Bitcoin is a cryptocurrency created by an unknown person or persons using the name of Satoshi Nakamoto. It is a decentralized, peer-to-peer currency. Even though all transactions are public, the identity of any particular party of a transaction is difficult to trace. Therefore, it is commonly used by criminals alongside legitimate users interested in privacy or novelty.
Discipline: Statistics
Faculty Mentor: Dr. Cristina Anton
This chapter focuses on achievement lies, involving determining opponents often with large amounts of stake. The subjects, suspects and liars are referred to as &s;suspected con-men&s; or &s;conmen&s; and they come in all shapes, sizes and colours. The chapter deals with most types of meetings and suggests how one can handle them to minimize the risks of being deceived. It concerns getting reliable evidence from willing and unwilling witnesses in complex fraud cases and obtaining a written account of their evidence. This may be in the form of a Proof of Evidence, affidavit, statement or criminal justice act statement and is required by lawyers to assess the strength of their case, pre-trial, and to know what the witness is expected to say during it. There are some main problems with witnesses. A person may not wish to become involved, for reasons ranging from apathy to fear, and in the corporate fraud area.
Abeer ElBahrawy, Laura Alessandretti, Anne Kandler, Romualdo PastorâSatorras · 5 authors
The cryptocurrency market surpassed the barrier of \$100 billion market capitalization in June 2017, after months of steady growth. Despite its increasing relevance in the financial world, however, a comprehensive analysis of the whole system is still lacking, as most studies have focused exclusively on the behaviour of one (Bitcoin) or few cryptocurrencies. Here, we consider the history of the entire market and analyse the behaviour of 1,469 cryptocurrencies introduced between April 2013 and June 2017. We reveal that, while new cryptocurrencies appear and disappear continuously and their market capitalization is increasing (super-)exponentially, several statistical properties of the market have been stable for years. These include the number of active cryptocurrencies, the market share distribution and the turnover of cryptocurrencies. Adopting an ecological perspective, we show that the so-called neutral model of evolution is able to reproduce a number of key empirical observations, despite its simplicity and the assumption of no selective advantage of one cryptocurrency over another. Our results shed light on the properties of the cryptocurrency market and establish a first formal link between ecological modelling and the study of this growing system. We anticipate they will spark further research in this direction.
This paper introduces Distributed Ledger Register that mimics the behavior of most popular ledgers such as Bitcoin or Ethereum. Our work is the first to make the connection between the Distributed Ledger Register and the classical theory of shared registers. We furthermore, propose an algorithm that emulates the distributed ledger register.
This paper introduces Distributed Ledger Register that mimics the behavior of most popular ledgers such as Bitcoin or Ethereum. Our work is the first to make the connection between the Distributed Ledger Register and the classical theory of shared registers. We furthermore, propose an algorithm that emulates the distributed ledger register.
While online services emerge in all areas of life, the voting procedure in many democracies remains paper-based as the security of current online voting technology is highly disputed. We address the issue of trustworthy online voting protocols and recall therefore their security concepts with its trust assumptions. Inspired by the Bitcoin protocol, the prospects of distributed online voting protocols are analysed. No trusted authority is assumed to ensure ballot secrecy. Further, the integrity of the voting is enforced by all voters themselves and without a weakest link, the protocol becomes more robust. We introduce a taxonomy of notions of distribution in online voting protocols that we apply on selected online voting protocols. Accordingly, blockchain-based protocols seem to be promising for online voting due to their similarity with paper-based protocols.
The release of the Fourth Policy Document on Spatial Planning in 1988 was the start of a new and highly dynamic age of spatial development in The Netherlands. The policy document itself embodied a major reorientation of the national spatial policy strategy. Development of the economy and infrastructure became the new goals of spatial policy, and thereby replaced the focus upon the public housing sector of the years before. The national airport Schiphol and the port of Rotterdam both expanded and became important focal points for the Dutch economy, new transport infrastructure including High Speed Railway was planned. In the cities, dilapidated districts were transformed into new urban residential areas and new suburban districts were built close to the cities. In the countryside many projects were started in order to transform agrarian land into ânew natureâ. On top of this, the Dutch spatial planning system itself faced a partial âregime shiftâ. Spatial development projects became more market-based instead of financed by public resources. But at the same time, the national government kept its central position in the planning system. Only fifteen years later, at the beginning of the new millennium, decentralization of spatial planning towards regional and local government became a major trend. This paper will focus upon the spatial transformation of the Netherlands during the 25 years after the release of the Fourth Policy Document on spatial planning. In order to assess the influence of the national spatial policy, I will give a brief review of the Fourth Policy Document. But the changes in the spatial policy strategy of the Fourth Policy Document did not came out of the blue. They were both result of and response to political and economic trends. Therefore, I will start with two major and interrelated trends: the urban crisis and globalization.
Youngbin Kim, Jurim Lee, Nuri Park, Jaegul Choo · 6 authors
Bitcoin is an online currency that is used worldwide to make online payments. It has consequently become an investment vehicle in itself and is traded in a way similar to other open currencies. The ability to predict the price fluctuation of Bitcoin would therefore facilitate future investment and payment decisions. In order to predict the price fluctuation of Bitcoin, we analyse the comments posted in the Bitcoin online forum. Unlike most research on Bitcoin-related online forums, which is limited to simple sentiment analysis and does not pay sufficient attention to note-worthy user comments, our approach involved extracting keywords from Bitcoin-related user comments posted on the online forum with the aim of analytically predicting the price and extent of transaction fluctuation of the currency. The effectiveness of the proposed method is validated based on Bitcoin online forum data ranging over a period of 2.8 years from December 2013 to September 2016.
In recent years a new type of tradable assets appeared, generically known as cryptocurrencies. Among them, the most widespread is Bitcoin. Given its novelty, this paper investigates some statistical properties of the Bitcoin market. This study compares Bitcoin and standard currencies dynamics and focuses on the analysis of returns at different time scales. We test the presence of long memory in return time series from 2011 to 2017, using transaction data from one Bitcoin platform. We compute the Hurst exponent by means of the Detrended Fluctuation Analysis method, using a sliding window in order to measure long range dependence. We detect that Hurst exponents changes significantly during the first years of existence of Bitcoin, tending to stabilize in recent times. Additionally, multiscale analysis shows a similar behavior of the Hurst exponent, implying a self-similar process.
In this article, I advance a theory of gendered money and demonstrate how couples give special symbolic meaning to menâs money in domestic exchanges. Unlike previous perspectives on gender and money such as resource theories and gender performance, this framework acknowledges money as a prop and tool that couples use to construct gender boundaries and signal normalcy in the marital relationship. Integrating concepts from economic sociology with Hochschildâs insights on the symbolism of domestic labor, I find that Ukrainians use money as a token and symbol of value, not as a commodity with which to obtain desired outcomes. Drawing on in-depth interviews with 56 married and cohabiting individuals, I discover that couples subvert market meanings of money to enact a Soviet-style gender ideology. By spending menâs money on ânecessaryâ items and avoiding accessing womenâs money in the household, couples construct menâs money as both visible and valuable while rendering womenâs money non-fungible. These practices highlight the primacy of culture and ideology over relative income, and can help explain the reproduction of male privilege in the household, despite gains in womenâs employment and earnings.
In theory, database transactions protect application data from corruption and integrity violations. In practice, database transactions frequently execute under weak isolation that exposes programs to a range of concurrency anomalies, and programmers may fail to correctly employ transactions. While low transaction volumes mask many potential concurrency-related errors under normal operation, determined adversaries can exploit them programmatically for fun and profit. In this paper, we formalize a new kind of attack on database-backed applications called an ACIDRain attack, in which an adversary systematically exploits concurrency-related vulnerabilities via programmatically accessible APIs. These attacks are not theoretical: ACIDRain attacks have already occurred in a handful of applications in the wild, including one attack which bankrupted a popular Bitcoin exchange. To proactively detect the potential for ACIDRain attacks, we extend the theory of weak isolation to analyze latent potential for non-serializable behavior under concurrent web API calls. We introduce a language-agnostic method for detecting potential isolation anomalies in web applications, called Abstract Anomaly Detection (2AD), that uses dynamic traces of database accesses to efficiently reason about the space of possible concurrent interleavings. We apply a prototype 2AD analysis tool to 12 popular self-hosted eCommerce applications written in four languages and deployed on over 2M websites. We identify and verify 22 critical ACIDRain attacks that allow attackers to corrupt store inventory, over-spend gift cards, and steal inventory.
Tien Tuan Anh Dinh, Ji Wang, Gang Chen, Rui Liu · 6 authors
Blockchain technologies are taking the world by storm. Public blockchains, such as Bitcoin and Ethereum, enable secure peer-to-peer applications like crypto-currency or smart contracts. Their security and performance are well studied. This paper concerns recent private blockchain systems designed with stronger security (trust) assumption and performance requirement. These systems target and aim to disrupt applications which have so far been implemented on top of database systems, for example banking, finance and trading applications. Multiple platforms for private blockchains are being actively developed and fine tuned. However, there is a clear lack of a systematic framework with which different systems can be analyzed and compared against each other. Such a framework can be used to assess blockchains' viability as another distributed data processing platform, while helping developers to identify bottlenecks and accordingly improve their platforms.
Tyler B. Wray, Philip A. Chan, Erik M. Simpanen, Don Operario
BACKGROUND: Men who have sex with men (MSM) are the group at highest risk for contracting human immunodeficiency virus (HIV) in the United States, but many do not test as frequently as recommended. Home-based self-testing (HBST) for HIV holds promise for promoting regular testing among these individuals, but currently available HBSTs have limited follow-up options, providing only a 1-800 number that participants can call. Failure to actively conduct follow-up counseling and referrals after HBST use could result in delays in seeking confirmatory testing and care among users receiving reactive (preliminary positive) test results. HBST also fails to connect users who test negative with other prevention services that can reduce their future risk for HIV. OBJECTIVE: The aim of our study was to use qualitative research methods with high-risk MSM to inform development of a "smart" HBST kit. The kit utilizes existing Internet-of-Things (IoT) technologies to monitor HBST use in real-time and enable delivery of timely, active follow-up counseling and referrals over the phone. METHODS: In phase 1, individual interviews (n=10) explored how participants might use HBST and their views and preferences for conducting counseling and referral after HBST. Based on these perspectives, we developed a smartphone app (iOS, Android) that uses data from light sensors on Bluetooth low energy (BLE) beacons to monitor when HBST kits are opened, facilitating timely follow-up phone contact with users. In phase 2, a usability study conducted among high-risk MSM (n=10) examined the acceptability and feasibility of this system and provided user perspectives after using the system along with HBST. RESULTS: Phase 1 themes suggested that MSM preferred HBST, that most thought active follow-up after HBST would be valuable, and that doing so over the phone within 24 h after testing was preferable. Phase 2 results showed that the eTEST system successfully detected HBST use in nearly all cases. Participant perspectives also suggested that the timing, method (ie, phone call), and duration of follow-up were appropriate and helpful. CONCLUSIONS: Using BLE beacons and a smartphone app to enable follow-up counseling and referral over the phone after HBST use is feasible and acceptable to high-risk MSM. Future research is needed to compare the effects of follow-up counseling on rates of repeat testing and receipt of referral services (eg, testing for sexually transmitted infections and initiation of preexposure prophylaxis) and to explore the acceptability of the eTEST system over longer periods of time.
This research is meant to assess the financial performance of the local government of East Flores district by using financial ratio analysis to the Local Government Budget of East Flores district in 2012-2014 fiscal years.This research is case study research and descriptive approach. The analysis which has been applied to analyze the local financial performance is independency ratio, fiscal decentralization level ratio, effectiveness ratio, efficiency ratio, and expenditure harmony ratio. Meanwhile, the calculation of share and growth, map of local financial capacity, and financial capability index has been applied to analysis the local financial capability.Based on the result of the analysis and the calculation of local financial performance, it can be concluded that the patterns of the correlation and the local independency level of East Flores district is in instructive criteria. The fiscal decentralization level of East Flores district is still low but the effectiveness level of local financial management of East Flores district can be stated quite effective and the efficiency level of local financial management of East Flores district can be stated less efficient. The expenditure harmony ratio describes that between direct expenditure and indirect spending has not balanced yet. Based on the result of the calculation and the analysis of local financial capability, it can be concluded that the condition of the financial capability of East Flores district has not ideal yet. It can be seen from the result of the calculation of share and growth which shows that the position of East Flores district is in the Quadrant II. The financial capability of East Flores district is in high category when it is considered from the result of the calculation of financial capability index of East Flores district. Keywords: local finance, financial ratio, local government budget, financial performance
Once focus on the field of Chinese Central-local relation and policy implementation in China, we may find it hard to induce a consistent pattern, but it doesnĂąâŹâąt mean the features are chaotic as to cannot be observed. In this paper, we mainly choose the perspective of fiscal relations between central and local governments and personnel system existed in the bureaucratic hierarchy. Based on the analysis of institutional transition of finance and personnel system, we can understand the cause of selective implementations which have been promoted by local governments as an organization (institution) or by the cadres as individuals. After 1949, China became a unified and multiethnic socialist country. Since then, center and local governmental relations are lasting to play an important role in the development of the country. In the view of the governmental organizations, we can see the different and subjective interests of the two parts (center and local governments), which hold most of the countyĂąâŹâąs resources and authority of the financial distribution, using the macro directions and the micro policies to distribute the resource and generate benefits in the name of the whole value of the people who they should response to , and without showing their own purposes in different ways of interpreting policies. In the other view of the individuals who are working in the government, we can also see how the personnel system influences the behaviors of cadres in different levels of the governments and how they use power to make their own benefits in the name of the whole value of governance. Not only the governmental organizations, but the cadres themselves can influence the implementation of policies, and the selective implementation is a complex and interesting phenomenon to be understood in China.
Like many countries, the health care industries of England 1 and the United States consume large amounts of resources and struggle to achieve equity and efficiency. They attempt to reach these goals in quite different ways, exhibiting common challenges familiar to reformers throughout the world. Recent activities in England and the United States suggest that significant changes being discussed in the United States or implemented in the United Kingdom could upset previously accepted policies and threaten some or many of the gains made to provide more equal and timely accessible care to all individuals. Policy makers in both countries wrestle with similar problems of redistribution and system design. Although in the United States, the issues of equity and expenditure controls do not have the same importance as in England, both countries seek the âHoly Grailâ of limiting spending both by government and the private sector by redesigning institutions that manifest inefficiency and contribute to inflationary pressures. Yet competing value systems permeate the political debate about how to accomplish these aims. These value systems underlie political preferences for regulation and markets. Although a minority in the United States advocates for universal care funded by a single payer, private employer-based insurance remains the bedrock mechanism. Unlike the United Kingdom and most Organisation for Economic Cooperation and Development (OECD) countries, the United States has never shown a political willingness to have government responsible for financial protection for all inhabitants against the cost of medical care. The United States has, however, accepted this responsibility for major components of society, namely, the aged, disabled, and low-income families and children (e.g., via Medicare, Medicaid, and the State Children's Health Insurance Program). This commitment was expanded with the Affordable Care Act (ACA) in 2010, commonly known as Obamacare. The outcomes of the two health care systems reflect a preference for collectivism in funding and access in the United Kingdom and for pluralism in funding (less third-party coverage) and a greater role for privately delivered care in the United States. But the battle continues in both countries as important groups advocate for the reversal of these preferences. Policy makers continually try to change their health care systems. Some of these changes seek to develop greater efficiency in how care is delivered as a means of controlling the burdens imposed on society by ever-increasing public and private expenditure. Both countries face common problems that have been well identified for decades but have proven difficult to resolve. Reformers face three common problems. First, unwarranted variations in clinical practice (Wennberg, 2008, Wennberg, 2012) are produced by price variations in insurance systems and volume variations elsewhere (Institute of Medicine, 2013). Second, both systems have been slow to develop measures of the value of health care outcomes, that is, improvements in the length and quality of life. Third, both health care systems have perverse incentives that inhibit efficiency-inducing change; for example, they use hospital pricing or tariff systems that incentivise activity with little regard to patient value. Inadequate evaluation and political resistance to change continue to produce inefficiency. The end result is unnecessary spending and unethical deprivation of beneficial care for some populations. The English single payer system is characterised by frugality and cycles of famine and plenty, with attendant bouts of supply side reform (Street & Maynard, 2007). Constrained funding in the 1980s led to the Thatcher reforms and the creation of the âquasimarketâ of purchaser and providers contracting for public and private care. These structural reforms received increased funding in the early 1990s. By the end of the 1990s, financial parsimony was creating renewed performance problems, for example, increased waiting times for elective surgery. As a consequence, the Blair government financed a large increase in funding. Since 2010, the Coalition and now Conservative government has exerted extreme expenditure controls, and current plans will result in real per capita funding falling by 2018. Since the Thatcher era, the often violent fluctuations in NHS funding have been accompanied by the âredisorganisationâ of structures and processes of care whilst maintaining universal cover age free at the point of use. The purchaser side of the National Health Service (NHS) market has evolved from health authorities to primary care trusts and now to clinical commissioning groups, all with similar functions and uncertain impact. The provider side of the market remains dominated by public institutions as private providers have made only marginal inroads to public funding. The current chronic underfunding of the NHS and social care, manifested currently by increased waiting times for elective procedures, has produced inevitable pursuit of the âHoly Grailâ of increased productivity. The Five Year Forward View (NHS, 2014) involved the acceptance of government parsimony and for the 2015â2020 period. Its authors argued that the NHS would require ÂŁ30 billion to meet demographic and technological demands, of which only ÂŁ8 billion was to be provided from tax revenues. The additional ÂŁ22 billion was to be funded from productivity increases. Current NHS spending is ÂŁ110 billion. Currently, a frenzy of structural reform proposals range from integration of currently fragmented hospital, primary and social care systems to hospital mergers to the abolition of the purchaser-provider âmarketâ with the creation of accountable care organisations. These proposals involve unevidenced merger plans and deskilling of nursing and other workforce changes. The Sustainability and Transformation Plans (https://www.england.nhs.uk/stps/) are radical but unlikely to yield ÂŁ22 billion of productivity gains in 5 years. There is little available funding to finance the change process, and its duration is likely to take many years to free up resources. Both options assume that healthcare is much more expensive in the United States than in any OECD country because American patients use too much medical care. Yet the evidence does not support this assumption. Americans are less likely to be admitted to a hospital and have a lower length of stay once in a hospital than many OECD countries. Americans also are less likely to see a doctor or use fewer pharmaceuticals than patients in OECD countries. U.S. patients do use more very expensive medical devices such as MRIs or new and expensive drugs, but on net, the pluses and minus may cancel out. What separates United States spending from that in OECD countries are the prices charged for all medical activities. The reasons for the higher prices are complicated and due to a myriad of factors including the higher wages paid to most participants in the healthcare system (not only physicians); the much higher prices Americans pay for drugs and medical devices; and the fact that the complexity of the U.S. system has evolved in a way that requires the use of many more lawyers, consultants, and administrators, all of whom are well paid. The latter consideration is possibly more central because some key providers such as primary care physicians receive relatively low compensation relative to education costs and work conditions. Additional efforts within the United States that are sometimes related to the ACA include a broad interest in insurance redesign, emphasis on value from services provided, and a focus on patient-centred outcomes. Value-based cost-sharing approaches are being implemented in the United States as well as other OECD countries (Thomson, Schang, & Chernew, 2013), though these approaches are more easily implemented for certain services such as pharmaceuticals. The Medicare program is testing a number of value-based payment innovations and incentive payments. The Patient-Centered Outcomes Research Institute is a nongovernmental institute created under ACA that was charged with assessing the effectiveness and appropriateness of medical treatments. However, the Patient-Centered Outcomes Research Institute is not able to mandate coverage or reimbursement for any treatments and infamously is prohibited from considering cost per quality-adjusted life years in its recommendations despite widespread interest in this measure in many other countries. The American and the English health and social care systems differ greatly, but they are surprisingly similar in some dimensions. Key differences pertain to who pays for care and how it is delivered, with the United States having a more decentralized and fragmented system leading to inequalities in the provision of care and its funding. The English system is universal and largely free at the point of consumption system but constrained by limited funding (which also generates inequalities in access to timely care). The supply side problems are more similar for both countries. Increasingly, U.S. reform in terms of payment mechanisms is being emulated by the English. Both systems seek better measurement and management of âvalue,â that is, the effects of health care on the length and quality of patients' lives. The hospital systems of both countries are attempting to integrate care function and move away from âfee for serviceâ to bundled or incentive payments. The American system is the product of producer incentives producing grossly inflated costs. Concomitantly, a growing proportion of the U.S. population has a limited view about who should be eligible for government-supported health care services and the types of services that should be supported. Despite greater underlying consensus in favour of universal coverage, the English system's crisis is a product of parsimony and fragmentation of funding and provision. Both systems are permeated by organisational inertia and the defence of political values and self-interest. The United States is grappling with more than a sea change given political restructuring and the very uncertain future of most expansions of insurance or medical cost coverage under the ACA. England faces potentially revolutionary structural changes in supply and a real political challenge in its single payment system. Although current trends are not positive, the authors maintain hope that both countries will prevent further deterioration in health care coverage and return towards more progressive policies to protect their inhabitants' access to care when subjected to the misfortunes of medical illness.
Dinesh Verma, Nirmit Desai, Alun Preece, Ian Taylor
To support dynamic communities of interests in coalition operations, new architectures for efficient sharing of ISR assets are needed. The use of blockchain technology in wired business environments, such as digital currency systems, offers an interesting solution by creating a way to maintain a distributed shared ledger without requiring a single trusted authority. In this paper, we discuss how a blockchain-based system can be modified to provide a solution for dynamic asset sharing amongst coalition members, enabling the creation of a logically centralized asset management system by a seamless policy-compliant federation of different coalition systems. We discuss the use of blockchain for three different types of assets in a coalition context, showing how blockchain can offer a suitable solution for sharing assets in those environments. We also discuss the limitations in the current implementations of blockchain which need to be overcome for the technology to become more effective in a decentralized tactical edge environment.
Existing distributed ledger implementations â specifically, several blockchain implementations â embody a cacophony of divergent capabilities augmenting innovations of cryptographic hashes, consensus mechanisms, and asymmetric cryptography in a wide variety of applications. Whether specifically designed for cryptocurrency or otherwise, several distributed ledgers rely upon modular mechanisms such as consensus or smart contracts. These components, however, can vary substantially among implementations; differences involving proof-of-work, practical byzantine fault tolerance, and other consensus approaches exemplify distinct distributed ledger variations. Such divergence results in unique combinations of modules, performance, latency, and fault tolerance. As implementations continue to develop rapidly due to the emerging nature of blockchain technologies, this paper encapsulates a snapshot of sensor and internet of things (IoT) specific implementations of blockchain as of the end of 2016. Several technical risks and divergent approaches preclude standardization of a blockchain for sensors and IoT in the foreseeable future; such issues will be assessed alongside the practicality of IoT applications among Hyperledger, Iota, and Ethereum distributed ledger implementations suggested for IoT. This paper contributes a comparison of existing distributed ledger implementations intended for practical sensor and IoT utilization. A baseline for characterizing distributed ledger implementations in the context of IoT and sensors is proposed. Technical approaches and performance are compared considering IoT size, weight, and power limitations. Consensus and smart contracts, if applied, are also analyzed for the respective implementationsâ practicality and security. Overall, the maturity of distributed ledgers with respect to sensor and IoT applicability will be analyzed for enterprise interoperability.
Pietro Danzi, Marko Angjelichinoski, Äedomir StefanoviÄ, Petar Popovski
Residential microgrids (MGs) may host a large number of Distributed Energy Resources (DERs). The strategy that maximizes the revenue for each individual DER is the one in which the DER operates at capacity, injecting all available power into the grid. However, when the DER penetration is high and the consumption low, this strategy may lead to power surplus that causes voltage increase over recommended limits. In order to create incentives for the DER to operate below capacity, we propose a proportional-fairness control strategy in which (i) a subset of DERs decrease their own power output, sacrificing the individual revenue, and (ii) the DERs in the subset are dynamically selected based on the record of their control history. The trustworthy implementation of the scheme is carried out through a custom-designed blockchain mechanism that maintains a distributed database trusted by all DERs. In particular, the blockchain is used to stipulate and store a smart contract that enforces proportional fairness. The simulation results verify the potential of the proposed framework.
Pietro Danzi, Marko Angjelichinoski, Äedomir StefanoviÄ, Petar Popovski
Residential microgrids (MGs) may host a large number of Distributed Energy\nResources (DERs). The strategy that maximizes the revenue for each individual\nDER is the one in which the DER operates at capacity, injecting all available\npower into the grid. However, when the DER penetration is high and the\nconsumption low, this strategy may lead to power surplus that causes voltage\nincrease over recommended limits. In order to create incentives for the DER to\noperate below capacity, we propose a proportional-fairness control strategy in\nwhich (i) a subset of DERs decrease their own power output, sacrificing the\nindividual revenue, and (ii) the DERs in the subset are dynamically selected\nbased on the record of their control history. The trustworthy implementation of\nthe scheme is carried out through a custom-designed blockchain mechanism that\nmaintains a distributed database trusted by all DERs. In particular, the\nblockchain is used to stipulate and store a smart contract that enforces\nproportional fairness. The simulation results verify the potential of the\nproposed framework.\n
Bitcoin is a cryptocurrency which has received increasing interest over the last five years. Built upon a decentralized peer to peer system, it supports transparent, fast, cost effective, and irreversible transactions, without the need for trusting third party financial institutions. We know however little about people's motivation and experience with bitcoin currency. This paper reports on interviews with 20 bitcoin users in Malaysia about their experience and trust challenges. Findings show that bitcoins are used more as store of value for speculative investment or savings' protection. The paper advances the HCI theories on trust by identifying main bitcoin characteristics and their impact on trust, such as decentralization, unregulation, embedded expertise, and reputation, as well as transactions' transparency, low cost, and easiness to complete. We discuss insecure transactions, the risk of dishonest traders and its mitigating strategies. The paper concludes with design implications including support for the transparency of two-way transactions, tools for materializing trust, and tools for supporting reversible transactions.