Blockchain Papers

Yousuke Watanabe

No abstract is available for this record.

Jong-Ho Noh, Hun-Yeong Kwon

The smart city is aiming for an intelligent connected society beyond the concept of U-City with simple ICT. In particular, the rapid development of information and communications, such as 5G, and blockchain, has led to a paradigm shift to a new digital urban environment. As smart energy and smart transportation are integrated or interlocked, the technical and institutional arrangement should be preceded from the time of user authentication to provide reliability, transparency, and efficiency. For this purpose, this study aims to investigate the technical and institutional plans for the implementation of safe urban life utilizing blockchain technology. In order to apply smart city services using block-chain technology, it is necessary to fully agree and practice among various stakeholders such as public, business, academia, and civic groups. It is expected to be implemented as a people-centered smart city by gradually applying the block chain-based pilot service, which is made and participated together.

Bing Jia, Tao Zhou, Wuyungerile Li, Zhenchang Liu · 5 authors

Crowd sensing is a perception mode that recruits mobile device users to complete tasks such as data collection and cloud computing. For the cloud computing platform, crowd sensing can not only enable users to collaborate to complete large-scale awareness tasks but also provide users for types, social attributes, and other information for the cloud platform. In order to improve the effectiveness of crowd sensing, many incentive mechanisms have been proposed. Common incentives are monetary reward, entertainment & gamification, social relation, and virtual credit. However, there are rare incentives based on privacy protection basically. In this paper, we proposed a mixed incentive mechanism which combined privacy protection and virtual credit called a blockchain-based location privacy protection incentive mechanism in crowd sensing networks. Its network structure can be divided into three parts which are intelligence crowd sensing networks, confusion mechanism, and blockchain. We conducted the experiments in the campus environment and the results shows that the incentive mechanism proposed in this paper has the efficacious effect in stimulating user participation.

Danwei Liang, Jian An, Jindong Cheng, Yang He · 5 authors

In most crowdsensing systems, the quality of the collected data is varied and difficult to evaluate while the existing crowdsensing quality control methods are mostly based on a central platform, which is not completely trusted in reality and results in fraud and other problems. To solve these questions, a novel crowdsensing quality control model is proposed in this paper. First, the idea of blockchain is introduced into this model. The credit-based verifier selection mechanism and twice consensuses are proposed to realize the non-repudiation and non-tampering of information in crowdsensing. Then, the quality grading evaluation (QGE) is put forward, in which the method of truth discovery and the idea of fuzzy theories are combined to evaluate the quality of sensing data, and the garbled circuit is used to ensure that evaluation criteria can not be leaked. Finally, the Experiments show that our model is feasible in time and effective in quality evaluation.

Kushal Singla, Joy Bose, Sharvil Katariya

Recently, there is a growing trend towards machine learning models that run on client devices such as smartphones, with constraints such as model size and time. Often, the user data on client devices is considered private and so cannot be uploaded to an external server for processing and running the model. Blockchain provides a new way of sharing data that is secure and decentralized. In this paper, we provide a way to use blockchain to run a machine learning model in a decentralized way using various nodes to compute part of the learning task. We apply our system in a smart home IoT setting to generate user customizations based on user activity prediction for IoT devices. We use distributed association rule mining to generate the rules of user activity from the device logs. We describe the system architecture and simulate the system using Ethereum based tools.

Akihiro Fujihara

No abstract is available for this record.

Bulat Nasrulin, Muhammad Muzammal, Qiang Qu

Mobile devices generate massive amounts of data that is used to get an insight into the user behavior by enterprise systems. Data privacy is a concern in such systems as users have little control over the data that is generated by them. Blockchain systems offer ways to ensure privacy and security of the user data with the implementation of an access control mechanism. In this demonstration, we present ChainMOB, a mobility analytics application that is built on top of blockchain and addresses the fundamental privacy and security concerns in enterprise systems. Further, the extent of data sharing along with the intended audience is also controlled by the user. Another exciting feature is that user is part of the business model and is incentivized for sharing the personal mobility data. The system also supports queries that can be used in a variety of application domains.

Wei Shao, Hang Li, Mengqi Chen, Chunfu Jia · 6 authors

No abstract is available for this record.

Charles Shen, Feniosky Peña‐Mora

Blockchain is considered one of the most disruptive technologies of our time. Numerous cities around the world are launching blockchain initiatives as part of the overall efforts toward shaping the urban future. However, the infancy stage of the blockchain industry leads to a severe gap between the knowledge we have and the actions urban policy makers are taking. This paper is an effort to narrow this rift. We provide a systematic literature review on concrete blockchain use cases proposed by the research community. At the macro-level, we discuss and organize use cases from 159 selected papers into nine sectors recognized as crucial for sustainable and smart urban future. At the micro-level, we identify a component-based framework and analyze the design and prototypes of blockchain systems studied in a subset of 71 papers. The high-level use case review allows us to illustrate the relationship between them and the four pillars of urban sustainability: social, economic, environmental, and governmental. The system level analysis helps us highlight interesting inconsistencies between well-known blockchain applicability decision rules and the approaches taken by the literature. We also offer two classification methodologies for blockchain use cases and elaborate on how they can be applied to stimulate cross-sector insights in the blockchain knowledge domain.

Petra Isenberg, Christoph Kinkeldey, Jean‐Daniel Fekete

We contribute a visual exploration system for analyzing the behavior of individual entities exchanging Bitcoins. Bitcoin is a cryptocurrency, popular for allowing pseudonymous financial transactions. The Bitcoin blockchain is the public ledger of the Bitcoin system holding data on millions of individual transactions between pseudonymous addresses. These addresses belong to individual entities such as people, services, or enterprises. Understanding how the Bitcoin system is used, however, is difficult because it is unclear which addresses belong to the same entities. Our tool addresses this problem by clustering addresses and displaying transaction detail for individual entities

Remo Manuel Frey, Denis Vuckovac, Alexander Ilic

No abstract is available for this record.

Alireza Beikverdi, JooSeok Song

Bitcoin, a distributed, peer to peer crypto currency, has gained a significant popularity among different users around the world by promising users a fully decentralized network with an inherently independence from governments and without the influence of any central authorities and organizations. Mining is the fundamental concept in Bitcoin which must be done in checking all monetary transactions and verifying them which in return generates Bitcoin as a reward to encourage this work. While the qualitative nature of this unique system is clearly accepted and understood, there are some issues regarding to its decentralized network environment. Based on our analysis due to the high variance of solo mining, the number of users joining top most famous Bitcoin mining pools are increasing due to the fact that users together under a Bitcoin pool will have a higher chance of generating next block in the Bitcoin's blockchain by reducing the variance and earning the mining reward. Furthermore, emerging huge mining farms with strong mining resources and fast processing power is another trend toward centralization. Although some might argue that, the protocol itself is purely decentralized and these are marketbased centralization, this trend clearly illustrates that the pure, decentralized protocol of Bitcoin is going toward centralization in its distributed network, where any kind of centralization should be considered carefully due to the 51% attack. By analysing all the created blocks from 2009 to 2014 we proposed a centralization factor which shows how centralized is the state of Bitcoin's network in different years. Centralization, due its simplicity, is a phenomenon that happens to any disciplined and organized system automatically, which in case of Bitcoin is against the pure initial decentralized nature of it and might arise some concerns and threats to the Bitcoin's unforeseeable future.

Amy Glasmeier, Susan Christopherson

How should we think about ‘smart cities’? This issue brings together a set of articles that examine current debates around the goals, ethics, potential and limitations of a concept that has become a metaphor for urban modernity. We also include an unusual addition, a short intervention that surfaces some of the controversial issues related to smart cities, as a conception and as a practical undertaking. Some of the seeds of today’s smart cities can be found in a series of conversations among scholars and practitioners in the 1980s, reflecting on the future of cities. In a book review, Phil Harris, describes a particularly significant intervention by Sheridan Tatsuno of NeoConcepts, a consultant connected to the Institute for Constructive Capitalism at the University of Texas at Austin, a think tank founded in the 1980s by George Kosmetsky, an entrepreneur turned academic. Like others at the conference, Tatsuno was writing at a time when Silicon Valley was the place to emulate and ventures such as the Research Triangle Park in North Carolina served as alternative examples of successful future industrialisation. He, like many others, was propagating the idea that any and every place could be Silicon Valley-like, if they simply followed a prescription: As Harris (1992) describes: Tatsuno calls out “the age of technopolis and the metamorphosis of traditional cities and even high-tech parks. One alternative is the global network city of dispersed, highly interactive economic nodes linked by massive networks of airports, highways, and communications. Another metaphor is the “intelligent city” featuring advanced information/communication technologies, complexes wired for satellite and fiber optics. These network cities are inhabited by “knowledge processors” engaged in rapid information exchanges (Harris, 1992). As Rob Kitchin lays out in his article in this issue, however, the origins of the smart city are not found solely in the search for technological utopias (Kitchin, 2015). They also originate in the 1980s prescriptions for managed, entrepreneurial cities—whose speed and flexibility in adapting to global markets make them more efficient and competitive (Logan and Molotch, 1987). Kitchin also raises the provocative question of whether another model of ‘smartness’, the digital or wired city, belongs in the ‘smart city’ genre. The wired city in fact offered a somewhat different vision, that of inclusiveness in access to digital technologies. These two competing visions of cities transformed by technologies have not been reconciled despite the recognition that the Internet and particularly, the Internet of things, is a central feature of smart city models. Although the ‘smart city’ concept has emerged from long-persisting ideas about urban technological utopias and the perfectly competitive city, it also differs from these urban visions in some important ways. What is new about the contemporary smart city narrative is the emphasis on places transformed by the application of technologies rather than, as in the case of Silicon Valley, places where sectors such as microelectronics and computers drive the urban economy. Smart cities are not just where new technologies might be born. They are the receptacles for technology, the target of its applications. Although saturated as consumer markets, cities present opportunities for firms seeking markets for modern sensing, forecasting and management technologies. Although 1990s city policymakers sought to replicate the job base and innovative milieu of high-tech centres, the contemporary purveyors of smart city technologies see city governments as markets for the products of the last 40 years of technology development. At the same time, ambitious politicians and civil servants are ever on the search for the next ‘big idea’ to move their city to the top of the rank of attractive places. The race to get on the bandwagon and become a smart city has encouraged city policymakers to endogenise the process of technology-led growth, directing municipal budgets toward investments that bestow smart city status. The public investments that confer smart city status are impressive. A recent report from a large Australian development company puts a dollar figure on the expected growth of smart cities. According to Ivan Fernandez, Industry Director for Frost & Sullivan, Australia and New Zealand, a consulting firm promoting growth through globalisation, The global smart city market will be valued at US$1.565 trillion in 2020. Over 26 Global Cities are expected to be Smart Cities in 2025, with more than 50% of these smart cities from Europe and North America. By 2025, it is expected that around 58% of the world’s population or 4.6 billion people will live in urban areas. In developed regions and cities, the urban population in cities could account for up to 81% of total population. This will pose serious challenges for city planners, who will have to re-think how they provide basic city services to residents in a sustainable manner. Governments of smart cities are transforming from a traditional model of a silo-based organization to a more collaborative, integrated service delivery model. Cities will collaborate with each other to drive smart city innovation by entering into partnerships with each other. Technology and ecosystem convergence, collaboration and partnerships between stakeholders from different industries, such as energy and infrastructure, IT, telecoms and government will also expedite the delivery of integrated services http://www.newswiretoday.com/news/148711/Global-Smart-Cities-Market-to-Reach-US1.56-Trillion-by-2020-Finds-Frost-and-Sullivan/ Smart city advocates include not only large information economy businesses, such as IBM, Intel, Siemens, CISCO and SAP, but also academic and philanthropic organisations. Each has a distinctive sense of what smart cities can accomplish. Academics are attracted to technology applications that offer the ability to ‘sense’ and track human use of urban infrastructure. They are drawn by the potential that these applications offer to remediate urban problems such as snarled traffic, the lack of parking spaces, and inefficient energy use and waste disposal. Philanthropists see solutions to urban ills with an eye toward greater equity, improved quality of life and citizen empowerment. The large information firms see the vastly expanding market for management applications in an urbanising world as an opportunity to develop stable revenue streams in the form of continuous contracts. These firms are, however, selling different visions of ‘smart’ and products to achieve the vision. Competing and sometimes contradictory stakeholder goals contribute to the inevitable conclusion that the smart city is a chaotic concept. What the smart cities movement has done, albeit perhaps inadvertently, is to reignite interest in cities as engines of growth. This has been perhaps most evident with the model cities created on greenfield sites. A few have gone beyond drawing boards and taken shape on the ground. Each of these cities is unique and hence an unlikely candidate for reproducibility as ‘the’ smart city model. The distinctiveness characteristic of Song Do in South Korean or Plan IT in Portugal belies one of the most common complaints about smart city applications, that they espouse only a single development model. What they do have in common, however, beyond encompassing expansive views of ‘smart city’ development, is acceptance of urban competitiveness and the primacy of economic goals as intrinsic to the smart city concept. Looking closely, there are a dizzying array of attempts at smart city formation and membership. As Hollands’s contribution to this special issue highlights, there are all manner and scale of potential candidates. He highlights eight well-known examples. Singapore’s iN2015 (intelligent nation) project, Songdo, South Korea’s purpose built, globally competitive, high-tech, environmentally sustainable, business city, or Guangzhou Knowledge City in China are designed to attract talent, skilled manpower and knowledge-based industries. Masdar City, in the UAE, is currently being designed as an ‘oasis of the future’ (quite literally as it is built in the desert) and intended to become the world’s first sustainable, renewable, energy-powered cleantech cluster (Kingsley, 2013). In Scandinavia and Europe, Helsinki and ‘Intelligent’ Thessaloniki (Greece) are held up as examples of encouraging the development of new mobile applications utilising open data and using IT to increase competitiveness and sustainability, respectively (Komninos et al., 2013). In Europe, Barcelona, continues to be renowned for its Smart City Model and in November 2014 hosted its fourth Smart City Expo World Congress in as many years (see http://www.smartcityexpo.com/), while the Amsterdam Smart City initiative is held up as the example of how to retrofit a city to improve living and economic conditions and reduce carbon emissions (Hollands, 2015; Kirby, 2013). An important takeaway from this list of smart cities is the tailored nature of their approach. The objective is not just as technology users but as shrines of economic development practice. Some are using the smart city title to gain status by offering annual events to newcomers wishing to take up the mantle of smart city development (http://smartcitiesportugal.net). There is frequently an alliance between the prototype smart city builders and scholars discussing the phenomenon. Their perspectives come together under the umbrella of cities as machines for living. Both promote at least somewhat utopian visions based on technological fixes for those aspects of urban settlement and the concentration of human beings that make for human frustration and slow the flow of goods and services. The authors in this special issue are all aware of this perspective although some emphasise it more than others. A special issue on such a nebulous topic can never be comprehensive, but authors in this issue place the smart city in historical context, provide concrete examples of smart city applications and point to arenas where the concept and practice differ from prior urban technological fixes. The authors also indicate where the urban technological fix, in both its historical and contemporary forms has failed—for example, in addressing equity concerns. They demonstrate that there is a difference between what we can measure and what we need to know. The limits of the smart city are created both by the absence of data applications that could drive collective rather than individual solutions and by the inability to address intangible qualities of cities that both improve and detract from the quality of urban life for city residents. These critiques have been part of the discussions on the closely related topic of ‘big data’. Although the authors in this issue approach the subject of smart cities from very different angles, they generally agree that smart city technologies are ill-suited to solving the problems that lie at the heart of improving the quality of urban life. Poverty is not on the agenda of smart city planners. They may solve traffic problems, but it is not clear how they will regenerate failing schools or find ways to include neighbourhoods facing disinvestment. The contradiction between the promise of smart cities and its limited policy scope is aptly demonstrated in one of the most celebrated smart cities, Rio de Janeiro. The city, with its control centre filled with wall size computer monitors, can perhaps use forecasts of threatening weather to send out warnings of storm intensity thus leading to speedier evacuation. 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Dorit Ron, Adi Shamir

Abstract. The Bitcoin scheme is a rare example of a large scale global payment system in which all the transactions are publicly accessible (but in an anonymous way). We downloaded the full history of this scheme, and analyzed many statistical properties of its associated transaction graph. In this paper we answer for the first time a variety of interesting questions about the typical behavior of users, how they acquire and how they spend their bitcoins, the balance of bitcoins they keep in their accounts, and how they move bitcoins between their various accounts in order to better protect their privacy. In addition, we isolated all the large transactions in the system, and discovered that almost all of them are closely related to a single large transaction that took place in November 2010, even though the associated users apparently tried to hide this fact with many strange looking long chains and fork-merge structures in the transaction graph.