Blockchain stores information into a chain of "blocks", whose integrity is usually guaranteed by Proof of Work (PoW). In many blockchain applications (including cryptocurrencies), users compete with each other to win the ownership of the blocks, a process commonly referred as "mining". Mining activities consume huge amount of power, while the outcome appears to be useless besides validating a block. Here we discuss the requirements of designing a new PoW algorithm. We also propose a PoW scheme to help solve high-dimension, non-linear optimization problems. Simulation experiments of blockchains generated by three miners solved an instance of Traveling Salesman Problem (TSP), a well-known NP-hard problem. The revised scheme enables us to address difficult scientific questions as a byproduct of mining.
The JPEG Committee had its 78th meeting in Rio de Janeiro, Brazil. Relevant to its ongoing standardization efforts in JPEG Privacy and Security, JPEG organized a special session to explore how to support blockchain and distributed ledger technologies to past, ongoing and future JPEG family of standards. This is motivated by the fact that considering the potential impact of such technologies in the future of multimedia, standardization will be required to enable interoperability between different systems and services of imaging relying on blockchain and distributed ledger technologies.
In our research we introduce “the forensic smart contract” as a punishment alternative for tiny law violations. After studied the legislation boundaries and legal power transfer example for out of court applications, we evaluated three Blockchain applications covering three various cases in smart contracting. A smart-Law-script to eliminate illegal cellphone car use, with best punishment an Irrevocable prepayment in digi-money for a car phone kit. Then a “Lawscript” resolving the double taxation problem in international tax conventions. Finally a Court launches a community sentence through a “Rehabilitation Law sentence script”. After mass adoption of our methodologies we faced an unexpected globalization peace factor in Blockchain and much wide adoption of CBDC (Central Bank Digital Currency).
Blockchain and Distributed ledger Technologies are increasingly becoming key enablers for vital innovation in financial services, manufacturing, government and other industries. One of the biggest challenges though is the level of support for semantics by most of the Block Chain and Distributed Ledger technologies. This paper reviews and categorises common block chain and DLT approaches and introduces a new approach to Blockchain / DLT promising to resolve the semantic problems inherent in other Blockchain / DLT approaches.
Background: Governments engage in setting health sector priorities among competing interests to maximize health system goals within the available resources. This is important as misalignment between health priorities and budget allocations can lead to low budget allocations and underspending in the health sector.\nGoal: The goals of the study are twofold. First, measure the extent of alignment between a stated government priority and actual government expenditure. Second, if there is misalignment, explain the underlying bottlenecks including institutions, structures, and capacities.\nMethod: The study focuses on one stated health sector priority shared between Kenya and Mozambique, which is improving geographical equity of governmental resources for health. An explanatory mixed methods design is used, in which quantitative analysis is followed by a qualitative assessment. In quantitative analysis, Gini index is used to summarize the differences in per capita health expenditures across regions. In addition, health expenditure is decomposed as a product of total budget, health budget priority, and health budget execution to identify whether resource allocation or resource utilization lead to geographical inequity. The qualitative assessment consisted of 23 semi-structured key informant interviews, 10 for Kenya, 11 for Mozambique, to explain the quantitative results.\nResults: In both Kenya and Mozambique there is geographical inequity in government health spending, which is inconsistent with the stated government priority (Gini greater than zero). The decomposition of health expenditure suggests that, in Kenya, the misalignment is driven by both resource allocation and utilization processes; in Mozambique, it is driven largely by the resource allocation process. \nThe qualitative analysis reveals several bottlenecks that are common between the two countries. At the institutional level, there is institutional separation between planning and budgeting, decision-making is ad hoc, and difficult decisions on hard choices and tradeoffs are left to the end of the budget process. At the structural level, rapid and unplanned decentralization in Kenya and the deconcentration model in Mozambique have led to inadequate structures to align planning and budgeting. At the capacity level, there are too many administrative demands on planning and budgeting staff, who also lack technical expertise and adequate data to make evidence-based decisions.
John Collomosse, Tu Bui, Alan Brown, John Sheridan · 9 authors
We present ARCHANGEL; a de-centralised platform for ensuring the long-term integrity of digital documents stored within public archives. Document integrity is fundamental to public trust in archives. Yet currently that trust is built upon institutional reputation --- trust at face value in a centralised authority, like a national government archive or University. ARCHANGEL proposes a shift to a technological underscoring of that trust, using distributed ledger technology (DLT) to cryptographically guarantee the provenance, immutability and so the integrity of archived documents. We describe the ARCHANGEL architecture, and report on a prototype of that architecture build over the Ethereum infrastructure. We report early evaluation and feedback of ARCHANGEL from stakeholders in the research data archives space.
Scott Eisele, Aron Laszka, Anastasia Mavridou, Abhishek Dubey
Internet of Things and data sciences are fueling the development of innovative solutions for various applications in Smart and Connected Communities (SCC). These applications provide participants with the capability to exchange not only data but also resources, which raises the concerns of integrity, trust, and above all the need for fair and optimal solutions to the problem of resource allocation. This exchange of information and resources leads to a problem where the stakeholders of the system may have limited trust in each other. Thus, collaboratively reaching consensus on when, how, and who should access certain resources becomes problematic. This paper presents SolidWorx, a blockchain-based platform that provides key mechanisms required for arbitrating resource consumption across different SCC applications in a domain-agnostic manner. For example, it introduces and implements a hybrid-solver pattern, where complex optimization computation is handled off-blockchain while solution validation is performed by a smart contract. To ensure correctness, the smart contract of SolidWorx is generated and verified.
Grover's algorithm confers on quantum computers a quadratic advantage over classical computers for searching in an arbitrary data set, a scenario that describes Bitcoin mining. It has previously been argued that the only side-effect of quantum mining would be an increased difficulty. In this work, we argue that a crucial argument in the analysis of Bitcoin security breaks down when quantum mining is performed. Classically, a Bitcoin fork occurs rarely, i.e., when two miners find a block almost simultaneously, due to propagation time effects. The situation differs dramatically when quantum miners use Grover's algorithm, which repeatedly applies a procedure called a Grover iteration. The chances of finding a block grow quadratically with the number of Grover iterations applied. Crucially, a miner does not have to choose how many iterations to apply in advance. Suppose Alice receives Bob's new block. To maximize her revenue, she should stop and measure her state immediately in the hopes that her block (rather than Bob's) will become part of the longest chain. The strong correlation between the miners' actions and the fact that they all measure their states at the same time may lead to more forks -- which is known to be a security risk for Bitcoin. We propose a mechanism that, we conjecture, will prevent this form of quantum mining, thereby circumventing the high rate of forks.
Since the invention of internet, identity has become a significant aspect for nearly every interaction that occurs online. In this position paper, we demonstrate and discuss current limitations of centralised Identity Management (IdM) systems by drawing from the cases of two of world’s largest biometric ID systems: India’s Unique Identification System Aadhar and China’s Social Credit system, Sesame Credit. This paper explores self-sovereign identity through innovative application from blockchain 3.0. We then identify some key characteristics of blockchain technologies to address the challenges centralised IdM services face and present opportunities for furthering HCI research around de-centralised IdM services to provoke workshop discussion.
Chris Elsden, Kate Symons, Chris Speed, John Vines · 5 authors
Abstract The OxChain project is investigating the design of blockchain applications in partnership with a large and traditionally trusted institution, Oxfam. We outline some of the potential opportunities that distributed ledger technologies could offer the charity and development sector as a whole, but focus on the challenges of undertaking co-design work in the context of large institutions. We suggest the need to leverage existing trusted relationships and understand the unique value that such institutions offer.
We consider users which may have renewable energy harvesting devices, or distributed generators. Such users can behave as consumer or producer (hence, we denote them as prosumers) at different time instances. A prosumer may sell the energy to other prosumers in exchange of money. We consider a demand response model, where the price of conventional energy depends on the total demand of all the prosumers at a certain time. A prosumer depending on its own utility has to select the amount of energy it wants to buy either from the grid or from other prosumers, or the amount of excess energy it wants to sell to other prosumers. However, the strategy, and the payoff of a prosumer inherently depends on the strategy of other prosumers as a prosumer can only buy if the other prosumers are willing to sell. We formulate the problem as a coupled constrained game, and seek to obtain the generalized Nash equilibrium. We show that the game is a concave potential game and show that there exists a unique generalized Nash equilibrium. We consider that a platform will set the price for distributed interchange of energy among the prosumers in order to minimize the consumption of the conventional energy. We propose a distributed algorithm where the platform sets a price to each prosumer, and then each prosumer at a certain time only optimizes its own payoff. The prosumer then updates the price depending on the supply and demand for each prosumer. We show that the algorithm converges to an optimal generalized Nash equilibrium. The distributed algorithm also provides an optimal price for the exchange market.
This paper examines the time series properties of cryptocurrency assets, such as Bitcoin, using established econometric inference techniques, namely models of the GARCH family. The contribution of this study is twofold. I explore the time series properties of cryptocurrencies, a new type of financial asset on which there appears to be little or no literature. I suggest an improved econometric specification to that which has been recently proposed in Chu et al (2017), the first econometric study to examine the price dynamics of the most popular cryptocurrencies. Questions regarding the reliability of their study stem from the authors mis-diagnosing the distribution of GARCH innovations. Checks are performed on whether innovations are Gaussian or GED by using Kolmogorov type non-parametric tests and Khmaladze's martingale transformation. Null of gaussianity is strongly rejected for all GARCH(p,q) models, with $p,q \in \{1,\ldots,5 \}$, for all cryptocurrencies in sample. For tests of normality, I make use of the Gauss-Kronrod quadrature. Parameters of GARCH models are estimated with generalized error distribution innovations using maximum likelihood. For calculating P-values, the parametric bootstrap method is used. Arguing against Chu et al (2017), I show that there is a strong empirical argument against modelling innovations under some common assumptions.
This work is organized as follows. In the first section we review the prior work and we have obtained our data. Next, we will look at address reuse in the Bitcoin network. We show that a great portion of users reuse their addresses which could enable us to cluster the addresses and attribute them to single users. Next, we will categorize the nodes based on their role in the network as a customer or seller. Finally, we do a study of nodes and network performance.
Francesco Parino, Mariano G. Beiró, Laëtitia Gauvin
As the first decentralized digital currency introduced in 2009 together with the blockchain, Bitcoin offers new opportunities both for developed and developing countries. Bitcoin peer-to-peer transactions are independent of the banking system, facilitating foreign exchanges with low transaction fees, such as remittances, and offering a high degree of anonymity. These opportunities together with other key factors led the Bitcoin to become extremely popular and caused its price to skyrocket during 2017 (Henry et al. in J Digit Bank 2(4):311–337, 2018 ). However, while the Bitcoin blockchain attracts a lot of attention, it remains difficult to investigate where this attention comes from, due to the pseudo-anonymity of the system, and consequently to appreciate its social impact. Here we make an attempt to characterize the adoption of the Bitcoin blockchain by country. In the first part of the work we show that information about the number of Bitcoin software client downloads, the IP addresses that act as relays for the transactions, and the Internet searches about Bitcoin provide together a coherent picture of the system evolution in different countries. Using these quantities as a proxy for user adoption, we identify several socio-economic indexes such as the GDP per capita, freedom of trade and the Internet penetration as key variables correlated with the degree of user adoption. In the second part of the work, we build a network of Bitcoin transactions between countries using the IP addresses of nodes relaying transactions and we develop an augmented version of the gravity model of trade in order to identify socio-economic factors linked to the flow of Bitcoin between countries. In a nutshell our study provides a new insight on Bitcoin adoption by country and on the potential socio-economic drivers of the international Bitcoin flow.
Francesco Parino, Mariano G. Beiró, Laëtitia Gauvin
As the first decentralized digital currency introduced in 2009 together with\nthe blockchain, Bitcoin offers new opportunities both for developed and\ndeveloping countries. Bitcoin peer-to-peer transactions are independent of the\nbanking system, thus facilitating foreign exchanges with low transaction fees\nsuch as remittances, with a high degree of anonymity. These opportunities\ntogether with other key factors led the Bitcoin to become extremely popular and\nmade its price skyrocket during 2017. However, while the Bitcoin blockchain\nattracts a lot of attention, it remains difficult to investigate where this\nattention comes from, due to the pseudo-anonymity of the system, and\nconsequently to appreciate its social impact. Here we make an attempt to\ncharacterize the adoption of the bitcoin blockchain by country. In the first\npart of the work we show that information about the number of Bitcoin software\nclient downloads, the IP addresses that act as relays for the transactions, and\nthe Internet searches about Bitcoin provide together a coherent picture of the\nsystem evolution in different countries. Using these quantities as a proxy for\nuser adoption, we identified several socio-economic indexes such as the GDP per\ncapita, freedom of trade and the Internet penetration as key variables\ncorrelated with the degree of user adoption. In the second part of the work, we\nbuild a network of Bitcoin transactions between countries using the IP\naddresses of nodes relaying transactions and we develop an augmented version of\nthe gravity model of trade in order to identify socio-economic factors linked\nto the flow of bitcoins between countries. In a nutshell our study provides a\nnew insight on the bitcoin adoption by country and on the potential\nsocio-economic drivers of the international bitcoin flow.\n
This workshop aims to develop an agenda within the CHI community to address the emergence of blockchain, or distributed ledger technologies (DLTs). As blockchains emerge as a general purpose technology, with applications well beyond cryptocurrencies, DLTs present exciting challenges and opportunities for developing new ways for people and things to transact, collaborate, organize and identify themselves. Requiring interdisciplinary skills and thinking, the field of HCI is well placed to contribute to the research and development of this technology. This workshop will build a community for human-centred researchers and practitioners to present studies, critiques, design-led work, and visions of blockchain applications.
There are limitations in client-server model of communication. Distributed architecture provides good accessibility to all the nodes in the network. A blockchain technology is follows distributed model. In the digital era, all the transactions are available in the digital form is called a ledger. This ledger belongs to all the users in the network are shared by all the users in the network. Every transaction is monitored and verified by every user in the network. The blockchain is a chain of blocks that contains a collection of transactions. Bitcoin is a cryptocurrency, depends on blockchain technology. The Bitcoins are generated from the mining of a block for the miner. Every user knows about each and every Bitcoin transaction in the blockchain network. The block is immutable, because every block is verified by each customer in the blockchain network. This is the initiation for new trend for security to the digital transactions in the world. This paper presents the logic in the blockchain and Bitcoin generation process using blockchain technology.
Mutlu Başaran Öztürk, Halil Arslan, Temur Kayhan, Mustafa Uysal
2017 yılında Bitcoin’in piyasa değerinde önemli bir artış yaşanmış ve 200 milyar dolar seviyesi aşılarak Bitcoin kurumsal yatırımcıların gündemine gelmeye başlamıştır. CME ve CBOE gibi dünyanın en büyük vadeli işlem borsaları Bitcoin’i listelerken Microsoft, PWC ve Overstock gibi kurumlar Bitcoin’i tanımlamaya başlamışlardır. Bitcoin’in bir yatırım aracı olarak görülebilmesi için bazı şartlar gereklidir. Verimli bir piyasada işlem görmesi, fiyatlama formasyonunun belirginleşmesi ve portföyler için bir çeşitlendirme aracı olabilmesi bunlardan bazıları olarak görülebilir. Ana akım varlık grupları ile Bitcoin arasındaki uzun vadeli ilişkiyi Johansen Eşbütünleşme testi ile inceleyen çalışma sonuçlarına göre Bitcoin’in altın haricinde diğer geleneksel finansal ve emtia varlıklarından bağımsız bir hareket gösterdiği ortaya çıkmıştır. Bitcoin’in söz konusu bağımsız hareketi Bitconomi olarak tanımlanırken bu durum mikro seviyede riskli bir varlığın makro anlamda portföylerin riskini düşürebileceği anlamına gelmektedir. Finansal sistemde çok küçük bir alanı işgal etmesi ve Bitcoin üretimindeki zorluk derecesinin klasik ekonomi ile çelişmesi korelasyonun anlamsız olmasının nedenleri arasında gösterilebilir. Kuzey Kore ve Ukrayna gerilimlerinde Bitcoin fiyatındaki artışlar ve altın ile Bitcoin arasındaki uzun vadeli pozitif ilişki yüksek varyansı nedeniyle eleştirilen Bitcoin’in gelecekte güvenli liman olabileceği gibi ilginç bir ironiye işaret etmektedir. Literatürdeki çalışmalar her geçen yıl Bitcoin’in varyansının gerilediğini göstermektedir.
Víctor Manuel Sámano Ortega, Faiza Bouchmal, José F. Monserrat
Vehicular communications, though a reality, must continue to evolve to support higher throughput and, above all, ultralow latency to accommodate new use cases, such as the fully autonomous vehicle. Cybersecurity must be assured since the risk of losing control of vehicles if a country were to come under attack is a matter of national security. This article presents the technological enablers that ensure security requirements are met. Under the umbrella of a dedicated network slice, this article proposes the use of content-centric networking (CCN), instead of conventional transmission control protocol/Internet protocol (TCP/IP) routing and permissioned blockchains that allow for the dynamic control of the source reliability, and the integrity and validity of the information exchanged.
Immigrants usually are pro-social towards their hometowns and try to improve them. However, the lack of trust in their government can drive immigrants to work individually. As a result, their pro-social activities are usually limited in impact and scope. This paper studies the interface factors that ease collaborations between immigrants and their home governments. We specifically focus on Mexican immigrants in the US who want to improve their rural communities. We identify that for Mexican immigrants having clear workflows of how their money flows and a sense of control over this workflow is important for collaborating with their government. Based on these findings, we create a blockchain based system for building trust between governments and immigrants. We finish by discussing design implications of our work and future directions.
Chris Elsden, Arthi Manohar, Jo Briggs, Mike Harding · 6 authors
Blockchain is an emerging infrastructural technology that is proposed to fundamentally transform the ways in which people transact, trust, collaborate, organize and identify themselves. In this paper, we construct a typology of emerging blockchain applications, consider the domains in which they are applied, and identify distinguishing features of this new technology. We argue that there is a unique role for the HCI community in linking the design and application of blockchain technology towards lived experience and the articulation of human values. In particular, we note how the accounting of transactions, a trust in immutable code and algorithms, and the leveraging of distributed crowds and publics around vast interoperable databases all relate to longstanding issues of importance for the field. We conclude by highlighting core conceptual and methodological challenges for HCI researchers beginning to work with blockchain and distributed ledger technologies.
Blockchain technology can be defined as an open ledger of information that is distributed and verified across a peer-to-peer network, rather than through one central server. In other words, it is a computerized public ledger that can apply to almost anything you may usually save to a spreadsheet or database. Each transaction or block is transmitted to all of the participants in the network and must be verified by each participant node solving a complex mathematical problem. Once a block is validated, it cannot be modified without changing it across the whole network. Distributed ledgers are inherently harder to attack because, instead of a single database, there are multiple shared copies of the same database. As no single person, institution or company hosts or controls the information, the storing of the information on the blockchain is perceived as (nearly) unhackable. Different types of data can be added to a blockchain, from transaction information to photos, videos and design documents and the technology is developing further with new types of distributed ledger technologies (DLTs), such as hashgraph software, which is meant to address the scalability issues of traditional DLT technology. While the traditional concept of blockchain is an open and anonymous network, there are also ‘private’ blockchains, mostly of interest to the financial and insurance industries, which pre-screen who is allowed to administer the ledger.
Blockchain has received much attention in recent years. This immense popularity has raised a number of concerns, scalability of blockchain systems being a common one. In this paper, we seek to understand how Ethereum, a well-established blockchain system, would respond to sharding. Sharding is a prevalent technique to increase the scalability of distributed systems. To understand how sharding would affect Ethereum, we model Ethereum blockchain as a graph and evaluate five methods to partition the graph. We analyze the results using three metrics: the balance among shards, the number of transactions that would involve multiple shards, and the amount of data that would be relocated across shards upon a repartitioning of the system.