A type of Bitcoin node called "Full Node" has to hold the entire of historical transaction data called "Blockchain" to verify that new transactions are correct or not. To operate nodes as Full Nodes, the required storage size will be too large for resource-constrained devices. In this paper, to mitigate storage size, we propose a storage load balancing scheme by distributed storage based on Distributed Hash Table (DHT). By our scheme, nodes in a DHT cluster can behave like Full Nodes without holding the entire of the blockchain.
Summary Decentralization, in the form of mesh networking and blockchain, two promising technologies, is coming to the telecommunications industry. Mesh networking allows wider low‐cost Internet access with infrastructures built from routers contributed by diverse owners, whereas blockchain enables transparency and accountability for investments, revenue, or other forms of economic compensations from sharing of network traffic, content, and services. Crowdsourcing network coverage, combined with crowdfunding costs, can create economically sustainable yet decentralized Internet access. This means that every participant can invest in resources and pay or be paid for usage to recover the costs of network devices and maintenance. While mesh networks and mesh routing protocols enable self‐organized networks that expand organically, cryptocurrencies and smart contracts enable the economic coordination among network providers and consumers. We explore and evaluate two existing blockchain software stacks, Hyperledger Fabric (HLF) and Ethereum geth with Proof of Authority (PoA) intended as a local lightweight distributed ledger, deployed in a real city‐wide production mesh network and in laboratory network. We quantify the performance and bottlenecks and identify the current limitations and opportunities for improvement to serve locally the needs of wireless mesh networks, without the privacy and economic cost of relying on public blockchains.
Energy storage units (ESUs) enable several attractive features of modern smart grids such as enhanced grid resilience, effective demand response, and reduced bills. However, uncoordinated charging of ESUs stresses the power system and can lead to a blackout. On the other hand, existing charging coordination mechanisms suffer from several limitations. First, the need for a central charging coordinator (CC) presents a single point of failure that jeopardizes the effectiveness of the charging coordination. Second, a transparent charging coordination mechanism does not exist where users are not aware whether the CC is honest or not in coordination charging requests among them in a fair way. Third, existing mechanisms overlook the privacy concerns of the involved customers. To address these limitations, in this paper, we leverage the blockchain and smart contracts to build a decentralized charging coordination mechanism without the need for a centralized charging coordinator. First ESUs should use tokens for anonymously authenticate themselves to the blockchain. Then each ESU sends a charging request that contains its State-of-Charge (SoC), Time-to-complete-charge (TCC) and amount of required charging to the smart contract address on the blockchain. The smart contract will then run the charging coordination mechanism in a self-executed manner such that ESUs with the highest priorities are charged in the present time slot while charging requests of lower priority ESUs are deferred to future time slots. In this way, each ESU can make sure that charging schedules are computed correctly. Finally, we have implemented the proposed mechanism on the Ethereum test-bed blockchain, and our analysis shows that execution cost can be acceptable in terms of gas consumption while enabling decentralized charging coordination with increased transparency, reliability, and privacy preserving.
Blockchains or distributed ledgers are an emerging technology that has drawn considerable interest from energy supply firms, startups, technology developers, financial institutions, national governments and the academic community. Numerous sources coming from these backgrounds identify blockchains as having the potential to bring significant benefits and innovation. Blockchains promise transparent, tamper-proof and secure systems that can enable novel business solutions, especially when combined with smart contracts. This work provides a comprehensive overview of fundamental principles that underpin blockchain technologies, such as system architectures and distributed consensus algorithms. Next, we focus on blockchain solutions for the energy industry and inform the state-of-the-art by thoroughly reviewing the literature and current business cases. To our knowledge, this is one of the first academic, peer-reviewed works to provide a systematic review of blockchain activities and initiatives in the energy sector. Our study reviews 140 blockchain research projects and startups from which we construct a map of the potential and relevance of blockchains for energy applications. These initiatives were systematically classified into different groups according to the field of activity, implementation platform and consensus strategy used. 1 Opportunities, potential challenges and limitations for a number of use cases are discussed, ranging from emerging peer-to-peer (P2P) energy trading and Internet of Things (IoT) applications, to decentralised marketplaces, electric vehicle charging and e-mobility. For each of these use cases, our contribution is twofold: first, in identifying the technical challenges that blockchain technology can solve for that application as well as its potential drawbacks, and second in briefly presenting the research and industrial projects and startups that are currently applying blockchain technology to that area. The paper ends with a discussion of challenges and market barriers the technology needs to overcome to get past the hype phase, prove its commercial viability and finally be adopted in the mainstream.
In this paper, we address the issue of electricity trading in residential electricity market. In recent years, the residential electricity trading has draw more and more attention, the households that produce excessive electricity sell electricity to households that lack of electricity, however the existence of the manage center brings a huge risk to users, once the center goes crashed, the households will suffer economics losses and there is a great possibility of the leakage of users' personal information. To tackle these issues, we propose a peer-to-peer electricity trading mechanism based on blockchain, under our mechanism each user has a distributed ledger maintained by all households and there is no existence of such a manage center, eliminating the danger of all users suffering huge economic losses when the management center goes crashed. Besides, each user in the market can have multiple virtual addresses that are used to sell and purchase electricity, and other users cansellers submit trading information includes unit pricenot identify their identities via virtual addresses, these virtual addresses protect users' privacy from leaking. The experimental results show the consumption of our proposed mechanism is logical and small, which illustrates the reasonability of our mechanism in time consumption.
It has been a long time since Nakamoto Satoshi introduced Bitcoin [1]. However, the underlying technology, blockchain, has been getting more and more attention. It is regarded as one of the most important technology for the fourth industrial revolution, although there exit few the real-world production-level applications due to the hardly tolerant performance of most of the existing blockchain systems. Therefore, how to improve its performance has been identified as one of the most significant research directions in order to use blockchain for practical applications. In this paper, we present a method to build a scalable and extendible blockchain system by multiple chains and sharding techniques.
Alexander Yakubov, Wazen M. Shbair, Nida Khan, Radu State · 6 authors
Pretty Good Privacy (PGP) is one of the most prominent cryptographic standards offering end-to-end encryption for email messages and other sensitive information. PGP allows to verify the identity of the correspondent in information exchange as well as the information integrity. PGP implements asymmetric encryption with certificates shared through a network of PGP key servers. Many recent breaches show that certificate infrastructure can be compromised as well as exposed to operational errors. In this paper we propose a new PGP management framework with the key server infrastructure implemented using blockchain technology. Our framework resolves some problems of PGP key servers focusing in particular on fast propagation of certificate revocation among key servers and elimination of man-in-the-middle risk. We also provided user access right control where only the certificate holder can change information related to the certificate. We designed and developed a prototype for key server deployment on permissioned Ethereum blockchain. Permissioned blockchain should allow to control the costs of PGP key server infrastructure maintenance at the present level.
Blockchain technology which is the fundamental system of Bitcoin running on a peer-to-peer (P2P) network, has attracted a lot of attention. This enables a practical P2P electronic money system with Byzantine fault tolerance and stability with all participating nodes having the same transaction ledger and using a distributed consensus algorithm called Proof of Work (PoW) that performs calculation work called mining. Many studies have proposed methods of enhancing scalability in terms of transaction processing of blockchain, however few studies have proposed them in term of network load in a P2P network architecture. To solve these problems, we propose a method in which all nodes are separated into mining nodes in a pure P2P network and blockchain data having nodes in a distributed hash table (DHT) network. Kademlia is incorporated as DHT network for processing responsible blocks' data for each node cluster and broadcasting efficiently. The results of a broadcast simulation show that our method improved the redundancy rate and average number of messages in the networks.
Blockchain is one of the most heavily invested technologies in recent years. Due to its tamper-proof and decentralization properties, blockchain has become an ideal utility for data storage that is applicable in many real world industrial scenarios. One important scenario is web log, which is treated as sources of technical significance and commercial revenues in major internet companies. In this paper, we illustrate our design of a web log storage system based on HyperLedger. HyperLedger yields higher throughput and lower latency compared with other blockchain systems. Alongside its efficiency advantages., HyperLeger is a permissioned blockchain, which is an ideal fit for enterprise software design scenario.
Jiemin Zhong, Haoran Xie, Di Zou, Dickson K.W. Chui
The blockchain technology has been a hot topic recently due to the skyrocketed price of Bitcoin, and many people have noticed the underlying technology of this cryptocurrency and applied it in diverse areas like finance or commerce industry. However, the application of blockchain in education is limited, which is a pity as the blockchain technology can address many issues like insufficient user interactivity and system interoperability in the e-learning systems. This paper aims to propose a conceptual model for e-learning systems and use word-learning community as an example by adopting the blockchain technology to address the above issues. The potential applications of blockchain are introduced and discussed, and a system evaluation is conducted based on an ISO quality model to verify the effectiveness of the proposed model.
Blockchain is an innovative distributed ledger technology which has attracted a wide range of interests for building the next generation of applications to address lack-of-trust issues in business. Blockchain as a service (BaaS) is a promising solution to improve the productivity of blockchain application development. The existing BaaS solutions mostly focus on easier and faster deployment of blockchain applications. However, design of blockchain applications is challenging to developers as it requires development experiences and deep understanding of blockchain technologies. Therefore, this paper summarises a set of design patterns and delivers them as a service to support design of blockchain application. We present a service platform which applies design patterns for data management and smart contract design of blockchain applications to address the scalability and security issues of blockchain. The platform also provides two auxiliary services, including key management and file comparison, which are often needed in blockchain applications. The feasibility of the proposed solutions is evaluated using a real-world quality tracing use case.
Daniela Mechkaroska, Vesna Dimitrova, Aleksandra Popovska‐Mitrovikj
Bitcoin and Smart Contract are the first major applications of the BlockChain technology. But, with increasing the number of transactions, the process of verification on every transaction is very slow. This is the reason for a third major innovation called a BlockChain scaling. The scalability is a process of taking certain steps in accelerating the performing of transactions in this new technology. In this paper we analyze the possibilities for BlockChain scalability and we examine the advantages and disadvantages of the proposed solutions.
Recently, the interest in using Blockchain as a secure and distributed ledger has increased dramatically. Although the main purpose of Blockchain by means of Bitcoin was about cryptocurrency and peer to peer transactions, its application to other systems has been widely used. One of the fields that has potential possibilities to benefit from BlockChain features is telecommunication. BlockChain can be applied in case of management of various networks to reduce some expenses. In this position paper, we apply a BlockChain network with smart contract in the cellular mobile networks. The Blockchain can provide a distributed HSS in a way that the core networks of different operators can use it in a secure manner. Moreover, the smart contract can act as a distributed Self Organizing Network features to handle self-transactions among mobile operators in return of sharing small cells' infrastructure.
Among several common financing methods for solar project, loans from banks requires many conditions that are not easy to meet. Finance lease is easier to acquire but the interest rate is usually higher than loans. Internet financing lacks credibility and efficient regulation methods. Blockchain provides a decentralized, tamper-resistant, auditable ledger. This paper proposed a design of photovoltaic plants financing platform based on blockchain technology. The open source blockchain framework Fabric is used and smart contracts are developed to conduct automatic and compulsory transactions, thus improving the efficiency of financing process.
Blockchains were originally used to support the Bitcoin cryptocurrency and now entire software ecosystems are being supported by blockchains. Despite their widespread use, not much is known about how peers in the bitcoin blockchain network use the system. We present visualizations to help in identifying some patterns in the usage of bitcoin blockchain supported technologies. In this paper, we observe the bitcoin transaction continent-wise via a visualization of the locations from where peers in the bitcoin blockchain network were making their transactions, using WebGL technology. We analyzed regional bitcoin blockchain usage patterns by observing their clusters formation over time. We also presented a pattern of how the value of the bitcoin changes over time.
Emmanuelle Anceaume, Antoine Guellier, Romaric Ludinard, Bruno Séricola
We propose a new way to organise both transactions and blocks in a distributed ledger to address the performance issues of permissionless ledgers. In contrast to most of the existing solutions in which the ledger is a chain of blocks extracted from a tree or a graph of chains, we present a distributed ledger whose structure is a balanced directed acyclic graph of blocks. We call this specific graph a SYC-DAG. We show that a SYC-DAG allows us to keep all the remarkable properties of the Bitcoin blockchain in terms of security, immutability, and transparency, while enjoying higher throughput and self-adaptivity to transactions demand. To the best of our knowledge, such a design has never been proposed so far.
Purpose The purpose of this paper is to examine the blockchain as a trusted computing platform. Understanding the strengths and limitations of this platform is essential to execute large-scale real-world applications in blockchains. Design/methodology/approach This paper proposes several modifications to conventional blockchain networks to improve the scale and scope of applications. Findings Simple modifications to cryptographic protocols for constructing blockchain ledgers, and digital signatures for authentication of transactions, are sufficient to realize a scalable blockchain platform. Originality/value The original contributions of this paper are concrete steps to overcome limitations of current blockchain networks.
Ethereum is the second most valuable cryptocurrency today, with a current market cap of over $68B. What sets Ethereum apart from other cryptocurrencies is that it uses the blockchain to not only store a record of transactions, but also smart contracts and a history of calls made to those contracts. Thus, Ethereum represents a new form of distributed system: one where users can implement contracts that can provide functionality such as voting protocols, crowdfunding projects, betting agreements, and many more. However, despite the massive investment, little is known about how contracts in Ethereum are actually created and used.
Ethereum, the second-largest cryptocurrency valued at a peak of $138 billion in 2018, is a decentralized, Turing-complete computing platform. Although the stability and security of Ethereum---and blockchain systems in general---have been widely-studied, most analysis has focused on application level features of these systems such as cryptographic mining challenges, smart contract semantics, or block mining operators. Little attention has been paid to the underlying peer-to-peer (P2P) networks that are responsible for information propagation and that enable blockchain consensus. In this work, we develop NodeFinder to measure this previously opaque network at scale and illuminate the properties of its nodes. We analyze the Ethereum network from two vantage points: a three-month long view of nodes on the P2P network, and a single day snapshot of the Ethereum Mainnet peers. We uncover a noisy DEVp2p ecosystem in which fewer than half of all nodes contribute to the Ethereum Mainnet. Through a comparison with other previously studied P2P networks including BitTorrent, Gnutella, and Bitcoin, we find that Ethereum differs in both network size and geographical distribution.
One of the defining features of a cryptocurrency is that its ledger, containing all transactions that have ever taken place, is globally visible. As one consequence of this degree of transparency, a long line of recent research has demonstrated that--even in cryptocurrencies that are specifically designed to improve anonymity--it is often possible to track money as it changes hands, and in some cases to de-anonymize users entirely. With the recent proliferation of alternative cryptocurrencies, however, it becomes relevant to ask not only whether or not money can be traced as it moves within the ledger of a single cryptocurrency, but if it can in fact be traced as it moves across ledgers. This is especially pertinent given the rise in popularity of automated trading platforms such as ShapeShift, which make it effortless to carry out such cross-currency trades. In this paper, we use data scraped from ShapeShift over a thirteen-month period and the data from eight different blockchains to explore this question. Beyond developing new heuristics and creating new types of links across cryptocurrency ledgers, we also identify various patterns of cross-currency trades and of the general usage of these platforms, with the ultimate goal of understanding whether they serve a criminal or a profit-driven agenda.
In the traditional educational understanding, individuals follow the path of getting graduate or post-graduate education if they wish, after continuing their education from kindergarten to high school. Today, by getting out of this stereotype, every literate person can choose different learning environments. Now, learning any subject is up to the tip of the fingers of an individual without depending on a school building with four walls or on certain time frame. In this study, it is aimed to verify digital certificates given to the participants at the Turkish stage of the International Informatics and Computational Thinking event by using Ethereum Block Chain based smart contract. The tasks in the event were transmitted to the students in Turkey via using exam module of the Moodle Learning Management System. For this study, first a smart contract was developed in which the certificate information could be stored on the Ethereum blockchain and could be check for control purposes if necessary. Then the certificate module developed by the researcher in 2014 which uses block structure in the Moodle Learning Management System was updated and then provided to work in accordance with the smart contract in the Ethereum blockchain.
Since the inception of blockchain and Bitcoin (Nakamoto (2008)), a decentralized-distributed ledger system and its associated cryptocurrency, respectively, the world has witnessed a slew of newer adaptations and applications. Although the original distributed ledger technology (DLT) of blockchain is deemed secure and decentralized, the confirmation of transactions is inefficient by design. Recently adopted, directed acyclic graph (DAG)-based distributed ledgers validate transactions efficiently without the physically and environmentally costly building process of blocks (Lerner (2015)). However, centrally-controlled confirmation against the odds of multiple validation disqualifies the DAG as a decentralized-distributed ledger. In this regard, we introduce an innovative DLT by reconstructing a chain of antichains based on a given DAG-pool of transactions. Each antichain (box) contains distinct nodes whose approved transactions are recursively validated by subsequently augmenting nodes. The boxer node closes the box and keeps the hash of all transactions confirmed by the box-genesis node. Designation of boxers and box-geneses is conditionally randomized for decentralization. The boxes are serially concatenated with recursive confirmation (boxchain) without incurring the cost of box generation. Rewards (boxcoin) are paid to the contributing nodes of the ecosystem whose trust is built on the doubly-secure protocol of confirmation. A value-preserving medium of payment (boxdollar) is among numerous practical applications discussed herein.