Tien Tuan Anh Dinh, Rui Liu, Meihui Zhang, Gang Chen · 6 authors
Blockchain technologies are gaining massive momentum in the last few years. Blockchains are distributed ledgers that enable parties who do not fully trust each other to maintain a set of global states. The parties agree on the existence, values, and histories of the states. As the technology landscape is expanding rapidly, it is both important and challenging to have a firm grasp of what the core technologies have to offer, especially with respect to their data processing capabilities. In this paper, we first survey the state of the art, focusing on private blockchains (in which parties are authenticated). We analyze both in-production and research systems in four dimensions: distributed ledger, cryptography, consensus protocol, and smart contract. We then present BLOCKBENCH, a benchmarking framework for understanding performance of private blockchains against data processing workloads. We conduct a comprehensive evaluation of three major blockchain systems based on BLOCKBENCH, namely Ethereum, Parity, and Hyperledger Fabric. The results demonstrate several trade-offs in the design space, as well as big performance gaps between blockchain and database systems. Drawing from design principles of database systems, we discuss several research directions for bringing blockchain performance closer to the realm of databases.
Steven Goldfeder, Harry Kalodner, Dillon Reisman, Arvind Narayanan
Abstract We show how third-party web trackers can deanonymize users of cryptocurrencies. We present two distinct but complementary attacks. On most shopping websites, third party trackers receive information about user purchases for purposes of advertising and analytics. We show that, if the user pays using a cryptocurrency, trackers typically possess enough information about the purchase to uniquely identify the transaction on the blockchain, link it to the user’s cookie, and further to the user’s real identity. Our second attack shows that if the tracker is able to link two purchases of the same user to the blockchain in this manner, it can identify the user’s cluster of addresses and transactions on the blockchain, even if the user employs blockchain anonymity techniques such as CoinJoin. The attacks are passive and hence can be retroactively applied to past purchases. We discuss several mitigations, but none are perfect.
A decentralized online quantum cash system, called qBitcoin, is given. We design the system which has great benefits of quantization in the following sense. Firstly, quantum teleportation technology is used for coin transaction, which prevents from the owner of the coin keeping the original coin data even after sending the coin to another. This was a main problem in a classical circuit and a blockchain was introduced to solve this issue. In qBitcoin, the double-spending problem never happens and its security is guaranteed theoretically by virtue of quantum information theory. Making a block is time consuming and the system of qBitcoin is based on a quantum chain, instead of blocks. Therefore a payment can be completed much faster than Bitcoin. Moreover we employ quantum digital signature so that it naturally inherits properties of peer-to-peer (P2P) cash system as originally proposed in Bitcoin.
Steven Goldfeder, Harry Kalodner, Dillon Reisman, Arvind Narayanan
We show how third-party web trackers can deanonymize users of\ncryptocurrencies. We present two distinct but complementary attacks. On most\nshopping websites, third party trackers receive information about user\npurchases for purposes of advertising and analytics. We show that, if the user\npays using a cryptocurrency, trackers typically possess enough information\nabout the purchase to uniquely identify the transaction on the blockchain, link\nit to the user's cookie, and further to the user's real identity. Our second\nattack shows that if the tracker is able to link two purchases of the same user\nto the blockchain in this manner, it can identify the user's entire cluster of\naddresses and transactions on the blockchain, even if the user employs\nblockchain anonymity techniques such as CoinJoin. The attacks are passive and\nhence can be retroactively applied to past purchases. We discuss several\nmitigations, but none are perfect.\n
Pedro Bonillo Bueno, Emilio Aragon Fortes, Konstantinos Vlachoski
Since its launch in 2008, Bitcoin becomes one of the most successful and fast-growing alternative currencies. As of 2017, the market capitalization is around $46 billion and arguably expected to continue growing. The Bitcoin to the US dollar exchange rate has been very volatile and fluctuating significantly. Although Bitcoin was designed as a medium of exchange, it is now more as an investment tool and thus the development of effective quantitative risk management tools becomes quite urgent for all the market participants. In this paper, we investigate empirical distribution of the Bitcoin exchange rate returns by using four types of widelyused heavy-tailed distribution and show that the Skewed t distribution has the best empirical performance. We further calculate the VaR based risk measures and found the Skewed t distribution generates the VaR values, which are closest to historical VaR values. Our results could be directly used in the industry’s stress testing practice, and help financial institutions fulfill the regulatory requirements.
Ao Lei, Haitham Cruickshank, Yue Cao, Philip Asuquo · 6 authors
As modern vehicle and communication technologies advanced apace, people begin to believe that the Intelligent Transportation System (ITS) would be achievable in one decade. ITS introduces information technology to the transportation infrastructures and aims to improve road safety and traffic efficiency. However, security is still a main concern in vehicular communication systems (VCSs). This can be addressed through secured group broadcast. Therefore, secure key management schemes are considered as a critical technique for network security. In this paper, we propose a framework for providing secure key management within the heterogeneous network. The security managers (SMs) play a key role in the framework by capturing the vehicle departure information, encapsulating block to transport keys and then executing rekeying to vehicles within the same security domain. The first part of this framework is a novel network topology based on a decentralized blockchain structure. The blockchain concept is proposed to simplify the distributed key management in heterogeneous VCS domains. The second part of the framework uses the dynamic transaction collection period to further reduce the key transfer time during vehicles handover. Extensive simulations and analysis show the effectiveness and efficiency of the proposed framework, in which the blockchain structure performs better in term of key transfer time than the structure with a central manager, while the dynamic scheme allows SMs to flexibly fit various traffic levels.
Payments architectures are on the verge of a great bifurcation that must be documented in order to be debated. Google is moving towards a quasi bank while Apple and Google disseminate payment systems over smartphones. At the same time, block chain might become a distributed ledger introducing a radical new model of trusted third-party. The detailed history of credit card systems helps understand why the game of security has always been trigged by a delegation process of the risk to third parties and by the cat-and-mouse game of security and fraud. Technologies were designed to solve these issues but have always been closely related to innovations in institutional assemblages. These payments systems shape our social life and the stakes of trust that we put in these architectures require a truly political examination.
Mustafa Al-Bassam, Alberto Sonnino, Shehar Bano, Dave Hrycyszyn · 5 authors
Chainspace is a decentralized infrastructure, known as a distributed ledger, that supports user defined smart contracts and executes user-supplied transactions on their objects. The correct execution of smart contract transactions is verifiable by all. The system is scalable, by sharding state and the execution of transactions, and using S-BAC, a distributed commit protocol, to guarantee consistency. Chainspace is secure against subsets of nodes trying to compromise its integrity or availability properties through Byzantine Fault Tolerance (BFT), and extremely high-auditability, non-repudiation and `blockchain' techniques. Even when BFT fails, auditing mechanisms are in place to trace malicious participants. We present the design, rationale, and details of Chainspace; we argue through evaluating an implementation of the system about its scaling and other features; we illustrate a number of privacy-friendly smart contracts for smart metering, polling and banking and measure their performance.
Mobility Scooters highlights that collective actions must raise common issues, thus placing a focus on the variation in damages across claimants. The MasterCard consumer action highlights the challenge in taking a ‘top-down’ approach (estimating aggregate damages and only subsequently considering how to distribute that amount across individuals) and also the role of individual issues in collective actions. Retailers’ claims in MasterCard make clear the need for courts to pay careful attention to economic analysis, notably in the context of complex settings such as two-sided markets and in deriving counterfactual scenarios. The Consumer Rights Act 2015 (CRA) introduced a new collective action regime to the competition law landscape in the UK, including the ability to bring opt-out actions.1 The defining feature of a collective action is that the Competition Appeal Tribunal (CAT) can consider a collection of individual claims together rather than considering all aspects of every individual claim separately. The UK’s collective action regime aims to facilitate redress for claims that might not otherwise be brought, while avoiding aspects of the US class-action regime. The fact that it can accommodate both opt-in and opt-out claims means it represents a potentially dramatic change in the competition law landscape. Opt-out claims introduce new opportunities for redress for potential claimants and may markedly change the risks and exposure of defendants in cases taken in the UK. Moreover, other member states are likely to draw lessons from the experience and, while the European Commission recommended that member states have collective redress systems by 2015, its recommendation was that they should, as a general rule, be based on the ‘opt-in’ principle.2 The development of the UK’s new regime has therefore potentially very significant ramifications for the approach across Europe. Two cases have so far reached the stage where the CAT has been asked to certify whether the matter can proceed to trial on a collective basis, Mobility Scooters3 and the MasterCard4 consumer case. This article first reviews the core legal test described by the CAT for class certification and then considers the key economic issues at the heart of these cases. The cases relate to two very different types of infringement. Mobility Scooters was a claim following an OFT5 infringement decision that manufacturer Pride had entered into vertical arrangements with eight of its UK-wide online retailers which had as their object the prevention, restriction or distortion of competition in the market for mobility scooters by6 ‘prohibiting the advertising of below RRP prices online in respect of certain Pride mobility scooters between February 2010 and February 2012.’ In the MasterCard consumer case, the claim relates to a finding by the European Commission that the defendant acted unlawfully and in breach of Article 101 TFEU in establishing and implementing certain fees known as Multilateral Interchange Fees (MIFs), which retailers were required to pay on credit and debit card transactions. In addition to the consumer claim, the CAT considered whether an individual retailer suffered damages in Sainsbury’s v. MasterCard, and in the judgement by Justice Popplewell, the High Court addressed at least 12 other claims brought by retailers.7 The consumer claim argues that the MIF was passed on by businesses to all 46.2 million individuals who purchased goods and/or services from UK businesses that accepted MasterCard. To issue a Collective Proceedings Order (CPO),8 the CAT must be satisfied that there is some basis in fact9 which establishes that three individual certification requirements are met, namely:10 The claims must be brought on behalf of an identifiable class of persons The claims must raise ‘common issues’ The claims must be ‘suitable’ to be brought in collective proceedings The CAT describes the first requirement thus: (i) it must be possible to say for any particular person, using an objective definition of the class, whether that person falls within the class; and (ii) that the class should be defined as narrowly as possible without arbitrarily excluding some people entitled to claim.11 Common issues are defined as the same, similar or related issues of fact or law.12 In other words, claims can be efficiently collected together when the issues the court must decide are common to each of the claims. Although the claims must raise common issues, that does not require that all the significant issues in the claims should be common issues13 and the final resolution of the claims will often require the assessment of individual issues.14 It is notable that this aspect of the UK threshold for certification is potentially less restrictive to certification than the US class-action system where common issues must also predominate.15 The CAT Rules describe that assessing whether claims are ‘suitable’ to be brought in collective proceedings can depend on a wide range of factors.16 One aspect is whether the claims are suitable for an aggregate award of damages,17 including whether such an award can be distributed between members of definable subclasses.18 Using language familiar to US class certification discussions,19 the CAT has described that its approach to certification ‘should be rigorous.’20 In practice, the question is how much rigorous analysis can really be undertaken at the CPO stage when ‘[t]he approach under the UK regime of collective proceedings is intended to be very different [from the US], with either no or only very limited disclosure and shorter hearings held within months of the claim form being served.’21 There will clearly be tensions between the desire for a rigorous analysis at the CPO stage and the desire to limit pre-CPO disclosure. More generally, the UK courts have accepted that the quantification of an overcharge always involves estimation,22 and that difficulties in quantifying compensation are to be dealt with ‘by the exercise of a sound imagination and the practice of the broad axe.’23 That said, as Mr Alan Bates vividly described during the Mobility Scooters case, ‘a broad axe is very different from a sort of crazed axeman swinging out all over the place because you do not have the…proper parameters for the exercise.’24 Moreover, Justice Popplewell (while replacing a broad axe with a broad brush) drew an explicit link between the quality of evidence and the appropriate size of a damages award:25 ‘[W]here the court is compelled to use a broad brush in the absence of precision in the evidence of the harm suffered by a claimant, it should err on the side of under-compensation so as (a) to reflect the uncertainty in the actual loss suffered and (b) to give the defendant the benefit of any doubts in the calculation.’ In Mobility Scooters the consumer claim followed an OFT decision that certain vertical agreements infringed Chapter 1 of the Competition Act (1998) since they involved a prohibition on ‘below RRP advertising of online prices’ (BROPA). Claimants argued26 they were harmed by the infringing agreements because price competition was less intense since retailers did not advertise the lower prices they might have absent the infringement, and that retailers either advertised higher prices or they advertised no prices and directed online purchasers towards telephone sales channels—advising them to ‘call for better prices.’ The claimants proposed estimating the overcharge by calculating a weighted average price during the infringement period (February 2010–February 2012) and comparing it to a calculated weighted average price from the post-infringement period (March 2012–December 2014). Claimants argued that prices in physical stores fell on average after the infringement period by 16.2 per cent and attributed that fall to the removal of the infringement. They further asserted that the differential between the two distribution channels (physical stores and online) was the same during and after the infringements so that the overcharge to online customers could also be estimated (see Fig. 1). The competitive benchmark in Mobility Scooters.Note: Author's estimates based on information available in the Mobility Scooters judgement. However, the CAT judgement in Mobility Scooters makes clear that evidence of declining prices alone is insufficient. Instead, the claimant must establish that there is a basis for demonstrating that an observed fall in prices is attributable to the end of the infringements and not to other factors, that is, provide evidence of causality.27 The CAT considered whether any overcharge in Mobility Scooters was a common issue among purchasers. The defendant argued that (i) the loss suffered by each customer would depend on that individual’s purchasing and search behaviour and so the damage caused would not be common; and (ii) that any methodology which allowed damages to be estimated on a common basis would require knowledge of whether a given individual did search the market and/or would have searched the market in the counterfactual. The claimant accepted there was marked price variation across individuals since prices were individually negotiated, but argued that overcharge was nonetheless a common issue. The claimant asserted the extra amount customers paid as a result of the infringing agreements was sufficiently similar to mean overcharge was a common issue, whether or not a given individual paid, say, £1,000 or £750 for the scooter.28 The most significant element of the quantification argumentation during the CPO application in Mobility Scooters related to quantity not price. The relevant quantity depended on whether any overcharge resulting from the conduct was market-wide, or whether it was limited to at most the customers of the eight retailers with whom infringing agreements were signed.29 The claimants submitted that the BROPA prohibition made it harder for consumers to shop around for the best price, and that the infringing agreements meant the competitive pressure on other retailers was absent while the eight retailers (with collective market share of around 15 per cent of sales) were not insignificant.30 the sales an overcharge was thus a issue for This issue also a role in the CPO application since the CAT was required to the relevant claimant in the CPO and subsequently would be required to award any aggregate damages for each The to of customers by (i) sales online per cent of sales) physical stores per cent of and (ii) whether or not customers purchased a that was by an infringing The CAT did these alone could an aggregate damages award since it and is within them sufficiently The CAT was that a different of damage may be to who purchased from the eight retailers and sales from other The application for a CPO was thus with the that a CPO application could be made by the claimants. the claimants their application for a The CAT its judgement for the CPO application in the MasterCard consumer claim in considering the consumer claim for it is to first consider the related claims by retailers MasterCard. This first considers the economic issues in these cases to the particular for economic analysis in the MasterCard consumer damages were for the breach of Chapter 1 of and/or Article 101 TFEU by of the at which the UK Multilateral Interchange or was for MasterCard The CAT and Sainsbury’s million in damages The in below how in card the MIF is per cent and the is per the an for the will and the and the in a card card MasterCard the UK the CAT that to the of than to the of and that would a higher UK MIF have no to in in the can from any such and to the In the would no have a UK MIF and Interchange Fees would have to be between and UK MIF means would have a than in the However, in other the analysis of is In the analysis that (i) have they do not have to issue MasterCard to their have the to between MasterCard, and and (ii) have their must all rather than the sales for no This in should the resulting counterfactual price. It is that the CAT a benchmark from a of in to the on the other that a an would in price in to its only when the other side of the the had all of the In there is marked between the of the analysis of and its to an as the benchmark for counterfactual competitive prices absent the of 12 further claims MasterCard were brought Justice Popplewell in the High Justice Popplewell that the that the counterfactual was not Instead, the there were two potentially relevant the MIF (i) being to or (ii) being to the MIF less than actual MIF and to the court is under Article Justice Popplewell considered whether MIF should be held at its actual in the counterfactual. That might not be the case, for it were on the basis of the infringement decision MasterCard that actual were also that the claimants would need to establish that and were In MIF was then its actual should form of the counterfactual since for the counterfactual is the and the court conduct as and it is to be Justice Popplewell thus that there would be a differential between and MasterCard in the counterfactual. Moreover, counterfactual MIF were while MIF at its actual would have both the ability and to their of from towards and so card would competition from would the It was then a to with MasterCard that its MIF was since it was to the of the MasterCard as a The question of whether prices should be in the counterfactual is a general to consider that the prices by may be it will not always make to price counterfactual and when finding that price would lower in the counterfactual than it was in the The challenge is to how prices would have in a new counterfactual this case, a new in a two-sided market The economic of card prices is best considered within the of two-sided In two-sided the there are on the the is to the other Justice of the economic on two-sided markets is both and In two-sided competitive prices reflect the between they do not reflect the or from side of the competition between can to or no for and fees for This feature was by Justice Popplewell, who described with the benchmark in based approach is not in any of the as any sound and 2015 describe it as by any and as with the whether the judgement the analysis of the of two-sided markets into a the judgement argues that to so competition between card systems to higher that must to and would thus need to The challenge in a competition under Article 101 is to decide the of MIF in of the under and also Justice Popplewell a benchmark price and to it using the best available The analysis that both and of MIF were higher than actual MIF and Justice Popplewell that there was therefore no In the CAT described that the is in not a at the need to that a claimant is sufficiently and not by a the key question relates to the of the actual of the damages suffered by the In the actual of the damages in the CAT consider that the legal definition of a from that of the in two an might to and the is only with identifiable in prices by a to its customers the in price must be with the and The CAT to the tensions between the legal and economic of In the that (i) the or can relate only to identifiable price by a to its and (ii) the price should be each to in for the the definition of with that approach since is defined to which a given change in a given change in is defined The shop was considered by the CAT to whether there were between legal and economic The CAT that a shop at price them to at price and that there was a which the price of say, per of on the higher price to the in the form of the shop to its its The CAT the question of whether the are considered by an since they would not to its definition of In respect of this whether an it or this conduct to the harm suffered from the shop In the shop actions to damage to the damages suffered from the the damage to the actions damage the customers quality of being and there is an potential claimant the conduct the of the CAT a on such in and it would no be to establish in practice, the to to be potentially of such an the of in fact the actual of damage In the CAT the of in to on the its approach to as by a of under-compensation to it considers at least as as the of In the CAT only to on the of the defendant has that there class of claimant, of the in the to whom the overcharge has been passed the defendant that the is on the the of such a class, consider that a of the overcharge by it should not be or on this that under a of definition of which allowed for or this approach would need to be but only to the that the defendant would need to that there other of claimant, and of the in the to whom damage was the the would on the defendant to to the court that the to but not means the damage award should be The CAT and evidence on whether would have in to an overcharge on It that MasterCard had to its of in to the the range of by and the of by Sainsbury’s in it would be to say of the price of any given was attributable to the UK in its the CAT also that there was in respect of In following the claimant should be allowed to actual including a loss of the claim is and The CAT the UK MIF was a common to Sainsbury’s and its consider that a amount of the UK MIF would have been not in a which would have to a of the CAT that Sainsbury’s per cent of the overcharge and so it suffered damage from lower in the and than it would have had absent the infringement. In it on damages based on the of Sainsbury’s that Sainsbury’s did not raise any during the claim and that it was appropriate to award on per cent of Sainsbury’s damages the that were not passed The approach in these two aspects to but the in by defendant and The by Justice Popplewell and the CAT in Sainsbury’s provide context for the decision on whether the requirements for class certification were in the MasterCard consumer In the CAT had to decide whether all of the 46.2 million individual claims ‘common issues’ and were ‘suitable’ to be brought in collective the of the consumer claim, the a methodology which to at a of the aggregate damages award calculated The then proposed a for the aggregate damages across individuals in the aspect of the proposed methodology is in The submitted that the aggregate damages could be calculated by a methodology which involved (i) the of (ii) the and or In of the the proposed using to the of made by consumers using MasterCard credit and debit to businesses in the UK each during the claims the and the across each of of and debit and and the CAT it would be to for each of and the in to Popplewell, in the MasterCard consumer claim the overcharge was to be the between the MasterCard UK MIF and the counterfactual that would have been had there been no infringement, either no MIF at all or a lower of MIF which for under Article The of the relevant counterfactual the CAT be a significant issue in the the application were to In each the economic followed the approach accepted and by the CAT in Sainsbury’s by calculating a weighted average MIF and counterfactual in to the overcharge for each of the of the claim and for each of the of in the There was no that passed on the MIF to in the form of a the question was how much of the was passed on to individual customers The argued that as a matter it was appropriate to a but not over weighted average across the UK That said, the accepted under that will be by such as of and and of regime. The further accepted within broad there was a wide of businesses which may have different of so that for may not be the same as for and that some of the may also across the UK. a weighted average for the of the UK would clearly be the it should be possible on the basis of (a) information from the retailer claims actions (b) disclosure from and available The CAT it (a) the difficulties of from evidence on cases claims made by (b) the and that would disclosure from and the difficulties of and a weighted average were calculated based on the limited amount of available In the CAT that the proposed across the UK over a period of would be a complex exercise to a wide range of It also that a would have had to be made to whether such a is by are the test from the CAT was on the basis of the in of it that there were available for the proposed methodology to be on a sufficiently sound basis, so it was not satisfied that the claims were suitable for an aggregate award of 1 describes aspects of the application which the CAT described would be relevant for an individual claim and, in whether each issue is common across individual claimants. The CAT that the did raise common issues, but that it also issues which were individual in Common and individual issues in the MasterCard consumer claim between different of goods and services between different of in the of sales made by that paid for by card to since the lower the actual overcharge which it has to over the prices of its goods or services between different of goods and services between different of in the of sales made by that paid for by card to since the lower the actual overcharge which it has to over the prices of its goods or services Common and individual issues in the MasterCard consumer claim between different of goods and services between different of in the of sales made by that paid for by card to since the lower the actual overcharge which it has to over the prices of its goods or services between different of goods and services between different of in the of sales made by that paid for by card to since the lower the actual overcharge which it has to over the prices of its goods or services The methodology is not from the of individual claimants but rather is to be ‘top-down’ to the issues by to to of a for all claims. The CAT that this of approach can be but only there is a and means of to the of individual aggregate damage award would need to be distributed across The proposed calculating the aggregate loss on an basis for each of the in the claims period and it on an per basis among all the class members for that of who were in the UK and over the of in that However, when the were asked this by the they that the proposed no to the individual They for that individual would depend on much a given individual on as as across a range of other and so The CAT considered how a loss would be estimated in an individual action for It that since no individual can be to or the of would be on the basis of an assessment of and then a broad of how that was between and and between of It on to say in the is that there is no of a very of the loss suffered by each individual claimant from the aggregate loss calculated to the proposed The CAT that the of the individual issues of the from whom they and the of which they made it to how the to individuals could be on any The application for a CPO was the UK courts have considered the first two collective Mobility Scooters and the MasterCard consumer claim, as as significant related actions for The courts have been asked to consider such as overcharge and in agreements in Mobility Scooters and a two-sided market in MasterCard. In at the CPO application these collective actions have a focus on the and of the variation in damage across claimants. the CAT has the CPO in both of these first two opt-out it does not mean that other cases will not the CAT will need to to consider how a it should place on the claimant a CPO when such must be made on the basis of limited disclosure.
Cüneyt Gürcan Akçora, Yulia R. Gel, Murat Kantarcıoğlu
Bitcoin and its underlying technology, blockchain, have gained significant popularity in recent years. Satoshi Nakamoto designed Bitcoin to enable a secure, distributed platform without the need for central authorities, and blockchain has been hailed as a paradigm that will be as impactful as Big Data, Cloud Computing, and Machine Learning. Blockchain incorporates innovative ideas from various fields, such as public-key encryption and distributed systems. As a result, readers often encounter resources that explain Blockchain technology from a single perspective, leaving them with more questions than answers. In this primer, we aim to provide a comprehensive view of blockchain. We will begin with a brief history and introduce the building blocks of the blockchain. As graph mining is a major area of blockchain analysis, we will delve into the graph-theoretical aspects of Blockchain technology. We will also discuss the future of blockchain and explain how extensions such as smart contracts and decentralized autonomous organizations will function. Our goal is to provide a concise but complete description of blockchain technology that is accessible to readers with no prior expertise in the field.
<p>This study is for observing the regional financial performance influence of regencies/cities in South Sumatera province. The research is implemented quantitatively by using the data panel double regression of the 2006 – 2015 time period. Regional financial performance covers fiscal decentralization, autonomy, effectiveness and efficiency. Based on a partial count, fiscal decentralization has a regression coefficient as large as 62.73185, which means fiscal decentralization has a positive and significant influence to economic growth. Then regional finance autonomy has a regression coefficient as large as -16.04656 which means that regional autonomy has a negative influence yet significant to economic growth. Observing from regional financial effectiveness which has a regression coefficient as large as -0.074855, which means that effectiveness has a negative influence and not significant to economic growth. Regional financial efficiency has a regression coefficient as large as -0.254122, which means that efficiency has a negative influence and not significant to economic growth. Based on the count as a whole it means that Fiscal Decentralization, Regional Finance Autonomy, Effectiveness, and Efficiency have significant influences to economic growth. This means regional financial performance is very influential to the economic growth of regencies/cities in South Sumatera Province in the 2006-2015 time period.</p><p><br />JEL Classification: E02, H70, H77<br />Keywords: Autonomy, Economic Growth, Effectiveness, Efficiency, Regional Financial Performance, Fiscal Decentralization</p>
Algebra is one of the important fields of mathematics. It concerns with the study and manipulation of mathematical symbols. It also concerns with the study of abstractions such as groups, rings, and fields. Due to the development of these abstractions, it is extended to consider other structures, such as vectors, matrices, and polynomials, which are non-numerical objects. Computer algebra is the implementation of algebraic methods as algorithms and computer programs. Recently, many algebraic cryptosystem protocols are based on non-commutative algebraic structures, such as authentication, key exchange, and encryption-decryption processes are adopted. Cryptography is the science that aimed at sending the information through public channels in such a way that only an authorized recipient can read it. Ring theory is the most attractive category of algebra in the area of cryptography. In this paper, we employ the algebraic structure called skew -Armendariz rings to design a neoteric algorithm for zero knowledge proof. The proposed protocol is established and illustrated through numerical example, and its soundness and completeness are proved.
<p><em>The purpose of this study was to determine the level of financial capability in Pamekasan in order to support the implementation of regional autonomy. This study took place in the Finance and Asset Management Agency Pamekasan </em><em>regency</em><em>. While the data used in this study is the financial data in the budget Finance and Asset Management Agency Regions 2011-2015 fiscal year. The data collection techniques is to study literature and documentation</em></p><p><em>This research method is descriptive quantitative, using financial ratios, ie the ratio of local financial independence, the ratio of the degree of decentralization, local financial dependency ratios. </em></p><em>The results of the analysis conducted of data obtained as follows: Based on the ratio of local financial independence shown by the average ratios are 36.53%% remained between 25% - 50% are categorized as instructive meaningful relationship patterns Pamekasan government's ability to meet funding needed to perform the duties of Government, Development and Social Services community is still relatively low despite the years has increased and decreased. The degree of decentralization ratio only has an average of 6.4%. this means that the level of financial independence still low Pamekasan in implementing autonomy. Based on the area of financial dependency ratios averaging 19% are in scale interval, 10.01 to 20.00% this means that This means revenue (PAD) has a dependency large enough to cover immediate expenses and Pamekasan government still depends on the source financial receipts from central government and provincial transfers.</em>
Cloud computing has become an irreversible trend. Together comes the pressing need for verifiability, to assure the client the correctness of computation outsourced to the cloud. Existing verifiable computation techniques all have a high overhead, thus if being deployed in the clouds, would render cloud computing more expensive than the on-premises counterpart. To achieve verifiability at a reasonable cost, we leverage game theory and propose a smart contract based solution. In a nutshell, a client lets two clouds compute the same task, and uses smart contracts to stimulate tension, betrayal and distrust between the clouds, so that rational clouds will not collude and cheat. In the absence of collusion, verification of correctness can be done easily by crosschecking the results from the two clouds. We provide a formal analysis of the games induced by the contracts, and prove that the contracts will be effective under certain reasonable assumptions. By resorting to game theory and smart contracts, we are able to avoid heavy cryptographic protocols. The client only needs to pay two clouds to compute in the clear, and a small transaction fee to use the smart contracts. We also conducted a feasibility study that involves implementing the contracts in Solidity and running them on the official Ethereum network.
Edwine Barasa, Anthony Muchai Manyara, Sassy Molyneux, Benjamin Tsofa
BACKGROUND: In 2013, Kenya transitioned into a devolved system of government with a central government and 47 semi-autonomous county governments. In this paper, we report early experiences of devolution in the Kenyan health sector, with a focus on public county hospitals. Specifically, we examine changes in hospital autonomy as a result of devolution, and how these have affected hospital functioning. METHODS: We used a qualitative case study approach to examine the level of autonomy that hospitals had over key management functions and how this had affected hospital functioning in three county hospitals in coastal Kenya. We collected data by in-depth interviews of county health managers and hospital managers in the case study hospitals (n = 21). We adopted the framework proposed by Chawla et al (1995) to examine the autonomy that hospitals had over five management domains (strategic management, finance, procurement, human resource, and administration), and how these influenced hospital functioning. FINDINGS: Devolution had resulted in a substantial reduction in the autonomy of county hospitals over the five key functions examined. This resulted in weakened hospital management and leadership, reduced community participation in hospital affairs, compromised quality of services, reduced motivation among hospital staff, non-alignment of county and hospital priorities, staff insubordination, and compromised quality of care. CONCLUSION: Increasing the autonomy of county hospitals in Kenya will improve their functioning. County governments should develop legislation that give hospitals greater control over resources and key management functions.
An existing pseudo-commodity and a smart contracts framework allow the creation of a purely automatic and self-sufficient price-stable cryptocurrency, without human intervention. This new currency, we denominated Toroid or TRD, can be used more extensively for commerce than pseudo commodity cryptocurrencies due to its lower volatility. Also, is suitable for investment, as the tokens in each account multiply, return interest, when the market grows. Like the controlled fiat money of a central bank plus the benefits of an inflation-adjusted perpetuity bond. Collateral in base coin, for example BTC or ETH, can be added to bootstrap your own Toroid investment or withdrawed after a very small investment period. So, the Toroids are not created from nothing nor have a limited monetary base. The minimum investment period can be very small, for example one day, and you keep the interest but you can return the Toroids and refund your collateral. That is a one-side only peg to a deflationary crypto-commodity. The stability is guaranteed by endogenous measurements of number of transactions and wallet pro-rated rebasement of balance to reduce volatility of price. Each account has its own rebasement due to the account creation timestamp. Rebasement control mechanism is progressive during initial bootstrap period because price manipulation protection is more severe when the capital involved is smaller. Rebasement has a quick positive start to incentivize early adopters that see only big growth in their TRD account during bootstrap period. Finally, the new rebasement control makes it economically infeasible for an attacker targeting the coin with manipulated transaction volume if we set the minimum rebasement greater than profits from massive currency manipulation.
Timothy H. Lucas, Xilin Liu, Milin Zhang, Sri Sritharan · 10 authors
BCI: brain–computer interface DCN: dorsal column nuclei ICMS: intracortical microstimulation LED: light-emitting diode PDMS: polydimethylsiloxane RF: radiofrequency The dexterous hand is a defining feature of human existence. Evolved over tens of millions of years, modern humans are able to perform remarkable tasks with their hands. From typing hundreds of words per minute to playing Rachmaninoff's Piano Concerto No. 2, the dexterous hand defines us. Unfortunately, a number of maladies rob us of this defining human characteristic. In the most extreme case, paralyzed individuals lose communication between the brain and the periphery. This condition affects an estimated 5.4 million people, or 2% of the US population.1 At present, no effective treatment restores function to these individuals. Regaining hand function is a principal concern for paralyzed patients. Toward this aim, significant advances in motor—or efferent—brain–computer interface (BCI) systems have occurred in recent years. Efferent BCI systems extract movement-relevant information from electrocorticography (ECoG) or electroencephalography (EEG). These analogue signals are transformed into control commands to drive robotic arms2 or evoke muscle contractions in paralyzed limbs.3-8 In the later example, compound wrist flexion may be evoked by brain-controlled functional electrical stimulation of forearm flexors. Planned clinical trials aim to capitalize upon these scientific advances to test efferent BCI across a range of conditions and control routines. While these proof-of-principal systems are encouraging, a number of substantial hurdles remain. Perhaps the most pressing barrier to restoring dexterous hand movements is the lack of systems to restore somatosensory feedback. Even in the presence of intact descending motor systems, precise hand movements are abolished when somatosensation is missing.9-16 Indeed, the majority of efferent BCI systems currently in testing rely solely upon visual guidance. This constraint is unnatural and unlikely to be useful if deployed clinically. Visual guidance requires constant vigilance and introduces substantial time-lags to error correct each movement. To restore naturalistic movements, bi-directional BCI systems that link movements and real-time sensory feedback must be developed. The feedback loop of bi-directional BCI is closed with sensory feedback. Unfortunately, the field of sensory—or afferent—brain–computer interface has not kept pace with the maturation of efferent systems. This is due, in part, to the challenges concerning sensory research in animals. Sensory perception is a uniquely subjective experience that does not lend itself readily to the quantitative metrics. For decades, experimentalists have attempted to characterize the perceptual experiences associated with stimulation of the sensory cortices, including primary somatosensory cortex (S1), secondary somatosensory cortex (S2), and parietal association areas in animal models. From this body of literature, we know that intracortical microstimulation (ICMS) of S1 yields sufficient percepts to permit limited binary decisions, such as differentiating between 2 stimulation frequencies or amplitudes.17-21 Despite exhaustive investigation, no study has convincingly reproduced the complex sensory phenomena that are fundamental to our routine encounters with the physical world. Compounding the problem, very limited human data are available to assess the efficacy of S1 stimulation. Animal studies do not answer the question of how stimulation feels. To answer these qualitative questions, we need human data. Most human data have been obtained during brief testing sessions in awake craniotomies or during stimulation in patients with implanted ECoG electrodes.22-24 Invariably, these patients reported that S1 stimulation yielded only vague ‘tingling’ sensations with modest regional localization. Flesher and colleagues recently reported the first human data using ICMS encoding in S1 with chronic penetrating arrays.25 In this experiment, a 28-yr-old male with a spinal cord injury underwent implantation of 2 32-channel multi-electrode arrays into primary somatosensory cortex (S1). Over the course of several months, the investigators mapped perceptual responses to ICMS up to 100 μA. The majority of responses (93%) were categorized as ‘possibly natural,’ ‘pressure’ sensations. The perceptual intensity was modulated by stimulation amplitude with increased pressure corresponding to increase stimulus amplitude. This finding mirrors that of ICMS in primary visual cortex where phosphine brightness is modulated by stimulus amplitude.26 These data constitute a substantial step toward clinical sensory BCI. However, there were a number of findings that tempered enthusiasm for immediately clinical implementation. For instance, none of the S1 electrodes activated sensory representations of the distal fingers where feedback is most needed. Instead, the majority of responses were localized to the palmar crease region of the hand proximal to the fingers. Also, the detection thresholds of a many electrode sites rose significantly over the short course of the study, raising the concern that the effect of S1 encoding will fade over time. Finally, few of the stimuli evoked properly ‘naturalistic’ percepts. These limitations and the disappointing results from similar work in visual cortex raise the question of whether cortical ICMS encoding is the optimal solution for sensory restoration. These unanswered questions motivate our research program. Our work aims to bridge the divide between current state-of-the-art and the clinical needs of our patients. Our overarching strategy is to develop closed-loop, autonomous bidirectional brain–machine interface systems. These systems, as conceived, provide real-time communication between the brain and body. Because the field of efferent BCI has vastly outpaced that of afferent BCI, our work primarily focuses on developing sensory-brain interfaces to couple with existing BCIs (see Bouton et al27 for example). Our strategy focuses on 3 critical intersections of engineering and neuroscience. The first is development of a suite of sensors that serve as mechanoreceptors for the paralyzed, insensate hand. The second is development of a chronic neural interface for artificial sensory encoding. The third is a body area network that links peripheral sensors with novel neural interfaces. The integration of these components is illustrated in Figure 1.FIGURE 1: Body area network. Fully integrated system with implantable force and flex sensors (1, 2), wearable analyzer (3), electrogoniometer (4), and neural interface (5).In this brief overview, we outline our approach, preliminary data, and future directions. This work collectively represents a fruitful collaboration between neurosurgery and electrical engineering. We are grateful to the National Science Foundation for funding our work. RESEARCH APPROACH Our research strategy follows 3 central aims: development of novel sensors, characterization of novel neural interfaces, and development of an autonomous body-area network. Novel Sensors Hand somatosensation can be characterized by a multidimensional space with axes defined by sensory modality (eg, light touch, proprioception), somatotopy, temporal dynamics, the influence of descending central inputs, and brain state. Restoring native somatosensation is perhaps too lofty a goal for a first-generation sensor–brain interface. Instead, we reduce the dimensionality of the problem to a single sensory modality at a single somatotopic location. We have developed a number of force sensors and a proprioceptive sensor as our first aim. The design of our force sensors is constrained by the form and function of the human hand. Relevant design features include: sensor sensitivity, range, power, form-factor, and complexity. Sensitivity is defined as a sensor's accuracy to convert mechanical force into voltage changes on the sensor. Dynamic range captures the extremes of mechanical force spanning interactions between the hand and the physical environment. The feature of power concerns both the requirements of the sensor (active or passive) as well as the sensor's efficiency to convert physical energy into electrical energy. For wireless sensors, the power feature also includes power harvesting and wireless transmission of data. Form-factor is defined as the mechanical properties of the sensor (size, shape) as well as the flexibility and elasticity of the substrate. Finally, the complexity of the sensor constrains fabrication and durability. These competing design constraints inevitably require engineering trade-offs. In the interest of brevity, we focus on 2 prototype force sensors and a proprioceptive sensor to illustrate these engineering trade-offs in the context of sensor–brain interface. First we consider scattering force sensors and optical force sensors before moving toward proprioceptive electrogoniometers. Scattering force sensors operate under the principle of radiofrequency (RF) back scatter. RF identification is a common technique used to track tags, like those attached to garments at a department store to prevent theft or those implanted subdermally in house pets to identify them when they are lost. The central concept is that RF energy polarizes conductive elements, such as the linear segments of an antenna, and scatter energy back in a measurable way. Deformations of the segment length or shape cause a shift in the back-scatter pattern as the polarization of each segment is related to its orientation in a pulsed electromagnetic field. By calibrating the back-scatter patterns induced by force-induced deformations of RF antenna segments, one may indirectly measure forces applied to a flexible antenna implanted under the skin. In the first series of experiments, our group characterized the back-scatter signatures of a number of antenna designs serving as passive sensor nodes. An advantage of passive sensors is that they do not require active power supplies. Therefore, flexible antennas can be implanted under the skin without the need of wires or batteries. Initial antennas were made with copper tape for rapid prototyping. Antenna shapes were constructed into space filling curves (eg, Hilbert, Peano curves) that varied in the number and length of conductive segments (Figure 2). Changes in size and shape of copper RF antennas were associated with reproducible batter scatter properties.FIGURE 2: Passive scattering force sensor design. A, Antenna shapes with different linear segments in second order Hilbert and Peano curves. B and C, Polarization of antenna segments within electromagnetic field. D, Radiofrequency response curves as a function of area of RF tag (left), and shifts in curves with ±2% change in area (right). E, Prototype indium–gallium tags in PDMS substrate. Central reservoir visible in series with antenna segments. F, RF tuning curve of indium–gallium tags in response to forces applied to central reservoir. Rapid shift noted in low end of force axes indicates appropriate sensitivity for precise finger grip.To build force sensitivity, our second series of experiments examined the flexibility of antennas across a range of forces routinely encountered by the human hand. Liquid metal indium–gallium antennas were designed within a flexible, skin-like polydimethylsiloxane (PDMS) substrate. Indium–gallium is a highly conductive eutectic alloy whose melting point is sufficiently low (∼ –2°F) to allow the alloy to remain in liquid phase at room temperature. Channels were laser-etched into the PDMS in the shape of space filling curves to house the alloy (Figure 2). Force sensitivity was amplified by creating a central compressible metal reservoir in series with the channels. When force was applied, the liquid metal filled the channel segments proportionally. As each successful segment of the antenna was filled with conductive metal, the RF back-scatter properties shifted (Figure 2). As can be seen in the RF response curve, the antenna was sufficiently sensitive to capture force changes within 5 N of fingertip pressure, appropriate for precision grip activities. These experiments verified the feasibility of force sensing RF tags. However, limitations to this technique include the need for sensitive detecting antennas to measure back scatter. For this reason, we examined force sensor designs that were independent of RF signal. Optical force sensing is a method to detect fingertip pressure without electromagnetic interference. An optical force sensor layers PDMS membrane on SiO2 within an implantable chip (Figure 3) that could be implanted subdermally. At one end of the floor of the sensor, an internal 80 μm2 light-emitting diode (LED) emits light. The light is reflected by the internal ceiling of the chip that is constructed of PDMS in an inverse lenticular structure. Reflected light is detected by a photodiode at the opposite end of the sensor. The intervening SiO2 acts as an optical waveguide. In the absence of force (or compressing pressure), the waveguide allows reflected light to excite the photodiode with an efficient electric-to-optical conversion, a high sensitivity (0.02 kPa−1) and a pressure sensing resolution (38 mPa). When force is applied, the PDMS ceiling bows downward, opening light channels in the membrane. This allows light to escape, which in turn decreases the voltage at the photodiode monotonically, and yields a scaled readout.FIGURE 3: Optical force sensor design. A, Side view of optical sensor in absence of load. Directional path of light shown in yellow reflected from internal surface of PDMS ceiling. LED emitter located in lower left of sensor; photodiode (PD) located in lower right. B, Applied forces reduce light received by photodiode end. C, Diagram of optical force sensor circuit. D, Idealized relationship between applied force and photodiode voltageBoth scatter sensors and optical sensors achieved their desired engineering goals of converting force into measurable data. Neither system represented optimal solutions. In the case of scatter sensors, environmental noise may obscure the back-scatter energy detected by a horn antenna. In the case of optical sensors, an active circuit is required. On-going experiments aim to address these limitations by increasing the signal-to-noise ratio (RF sensors) and integrating rechargeable power (optical sensors). Beyond touch sensation, proprioception is a fundamental sensory modality that informs us about limb position. To restore proprioception across large joints, we developed a wireless electrogoniometer.28 Unlike other electrogoniometers that require strain gauges or power-hungry potentiometers, our system was designed to have very low power requirements (∼20 μW) both in terms of sensing and wireless data transmission. This was achieved using a pair of impulse-radio ultrawide band wireless smart sensor nodes interfacing with low-power 3-axis accelerometers through event-driven analog-to-digital converters. Electrogoniometers are designed to operate across large joints, such as the elbow, which are too large for strain sensors or other position sensors. On-going experiments aim to combine multiple sensor modalities in the same organism. Novel Central Nervous System Targets Our second aim is to identify optimal sensory encoding nodes along the neuraxis. Cortical encoding has been attempted for decades in animals, and recently in humans, with mixed results. It remains to be seen how well S1 ICMS will faithfully reproduce naturalistic perception. ICMS in other sensory areas, like primary visual cortex, generates phosphenes but not complex visual images.26 This may be due to the fact that cortical representations are distributed. Complex experiential phenomena, like rich somatosensory percepts, are therefore unlikely to be reproduced with focal stimulation without activation of a larger network. Upstream sensory circuits have To to this we developed the first chronic neural interface of the dorsal column nuclei to and stimulation in awake The a for sensory encoding. These nuclei on the dorsal surface of the and proprioceptive signals from primary (Figure from the high information to the for sensory the descending from that may sensory column nuclei interface. A, between and nuclei and in are readily with of the B, implanted in the of a at of in for several C, of of electrode in to studies of the were limited to or In our first of in were implanted with multi-electrode arrays to the feasibility of a chronic interface. 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A, evoked responses to stimulation. to the which B, of frequencies stimulation. the stimulus at a well the stimulus feasibility of and encoding testing not from these experiments have for somatosensory currently will characterize responses and their to nodes including the and sensory Novel BCI Novel systems are to link peripheral sensor nodes and sensory encoding We developed a bidirectional brain–machine the as our third aim. This when links a suite of implantable and wearable peripheral sensor nodes with neural and electrodes (Figure the system and its nodes are to as a body area network. At the of the are wireless including a neural a neural a sensor and a The of a neural neural feature neural and associated The neural feature are for or field the system includes an neural energy and a detection with control is in the form of a that sensor data from peripheral sensors to desired patterns related to somatosensory cortex (Figure of brain–computer interface A, intersections between BCI systems and in the case of paralyzed or feedback control from nodes within in B, control loop integrating neural and stimulation in the flexibility to paralyzed or neural may be to or or stimulation with a voltage of Our the to current the that that neural and current current stimulation with a to a phase that neural However, changes due to during the Over millions of develop and in that the interface and To properly for this we a feedback that the phase when a point is detected (Figure The of this circuit is an error that error by the during stimulus the are the range, stimulation are as error that this method over that the system will have in experiments are to test this principle A, and of between phase and phase shown Idealized shown in shown in B, the on of point body area network requires real-time communication between the is with an impulse-radio band The and components to and between For clinical communication between nodes must be and operate within an of data The features an data of 2 in The error was over a of 3 of these are well within the desired for human moving toward human a number of must be of the system must be in must also be to To whether of the system was and effective at percepts, we designed in experiments on the the were to a to the by visual a pattern the is were to ICMS by the as a on the (Figure As the animal the stimulation As significantly in the presence of perception. When the was during was are able to systems to perception in a and effective In feasibility testing of novel systems. A, B, design is to in by ICMS as Idealized illustrated from with and optimal in presence of In our strategy to develop a sensor–brain interface system focuses on 3 aims: development of novel sensors, characterization of novel neural and development of autonomous body-area network. We have made in each of these areas, but substantial work We to our systems up to channel peripheral sensors and our In we our systems to animal models. It is our goal to this sensor brain interface with existing efferent systems to a bidirectional BCI to paralyzed This work was in by the National Science The have no or interest in of the or in this
Almost all real world activities have been digitized and there are various client server architecture based systems in place to handle them. These are all based on trust on third parties. There is an active attempt to successfully implement blockchain based systems which ensures that the IT systems are immutable, double spending is avoided and cryptographic strength is provided to them. A successful implementation of blockchain as backbone of existing information technology systems is bound to eliminate various types of fraud and ensure quicker delivery of the item on trade. To adapt IT systems to blockchain architecture, an efficient consensus algorithm need to be designed. Blockchain based on proof of work first came up as the backbone of cryptocurrency. After this, several other methods with variety of interesting features have come up. In this paper, we conduct a survey on existing attempts to achieve consensus in block chain. A federated consensus method and a proof of validation method are being compared.
We’ve seen repeatedly that ideas in the research literature can be gradually forgotten or lie unappreciated, especially if they are ahead of their time, even in popular areas of research. Both practitioners and academics would do well to revisit old ideas to glean insights for present systems. Bitcoin was unusual and successful not because it was on the cutting edge of research on any of its components, but because it combined old ideas from many previously unrelated fields. This is not easy to do, as it requires bridging disparate terminology, assumptions, etc., but it is a valuable blueprint for innovation.
The article is aimed at studying the history of origins, the preconditions for development, the main problems of functioning, and the prospects of legalizing the cryptocurrency market in Ukraine. One of the key risks when implementing advances of the IT in the financial sphere is the possibility of physical disappearance of banking system in its classical form because of its inability to compete with new technologies. The most troubling, versus the classical banks, may be considered such new technologies as credit electronic platforms and blockchain. In the recent time the bitcoin course has been growing rapidly, giving all the reasons to consider it primarily a classical «pyramid scheme». The cryptocurrency market may also be characterized a «pyramid scheme» because of the fact that the course of such a currency has not any coverage except increase in the number of participants and investors. Ukraine is not a leader in the international cryptocurrency market, albeit not an outsider. In order to secure a reliable State control of the «gray» cryptocurrency market, which is actually present in Ukraine, the article suggests some necessary actions directed towards legalizing and ordering this phenomenon.
The article is aimed at determining the major problems in the financing of education sphere in the current context of the reform of decentralization of power in Ukraine and developing directions for solving them. The main directions and results of educational reform have been analyzed, and the ranking of Ukraine according to the Global Competitiveness Index has been defined. The positive points of the decentralization of education have been noted. The expenditure of the budget of Ukraine have been analyzed and the proportion of expenditure on education has been determined as to the total budget expenditure. Along with this, the main circle of problems of the budget provision for the education sector has been outlined. It has been proposed: to increase the efficiency of allocation of budgetary means at all levels of the budget system; to enhance the possibilities of educational institutions to attract additional financial resources through educational innovation, and to expand the list of paid services provided by such institutions; to decentralize education, taking into account the characteristics of development of regions, their productive potential, the demographic situation, and the interests of the territorial communities.
A distributed and tamper proof media transaction framework is proposed based on the blockchain model. Current multimedia distribution does not preserve self-retrievable information of transaction trails or content modification histories. For example, digital copies of valuable artworks, creative media and entertainment contents are distributed for various purposes including exhibitions, gallery collections or in media production workflow. Original media is often edited for creative content preparation or tampered with to fabricate false propaganda over social media. However there is no existing trusted mechanism that can easily retrieve either the transaction trails or the modification histories. We propose a novel watermarking based Multimedia Blockchain framework that can address such issues. The unique watermark information contains two pieces of information: a) a cryptographic hash that contains transaction histories (blockchain transactions log) and b) an image hash that preserves retrievable original media content. Once the watermark is extracted, first part of the watermark is passed to a distributed ledger to retrieve the historical transaction trail and the latter part is used to identify the edited / tampered regions. The paper outlines the requirements, the challenges and demonstrates the proof of this concept.
Open access
Advanced Steganography and Watermarking Techniques