synthesize commutativity conditions for a range of data structures including Set, HashTable, Accumulator, Counter, and Stack. (ii) We consider an Ethereum smart contract called BlockKing, and show that Servois can detect serious concurrency-related vulnerabilities and guide developers to construct robust and efficient implementations.
Guilherme Albuquerque Barbosa Silva, Carlo Kleber da Silva Rodrigues
Este artigo tem o objetivo de analisar a rentabilidade econômica da mineração individual de criptomoedas bitcoins e litecoins. Essa análise é baseada na avaliação da métrica eficiência energética de cada criptomoeada em cinco países da América Latina, almejando-se uma margem de lucro de 0,10 USD/hora. Três variáveis são consideradas para o cálculo da métrica em comento: a taxa de processamento de hashes do equipamento, o consumo de energia elétrica do equipamento em watts, e o valor do quilowatt-hora do país onde se realiza a mineração. Os resultados obtidos indicam que a criptomoeda litecoin é uma alternativa mais viável para mineração que a criptomoeda bitcoin. Por fim, sugestões para trabalhos futuros encerram este artigo.
Since 2004, different research was handling the challenges in the centralized voting systems, e-voting protocols and recently the decentralized voting. So electronic voting puts forward some difficulties regarding the voter anonymity, the secure casting of the votes and to prevent the voting process from frauding. The Decentralized property of the technology called "blockchain" could have the solution for many of the challenges in voting research area and brings a new secure mechanism of safe and transparent voting. In this paper, a broad comparison between ongoing voting systems has studied by analyzing their structure and the drawbacks that should consider in future to improve the whole election process from keeping the privacy of the voter, casting a vote with the possibility to check if it was counted correctly to publishing the results. The result of the paper will give a new approach to extend the target of the election from small scale to large scale despite the fact of Ethereum limitation which can cast on the blockchain just five votes per minute. The primary challenge is to find an answer for this question: "How to balance between voter privacy and transparency without breaking the important rule where the voter can proof for a specific candidate that he voted for him in a bribe situation?".
Bitcoin is the first implementation of what has become known as a 'public permissionless' blockchain. Guaranteeing security and protocol conformity through its elegant combination of cryptographic assurances and game theoretic economic incentives, it permits censorship resistant public read-write access to its append-only blockchain database without the need for any mediating central authority. Not until its advent has such a trusted, transparent, comprehensive and granular data set of digital economic behaviours been available for public network analysis. In this article, by translating the cumbersome binary data structure of the Bitcoin blockchain into a high fidelity graph model, we demonstrate through various analyses the often overlooked social and econometric benefits of employing such a novel open data architecture. Specifically we show (a) how repeated patterns of transaction behaviours can be revealed to link user activity across the blockchain; (b) how newly mined bitcoin can be associated to demonstrate individual accumulations of wealth; (c) through application of the naive quantity theory of money that Bitcoin's disinflationary properties can be revealed and measured; and (d) how the user community can develop coordinated defences against repeated denial of service attacks on the network. All of the aforementioned being exemplary benefits that would be lost with the closed data models of the 'private permissioned' distributed ledger architectures that are dominating enterprise level development due to existing blockchain issues of governance, scalability and confidentiality.
Antonio Fernández Anta, Chryssis Georgiou, Kishori M. Konwar, Nicolas Nicolaou
Despite the hype about blockchains and distributed ledgers, no formal abstraction of these objects has been proposed. To face this issue, in this paper we provide a proper formulation of a distributed ledger object. In brief, we define a ledger object as a sequence of records, and we provide the operations and the properties that such an object should support. Implementation of a ledger object on top of multiple (possibly geographically dispersed) computing devices gives rise to the distributed ledger object. In contrast to the centralized object, distribution allows operations to be applied concurrently on the ledger, introducing challenges on the consistency of the ledger in each participant. We provide the definitions of three well known consistency guarantees in terms of the operations supported by the ledger object: (1) atomic consistency (linearizability), (2) sequential consistency, and (3) eventual consistency. We then provide implementations of distributed ledgers on asynchronous message passing crash-prone systems using an Atomic Broadcast service, and show that they provide eventual, sequential or atomic consistency semantics. We conclude with a variation of the ledger - the validated ledger - which requires that each record in the ledger satisfies a particular validation rule.
Alberto Sonnino, Mustafa Al-Bassam, Shehar Bano, Sarah Meiklejohn · 5 authors
Coconut is a novel selective disclosure credential scheme supporting distributed threshold issuance, public and private attributes, re-randomization, and multiple unlinkable selective attribute revelations. Coconut integrates with blockchains to ensure confidentiality, authenticity and availability even when a subset of credential issuing authorities are malicious or offline. We implement and evaluate a generic Coconut smart contract library for Chainspace and Ethereum; and present three applications related to anonymous payments, electronic petitions, and distribution of proxies for censorship resistance. Coconut uses short and computationally efficient credentials, and our evaluation shows that most Coconut cryptographic primitives take just a few milliseconds on average, with verification taking the longest time (10 milliseconds).
Nowadays, the Internet is indispensable when it comes to information dissemination. People rely on the Internet to inform themselves on current news events, as well as to verify facts. We, as a community, are quickly approaching an 'electronic information age' where the majority of information will be distributed electronically and tools to preserve this information will become essential. While archiving online digital information is a good way to preserve online information for future generations, it has many disadvantages including the easy manipulation of archived information, e.g. by the archiving authority. Online information is also prone to getting hacked or being taken offline. Therefore, it is necessary that archived online news information is securely time-stamped with the date and time when it was first archived in a way that cannot be manipulated. The process of 'trusted timestamping' is an established approach for claiming that particular digital information existed at a particular 'point in time' in the past. However, traditional approaches for trusted timestamping depend on the time-stamping authority's fidelity. Directly embedding the hash of a digital file into the blockchain of a cryptocurrency is a more recent method that allows for secure time-stamping, since digital information is stored as part of the transaction information in, e.g. Bitcoin's, blockchain, and not stored at a centralized time-stamping authority. However, there is no system yet available, which uses this approach for archiving and time-stamping online news articles. Therefore, the aim of this thesis is to develop a system that 1) enables decentralized trusted time-stamping of web and news articles as a means of making future manipulation of online information identifiable, and 2) allows users to determine the authenticity of articles by checking different versions of the same article online.
Memories of the Cold War are virtually inseparable from those of several trials and Congressional hearings that took place around 1950. Following one another in rapid succession, all reflected, and fueled, what has been called the Great Fear of the era. But concerns and targets varied. Some—like the trials of Alger Hiss (l950) and of Julius and Ethel Rosenberg (l951)—were focused on spies and spying; others—like the hearings launched in the late 1940s by HUAC (the House Committee on Un-American Activities) and those held by the Tydings Committee (1951)—were designed to root out subversion in worlds as diverse as those of entertainment and the State Department. In a somewhat different vein, the Congressional hearings led in 1950–1951 by Senator Estes Kefauver of Tennessee were charged with investigating the role of organized crime in America. Speaking of the gangsters who paraded before Kefauver and his committee, in a vivid passage Eric F. Goldman writes that the televised hearings, with their parade of endless “shadowy figures that obviously controlled so much, catalyzed the whole vague feeling that corruption was moving through all American life like a swarm of maggots.”1 This article would like to explore still another trial of the era that, like the Kefauver hearings, was haunted by the threat of gangsters and of moral corruption. In this case, the principal defendant was a thirty-eight year old Jewish New York attorney, Irwin Slater, who, in 1950, was accused of what was popularly known as “baby-selling” or “black market baby racketeering.” Indicted along with Slater were two Jewish colleagues: Harry Wolfson, a fellow attorney and friend, and Bess Bernard, a homemaker who had served for twelve years as executive director of the Hebrew Kindergarten and Infants Home in Queens. On December 4, 1949, the three became the first persons to be indicted under a New York State law mandating that only parents or legal guardians could “place out” babies for adoption. The charges against them included conspiracy, the illegal or “unauthorized” placement of children, and receiving compensation for such placements. By the end of the trial that took place six months later, Slater had been found guilty on two counts of illegal placements and on one count of receiving compensation. Bess Bernard was convicted on similar grounds, while Harry Wolfson (who worked on legal papers for Slater and never handled the babies who were “placed out”) was acquitted on all counts. Unlike the Kefauver hearings—or the other famous trials and hearings of the era—the Slater case has receded into the darkest corners of the past. However, it deserves to be revisited for in its way, it, too—to borrow a term that Cold War historian Ellen Schrecker applies to the trials of Alger Hiss and the Rosenbergs—was “iconic” of an important constellation or cluster of fears and beliefs.2 Set in the fraught landscape of adoption, it revealed how deeply this landscape—like so many aspects of life at mid-century—was infected by the paranoia and heated religious passions of the era. Deeply imbued with tensions between Catholics and Jews, it pointed to the contrasting images and roles assigned to these two religious minorities in the postwar era. 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had babies that as a of months later, in the New York a of in to the by of the that such while babies had been with parents who out to be and still other babies were could only with the of one to their to for an baby who was with these and with for the New York took years of it with a designed to what was as the market in by in of 1949, it principal only could for a only and legal guardians could place had to be before a all had to be to the State of one would that the the in it to a case against Slater and his six months the was Slater, along with Bess Bernard and Harry Wolfson, was months later, on December 1949, became the first indicted on charges from the that with the illegal placement of babies were legal and with receiving compensation for such In of the fears and passions the of what was called “black market baby it that Slater and the were indicted the the of all of what were New many it that the case fears of and of of and the “black as in York In several of the or “black market baby and on the fears for that were the The it important the trial of Alger The it a on the of to the in the of The it took the The by the their was a that, in one the of the case by the in attorney by what a a case to the or by the for the of the of was a it the of its that had Slater, Bernard and Wolfson were of a of organized charged that were in on an with Slater in of Wolfson as his and Bernard in of placement and of the of this the case against that Slater would by in place a for it the placement of in such as The and the as as the Jewish these and were to their babies Slater would a with would for their and as as for in for would their babies to would the babies to or to for a that was in would the babies to their who were in the New York as an and or for legal the that would to Slater at the that the of his the of the this was in a in had a The article to the in the of the that included of and of the who would the case in a with the of with to of the charges against by 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that the of would the case was in it that Slater had been in the of before the trial the it the of diverse and against the of the to the role of a and its with a to at all the assigned to the in the In of all these it all the that in all Slater would been indicted and were it for the of a that to the role by the in a for role by and tensions between Catholics and was the the in New it was a of the a and with a in and the who worked as the executive in of and of in the of had to Slater and only was babies with of on a was obviously on as and in their on the of the was in to the important role in the only the a role as it took its the in New York to for the to the between the and the or the in it the between and it was to that had the of in the of York to a that the case, and the papers found in the in role in the in a On 1949, an known as later, as who had baby to Slater, the in to that for old while was in the had a for that included for and that the had with it to the at them the with and in New York that had Slater, had to that was an attorney from New York who to place with of In of the that virtually launched the one would to the that at for a from with Slater as had to to to the had through and in the obviously for But or led to with Slater to the at had a that the of and into a with a to an end to Slater and his to to a with on 1949, another of a by the of to Slater in to the that had had with Slater to In to was Slater suggested baby to that to the to to to out on this But it that for several one the was for was a of would be at his the of was in the But in the case that this was into on several a that would the by a to the New York of in them to the case with the the through of other who were in with out the and of in and an that Slater had in a The Jewish In the of the of the case took a that with the of the in New the are with and from as as of with or how their that the of through the of and to But it it that by of a in a with executive of the of had to a the in could a or one had an for to the of a or that of a to the was obviously on by a of the of babies with Jewish with and to what as for the of a at the a baby as that of was to its parents as and the that the a a had it with an was with with like a Jewish first The first Jewish and that be to out baby this that with or with the of the the that only was in a to of in that could the case the were against Slater and his to had to on that only their in could that the the or had an role in the babies out for adoption. it in a had to be in the handled the of the and controlled the of the In with this in a on to to the case of would important at the to all the through to the in the of all the Slater, and role was so in that at it as the in New were in of the the in one to before with the The to the so are on that for the In still for the and of a baby so could a of obviously took in and in with the one as the of a to by Slater and how this to an be the one as on the to the would and would 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from the to had the or was the of a in what called a was important to the in case, it was Bess Bernard, Slater, who was and of baby that Slater was a at the and the trial that Slater had that baby be a was a and the baby was and the baby in a that would be the were it would be that the of to be that was or with it that the two of were to the to on the But and with
Abstract A functional credential allows a user to anonymously prove possession of a set of attributes that fulfills a certain policy. The policies are arbitrary polynomially computable predicates that are evaluated over arbitrary attributes. The key feature of this primitive is the delegation of verification to third parties, called designated verifiers. The delegation protects the privacy of the policy : A designated verifier can verify that a user satisfies a certain policy without learning anything about the policy itself. We illustrate the usefulness of this property in different applications, including outsourced databases with access control. We present a new framework to construct functional credentials that does not require (non-interactive) zero-knowledge proofs. This is important in settings where the statements are complex and thus the resulting zero-knowledge proofs are not efficient. Our construction is based on any predicate encryption scheme and the security relies on standard assumptions. A complexity analysis and an experimental evaluation confirm the practicality of our approach.
The trading volume of Bitcoin has increased immensely since its conception. Bitcoin is a cryptocurrency, it is not a legal currency but rather a private monetary system that manages by itself and does not depend on governments or central banks. It is an autonomous currency system that is not liable to any governing body. Some fear that the increase of Bitcoin usage, as it is quite different from traditional currencies and is free from control or regulations by monetary authorities. Although its popularity has grown worldwide, fluctuations of the prices are sometimes erratic. Hence, such large and sudden movements would dampen the sound development of Bitcoin. This paper examines how the volatile price of Bitcoin changes empirically. The empirical results show that there is a difference between short-term volatility and long-term volatility. Traders should see not only the short-term movements in volatile Bitcoin pricing but also long-term developments.
Purpose The purpose of this paper is to argue for the role of the blockchain, i.e., distributed ledger technology, in building innovative business models, including machine money, autonomous economic agents and decentralised organisations. Design/methodology/approach The paper is conceptual/argumentative. As such, it draws on research on (e-)commerce, theories of markets, disruptive innovation and extant studies and conceptual work at the intersection of cryptocurrencies, machine-to-machine commerce and the Internet of Things. Findings The authors highlight three application areas for blockchains, whereby they can function as applications, can help develop autonomous economic agents and can lead the development of decentralised autonomous organisations. With regards to the question of market disintermediation, the authors suggest that, rather than complete disintermediation, the most probable scenario is that of new types of intermediaries finding previously unthinkable roles to play in mediating blockchain-based economic transactions. With regards to the inhibitors that slow down the technology’s adoption and, therefore, the development of new business applications, the authors posit that these relate mainly to the inherent risk of the technology, infrastructure requirements, scepticism of early decision makers and the lack of required new skills and competencies. Originality/value The authors examine how new forms of digital money and technologies embedding trust in decentralised networks will alter markets and commerce, at a time when many regulatory issues remain unresolved; in doing so, the authors focus on how blockchain-enabled technologies can be used to enable and further develop decentralised trusted peer-to-peer transaction ledger systems and applications and lead to sustainable business models.
Blockchain is receiving increasing attention from academy and industry, since it is considered a breakthrough technology that could bring huge benefits to many different sectors. In 2017, Gartner positioned blockchain close to the peak of inflated expectations, acknowledging the enthusiasm for this technology that is now largely discussed by media. In this scenario, the risk to adopt it in the wake of enthusiasm, without objectively judging its actual added value is rather high. Insurance is one the sectors that, among others, started to carefully investigate the possibilities of blockchain. For this specific sector, however, the hype cycle shows that the technology is still in the innovation trigger phase, meaning that the spectrum of possible applications has not been fully explored yet. Insurers, as with many other companies not necessarily active only in the financial sector, are currently requested to make a hard decision, that is, whether to adopt blockchain or not, and they will only know if they were right in 3–5 years. The objective of this paper is to support actors involved in this decision process by illustrating what a blockchain is, analyzing its advantages and disadvantages, as well as discussing several use cases taken from the insurance sector, which could easily be extended to other domains.
Farid Ablayev, D. A. Bulychkov, D. A. Sapaev, Alexander Vasiliev · 5 authors
Bitcoin and blockchain in general is a hot topic nowadays. In the paper we propose a quantum empowering of this technology and show how to speed-up the mining procedure using the modified Grover's algorithm.
Smart contracts---stateful executable objects hosted on blockchains like Ethereum---carry billions of dollars worth of coins and cannot be updated once deployed. We present a new systematic characterization of a class of trace vulnerabilities, which result from analyzing multiple invocations of a contract over its lifetime. We focus attention on three example properties of such trace vulnerabilities: finding contracts that either lock funds indefinitely, leak them carelessly to arbitrary users, or can be killed by anyone. We implemented MAIAN, the first tool for precisely specifying and reasoning about trace properties, which employs inter-procedural symbolic analysis and concrete validator for exhibiting real exploits. Our analysis of nearly one million contracts flags 34,200 (2,365 distinct) contracts vulnerable, in 10 seconds per contract. On a subset of3,759 contracts which we sampled for concrete validation and manual analysis, we reproduce real exploits at a true positive rate of 89%, yielding exploits for3,686 contracts. Our tool finds exploits for the infamous Parity bug that indirectly locked 200 million dollars worth in Ether, which previous analyses failed to capture.
Patrick G. Sylim, Fang Liu, Alvin Marcelo, Paul Fontelo
<sec> <title>BACKGROUND</title> Drug counterfeiting is a global problem with significant risks to consumers and the general public. In the Philippines, 30% of inspected drug stores in 2003 were found with substandard/spurious/falsely-labeled/falsified/counterfeit drugs. The economic burden on the population drug expenditures and on governments is high. The Philippine Food and Drug Administration (FDA) encourages the public to check the certificates of product registration and report any instances of counterfeiting. The National Police of Philippines responds to such reports through a special task force. However, no literature on its impact on the distribution of such drugs were found. Blockchain technology is a cryptographic ledger that is allegedly immutable through repeated sequential hashing and fault-tolerant through a consensus algorithm. This project will develop and test a pharmacosurveillance blockchain system that will support information sharing along the official drug distribution network. </sec> <sec> <title>OBJECTIVE</title> This study aims to develop a pharmacosurveillance blockchain system and test its functions in a simulated network. </sec> <sec> <title>METHODS</title> We are developing a Distributed Application (DApp) that will run on smart contracts, employing Swarm as the Distributed File System (DFS). Two instances will be developed: one for Ethereum and another for Hyperledger Fabric. The proof-of-work (PoW) consensus algorithm of Ethereum will be modified into a delegated proof-of-stake (DPoS) or practical Byzantine fault tolerance (PBFT) consensus algorithm as it is scalable and fits the drug supply chain environment. The system will adopt the GS1 pedigree standard and will satisfy the data points in the data standardization guidelines from the US FDA. Simulations will use the following 5 nodes: for FDA, manufacturer, wholesaler, retailer, and the consumer portal. </sec> <sec> <title>RESULTS</title> Development is underway. The design of the system will place FDA in a supervisory data verification role, with each pedigree type–specific data source serving a primary data verification role. The supply chain process will be initiated by the manufacturer, with recursive verification for every transaction. It will allow consumers to scan a code printed on the receipt of their purchases to review the drug distribution history. </sec> <sec> <title>CONCLUSIONS</title> Development and testing will be conducted in a simulated network, and thus, results may differ from actual practice. The project being proposed is disruptive; once tested, the team intends to engage the Philippine FDA to discuss implementation plans and formulate policies to facilitate adoption and sustainability. </sec> <sec> <title>REGISTERED REPORT IDENTIFIER</title> RR1-10.2196/10163 </sec>
British Financial Supervision and Control Authority has identified new technologies as a component of fintech. These components include regtech, insurtech, blockchain. These new areas of the market development are incomprehensible to a wide range of people. However, this area attracts venture capital which is actively growing worldwide. The prospects of development of these areas are interesting for many reasons: reduction of financial costs for market participants, reduction of information processing time, security of financial transactions, information security and completeness. The article describes: objective reasons of the occurrence of such a kind of the product, risks of using these products and advantages of their introduction in all spheres of life, as well as the scope of regtech implementation.Keywords: Fintech, regtech, blockchain, insurtech
Auf dem bisherigen Höchststand des Bitcoins-Kurses Mitte Dezember 2017 kündigte die Generalstaatsanwaltschaft Frankfurt an, sie wolle 126 beschlagnahmte Bitcoins (damaliger Wert: 1,9 Millionen Euro) veräußern. Die in Gießen angesiedelte Außenstelle der hessischen Zentralstelle zur Bekämpfung der Internet- und Computerkriminalität ZIT hatte 2014 mehrere Online-Marktplätze abgeschaltet, auf denen u.a. mit Drogen gehandelt wurde. Bei einer Razzia beschlagnahmte sie die Server der Betreiber und gelangte so in den Besitz von Bitcoins. Im Folgenden wird erläutert, wie eine die Beschlagnahme bzw. Sicherstellung von Bitcoins strafprozessual und polizeirechtlich umgesetzt wird und warum die erhofften Millionengewinne die Ausnahme bleiben werden.
The paper is devoted to the analysis of issues of regulation of use of cryptocurrency in the Russian Federation and offers the possible measures to solve them. The conclusion is made that the ideal desired result would be the creation of such a controlled financial and economic mechanism based on blockchain technology that would become more attractive for its potential participants than the "usual" cryptocurrencies and smart contract systems. Key words: cryptocurrency, legal regulation, financial system, transactions, financial risks, financial mechanism.
The article discusses the retrospective of cryptocurrencies, theoretical understanding of the digital currency, its value and essence. The tendencies and prospects of cryptocurrencies development. The article focuses on the lack of a legal framework regulating relations in the field of "mining" and circulation of cryptocurrencies. Keywords: cryptocurrency; digital currencies; bitcoin; electronic money; mining; cryptographic methods of information protection.
The technology of BlockChain and cryptocurrency is an actual topic for humanity today. There are different policies regulating cryptocurrencies, but they are still far from perfect. The difficulty of technical regulation of these systems is beyond doubt, many countries are only at the stage of discussing the status of the currencies, some are extremely supportive of them. However, it is undeniable that more and more countries will introduce regulations in the field of cryptocurrencies, focusing, firstly, on the structure of their own economy. Keywords: BlockChain, cryptocurrency, Bitcoin, mining.
The article provides an analytical overview of cryptocurrencies, the dynamics of bitcoin from the origin to the present time. The specific risks of the virtual currencies use were identified.Keywords: bitcoin, cryptocurrency, risks, electronic money; financial technology.
This article explores the mechanisms of the organization and operation of virtual payment systems. The appearance of such payment systems is associated with the development of Internet technologies in the field of mutual settlements for goods (works and services). The study aims at analyzing the classification, types of emission of cryptocurrencies, the mechanism of functioning of cryptocurrency systems; evaluating their impact on the monetary system and the involvement of individuals in the laundering of illegal incomes using cryptocurrencies; estimating prospects for the development of virtual payment systems in Russia and abroad, and defining mechanisms to counteract illegal activities. As a result, the current status of virtual cryptocurrency systems is estimated, their distinctive features and advantages are considered. The study also identifies drawbacks in the use of cryptocurrency with the involvement of individuals in the system of non-cash settlements. The results of the analysis of cryptocurrency systems can be useful for the improvement of the state monetary policy. Keywords: electronic money, bitcoin, cryptocurrency, blockchain, money laundering.