The blockchain paradigm provides a mechanism for content dissemination and distributed consensus on Peer-to-Peer (P2P) networks. While this paradigm has been widely adopted in industry, it has not been carefully analyzed in terms of its network scaling with respect to the number of peers. Applications for blockchain systems, such as cryptocurrencies and IoT, require this form of network scaling. In this paper, we propose a new stochastic network model for a blockchain system. We identify a structural property called \emph{one-endedness}, which we show to be desirable in any blockchain system as it is directly related to distributed consensus among the peers. We show that the stochastic stability of the network is sufficient for the one-endedness of a blockchain. We further establish that our model belongs to a class of network models, called monotone separable models. This allows us to establish upper and lower bounds on the stability region. The bounds on stability depend on the connectivity of the P2P network through its conductance and allow us to analyze the scalability of blockchain systems on large P2P networks. We verify our theoretical insights using both synthetic data and real data from the Bitcoin network.
Yan Zhang, Bing Li, Ben Liu, Jiaxin Wu · 6 authors
The Internet of Things (IoT) benefits our lives by integrating physical devices to the real world and offers a crucial internet infrastructure for future civilization. Because IoT devices are widely distributed and restricted in resources, it is difficult for them to adopt traditional security methods to resist malicious attacks. Unauthorized access to IoT devices, which results in severe privacy and security problems, has become a major challenge that has impeded IoT technology from being widely adopted. Therefore, the access control for IoT devices urgently needs to be improved when dealing with authorization issues. In this paper, we propose an attribute-based access control scheme that provides decentralized, flexible, and fine-grained authorization for IoT devices. Blockchain is utilized to provide authentic and reliable credentials. More importantly, a verifiable collaboration mechanism is designed to meet the needs of controlled access authorization in emergencies. Authority nodes are constructed to execute major computation tasks and interact with the blockchain. The security analysis shows that our scheme can reliably guarantee the security of authorized access. More than security assurance, a proof-of-concept prototype has been implemented to prove that our scheme is scalable, efficient, and accommodates IoT devices well.
Jianhong Lin, Kevin Primicerio, Tiziano Squartini, Christian Decker · 5 authors
Abstract The Bitcoin lightning network (BLN), a so-called ‘second layer’ payment protocol, was launched in 2018 to scale up the number of transactions between Bitcoin owners. In this paper, we analyse the structure of the BLN over a period of 18 months, ranging from 12th January 2018 to 17th July 2019, at the end of which the network has reached 8.216 users, 122.517 active channels and 2.732,5 transacted Bitcoins. Here, we consider three representations of the BLN: the daily snapshot one, the weekly snapshot one and the daily-block snapshot one. By studying the topological properties of the binary and weighted versions of the three representations above, we find that the total volume of transacted Bitcoins approximately grows as the square of the network size; however, despite the huge activity characterising the BLN, the Bitcoins distribution is very unequal: the average Gini coefficient of the node strengths (computed across the entire history of the Bitcoin lightning network) is, in fact, ≃0.88 causing the 10% (50%) of the nodes to hold the 80% (99%) of the Bitcoins at stake in the BLN (on average, across the entire period). This concentration brings up the question of which minimalist network model allows us to explain the network topological structure. Like for other economic systems, we hypothesise that local properties of nodes, like the degree, ultimately determine part of its characteristics. Therefore, we have tested the goodness of the undirected binary configuration model (UBCM) in reproducing the structural features of the BLN: the UBCM recovers the disassortative and the hierarchical character of the BLN but underestimates the centrality of nodes; this suggests that the BLN is becoming an increasingly centralised network, more and more compatible with a core-periphery structure. Further inspection of the resilience of the BLN shows that removing hubs leads to the collapse of the network into many components, an evidence suggesting that this network may be a target for the so-called split attacks .
BatPay is a proxy scaling solution for the transfer of ERC20 tokens. It is suitable for micropayments in one-to-many and few-to-many scenarios, including digital markets and the distribution of rewards and dividends. In BatPay, many similar operations are bundled together into a single transaction in order to optimize gas consumption on the Ethereum blockchain. In addition, some costly verifications are replaced by a challenge game, pushing most of the computing cost off-chain. This results in a gas reduction of the transfer costs of three orders of magnitude, achieving around 1700 transactions per second on the Ethereum blockchain. Furthermore, it includes many relevant features, like meta-transactions for end-user operation without ether, and key-locked payments for atomic exchange of digital goods.
Personal IoT data is a new economic asset that individuals can trade to generate revenue on the emerging data marketplaces. Typically, marketplaces are centralized systems that raise concerns of privacy, single point of failure, little transparency and involve trusted intermediaries to be fair. Furthermore, the battery-operated IoT devices limit the amount of IoT data to be traded in real-time that affects buyer/seller satisfaction and hence, impacting the sustainability and usability of such a marketplace. This work proposes to utilize blockchain technology to realize a trusted and transparent decentralized marketplace for contract compliance for trading IoT data streams generated by battery-operated IoT devices in real-time. The contribution of this paper is two-fold: (1) we propose an autonomous blockchain-based marketplace equipped with essential functionalities such as agreement framework, pricing model and rating mechanism to create an effective marketplace framework without involving a mediator, (2) we propose a mechanism for selection and allocation of buyers' demands on seller's devices under quality and battery constraints. We present a proof-of-concept implementation in Ethereum to demonstrate the feasibility of the framework. We investigated the impact of buyer's demand on the battery drainage of the IoT devices under different scenarios through extensive simulations. Our results show that this approach is viable and benefits the seller and buyer for creating a sustainable marketplace model for trading IoT data in real-time from battery-powered IoT devices.
John Kolb, Moustafa AbdelBaky, Randy H. Katz, David Culler
Blockchains are a topic of immense interest in academia and industry, but their true nature is often obscured by marketing and hype. In this tutorial, we explain the fundamental elements of blockchains. We discuss their ability to achieve availability, consistency, and data integrity as well as their inherent limitations. Using Ethereum as a case study, we describe the inner workings of blockchains in detail before comparing blockchains to traditional distributed systems. In the second part of our tutorial, we discuss the major challenges facing blockchains and summarize ongoing research and commercial offerings that seek to address these challenges.
Christian Sillaber, Bernhard Waltl, Horst Treiblmaier, Ulrich Gallersdörfer · 5 authors
Abstract Smart contracts are seen as the major building blocks for future autonomous blockchain- and Distributed Ledger Technology (DLT)-based applications. Engineering such contracts for trustless, append-only, and decentralized digital ledgers allows mutually distrustful parties to transform legal requirements into immutable and formalized rules. Previous experience shows this to be a challenging task due to demanding socio-technical ecosystems and the specificities of decentralized ledger technology. In this paper, we therefore develop an integrated process model for engineering DLT-based smart contracts that accounts for the specificities of DLT. This model was iteratively refined with the support of industry experts. The model explicitly accounts for the immutability of the trustless, append-only, and decentralized DLT ecosystem, and thereby overcomes certain limitations of traditional software engineering process models. More specifically, it consists of five successive and closely intertwined phases: conceptualization, implementation, approval, execution, and finalization. For each phase, the respective activities, roles, and artifacts are identified and discussed in detail. Applying such a model when engineering smart contracts will help software engineers and developers to better understand and streamline the engineering process of DLTs in general and blockchain in particular. Furthermore, this model serves as a generic framework which will support application development in all fields in which DLT can be applied.
Alberto Garoffolo, Dmytro Kaidalov, Roman Oliynykov
Sidechains are an appealing innovation devised to enable blockchain scalability and extensibility. The basic idea is simple yet powerful: construct a parallel chain -- sidechain -- with desired features, and provide a way to transfer coins between the mainchain and the sidechain. In this paper, we introduce Zendoo, a construction for Bitcoin-like blockchain systems that allows the creation and communication with sidechains of different types without knowing their internal structure. We consider a parent-child relationship between the mainchain and sidechains, where sidechain nodes directly observe the mainchain while mainchain nodes only observe cryptographically authenticated certificates from sidechain maintainers. We use zk-SNARKs to construct a universal verifiable transfer mechanism that is used by sidechains. Moreover, we propose a specific sidechain construction, named Latus, that can be built on top of this infrastructure, and realizes a decentralized verifiable blockchain system for payments. We leverage the use of recursive composition of zk-SNARKs to generate succinct proofs of sidechain state progression that are used to generate certificates' validity proofs. This allows the mainchain to efficiently verify all operations performed in the sidechain without knowing any details about those operations.
Iago Sestrem Ochôa, Luís Augusto Silva, Gabriel de Mello, Nuno M. García · 6 authors
Smart grid systems have become popular and necessary for the development of a sustainable power grid. These systems use different technologies to provide optimized services to the users of the network. Regarding computing, these systems optimize electrical services by processing a large amount of the data generated. However, privacy and security are essential in this kind of system. With a large amount of data generated, it is necessary to protect the privacy of users, because this data may reveal the users' personal information. Today, blockchain technology has proven to be an efficient architecture for solving privacy and security problems in different scenarios. Over the years, different blockchain platforms have emerged, attempting to solve specific problems in different areas. However, the use of different platforms fragmented the market, which was no different in the smart grid scenario. This work proposes a blockchain architecture that uses sidechains to make the system scalable and adaptable. We used three blockchains to ensure privacy, security, and trust in the system. To universalize the proposed solution, we used the Open Smart Grid Protocol and smart contracts. The results show that architecture security and privacy are guaranteed, making it feasible for implementation in real systems; although scalability issues regarding the storage of the data generated still exist.
The Rapid growth of agile gadgets has led to tremendous increase in digital media utilization, mostly for mobile video in ease of marketing. As encryption provides better user confidentiality and perseveration, greater number of online movement is associated with end-to-end encryption form. Irrevlant content such as unreal, violent and unconstitutional videos are being circulated online without being identified its truthfulness creating a platform for intruders and attackers. It is necessary for users to identify and report the contents of the video. Sometimes these videos act as evidence in courts to prove the guilty and the proper state and contents recorded in it .We aim a system to detect and classify the video's truthfulness to solve these problems. A detailed collection of studies has been toted to demonstrate the efficacy of new program over current literature.
Open access
Advanced Steganography and Watermarking Techniques
Cryptocurrencies are nowadays one of the most important alternative investment markets and therefore have been in spotfor regulatory purposes. One of the main characteristics is to be easy traded all over the world without governmentalinterference
Two taxonomies of money that include cryptocurrencies are analyzed. A definition of the term cryptocurrency is given and a taxonomy of them is presented, based on how its price is fixed. The characteristics of the use of current fiat money and the operation of two-level banking systems are discussed. Cryptocurrencies are compared with fiat money and the aspects in which the latter cannot be overcome are indicated. The characteristics of blockchains and databases are described. The possible cases of use of both technologies are compared, and it is noted that blockchains, in addition to cryptocurrencies and certain records, have not yet shown their usefulness, while databases constitute the foundation of most of the automated systems in operation.
Cyril Grunspan, Gabriel Lehéricy, Ricardo Pérez-Marco
The ambition of the Lightning Network is to provide a second layer to the Bitcoin network to enable transactions confirmed instantly, securely and anonymously with a world scale capacity using a decentralized protocol. Some of the current propositions and implementations present some difficulties in anonymity, scaling and decentalization. The Ant Routing algorithm for the Lightning Network was proposed in \cite{GrunspanPerez} for maximal decentralization, anonymity and potential scaling. It solves several problems of current implementation, such as channel information update and centralization by beacon nodes. Ant Routing nodes play all the same role and don't require any extra information on the network topology beside for their immediate neighbors. The goal of LN transactions are completed instantaneously and anonymously. We study the scaling of the Ant Routing protocol. We propose a precise implementation, with efficient memory management using AVL trees. We evaluate the efficiency of the algorithm and we estimate the memory usage of nodes by local node workload simulations. We prove that the number of transactions per second that Ant Routing can sustain is of the order of several thousands which is enough for a global payment network.
Numberlink is a logic puzzle with an objective to connect all pairs of cells with the same number by non-crossing paths in a rectangular grid. In this paper, we propose a physical protocol of zero-knowledge proof for Numberlink using a deck of cards, which allows a prover to convince a verifier that he/she knows a solution without revealing it. In particular, the protocol shows how to physically count the number of elements in a list that are equal to a given secret value without revealing that value, the positions of elements in the list that are equal to it, or the value of any other element in the list. Finally, we show that our protocol can be modified to verify a solution of the well-known $k$ vertex-disjoint paths problem, both the undirected and directed settings.
Regional Autonomy in the reform era along with changes in legislation regarding the management of the education financing system has had a serious impact on the education system that was initially centralizedto decentralized. This change has a positive impact on the region in the management of education, especially financing in the process of advancing education in each region, especially Islamic education. Because the needs of each region differ in conditions and problems, the central government provides a mandatory through the basic law in Law No. 22 of 1999 concerning regional government and Law No. 25 of 1999 concerning financial balance between the central government and the regions, which was later revised to Law No. 32 of 2004 concerning regional government and Law No. 33 of 2004, namely the regulation of two new regional revenue sources, namely regional balance funds and loans. With the decentralization of central authority to the regions means that a region is given the opportunity to recognize and find solutions to the problems of the region in advancing Islamic education.
Although business models presumably have a prominent role in socio-technical change remarkably little research has been conducted in this domain, more particularly in the context of developing economies. In this paper, we tap into this knowledge gap and study business model components and the challenges they face. We argue that the market value of renewable energy technologies will increase when new business models are implemented to overcome financial and institutional challenges. We complement concepts of the business model literature with the insights from the sustainable transitions literature. This paper addresses two research questions: What are the challenges of business and financial models in the transition towards decentralized solar energy driven systems? And what are the promising opportunities for new business models in a developing country context? To answer these research questions, we use a case study research design focusing on niche market development of solar thermal and solar photovoltaic (PV) technology in Lebanon. Data collection involved analysis of relevant text documents and expert interviews with 30 informants across different groups of stakeholders. Data analysis involved qualitative interpretation of collected data against concepts from the business model and Strategic Niche Management literatures. The results show that business model challenges initially were highly dependent on donor aid, which contributed to the launch and network creation of niche markets. Later, a shift to micro-finance and business startup models was observed, which showed promising development. Knowledge transfer and community empowerment were found to play an important role in developing new business models that involve consumers more closely. As this development is expected to take place more often, we expect that new opportunity pathways will develop in developing economies like Lebanon.
Blockchain shows great potential to be applied in wireless IoT ecosystems for establishing the trust and consensus mechanisms without central authority's involvement. Based on RAFT consensus mechanism, this letter investigates the security performance of wireless blockchain networks in the presence of malicious jamming. We first map and model the blockchain transaction as a wireless network composed of uplink and downlink transmissions by assuming the follower nodes' position as a Poisson Point Process (PPP) with selected leader location. The probability of achieving successful blockchain transactions is derived and verified by extensive simulations. The results provide analytical guidance for the practical deployment of wireless blockchain networks.
Smart cameras and image sensors are widely used in industrial processes, from the designing to the quality checking of the final product. Images generated by these sensors are at continuous risk of disclosure and privacy breach in the industrial Internet of Things (IIoT). Traditional solutions to secure sensitive data fade in IIoT environments because of the involvement of third parties. Blockchain technology is the modern-day solution for trust issues and eliminating or minimizing the role of the third party. In the context of the IIoT, we propose a permissioned private blockchain-based solution to secure the image while encrypting it. In this scheme, the cryptographic pixel values of an image are stored on the blockchain, ensuring the privacy and security of the image data. Based on the number of pixels change rate (NPCR), the unified averaged changed intensity (UACI), and information entropy analysis, we evaluate the strength of proposed image encryption algorithm ciphers with respect to differential attacks. We obtained entropy values near to an ideal value of 8, which is considered to be safe from brute force attack. Encrypted results show that the proposed scheme is highly effective for data leakage prevention and security.
Open access
Chaos-based Image/Signal Encryption
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
As eBook readers have expanded on the market, various online eBook markets have arisen as well. Currently, the online eBook market consists of at least publishers and online platform providers and authors, and these actors inevitably incur intermediate costs between them. In this paper, we introduce a blockchain-based eBook market system that enables self-published eBook trading and direct payments from readers to authors without any trusted party; because authors publish themselves and readers purchase directly from authors, neither actor incurs any intermediate costs. However, because of this trustless environment, the validity, ownership and intellectual property of digital contents cannot be verified and protected, and the safety of purchase transactions cannot be ensured. To address these shortcomings, we propose a secure and reliable eBook transaction system that satisfies the following security requirements: (1) verification of the ownership of each eBook, (2) confidentiality of eBook contents, (3) authorization of a right to read a book, (4) authentication of a legitimate purchaser, (5) verification of the validity and integrity of eBook contents, (6) safety of direct purchase transactions, and (7) preventing eBook piracy and illegal distribution. We provide practical cryptographic protocols for the proposed system and analyze the security and simulated performance of the proposed schemes.
Open access
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
The optimal deployment of heterogeneous energy storage (HES), mainly consisting of electrical and thermal energy storage, is essential for increasing the holistic energy utilization efficiency of multienergy systems. Consequently, this article proposes a risk-averse method for HES deployment in a residential multienergy microgrid (RMEMG), considering the diverse uncertainties and multienergy demand-side management (DSM). Apart from the HES size and location planning, its optimal investment phase is also determined by maximizing the system equivalent daily profit (EDP) and minimizing the risk. To handle the system uncertainties from renewable energy sources, power demands, outdoor temperature, and residential hot water needs, the multistage adaptive stochastic optimization approach is utilized. Then, through the constraint linearization and stochastic scenario sampling, the original nonlinear deployment model is converted to a mixed-integer linear programming one and tested on an IEEE 33-bus distribution network based RMEMG. The effectiveness of the proposed method is verified by comparing it with the existing practices. The comparison results indicate that the proposed risk-averse deployment method can effectively increase the system EDP and more immune to the uncertainties. Besides, this method can be practically applied for the emerging RMEMGs, such as smart buildings, intelligent homes, etc., which get long-term DSM contracts.
Monitoring and keeping track of the health status of a patient at home is a difficult task.Especially old age patients should be periodically monitored and their health status needs to be informed to the concerned doctor from time to time so that an immediate required action can be taken.Our aim is to address these challenges.In this paper, we propose a system that puts forward a smart health monitoring system that uses sensors to track patient's health and uses internet to inform their respective doctor or family members in case of any emergency issues.The system is developed for patients who are not in critical condition but need to be periodically monitored by the doctor or any family member.Our system uses temperature as well as heartbeat sensor to keep track of patient health.It mainly focuses on the situation where the doctors and patients are at distant location and it is very important to give the entire details about the patient to the doctor.If the system detects any abrupt changes such as body temperature rises above the given limit or abnormality in the heartbeat, the system automatically alerts the doctor about the patient's status over IOT device.As per tracked by the smart patient health monitoring system, the doctor can take the required action.The information that has been sent to the doctor can be made secure without any interference of the third party through Blockchain technology by making use of smart contract.
Multiple-operators (multi-OPs) spectrum sharing mechanism can effectively improve the spectrum utilization in fifth-generation (5G) wireless communication networks. The secondary users are introduced to opportunistically access the licensed spectrum of idle operators (OPs). However, the identity privacy and data security issues raise great concerns about the secure spectrum sharing among multi-OPs. To address these challenges, a consortium blockchain trust framework is proposed for the spectrum sharing in multi-OPs wireless communication networks in this paper. A real consortium blockchain is constructed among multi-OPs. The Multi-Ops Spectrum Sharing (MOSS) smart contract is designed on the constructed consortium blockchain to implement the spectrum trading among multi-OPs. Without the need of trustless spectrum broker, the MOSS smart contract enforces multi-OPs to share the spectrum truthfully and designs a punishment mechanism to punish malicious OPs. Simulation results tested on the Remix integrated development environment (IDE) indicate the feasibility of the designed MOSS smart contract. The performance analysis of the proposed consortium blockchain trust framework demonstrates that the privacy, openness and fairness of the proposed solution are better than traditional spectrum allocation solutions.