A blockchain-based smart contract or a "smart contract" for short, is a computer program intended to digitally facilitate the negotiation or contractual terms directly between users when certain conditions are met. With the advance in blockchain technology, smart contracts are being used to serve a wide range of purposes ranging from self-managed identities on public blockchains to automating business collaboration on permissioned blockchains. In this paper, we present a comprehensive survey of smart contracts with a focus on existing applications and challenges they face.
Lukasz Dykcik, Laurent Chuat, Pawel Szalachowski, Adrian Perrig
This paper describes BlockPKI, a blockchain-based public-key infrastructure that enables an automated, resilient, and transparent issuance of digital certificates. Our goal is to address several shortcomings of the current TLS infrastructure and its proposed extensions. In particular, we aim at reducing the power of individual certification authorities and make their actions publicly visible and accountable, without introducing yet another trusted third party. To demonstrate the benefits and practicality of our system, we present evaluation results and describe our prototype implementation.
Organisations are increasingly open to scrutiny, and need to be able to prove that they operate in a fair and ethical way. Accountability should extend to the production and use of the data and knowledge assets used in AI systems, as it would for any raw material or process used in production of physical goods. This paper considers collective intelligence, comprising data and knowledge generated by crowd-sourced workforces, which can be used as core components of AI systems. A proposal is made for the development of a supply chain model for tracking the creation and use of crowdsourced collective intelligence assets, with a blockchain based decentralised architecture identified as an appropriate means of providing validation, accountability and fairness.
A blockchain is a decentralized, disseminated and digital ledger that can’t be altered retroactively without modifying every single blocks and the consensus of the network. Blockchain can be used in smart contracts, Banks, IoT devices, Database management, etc., Due to recent times flaws and leakage of Aadhaar information (Aadhaar which is the largest government databases of the Indian citizens) in Internet the security and privacy of Aadhaar became questionable. In order to ensure the security of Aadhaar, Blockchain has the potential to overcome security and privacy challenges in Aadhaar. In this project we are going to create a Blockchain for Aadhaar database and implement light weight algorithm for efficiency, optimization and scalability along with the Blockchain securing algorithm.
The rise of decentralized ledger (bookkeeping) systems that operate as public transaction archives to store value records (such as payments in a cryptocurrency) and maintain consensus about agreements also seems to promise solutions for the problem of scaling trust-based decision-making processes. Once linked almost exclusively to finance (“cryptocurrencies”), the “blockchain space” has become a terrain of social and technological experimentation. While these changes are likely to substantially transform the way, we organize our collective actions, few digital content creators; artists, designers, and other actors not directly linked to processes of technological innovation are currently involved. In this essay, we describe how such a co-creative approach to such involvement can be developed through the public prototyping of Spectrum, a blockchain-based tool for digital creators. What we found is that such an approach offers opportunities to more fully comprehend value chains, but also highlights need for co-creation approaches that cut across existing audiences and bring in new actors. This matters because blockchain-based strategies for technology design are about to transform the way we create, share, and cooperate. Given the promise and potential stakes of shifting the creation of digital arts-and-cultural assets to infrastructures based on such distributed ledger technologies, it is crucial that artists and other digital creators engage with the design both of these infrastructures and the systems of governance structuring their operation.
Povijest Bitcoin digitalne valute započela je 2008. godine objavom vrlo popularnog članka "Bitcoin: A Peer to-Peer Electronic Cash System" pod pseudonimom imena Satoshi Nakamoto. Od tada pa sve do danas bitcoin je prošao kroz snažne promjene obilježene naglim porastom i padom vrijednosti same valute koje su bile popraćene velikim interesom javnosti. Bitcoin je sustav koji je utemeljen na vrlo složenim kriptografskim algoritmima, bez postojanja glavnog središnjeg autoriteta koji nadzire takve transakcije ili izdaje novac. Mnogi stručnjaci vode rasprave može li bitcoin postati nova glavna globalna valuta koja neće biti podložna utjecaju centralnih banaka ili inflaciji same valute. Posebno je istaknuta decentraliziranost i nereguliranost sustava koja predstavlja veliku prednost, ali se pokazala i kao osnovni uzrok izrazito velike volatilnosti jer cijena bitcoina ovisi isključivo o odnosu ponude i potražnje za tom valutom. U radu se analizira uloga bitcoina na svjetskom financijskom tržištu, investicijski potencijal i budućnost najpoznatije kriptovalute.
This chapter introduces the role of information security and consensus mechanisms as they apply for autonomous, artificial intelligence (AI). It provides an overview of different consensus mechanisms and illustrates the need for incorruptible information records corresponding to the AI decision inputs, decision records, and feedback records used to correct and supplement AI decision making. The chapter presents an overview of Leveraging Blockchain and cryptographic implications, which are leveraged both in common and by default among leading Blockchain implementations. It introduces consensus algorithms commonly used in Blockchain solutions and discusses the trade-offs therein and provides the key reasons to leverage Blockchain features to supplement AI. The chapter looks forward to how distributed ledgers can support distributed AI, closed-loop feedback mechanisms, and introduces a future relevant concept of parliamentary AI for higher order decision making using secure information sharing. Applying Blockchain-backed AI instances within orchestration systems such as Software-Defined Networks allows for native closed-loops of inputs, action, results, and corrections.
Benjamin Hellouin de Ménibus, Ville Salo, Guillaume Theyssier
Abelian cellular automata (CAs) are CAs which are group endomorphisms of the full group shift when endowing the alphabet with an abelian group structure. A CA randomizes an initial probability measure if its iterated images have weak*-convergence towards the uniform Bernoulli measure (the Haar measure in this setting). We are interested in structural phenomena, i.e., randomization for a wide class of initial measures (under some mixing hypotheses). First, we prove that an abelian CA randomizes in Cesàro mean if and only if it has no soliton, i.e., a non-zero finite configuration whose time evolution remains bounded in space. This characterization generalizes previously known sufficient conditions for abelian CAs with scalar or commuting coefficients. Second, we exhibit examples of strong randomizers, i.e., abelian CAs randomizing in simple convergence; this is the first proof of this behaviour to our knowledge. We show, however, that no CA with commuting coefficients can be strongly randomizing. Finally, we show that some abelian CAs achieve partial randomization without being randomizing: the distribution of short finite words tends to the uniform distribution up to some threshold, but this convergence fails for larger words. Again this phenomenon cannot happen for abelian CAs with commuting coefficients.
We obtain lower tail estimates for the smallest singular value of random matrices with independent but nonidentically distributed entries. Specifically, we consider $n\times n$ matrices with complex entries of the form \[M=A\circ X+B=(a_{ij}\xi_{ij}+b_{ij}),\] where $X=(\xi_{ij})$ has i.i.d. centered entries of unit variance and $A$ and $B$ are fixed matrices. In our main result, we obtain polynomial bounds on the smallest singular value of $M$ for the case that $A$ has bounded (possibly zero) entries, and $B=Z\sqrt{n}$ where $Z$ is a diagonal matrix with entries bounded away from zero. As a byproduct of our methods we can also handle general perturbations $B$ under additional hypotheses on $A$, which translate to connectivity hypotheses on an associated graph. In particular, we extend a result of Rudelson and Zeitouni for Gaussian matrices to allow for general entry distributions satisfying some moment hypotheses. Our proofs make use of tools which (to our knowledge) were previously unexploited in random matrix theory, in particular Szemerédi’s regularity lemma, and a version of the restricted invertibility theorem due to Spielman and Srivastava.
Moritz Piatti-Fünfkirchen, Magnus Lindelöw, Katelyn Jison Yoo
Progress toward universal health care (UHC) in Africa will require sustained increases in public spending on health and reduced reliance on out-of-pocket financing. This article reviews trends and patterns of government spending in the East and Southern Africa regions and points out methodological challenges with interpreting data from the World Health Organization's (WHO) Global Health Expenditure Database (GHED) and other sources. Government expenditure for health has increased for most countries, albeit at a slower rate than gross domestic product (GDP). In most countries there has been a prioritization away from health in government budgets, putting the onus on the private sector and donors to fill the gap. Donor support is important in the region but reliance on external spending is not consistent with countries' stated ambitions of universal health coverage. A number of methodological challenges with estimating health expenditures are identified. Capturing health expenditures adequately across agencies and levels of decentralization can be challenging, and off-budget funds and arrears are evasive. Measurement error can be significant because actual expenditure information can be hard to come by and is often dated and unreliable. Furthermore, how external financing is captured will affect government health expenditure estimates. These factors have contributed to differences in expenditure estimates between the WHO GHED and country-specific public expenditure reviews and complicate interpretation. The article concludes that it is critical to strengthen national data capacity and international efforts to promote quality and consistency of data. The GHED is an invaluable resource for monitoring and benchmarking health expenditures. It is best used in combination with deep dive country expenditure assessments.
Cryptocurrencies and their foundation technology, the Blockchain, are reshaping finance and economics, allowing a decentralized approach enabling trusted applications with no trusted counterpart. More recently, the Blockchain and the programs running on it, called Smart Contracts, are also finding more and more applications in all fields requiring trust and sound certifications. Some people have come to the point of saying that the "Blockchain revolution" can be compared to that of the Internet and the Web in their early days. As a result, all the software development revolving around the Blockchain technology is growing at a staggering rate. The feeling of many software engineers about such huge interest in Blockchain technologies is that of unruled and hurried software development, a sort of competition on a first-come-first-served basis which does not assure neither software quality, nor that the basic concepts of software engineering are taken into account. This paper tries to cope with this issue, proposing a software development process to gather the requirement, analyze, design, develop, test and deploy Blockchain applications. The process is based on several Agile practices, such as User Stories and iterative and incremental development based on them. However, it makes also use of more formal notations, such as some UML diagrams describing the design of the system, with additions to represent specific concepts found in Blockchain development. The method is described in good detail, and an example is given to show how it works.
Every year lakhs of students graduating from different university, after passing from university different students have different plans. All students who graduated will have different certificate such as marksheets, degree certificate, best performance certificate and etc. Some students have plans to get employed in companies or to do higher studies. Wherever students go they need submit the certificate for important reference. Due to lack of anti-forge mechanism some started to forge the certificate to get the employed or for further steps. In the digital certificate verification based on blockchain done only for the degree certificates. In the proposing system along with the degree certificate entire personality and behaviour activities of the person using personal id will be uploaded in blockchain. Because of unmodifiable property it is stored in block chain. Initially the student request for the e-certificate by uploading certificate or personal id to electronic certificate system. If requesting for e-cert then the system will review certificate from the university or schools or from organization and get the assurance and store the serial number and e-certificate to the block chain. The system will be generating the QR code and send it to the user. when applying for company user will send only the certificate serial number and QR code received from the e-certificate company. Â
Overconfidence is a universal psychological behavior. Overconfidence on demand awareness will have a significant impact on operation decisions. The supplier estimated the demand with excessive precision which influences the inventory financing decision-making deeply. We built the demand function based on the supplier’s overconfidence. Then we established the retailer, supplier, and the Bank’s profit function, respectively. Through the analysis of the bilevel Stackelberg game, we obtained the order quantity of the retailer with the capital constraint, the wholesale price of overconfident supplier, and the loan-to-value ratio of Bank, and we analyzed the influence of overconfidence on the decision variables. We have several findings as follows. First, the overconfidence makes the decisions of the retailer, supplier, and Bank deviate from the rational decisions. Second, the space of the market profit will affect the decision variables in the joint decision-making. Third, the financing supply chain (including the Bank and supply chain) should have a positive attitude towards the overconfidence of the supplier. Forth, in the joint decision-making, the supplier need determines the buyback price according to the capital demand; and in the decentralized decision-making, the supplier should try to use high buyback price strategy.
Abstract Based on a systematic review of influential publications among 402 papers published between 2010 and 2018, this paper identifies gaps in Economics and Finance research regarding two applications of FinTech: crowdfunding and blockchain. Analysing these records shows that (i) current research on FinTech is fragmented with limited theoretical grounding; (ii) crowdfunding and blockchain can be regarded as two innovations that may disrupt traditional financial intermediation but in different ways; (iii) crowdfunding platforms substitute for traditional financial intermediaries and serve as a new intermediary, without eliminating the need for intermediation; (iv) similar to crowdfunding, blockchain also creates new intermediaries; and (v) the trust element inherent in blockchain enables blockchain to eliminate the need for intermediaries in some financial areas but not all.
A central theme in internet history since the 1990s is the rise of algorithmic power, enabled through the self-restraint of human governments. Digital platforms were born weak and clumsy. Governments could have stamped them out to enforce traditional territorial boundaries and regulatory categories. They chose not to. Once the digital tornado was unleashed, however, its path was not easily directed. Fledgling innovators in need of protection developed into dominant platforms that transformed many aspects of the world for the better, but also created serious harms through pervasive data collection and automated decision-making. The threats arose from the very attributes that made these digital systems so appealing.
The cycle is now repeating itself. Another broad-based technological shift is empowering market entrants that promise huge gains in both efficiency and freedom. And once again, the deeper challenge is how to regulate their own penchant for algorithmic overreach.
Blockchain and cryptocurrency technologies are today’s digital tornado. Like the internet, they are stimulating dramatic levels of investment, startup activity, and media attention, as well as creating massive disruption of industries and passionate visions of societal transformation. As with the internet, this excitement often gets ahead of reality. The internet economy recovered from the dotcom crash of the early 2000s to realize its potential through the growth of social media, cloud computing, and mobile connectivity. The crypto economy seems likely to experience a similar trajectory over time. To succeed at scale, however, blockchain-based networks and services will need address the problem of governance. Immutability, the mechanism that allows these systems to generate trust without central authorities, also creates inherent weaknesses that sometimes turn into catastrophic failures.
In the long journey of development of a government increasingly multiply and enrich the understanding of the government itself, so that the concepts of government can be viewed from various angles and aspects that can further clarify the notion of the concept of government itself, one of which is the concept of the principle of governance. The existence of a Local Government in the system of government is an integral part of a system of state government or national government, even the concept and theoretical existence of local government is much earlier than the existence of elements of central government or state government. The principle of "Medebewin" as a relic of the Indies government system, at the beginning of the revolution, precisely in 1948, was called "uncompleted surrender", to overcome the principle of full-fledged decentralization. The difference with the principle of decentralization is that the "medebewind" governmental affairs are only handed over the task of execution alone, excluding the authority that determines the policies, the financing, and the execution workers. One of the principles of local governance that has been applied in Indonesia in the history of local governance is the Assistance Task Principle, apart from the principles of decentralization and deconcentration. The principle of the implementation of regional government consists of the principle of decentralization, the principle of deconcentration and the principle of co-administration. In Dutch legislation, between co-administration and medebewin are divided into two, namely mechanical medebewind or more detailed andfacultative medebewind or which provide wider freedom to determine the wisdom of the medebewind ". Definition of assistance task is; assignment with an obligation to account for its execution to the assignee. In its implementation the task of assistance has its own development and dynamics in accordance with the Law on Regional Government which regulates it.
Mustafa Al-Bassam, Alberto Sonnino, Vitalik Buterin
Light clients, also known as Simple Payment Verification (SPV) clients, are nodes which only download a small portion of the data in a blockchain, and use indirect means to verify that a given chain is valid. Typically, instead of validating block data, they assume that the chain favoured by the blockchain's consensus algorithm only contains valid blocks, and that the majority of block producers are honest. By allowing such clients to receive fraud proofs generated by fully validating nodes that show that a block violates the protocol rules, and combining this with probabilistic sampling techniques to verify that all of the data in a block actually is available to be downloaded, we can eliminate the honest-majority assumption, and instead make much weaker assumptions about a minimum number of honest nodes that rebroadcast data. Fraud and data availability proofs are key to enabling on-chain scaling of blockchains (e.g. via sharding or bigger blocks) while maintaining a strong assurance that on-chain data is available and valid. We present, implement, and evaluate a novel fraud and data availability proof system.
Abstract The oil and Gas industry has recently transformed itself into a data-intensive industry – artificial intelligence, machine learning and internet of things. With such growth and expansion, distributed ledger technology, commonly known as blockchain, can carry the industry's transformation forward. This technology can help the industry to overcome various challenges such as price volatility, supply chain, accounting, data management and security. It can also help in streamlining various engineering and technical decisions. Technologically, the oil and gas industry has been very innovative – 3-D seismic, hydraulic fracturing, geosteering, imaging beneath salt, etc. However, the administrative and managerial functions are still done in a somewhat traditional way. The Blockchain technology can help the industry become more efficient by streamlining these traditional methodologies. This paper presents the four major areas where the blockchain technology can help the industry overcome various day to day challenges – (1) Supply Chain and Trading, (2) Regulatory, (3) Database Management and (4) Cyber Security. Like any new technology, the blockchain technology might not get a full embrace at the beginning, but the idea is to present a qualitative study about its benefits. The industry currently has little or no knowledge about this technology, which is expected to bring transparency, security and convenience in one place. The objective of this paper is to help the industry peers understand the idea behind this technology and how it can transform the way the industry currently operates. It provides a frame of reference for the industry to realize the potential of this technology and assess its benefits.
A cryptocurrency token offers a method of incentivizing behavior in a way that supports trusted interaction (through its blockchain-based infrastructure). It also acts as a multipurpose instrument that may fulfill a variety of roles, such as facilitating digital use cases or acting as a store of value. Understanding how to value such an instrument is complicated by these multiple roles because the relative valuation of one role cannot be disentangled from another role—a token is a ‘bundled’ good. In this work a general pricing model for cryptocurrency tokens is derived, based upon and extending the hedonic pricing framework of Rosen (1974) in a partial equilibrium framework. It is shown that individual roles (or characteristics) of a token may be priced by inverting in a special way the relationship between the token’s aggregate quantity and its provision of characteristics. Interaction between a monopolistic token seller and a representative buyer results in an equilibrium that clears both the aggregate token market and the characteristic market. Particular attention is given to the case in which a token possesses a security role, as this has been a focus of existing discussions regarding the regulation of the cryptocurrency market. JEL Codes: D46, C60.