In this article, we propose a blockchain verification protocol as a method for enabling and securing spectrum sharing in moving cognitive radio (CR) networks. The spectrum-sharing mechanism is used as a medium-access protocol for accessing wireless bandwidth among competing CRs. We introduce a virtual currency, called Specoins, for payment to access the spectrum. An auction mechanism based on a first-come-first-served queue is used, with the price for the spectrum advertised by each primary user in a decentralized fashion. The blockchain protocol facilitates the transactions between primary and secondary users and is used to validate and save each user's virtual wallet. Also important for mobile networks, the blockchain serves as a distributed database that is visible by all participating parties, and any node can volunteer to update the blockchain. The volunteer nodes are called miners, and they are awarded with Specoins. We propose diverse methods to exchange the Specoins to make leasing possible even by CRs that are not miners. We show the improvement of the proposed algorithm compared with the conventional Aloha medium-access protocol in terms of spectrum usage. This difference is investigated using small-scale fading variation in the wireless channel to compare the performance of our secure method with the conventional medium access used in vehicular communications. The secure blockchain verification protocol is not only secure but also outperforms the conventional system in moderate cases of small-scale fading. In the case of severe small-scale fading, the blockchain protocol will outperform the conventional system if multipath diversity is not used.
While cryptocurrencies and blockchain applications continue to gain popularity, their energy cost is evidently becoming unsustainable. In most instances, the main cost comes from the required amount of energy for the Proof-of-Work, and this cost is inherent to the design. In addition, useless costs from discarded work (e.g., the so-called Forks) and lack of scalability (in number of users and in rapid transactions) limit their practical effectiveness. In this paper, we present an innovative scheme which eliminates the nonce and thus the burden of the Proof-of-Work which is the main cause of the energy waste in cryptocurrencies such as Bitcoin. We prove that our scheme guarantees a tunable and bounded average number of simultaneous mining whatever the size of the population in competition, thus by making the use of nonce-based techniques unnecessary, achieves scalability without the cost of consuming a large volume of energy. The technique used in the proof of our scheme is based on the analogy of the analysis of a green leader election. The additional difference with Proof-of-Work schemes (beyond the suppression of the nonce field that is triggering most of the waste), is the introduction of (what we denote as) "empty blocks" which aim are to call regular blocks following a staircase set of values. Our scheme reduces the risk of Forks and provides tunable scalability for the number of users and the speed of block generation. We also prove using game theoretical analysis that our scheme is resilient to unfair competitive investments (e.g., "51 percent" attack) and block nursing.
he article presents the characteristic of the scientific genesis of public risk management in construction in Ukraine, in global and local dimen- sions. The essence of the working organization of risk management in the con- struction and operation of buildings, taking into account the transformational processes in society, is disclosed. On the basis of the analysis of risks in construc- tion and taking into account the current realities, scientifically grounded ap- proaches to the formation of the risk system in the construction and operation of facilities in the system of public administration. It is noted that the risks and crisis phenomena in the construction complex gave a powerful impetus to un- derstanding the causes of the problems of decentralization and finding mecha- nisms for their elimination, in general. The trilateral mission of the state in the conditions of decentralization is the regulation of the macroeconomic role of the construction complex, the mechanism of economic relations of its participants, and ensuring the effectiveness of design decisions in the construction sector, by extending their competences on prevention and risk reduction in the construction industry by the local self-government bodies. To form a state decentraliza- tion policy for construction is required on the basis of knowledge of objective regional macro- and microeconomic investment-construction processes in ci- ties, economic mechanism and indicators of development of investment-build- ing complex and dynamics of social and economic development of regions. The mechanism of the construction complex needs to be improved, using new sources and forms of financing, achieving the balance of the goals of decentralization and its financial support. In addition, taking into account the European integration course of the announced reforms, the European understanding of the essence of risk management in construction during decentralization becomes of paramount importance. Therefore, further research requires the study of the experience of European countries in the implementation of risk management processes in con- struction during the decentralization of power and the analysis of foreign systems of management mechanisms, in the context of their implementation in the na- tional practice of public administration.
N.I. Indera, Ahmad Ihsan Mohd Yassin, Azlee Zabidi, Zairi Ismael Rizman
This paper presents a Multi-Layer Exogeneous Inputs (NARX) Bitcoin price forecasting model using the opening, closing, minimum and maximum past prices together with Moving Average (MA) technical indicators.
As we observe a trend towards the recentralisation of the Internet, this paper raises the question of guaranteeing an everlasting decentralisation. We introduce the properties of strong and soft uncentralisability in order to describe systems in which all authorities can be untrusted at any time without affecting the system. We link the soft uncentralisability to another property called perfect forkability. Using that knowledge, we introduce a new cryptographic primitive called uncentralisable ledger and study its properties. We use those properties to analyse what an uncentralisable ledger may offer to classic electronic voting systems and how it opens up the realm of possibilities for completely new voting mechanisms. We review a list of selected projects that implement voting systems using blockchain technol- ogy. We then conclude that the true revolutionary feature enabled by uncentralisable ledgers is a self-sovereign and distributed identity provider.
Consensus protocols inherently rely on the notion of leader election, in which one or a subset of participants are temporarily elected to authorize and announce the network's latest state. While leader election is a well studied problem, the rise of distributed ledgers (i.e., blockchains) has led to a new perspective on how to perform large-scale leader elections via solving a computationally difficult puzzle (i.e., proof of work). In this paper, we present Caucus, a large-scale leader election protocol with minimal coordination costs that does not require the computational cost of proof-of-work. We evaluate Caucus in terms of its security, using a new model for blockchain-focused leader election, before testing an implementation of Caucus on an Ethereum private network. Our experiments highlight that one variant of Caucus costs only $0.10 per leader election if deployed on Ethereum.
In this article, I shall examine the compatibility of Bitcoin and other cryptocurrencies within the context of Islamic law. I shall begin by an introduction of Bitcoin and other cryptocurrencies. I will then discuss the history of money in Islamic history, with an emphasis on the importance ethical financial dealings. I will then argue that Bitcoin and other cryptocurrencies are highly compatible within Islamic finance, and in many cases, actually provide solutions to problems of government institution controlled currencies, arguing that Bitcoin and other cryptocurrencies better address several problems that early Islamic finance scholars were concerned with. Unlike traditional fiat, the supply of Bitcoin and many other digital currencies are fixed, thereby eliminating potential for gharar (deception), and also inflation. In addition, unlike fiat and precious metal coins, digital currencies cannot be altered, forged, or manipulated. Moreover, cryptocurrencies’ peer-to-peer transactions remove the need for any banking institution, thereby eliminating any risk with a third party controlling one’s money. I shall then conclude with a summary of the main points of the article, and examine future possibilities with regards to the role of digital and cryptocurrencies.
We present a formalization of blockchain as a state machine, focusing upon permissionless blockchains due to general audience awareness of its most popular implementation, Bitcoin (permissioned blockchains are treated similarly without loss of generality). After presenting a typical Bitcoin transaction workflow, a general blockchain state representation is derived. It is demonstrated that the proper mathematical object defining the state of a blockchain is a topological fiber bundle, because it is not possible to globally `parametrize' blocks (or ledgers of blocks) by time due to their dependence upon cryptographic hash functions. In addition, we specify a general transition function between blockchain states that is agnostic to the consensus mechanism used to write blocks into the ledger, and which is probabilistic in nature, so that blockchain may be regarded as a probabilistic state machine. We then interpret agents (both human and code-based, such as `chaincode', `smart contracts', or other artificial intelligence) as automata interacting with blockchain technology, drawing upon the theory of non-cooperative repeated interaction games. Finally, blockchain as a hierarchy of state machines is defined, and future research directions are presented using this hierarchy as a point of departure for modeling blockchain dynamics.
Despite its undoubted centrality in modern society, Love has not received the attention it deserves in the study of organizations. Among the reasons for this avoidance is the fact that love is passionate and not authoritative; personal and subjective but not public. To understand the way organizational research can incorporate love, I explore and discuss three interweaving constructs. Eros (or a tale of the self) calls for an expression of the individuality in organizations, in terms of creativity, sense making and experience. Philia (or a tale of trust) contributes to explore trustworthy relationships, welcoming the other and enabling individuals to flourish in the workplace. Agape (or a tale of compassion) refers to generalized love for humanity and opens to the understanding of compassionate leadership. In the discussion, I call for new directions in the study of love as the organization and the organization as love.
Hélder Sebastião, António Portugal Duarte, Gabriel Guerreiro
This paper analyses the price discovery in the USD/Bitcoin market since Mar‑2014 to Nov‑2016. The results show a positive relationship between the informational relevance of exchanges and their market shares. Information is mostly transmitted between exchanges within an hour, at least for the main exchanges, although lagged feedbacks occur from the major exchanges. Minor exchanges are merely satellite ones and react to price information with some delay. Bitfinex is the most important exchange: the lagged feedback from this exchange to the market is 18.3%, while the reverse feedback accounts only for 0.6% of the total feedback. Volatility in the major exchanges is the main factor explaining the feedback measures, which sustains the claim that the relative importance of the information-based component of volatility increases with the relative dimension of the exchange.
Husam Al Jawaheri, Mashael Al Sabah, Yazan Boshmaf, Aiman Erbad
With the rapid increase of threats on the Internet, people are continuously seeking privacy and anonymity. Services such as Bitcoin and Tor were introduced to provide anonymity for online transactions and Web browsing. Due to its pseudonymity model, Bitcoin lacks retroactive operational security, which means historical pieces of information could be used to identify a certain user. We investigate the feasibility of deanonymizing users of Tor hidden services who rely on Bitcoin as a payment method by exploiting public information leaked from online social networks, the Blockchain, and onion websites. This, for example, allows an adversary to link a user with @alice Twitter address to a Tor hidden service with private.onion address by finding at least one past transaction in the Blockchain that involves their publicly declared Bitcoin addresses.
To demonstrate the feasibility of this deanonymization attack, we carried out a real-world experiment simulating a passive, limited adversary. We crawled 1.5K hidden services and collected 88 unique Bitcoin addresses. We then crawled 5B tweets and 1M BitcoinTalk forum pages and collected 4.2K and 41K unique Bitcoin addresses, respectively. Each user address was associated with an online identity along with its public profile information. By analyzing the transactions in the Blockchain, we were able to link 125 unique users to 20 Tor hidden services, including sensitive ones, such as The Pirate Bay and Silk Road. We also analyzed two case studies in detail to demonstrate the implications of the resulting information leakage on user anonymity. In particular, we confirm that Bitcoin addresses should always be considered exploitable, as they can be used to deanonymize users retroactively. This is especially important for Tor hidden service users who actively seek and expect privacy and anonymity.
Blockchains enables tamper-proof, ordered logging for transactional data in a decentralized manner over open-access, overlay peer-to-peer networks. In this paper, we propose a decentralized framework of proactive caching in a hierarchical wireless network based on blockchains. We employ the blockchain-based smart contracts to construct an autonomous content caching market. In the market, the cache helpers are able to autonomously adapt their caching strategies according to the market statistics obtained from the blockchain, and the truthfulness of trustless nodes are financially enforced by smart contract terms. Further, we propose an incentive-compatible consensus mechanism based on proof-of-stake to financially encourage the cache helpers to stay active in service. We model the interaction between the cache helpers and the content providers as a Chinese restaurant game. Based on the theoretical analysis regarding the Nash equilibrium of the game, we propose a decentralized strategy-searching algorithm using sequential best response. The simulation results demonstrate both the efficiency and reliability of the proposed equilibrium searching algorithm.
Husam Al Jawaheri, Mashael Al Sabah, Yazan Boshmaf, Aiman Erbad
With the rapid increase of threats on the Internet, people are continuously seeking privacy and anonymity. Services such as Bitcoin and Tor were introduced to provide anonymity for online transactions and Web browsing. Due to its pseudonymity model, Bitcoin lacks retroactive operational security, which means historical pieces of information could be used to identify a certain user. We investigate the feasibility of deanonymizing users of Tor hidden services who rely on Bitcoin as a payment method by exploiting public information leaked from online social networks, the Blockchain, and onion websites. This, for example, allows an adversary to link a user with @alice Twitter address to a Tor hidden service with private.onion address by finding at least one past transaction in the Blockchain that involves their publicly declared Bitcoin addresses. To demonstrate the feasibility of this deanonymization attack, we carried out a real-world experiment simulating a passive, limited adversary. We crawled 1.5K hidden services and collected 88 unique Bitcoin addresses. We then crawled 5B tweets and 1M BitcoinTalk forum pages and collected 4.2K and 41K unique Bitcoin addresses, respectively. Each user address was associated with an online identity along with its public profile information. By analyzing the transactions in the Blockchain, we were able to link 125 unique users to 20 Tor hidden services, including sensitive ones, such as The Pirate Bay and Silk Road. We also analyzed two case studies in detail to demonstrate the implications of the resulting information leakage on user anonymity. In particular, we confirm that Bitcoin addresses should always be considered exploitable, as they can be used to deanonymize users retroactively. This is especially important for Tor hidden service users who actively seek and expect privacy and anonymity.
Rhys Bowden, Paul Keeler, A. E. Krzesinski, Peter Taylor
Bitcoin is a electronic payment system where payment transactions are verified and stored in a data structure called the blockchain. Bitcoin miners work individually to solve a computationally intensive problem, and with each solution a Bitcoin block is generated, resulting in a new arrival to the blockchain. The difficulty of the computational problem is updated every 2,016 blocks in order to control the rate at which blocks are generated. In the original Bitcoin paper, it was suggested that the blockchain arrivals occur according to a homogeneous Poisson process. Based on blockchain block arrival data and stochastic analysis of the block arrival process, we demonstrate that this is not the case. We present a refined mathematical model for block arrivals, focusing on both the block arrivals during a period of constant difficulty and how the difficulty level evolves over time.
Vehicular Ad Hoc Networks (VANETs) play a vital role in enabling smart transportation systems by facilitating communication between vehicles. However, existing vehicular announcement systems face two major challenges: preserving user privacy and motivating users to share reliable traffic information. In this paper, we propose CreditCoin, a privacy-presing blockchain-based incentive announcement network. The system utilizes an anonymous vehicular announcement aggregation protocol combined with blockchain technology to ensure secure, tamper-resistant, and decentralized communication. Users can broadcast traffic updates anonymously while earning incentives for participation, thereby improving network reliability. A Trace Manager enables conditional privacy by identifying malicious users without compromising honest participants. The proposed system is implemented using Python, Web3, and a simulated VANET environment. Experimental results demonstrate improved efficiency, reduced computation time, and enhanced data reliability compared to traditional approaches. This work contributes toward secure and incentive-driven communication in smart transportation systems. In this paper, we propose CreditCoin, a privacy-preserving blockchain-based incentive announcement network. The system utilizes an anonymous vehicular announcement aggregation protocol combined with blockchain technology to ensure secure, tamper-resistant, and decentralized communication. Users can broadcast traffic updates anonymously while earning incentives for participation, thereby improving network reliability. A Trace Manager enables conditional privacy by identifying malicious users without compromising honest participants. Keywords— VANET; Blockchain; Privacy Preservation; Incentive Mechanism; Smart Vehicles; CreditCoin
Bitcoin and its enabling technology, the blockchain, are front and center in discussions of the future of finance and “fintech.” This essay argues that Bitcoin is a special case and a weak analogy for future applications of blockchain technology. Adoption will grow, and applications will spread, but the nature of the technology and of the financial markets suggest that instead of being disruptive to major incumbent institutions, blockchain-based innovation will tend to strengthen existing market participants, serving more to lower costs than to encourage new entrants or new business methods. <b>TOPICS:</b>Currency, global
Access to energy has increasingly been provided by the Chinese Government via new alternative energy sources known as renewables in recent years. Meanwhile, the development and use of environmentally friendly renewables gradually become the basic requirements for the sustainable development in the future society. The integration of blockchain technology with distributed photovoltaic (PV) energy may break the existing pattern where the production, transportation, distribution, and sales of energy are centralized. This paper first reviews the current overall situation of China's distributed PV and further analyzes the policy environment with respect to the development of distributed PV. On the basis of the analysis of the status quo, the paper then discusses the internalities (strengths and weaknesses) and the externalities (opportunities and threats) that have driven the development of China's distributed PV by illustrating the SWOT analysis. The data structure and characteristics of blockchain are analyzed to identify the application mode of blockchain technology in the distributed PV industry for the first time. Through our research, some conclusions and policy proposals are finally put forward to provide support to the formulation of related policy in the Chinese Government and industry association.
In its first decade, Bitcoin has not proven to be a practical money form for most circumstances, but it has become a staging ground for debate around the cultural role of money in society. This debate is poised between two related but ultimately incompatible techno-economic imaginaries: infrastructural mutualism and digital metallism. Each offers a theory not just of money, but also of relations, identities, and the larger imaginaries we call ‘society’ and ‘the economy’. In particular, they offer distinct visions of what it means to be a ‘peer’ in a peer-to-peer money system, and perhaps, a peer-to-peer society. This article traces the pre-history of Bitcoin, as well as more recent developments, to inquire about its future, as well as the future of money more broadly.
Bitcoin and other similar digital currencies on blockchains are not ideal means for payment, because their prices tend to go up in the long term (thus people are incentivized to hoard those currencies), and to fluctuate widely in the short term (thus people would want to avoid risks of losing values). The reason why those blockchain currencies based on proof of work are unstable may be found in their designs that the supplies of currencies do not respond to their positive and negative demand shocks, as the authors have formulated in our past work. Continuing from our past work, this paper proposes minimal changes to the design of blockchain currencies so that their market prices are automatically stabilized, absorbing both positive and negative demand shocks of the currencies by autonomously controlling their supplies. Those changes are: 1) limiting re-adjustment of proof-of-work targets, 2) making mining rewards variable according to the observed over-threshold changes of block intervals, and 3) enforcing negative interests to remove old coins in circulation. We have made basic design checks and evaluations of these measures through simple simulations. In addition to stabilization of prices, the proposed measures may have effects of making those currencies preferred means for payment by disincentivizing hoarding, and improving sustainability of the currency systems by making rewards to miners perpetual.
The objective of this paper is to describe the contemporary issues that supply chains face using the information sharing dimension and analyze blockchain technology’s capabilities to address these issues. We discuss select issues in managing contemporary supply chains from an information sharing perspective namely, information coordination challenges, effect of product and service manifestation on information complexity, effect of customer demand manifestation on information flow, outsourcing and globalization effects on information flow, and new emerging threats to supply chains by affecting information vulnerability. These issues are further categorized into- confidentiality and trust issues, inability to share information between supply chain partners, limitations of IT systems and lack of data standards. To address these issues, a unifying framework describing the applicability of blockchain has been presented that will guide companies in designing and implementing potential blockchain solutions to address issues in information exchange among supply chain partners. Blockchain based research is in nascent stages and this paper aims to add to this emerging research paradigm by analyzing blockchain technology through the information sharing dimension of supply chains. (this record is metadata only)