Recently, a new generation of P2P systems capable of addressing data integrity and authenticity has emerged for the development of new applications for a "more" decentralized Internet, i.e., Distributed Ledger Technologies (DLT) and Decentralized File Systems (DFS). However, these technologies still have some unanswered issues, mostly related to data lookup and discovery. In this paper, first, we propose a Distributed Hash Table (DHT) system that efficiently manages decentralized keyword-based queries executed on data stored in DFS. Through a hypercube logical layout, queries are efficiently routed among the network, where each node is responsible for a specific keywords set and the related contents. Second, we provide a framework for the governance of the above network, based on a Decentralized Autonomous Organization (DAO) implementation. We show how the use of smart contracts enables organizational decision making and rewards for nodes that have actively contributed to the DHT. Finally, we provide experimental validation of an implementation of our proposal, where the execution of the same protocol for different logical nodes of the hypercube allows us to evaluate the efficiency of communication within the network.
There are a growing number of blockchain applications in energy systems, but surprisingly little is known about their direct energy demand outside of cryptocurrency applications. Addressing this knowledge gap should be a key policy priority so that the energy use of blockchain systems can be better understood and managed as applications proliferate. To help policy makers and energy analysts achieve this goal, this article makes three contributions. First, we present a brief review of blockchain system components, energy demand drivers, and emerging applications to provide a common conceptual foundation. Second, we propose best practices for energy analysis of blockchain systems and identify best practice lapses in previous literature that presently cloud our understanding of energy use. Finally, we propose priority research areas to address identified lapses and knowledge gaps, which would ensure future research produces data and estimates that are maximally relevant to energy policy decisions.
IOTA is a distributed ledger technology (DLT) platform proposed for the internet of things (IoT) systems in order to tackle the limitations of Blockchain in terms of latency, scalability, and transaction cost. The main concepts used in IOTA to reach this objective are a directed acyclic graph (DAG) based ledger, called Tangle, used instead of the chain of blocks, and a new validation mechanism that, instead of relying on the miners as it is the case in Blockchain, relies on participating nodes that cooperate to validate the new transactions. Due to the different IoT capabilities, IOTA classifies these devices into full and light nodes. The light nodes are nodes with low computing resources which seek full nodes' help to validate and attach its transaction to the Tangle. The light nodes are manually connected to the full nodes by using the full node IP address or the IOTA client load balancer. This task distribution method overcharges the active full nodes and, thus, reduces the platform's performance. In this paper, we introduce an efficient mechanism to distribute the tasks fairly among full nodes and hence achieve load balancing. To do so, we consider the task allocation between the nodes by introducing an enhanced resource allocation scheme based on the weight least connection algorithm (WLC). To assess its performance, we investigate and test different implementation scenarios. The results show an improved balancing of data traffic among full nodes based on their weights and number of active connections.
As IoT (Internet of Things) devices are diversified in the fields of use (manufacturing, health, medical, energy, home, automobile, transportation, etc.), it is becoming important to analyze and process data sent and received from IoT devices connected to the Internet. Data collected from IoT devices is highly dependent on secure storage in databases located in cloud environments. However, storing directly in a database located in a cloud environment makes it not only difficult to directly control IoT data, but also does not guarantee the integrity of IoT data due to a number of hazards (error and error handling, security attacks, etc.) that can arise from natural disasters and management neglect. In this paper, we propose an optimized hash processing technique that enables hierarchical distributed processing with an n-bit-size blockchain to minimize the loss of data generated from IoT devices deployed in distributed cloud environments. The proposed technique minimizes IoT data integrity errors as well as strengthening the role of intermediate media acting as gateways by interactively authenticating blockchains of n bits into n + 1 and n - 1 layers to normally validate IoT data sent and received from IoT data integrity errors. In particular, the proposed technique ensures the reliability of IoT information by validating hash values of IoT data in the process of storing index information of IoT data distributed in different locations in a blockchain in order to maintain the integrity of the data. Furthermore, the proposed technique ensures the linkage of IoT data by allowing minimal errors in the collected IoT data while simultaneously grouping their linkage information, thus optimizing the load balance after hash processing. In performance evaluation, the proposed technique reduced IoT data processing time by an average of 2.54 times. Blockchain generation time improved on average by 17.3% when linking IoT data. The asymmetric storage efficiency of IoT data according to hash code length is improved by 6.9% on average over existing techniques. Asymmetric storage speed according to the hash code length of the IoT data block was shown to be 10.3% faster on average than existing techniques. Integrity accuracy of IoT data is improved by 18.3% on average over existing techniques.
Due to the distributed and dynamic characteristics of the Internet of Vehicles (IoV) and the continuous growth in the number of devices, content-centric decentralized vehicular named data networking (VNDN) has become more suitable for content-oriented applications in IoV. However, the existing centralized architecture is prone to the failure of single points, which results in trust problems in key verification between cross-domain nodes and consuming more power and reducing the lifetime. Focusing on secure key management and power-efficient routing, this article proposes a blockchain-based key management and green routing scheme for VNDN. A blockchain-based key management scheme is presented to achieve secure and efficient distribution and verification of keys. Specifically, all trusted agencies (TAs) form a consortium blockchain for storing public key hashes to ensure the authenticity of users’ public keys. A green global routing scheme based on node relaying pressure (GGNRP) is proposed to save power consumption and reduce the forwarding delay. A new node relay pressure metric is introduced to assist with routing decisions. Detailed experiments and analysis show that, compared with the existing scheme, the proposed scheme can achieve secure key management and GGNRP can decrease the power consumption and average delay by 15.8% and 63.2%, respectively.
Blockchain being a leading technology in the 21st century is revolutionizing each sector of life. Services are being provided and upgraded using its salient features and fruitful characteristics. Businesses are being enhanced by using this technology. Countries are shifting towards digital currencies i.e., an initial application of blockchain application. It omits the need of central authority by its distributed ledger functionality. This distributed ledger is achieved by using a consensus mechanism in blockchain. A consensus algorithm plays a core role in the implementation of blockchain. Any application implementing blockchain uses consensus algorithms to achieve its desired task. In this paper, we focus on provisioning of a comparative analysis of blockchain’s consensus algorithms with respect to the type of application. Furthermore, we discuss the development platforms as well as technologies of blockchain. The aim of the paper is to provide knowledge from basic to extensive from blockchain architecture to consensus methods, from applications to development platform, from challenges and issues to blockchain research gaps in various areas.
The innovation provided by network virtualization in 5G, together with standardization and openness boosted by the Open Radio Access Network (O-RAN) Alliance, has paved the way to a collaborative future in cellular systems, driven by flexible network sharing. Such advents are expected to attract new players like content providers and verticals, increasing competitiveness in the telecom market. However, scalability and trust issues are expected to arise, given the criticality of ownership traceability and resource exchanging in a sharing ecosystem. To address that, we propose integrating blockchain technology for enabling mobile operators and other players to exchange radio access network (RAN) resources (e.g., infrastructure) in the form of virtual network functions autonomously and dynamically. Blockchain will provide automation, robustness, trustworthiness, and reliability to mobile networks, thus bringing confidence to open RAN environments. In particular, we define a novel O-RAN-based blockchain-enabled architecture that allows automating RAN sharing procedures through either auction or marketplace-based mechanisms. The potential advantages of the proposed solution are demonstrated through simulation results. The used simulation platform is openly released.
The days, the usage of E-commerce applications in the distributed network has been increasing progressively. These applications bring many advantages such as online shopping from different places. For the sake of simplicity, offloading data of applications from user devices to servers lead to many research challenges. This paper devises a novel blockchain-enabled system for E-commerce applications. The network consists of ethereum nodes that can implement symmetric security to provide valid and secure hashing of data in distributed computing. The simulation results show that the proposed blockchain-enabled system outperforms all existing systems in terms of security
Summary Ethereum is arguably the second most popular cryptocurrency‐based network after Bitcoin. Both use the distributed ledger technology known as the blockchain, which is considered secure. However, the provided security level is proportional to the number of connected nodes, the number of influential nodes, and the supported amount of hash power. Thus, the knowledge of the network properties and nodes' behavior is helpful to protect the network from possible attacks such as double‐spending attacks, DDoS attacks, 51% attacks, and Sybil attacks. This paper proposes a node discovery mechanism, which performs a P2P link discovery on the Ethereum main network. For that, we develop Search‐node, a modified version of Ethereum client that searches for all participating nodes in the blockchain network, stores the node information in the Bucket, and then processes the peer discovery method. Based on the collected data, we first visualize the Ethereum network topology and analyze the attributes of the network such as node degree, path length, diameter, and clustering coefficient. We then analyze the node properties and provide analytical results regarding the relationship between nodes, heavily connected nodes, node geo‐distribution, security issues, and possible attacks over the influential nodes. As a result, we have identified 68,406 nodes with a total of 642,034 edges. By analyzing the collected data, we have found that the diameter in the Ethereum network is equal to 8. The node degree is over 19, which is two times higher than the default configuration.
We are proposing an approach employing microgrid through which community can efficiently fulfill each other needs of energy. This model will allow micro-grid prosumers to produce, consume and trade energy deprived of any barrier. At present, such a system is not accepted because it requires the “collaboration” of central energy distributors. In our solution, we visualize the use of a blockchain system with the support of smart contracts to provide decentralization. The energy is sent to the central energy storage from the prosumer and is stored there until the consumer claims it. Using smart energy (electricity) meters the flow of electricity can be tracked accurately in both ways, neighbors can purchase spare electricity using tokens rather than paying money. As blockchain takes care of the accounting part, it records the terms of the contracts, tracks how many energy credits have been sold, by whom and to whom. The micro-grid is facilitated by its own smart contract and it can share a desired amount of energy to a connected energy consumer. The customer is aware of how much consumption energy is available at any time in the central storage. The smart contract of the micro-grid takes as input HECs (helios coin) or a bit coin and then releases the energy that corresponds to the calculated amount of HECs or bit coin received by the sender in form of the payment. The test is to monitor these exchanges and repay purchasers and dealers likewise. This project is an effort to utilize blockchain methodology for the trade of sun-based power among members effectively, without any need of third party vendors.
Le concept de villes intelligentes gagne de plus en plus en importance dans les métropoles modernes en raison de l’émergence et de la diffusion d’appareils, de systèmes et de technologies intelligents embarqués et connectés dans la vie quotidienne, qui ont créé l’opportunité de connecter chaque “chose" à Internet. Dans l'ère à venir de l'Internet des objets, l'Internet des véhicules (IoV) jouera un rôle crucial dans la construction d'une ville intelligente. En fait, l'IoV a le potentiel de résoudre efficacement divers problèmes de trafic. Il est essentiel pour améliorer l'utilisation des routes, réduire la consommation d'énergie et la pollution et améliorer la sécurité routière. Néanmoins, le principal problème concernant l'IoV, et en particulier le Véhicule-à-Véhicule (V2V) et le Véhicule-à-infrastructure (V2I), est l'établissement de paiements et de communications sécurisés et instantanés. Pour répondre à ce défi, ce travail propose une solution basée sur la Blockchain pour mettre en place un paiement et une communication sécurisés afin d'étudier l'utilisation de la Blockchain comme middleware entre différents acteurs des systèmes de transport intelligents.Dans cette étude, nous avons évalué les propriétés les plus importantes de la solution développée, à savoir la consommation de la mémoire et de l’énergie, l’immutabilité, la confidentialité, la cohérence, l’intégrité, le temps d’exécution et le coût. L’objet de cette évaluation est de vérifier la capacité de la plateforme basée sur la Blockchain à assurer une communication efficace et un paiement sécurisé avec l’IoV. Selon les résultats, cette plateforme peut contribuer à résoudre les défis les plus critiques de la communication véhicule-à-tout (V2X) en améliorant la sécurité et l’évolutivité.
Blockchain technology has emerged as the cornerstone of many decentralized applications operating among otherwise untrusted peers. However, it is well known that existing blockchain systems do not scale well. Transactions are often executed and committed sequentially in order to maintain the same view of the total order. Furthermore, it is necessary to duplicate both transaction data and their executions in every node in the blockchain network for integrity assurance. Such storage and computation requirements put significant burdens on the blockchain system, not only limiting system scalability but also undermining system security and robustness by making the network more centralized. To tackle these problems, in this paper, we propose SlimChain, a novel blockchain system that scales transactions through off-chain storage and parallel processing. Advocating a stateless design, SlimChain maintains only the short commitments of ledger states on-chain while dedicating transaction executions and data storage to off-chain nodes. To realize SlimChain, we propose new schemes for off-chain smart contract execution, on-chain transaction validation, and state commitment. We also propose optimizations to reduce network transmissions and a new sharding technique to improve system scalability further. Extensive experiments are conducted to validate the performance of the proposed SlimChain system. Compared with the existing systems, SlimChain reduces the on-chain storage requirements by 97% ~ 99%, while also improving the peak throughput by 1.4× ~ 15.6×.
Blockchain and the proof-of-work (PoW) distributed consensus protocol rely on peer-to-peer (P2P) networking. We build a PoW P2P simulator for the modeling and analyses of permissionless blockchain networking. Our simulator utilizes a built-in randomness generator for the simulations, has an easy-to-use interface and intuitive visualization, supports dynamic/programmable control and modifications, and can generate simulation data for further processing. We publish our simulator in open source to facilitate its use for blockchain and P2P networking research and especially recommend it for scalability research or preliminary testing. To highlight its features and capabilities, we demonstrate the simulator use in this paper to analyze the recent blockchain security research, including 51% attack, eclipse, partitioning, and DoS attack.
Abigael Okikijesu Bada, Amalia Damianou, Constantinos Marios Angelopoulos, Vasilios Katos
Organizations all over the world are under pressure to reduce their use of non-renewable energy sources and carbon emissions into the atmosphere due to its increasing negative impact on the ongoing climate crisis. Blockchain is a disruptive technology popularised by its use in Bitcoin, which has subsequently been adopted for various use cases. However, recently Blockchain has started attracting negative attention due to its propensity for high energy consumption depending on the adopted consensus mechanism. In this work, we explore the need for green (sustainable) Blockchain by comprehensively reviewing the various existing consensus mechanisms and their energy consumption to present a framework that will contribute towards developing more sustainable and environment friendly Blockchain-enabled systems.
Public blockchains have spurred the growing popularity of decentralized transactions and smart contracts, especially on the financial market. However, public blockchains exhibit their limitations on the transaction throughput, storage availability, and compute capacity. To avoid transaction gridlock, public blockchains impose large fees and per-block resource limits, making it difficult to accommodate the ever-growing high transaction demand. Previous research endeavors to improve the scalability and performance of blockchain through various technologies, such as side-chaining, sharding, secured off-chain computation, communication network optimizations, and efficient consensus protocols. However, these approaches have not attained a widespread adoption due to their inability in delivering a cloud-like performance, in terms of the scalability in transaction throughput, storage, and compute capacity. In this work, we determine that the major obstacle to public blockchain scalability is their underlying unstructured P2P networks. We further show that a centralized network can support the deployment of decentralized smart contracts. We propose a novel approach for achieving scalable decentralization: instead of trying to make blockchain scalable, we deliver decentralization to already scalable cloud by using an Ethereum smart contract. We introduce Blockumulus, a framework that can deploy decentralized cloud smart contract environments using a novel technique called overlay consensus. Through experiments, we demonstrate that Blockumulus is scalable in all three dimensions: computation, data storage, and transaction throughput. Besides eliminating the current code execution and storage restrictions, Blockumulus delivers a transaction latency between 2 and 5 seconds under normal load. Moreover, the stress test of our prototype reveals the ability to execute 20,000 simultaneous transactions under 26 seconds, which is on par with the average throughput of worldwide credit card transactions.
Jun 29, 2021·Proceedings of the Twenty-second International Symposium on Theory, Algorithmic Foundations, and Protocol Design for Mobile Networks and Mobile Computing
Sharding is one of the most promising and practical methods to achieve horizontal scalability of blockchain networks. However, the increasing number of cross-shard transactions in blockchain sharding protocols may degrade the system throughput. In this paper, we investigate how to distribute users properly in the shard-based blockchains to boost the system transaction performance. We first build an open Jackson queueing network model to capture users' transaction dynamics on shards. Then we cast users' interactions as a shard-based blockchain game, wherein each user aims to minimize its transaction confirmation time and transaction fee. We investigate the equilibrium of the game, and design a polynomial-time algorithm to find efficient equilibria with good system performance. We further design a novel sharding protocol with dynamic user distribution for the permissionless blockchain, and the protocol can maintain good performance in long-term dynamic environment. Extensive numerical results using realistic blockchain transaction data demonstrate that the proposed algorithm and the designed protocol can achieve superior performance for shard-based blockchains.
Pol Alemany, Ricard Vilalta, Raül Muñoz, Ramon Casellas · 5 authors
Hierarchical Software Define Networking (SDN) architectures is used to manage the co-existence of multiple domains by having an element on top. A collaborative relation-ship between domains, might solve this issue. Blockchain may become the key element for this change to happen. This paper presents a Blockchain-based architecture to provide SDN actions to configure connectivity services in transport domains. The results presented show that the use of Blockchain is a promising candidate for inter-domain SDN control.
Lei Zeng, Weiwei Qiu, Xiaoyi Wang, Hongkai Wang · 6 authors
In the context of advocating the reduction of greenhouse gases, green energy trade has become the focus of attention. At this stage, green energy is relatively dispersed (such as wind power, hydropower, solar power, etc.), and energy generation is real-time. At present, green energy trading based on blockchain has become a better solution. In the transaction itself, the blockchain has better security and traceability, but in terms of statistical information and interval query, because the basic data structure of the blockchain is a key-value data structure, performance problems are prone to occur. A transaction-based static indexing method is proposed, which can effectively improve the efficiency of statistical information and interval query on the chain.
Xuan Chen, Shujuan Tian, Kien Nguyen, Hiroo Sekiya
With data transparency and immutability, the blockchain can provide trustless and decentralized services for Internet of Things (IoT) applications. However, most blockchain-IoT networks, especially those with a private blockchain, are built on top of an infrastructure-based wireless network (i.e., using Wi-Fi access points or cellular base stations). Hence, they are still under the risk of Single-Point-of-Failure (SPoF) on the network layer, hindering the decentralization merit, for example, when the access points or base stations get failures. This paper presents an Optimized Link State Routing (OLSR) protocol-based solution for that issue in a private blockchain-IoT application. By decentralizing the underlying network with OLSR, the private blockchain network can avoid SPoF and automatically recover after a failure. Single blockchain connections can be extended to multiple ad hoc hops. Services over blockchain become flexible to fit various IoT scenarios. We show the effectiveness of our solution by constructing a private Ethereum blockchain network running on IoT devices (i.e., Raspberry Pi model 4) with environmental data sensing (i.e., Particular Matter (PM)). The IoT devices use OLSR to form an ad hoc network. The environment data are collected and propagated in transactions to a pre-loaded smart contract periodically. We then evaluate the IoT blockchain network’s recovery time when facing a link error. The evaluation results show that OLSR can automatically recover after the failure. We also evaluate the transaction-oriented latency and block-oriented latency, which indicates the blocks have a high transmission quality, while transactions are transferred individually.
Mengqian Zhang, Yukun Cheng, Xiaotie Deng, Bo Wang · 7 authors
For a blockchain system, the network layer is of great importance for scalability and security. The critical task of blockchain networks is to provide a fast delivery of data. A rapid spread accelerates the transactions to be included into blocks and then confirmed. Existing blockchain systems, especially the cryptocurrencies like Bitcoin, take a simple strategy that requires relay nodes to verify all received transactions and then forward valid ones to all outbound neighbors. Unfortunately, this design is inefficient and slows down the transmission of transactions. In this paper, we introduce the concept of reputation and propose a novel relay protocol, RepuLay, to accelerate the transmission of transactions across the network. First of all, we design a reputation mechanism to help each node identify the unreliable and inactive neighbors. In this mechanism, two values are used to define one’s reputation. Each node keeps a local list of reputations of all its neighbors. Based on the reputation mechanism, RepuLay adopts probabilistic strategies to process transactions. More specifically, after receiving a transaction, the relay node verifies it with a certain probability, which is deduced from the first value of sender’s reputation. Next, the valid and unverified transactions are forwarded to some neighbors. Each neighbor has some probability to be chosen as a receiver and the probability is determined by its second value of reputation. Theoretically, we prove that our design can guarantee the quality of relayed transactions. Further simulation results confirm that RepuLay effectively accelerates the spread of transactions and optimize the usage of nodes’ bandwidths.
Energy storage provides an effective way of shifting temporal energy demands and supplies, enabling significant cost reduction under dynamic energy pricing. Despite its promising benefits, the cost of present energy storage remains expensive, presenting a major obstacle to practical deployment. A more viable solution to improve cost-effectiveness is by sharing energy storage, such as community sharing, cloud energy storage and peer-to-peer sharing. However, revealing private energy demand data in energy storage sharing may compromise user privacy, susceptible to data misuses and breaches. In this paper, we explore a novel approach to support energy storage sharing with privacy protection, based on privacy-preserving blockchain and secure multi-party computation. We present an integrated solution to enable privacy-preserving energy storage sharing, such that energy storage service scheduling and cost-sharing can be attained without the knowledge of individual users' demands. It also supports auditing and verification by the grid operator via blockchain. Furthermore, our privacy-preserving solution can safeguard against a dishonest majority of users, who may collude in cheating, without requiring trusted third-parties. We implemented our solution as a smart contract on real-world Ethereum blockchain platform, with empirical evaluation.
Online Social Networks (OSNs) have become one of the most popular applications of the daily life of users in the worldwide. Today, the number of Social Media users is more than 4 billion, and this trend increases year after year with a high impact on the privacy issue. During the last years, decentralization of social services has been considered as a big opportunity to overcome the main privacy issues in OSNs, and not only (fake news, censorship, etc.). Blockchain technology represents today the most well-known decentralized technique, which has been taken into account to develop the new generation of decentralized social platforms. Blockchain-based Online Social Media (BOSMs) are decentralized Social Media platforms that use the blockchain technology as the underlying technology or as a tool in order to provide rewarding strategies. In this tutorial, we will highlight the BOSMs scenario by presenting their main characteristics and how data could be collected and analysed.