The past decade has witnessed the rapid evolution in blockchain technologies, which has attracted tremendous interests from both the research communities and industries. The blockchain network was originated from the Internet financial sector as a decentralized, immutable ledger system for transactional data ordering. Nowadays, it is envisioned as a powerful backbone/framework for decentralized data processing and data-driven self-organization in flat, open-access networks. In particular, the plausible characteristics of decentralization, immutability, and self-organization are primarily owing to the unique decentralized consensus mechanisms introduced by blockchain networks. This survey is motivated by the lack of a comprehensive literature review on the development of decentralized consensus mechanisms in blockchain networks. In this paper, we provide a systematic vision of the organization of blockchain networks. By emphasizing the unique characteristics of decentralized consensus in blockchain networks, our in-depth review of the state-of-the-art consensus protocols is focused on both the perspective of distributed consensus system design and the perspective of incentive mechanism design. From a game-theoretic point of view, we also provide a thorough review of the strategy adopted for self-organization by the individual nodes in the blockchain backbone networks. Consequently, we provide a comprehensive survey of the emerging applications of blockchain networks in a broad area of telecommunication. We highlight our special interest in how the consensus mechanisms impact these applications. Finally, we discuss several open issues in the protocol design for blockchain consensus and the related potential research directions.
The past decade has witnessed the rapid evolution in blockchain technologies, which has attracted tremendous interests from both the research communities and the industry. The blockchain network was originated in the Internet finical sector as a decentralized, immutable ledger system for transactional data ordering. Nowadays, it is envisioned as a powerful backbone/framework for decentralized data processing and data-driven self-organization in flat, open-access networks. In particular, the plausible characteristics of decentralization, immutability and self-organization are primarily owing to the unique decentralized consensus mechanisms introduced by blockchain networks. This survey is motivated by the lack of a comprehensive literature review on the development of decentralized consensus mechanisms in blockchain networks. In this survey, we provide a systematic vision of the organization of blockchain networks. By emphasizing the unique characteristics of incentivized consensus in blockchain networks, our in-depth review of the state-of-the-art consensus protocols is focused on both the perspective of distributed consensus system design and the perspective of incentive mechanism design. From a game-theoretic point of view, we also provide a thorough review on the strategy adoption for self-organization by the individual nodes in the blockchain backbone networks. Consequently, we provide a comprehensive survey on the emerging applications of the blockchain networks in a wide range of areas. We highlight our special interest in how the consensus mechanisms impact these applications. Finally, we discuss several open issues in the protocol design for blockchain consensus and the related potential research directions.
Doriane Perard, Jérôme Lacan, Yann Bachy, Jonathan Detchart
The concept of a decentralized ledger usually implies that each node of a blockchain network stores the entire blockchain. However, in the case of popular blockchains, which each weigh several hundreds of GB, the large amount of data to be stored can incite new or low-capacity nodes to run lightweight clients. Such nodes do not participate to the global storage effort and can result in a centralization of the blockchain by very few nodes, which is contrary to the basic concepts of a blockchain. To avoid this problem, we propose new low storage nodes that store a reduced amount of data generated from the blockchain by using erasure codes. The properties of this technique ensure that any block of the chain can be easily rebuild from a small number of such nodes. This system should encourage low storage nodes to contribute to the storage of the blockchain and to maintain decentralization despite of a globally increasing size of the blockchain. This system paves the way to new types of blockchains which would only be managed by low capacity nodes.
Blockchain technology has the potential to decentralise many traditionally centralised systems. However, scalability remains a key challenge. A horizontally scalable solution, where performance increases by adding more nodes, would move blockchain systems one step closer to ubiquitous use. We design a novel blockchain system called CHECO. Each node in our system maintains a personal hash chain, which only stores transactions that the node is involved in. A consensus is reached on special blocks called checkpoint blocks rather than on all transactions. Checkpoint blocks are effectively a hash pointer to the personal hash chains; thus a single checkpoint block may represent an arbitrarily large set of transactions. We introduce a validation protocol so that any node can check the validity of any transaction. Since transaction and validation protocols are point-to-point, we achieve horizontal scalability. We analytically evaluate our system and show a number of highly desirable correctness properties such as consensus on the validity of transactions. Further, we give a free and open-source implementation of CHECO and evaluate it experimentally. Our results show a strong indication of horizontal scalability.
Gultekin Berahan Mermer, Engin Zeydan, Şuayb S. Arslan
Blockchain is a recently emerging technology that has the potential to revolutionize the way society interacts and trades between each other. The main advantage this technology provides is its ability to exchange transactions without relying on a trusted third party entities of any means. It can also provide data integrity, in-built authenticity and user transparency. Blockchain is envisioned to be the new internet on which many revolutionary applications will be based. In this work, we provide an overview of blockchain technologies including their principles, opportunities and challenges ahead.
Vishal Sharma, Ilsun You, Francesco Palmieri, Dushantha Nalin K. Jayakody · 5 authors
Modern fog network architectures, empowered by IoT applications and 5G communications technologies, are characterized by the presence of a huge number of mobile nodes, which undergo frequent handovers, introducing a significant load on the involved network entities. Considering the distributed and flat nature of these architectures, DMM can be the only viable option for efficiently managing handovers in these scenarios. The existing DMM solutions are capable of providing smooth handovers, but lack robustness from the security point of view. Indeed, DMM depends on external mechanisms for handover security and uses a centralized device, which has obvious security and performance implications in flat architectures where hierarchical dependencies can introduce problems. We propose a new DMM schema based on the blockchain, capable of resolving hierarchical security issues without affecting the network layout, and also satisfying fully distributed security requirements with less consumption of energy.
Eleftherios Kokoris-Kogias, Philipp Jovanovic, Linus Gasser, Nicolas Gailly · 6 authors
Designing a secure permissionless distributed ledger (blockchain) that performs on par with centralized payment processors, such as Visa, is a challenging task. Most existing distributed ledgers are unable to scale-out, i.e., to grow their total processing capacity with the number of validators; and those that do, compromise security or decentralization. We present OmniLedger, a novel scale-out distributed ledger that preserves longterm security under permissionless operation. It ensures security and correctness by using a bias-resistant public-randomness protocol for choosing large, statistically representative shards that process transactions, and by introducing an efficient cross-shard commit protocol that atomically handles transactions affecting multiple shards. OmniLedger also optimizes performance via parallel intra-shard transaction processing, ledger pruning via collectively-signed state blocks, and low-latency "trust-but-verify" validation for low-value transactions. An evaluation of our experimental prototype shows that OmniLedger's throughput scales linearly in the number of active validators, supporting Visa-level workloads and beyond, while confirming typical transactions in under two seconds.
Miguel Pincheira, Muhammad Salek Ali, Massimo Vecchio, Raffaele Giaffreda
The recent, exponential rise in adoption of the most disparate Internet of Things (IoT) devices and technologies has reached also Agriculture and Food (Agri-Food) supply chains, drumming up substantial research and innovation interest towards developing reliable, auditable and transparent traceability systems. Current IoT-based traceability and provenance systems for Agri-Food supply chains are built on top of centralized infrastructures and this leaves room for unsolved issues and major concerns, including data integrity, tampering and single points of failure. Blockchains, the distributed ledger technology underpinning cryptocurrencies such as Bitcoin, represent a new and innovative technological approach to realizing decentralized trustless systems. Indeed, the inherent properties of this digital technology provide fault-tolerance, immutability, transparency and full traceability of the stored transaction records, as well as coherent digital representations of physical assets and autonomous transaction executions. This paper presents AgriBlockIoT, a fully decentralized, blockchain-based traceability solution for Agri-Food supply chain management, able to seamless integrate IoT devices producing and consuming digital data along the chain. To effectively assess AgriBlockIoT, first, we defined a classical use-case within the given vertical domain, namely from-farm-to-fork. Then, we developed and deployed such use-case, achieving traceability using two different blockchain implementations, namely Ethereum and Hyperledger Sawtooth. Finally, we evaluated and compared the performance of both the deployments, in terms of latency, CPU, and network usage, also highlighting their main pros and cons.
Engineers and researchers have recently paid attention to Blockchain. Blockchain is a fault-tolerant distributed ledger without administrators. Blockchain is originally derived from cryptocurrency, but it is possible to be applied to other industries. Transferring digital asset is called a transaction. Blockchain holds all transactions, so the total amount of Blockchain data will increase as time proceeds. On the other hand, the number of Internet of Things (IoT) products has been increasing. It is difficult for IoT products to hold all Blockchain data because of their storage capacity. Therefore, they access Blockchain data via servers that have Blockchain data. However, if a lot of IoT products access Blockchain network via servers, server overloads will occur. Thus, it is useful to reduce workloads and improve throughput. In this paper, we propose a caching technique using a Field Programmable Gate Array-based (FPGA) Network Interface Card (NIC) which possesses four 10Gigabit Ethernet (10GbE) interfaces. The proposed system can reduce server overloads, because the FPGA NIC instead of the server responds to requests from IoT products if cache hits. We implemented the proposed hardware cache to achieve high throughput on NetFPGA-10G board. We counted the number of requests that the server or the FPGA NIC processed as an evaluation. As a result, the throughput improved by on average 1.97 times when hitting the cache.
Chris Elsden, Kate Symons, Chris Speed, John Vines · 5 authors
Abstract The OxChain project is investigating the design of blockchain applications in partnership with a large and traditionally trusted institution, Oxfam. We outline some of the potential opportunities that distributed ledger technologies could offer the charity and development sector as a whole, but focus on the challenges of undertaking co-design work in the context of large institutions. We suggest the need to leverage existing trusted relationships and understand the unique value that such institutions offer.
Víctor Manuel Sámano Ortega, Faiza Bouchmal, José F. Monserrat
Vehicular communications, though a reality, must continue to evolve to support higher throughput and, above all, ultralow latency to accommodate new use cases, such as the fully autonomous vehicle. Cybersecurity must be assured since the risk of losing control of vehicles if a country were to come under attack is a matter of national security. This article presents the technological enablers that ensure security requirements are met. Under the umbrella of a dedicated network slice, this article proposes the use of content-centric networking (CCN), instead of conventional transmission control protocol/Internet protocol (TCP/IP) routing and permissioned blockchains that allow for the dynamic control of the source reliability, and the integrity and validity of the information exchanged.
Immigrants usually are pro-social towards their hometowns and try to improve them. However, the lack of trust in their government can drive immigrants to work individually. As a result, their pro-social activities are usually limited in impact and scope. This paper studies the interface factors that ease collaborations between immigrants and their home governments. We specifically focus on Mexican immigrants in the US who want to improve their rural communities. We identify that for Mexican immigrants having clear workflows of how their money flows and a sense of control over this workflow is important for collaborating with their government. Based on these findings, we create a blockchain based system for building trust between governments and immigrants. We finish by discussing design implications of our work and future directions.
Emanuel Ferreira Jesus, Vanessa R. L. Chicarino, Célio Albuquerque, Antônio A. de A. Rocha
The Internet of Things (IoT) is increasingly a reality today. Nevertheless, some key challenges still need to be given particular attention so that IoT solutions further support the growing demand for connected devices and the services offered. Due to the potential relevance and sensitivity of services, IoT solutions should address the security and privacy concerns surrounding these devices and the data they collect, generate, and process. Recently, the Blockchain technology has gained much attention in IoT solutions. Its primary usage scenarios are in the financial domain, where Blockchain creates a promising applications world and can be leveraged to solve security and privacy issues. However, this emerging technology has a great potential in the most diverse technological areas and can significantly help achieve the Internet of Things view in different aspects, increasing the capacity of decentralization, facilitating interactions, enabling new transaction models, and allowing autonomous coordination of the devices. The paper goal is to provide the concepts about the structure and operation of Blockchain and, mainly, analyze how the use of this technology can be used to provide security and privacy in IoT. Finally, we present the stalker, which is a selfish miner variant that has the objective of preventing a node to publish its blocks on the main chain.
We present SBFT: a scalable decentralized trust infrastructure for Blockchains. SBFT implements a new Byzantine fault tolerant algorithm that addresses the challenges of scalability and decentralization. Unlike many previous BFT systems that performed well only when centralized around less than 20 replicas, SBFT is optimized for decentralization and can easily handle more than 100 active replicas. SBFT provides a smart contract execution environment based on Ethereum's EVM byte-code.
We tested SBFT by running 1 million EVM smart contract transactions taken from a 4-month real-world Ethereum workload. In a geo-replicated deployment that has about 100 replicas and can withstand $f=32$ Byzantine faults our system shows speedups both in throughput and in latency. SBFT completed this execution at a rate of 50 transactions per second. This is a $10\times$ speedup compared to Ethereum current limit of $5$ transactions per second. SBFT latency to commit a smart contract execution and make it final is sub-second, this is more than $10\times$ speedup compared to Ethereum current $>15$ second block generation for registering a smart contract execution and several orders of magnitude speedup relative to Proof-of-Work best-practice finality latency of one-hour.
IOTA is a revolutionary new, next generation public distributed ledger that utilizes a novel invention, called a “Tangle”, at its core. The Tangle is a new data structure based on a Directed Acyclic Graph (DAG). As such it has no Blocks, no Chain and also no Miners. Because of this radical new architecture, things in IOTA work quite differently compared to other Blockchains.
Leonardo da Costa, André Avelino da Silva Neto, Billy Pinheiro, Roberto Araújo · 6 authors
In blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions, and light clients (LCs) are those which outsource chain verification to FNs (as they lack computing resources required to do so). In general, LCs perform simpler verification protocols, e.g. Simple Payment Verification (SPV), by offloading the execution of blockchain operations to FNs. To cope with byzantine faults (like malicious behavior), a current approach for blockchain transaction verification is requiring that LCs outsource their requests to multiple FNs, and compare received results. This approach, however, requires that LCs establish secure connections to each FN, which leads to client-side complexity and slower verification. To tackle this issue, we propose Distributed Lightweight Client Protocol (DLCP), a protocol for secure verification in blockchain. In summary, DLCP requires LCs to encrypt a request once, allowing a pre-determined set of FNs to access and process it. Through DLCP, LCs become able to verify whether FNs have agreed on the operation outcome. From some preliminary evaluation, we observed that DLCP decreased computing and communication overhead in LCs, while providing lower latency.
Michael Mylrea, Sri Nikhil Gupta Gourisetti, Randy Bishop, Matthew Johnson
The U.S. power grid is a complex system of systems that requires secure, reliable and trustworthy energy delivery systems. Grid modernization has increased the speed and size of data sets exchanged on these systems. Exasperating the challenge is these systems are increasingly distributed creating new data fidelity and interoperability challenges for grid operators struggling to balance and incorporate distributed energy resources. Blockchain technology provides an atomically verifiable cryptographic signature to help increase the trustworthiness of energy delivery systems at the grid's edge. This is especially important as distribution level as energy delivery systems and field devices have increasing operational and security requirements that are often diametrically opposed: as data, speed and analytic requirements increase, security and functionality requirements increase, as the grid's edge incorporate distributed energy resources and transacts in real time, availability is prioritized over the integrity and confidentially of that data. This paper explores how a keyless signature blockchain infrastructure (KSBI) technology may help facilitate NERC CIP compliance and securing critical energy infrastructure from evolving cyber threats and vulnerabilities.
Khaled Shuaib, Juhar Abdella, Farag Sallabi, Mohammed Abdel‐Hafez
Due to the expansion of small scale distributed energy resources such as solar rooftop and PEVs, decentralized energy trading is expected to be one of the most important components of next generation power systems. Decentralized peer-to-peer energy exchange systems are believed to be a promising solution not only to solve the scalability and mobility problems in the existing system but also to create a competitive market that can benefit small scale prosumers and consumers. However, such systems need to be equipped with the necessary security, privacy and payment transaction mechanisms to be efficient and trusted. In this paper, we propose a decentralized energy exchange system based on Blockchains. Blockchains is a technology that supports secure transactions between participating entities in a decentralized peer-to-peer network. The proposed system allows for energy exchange between prosumers using a form of smart electronic contracts which are based on Blockchains.
Ali Mohammad Saghiri, Monireh Vahdati, Kamran Gholizadeh HamlAbadi, Mohammad Reza Meybodi · 6 authors
Internet of Things, cognitive systems, and blockchain technology are three fields which have created numerous revolutions in software development. It seems that a combination among these fields may results in emerging a high potential and interesting field. Therefore, in this paper, we propose a framework for Internet of Things based on cognitive systems and blockchain technology. To the best of our knowledge, there is no framework for Internet of Things based on cognitive systems and blockchain. In order to study the applicability of the proposed framework, a recommender system based on the proposed framework is suggested. Since the proposed framework is novel, the suggested recommender system is novel. The suggested recommender system is compared with the existing recommender systems. The results show that the suggested recommender system has several benefits which are not available in the existing recommender systems.
Wazen M. Shbair, Mathis Steichen, Jérôme François, Radu State
Conducting experiments to evaluate blockchain applications is a challenging task for developers, because there is a range of configuration parameters that control blockchain environment. Many public testnets (e.g. Rinkeby Ethereum) can be used for testing, however, we cannot adjust their parameters (e.g. Gas limit, Mining difficulty) to further the understanding of the application in question and of the employed blockchain. This paper proposes an easy to use orchestration framework over the Grid'5000 platform. Grid'5000 is a highly reconfigurable and controllable large-scale testbed. We developed a tool that facilitates nodes reservation, deployment and blockchain configuration over the Grid'5000 platform. In addition, our tool can fine-tune blockchain and network parameters before and between experiments. The proposed framework offers insights for private and consortium blockchain developers to identify performance bottlenecks and to assess the behavior of their applications in different circumstances.
Mengting Liu, F. Richard Yu, Yinglei Teng, Victor C. M. Leung · 5 authors
Blockchain is widely deemed as a key enabling technology of current digital currency. However, the application of blockchain to wireless mobile networks is challenged by a computational difficult problem called proof-of-work puzzle. Accordingly, mobile edge computing (MEC) appears to be a promising solution by offloading the computation-intensive mining tasks to nearby edge computing nodes. Meanwhile, caching is also popular due to its capability in handling the ever-increasing Internet traffic. In this paper, we study computation offloading and content caching in wireless blockchain networks with MEC. Specifically, offloading mode selection (offloaded to a nearby access point (AP) or a group of device-to-device (D2D) users) and caching strategy (whether to cache the requested content and computation results or not) are jointly investigated and formulated as an optimization problem. Further, an alternating direction method of multipliers (ADMM) based algorithm is proposed to solve the optimization problem in a distributed way. Finally, the effectiveness of the proposed algorithm is demonstrated by simulation results with different system parameters.
The Blockchain paradigm provides a popular mechanism for establishing trust and consensus in distributed environments. While Blockchain technology is currently primarily deployed in crypto-currency systems like Bitcoin, the concept is also expected to emerge as a key component of the Internet-of-Things (IoT), enabling novel applications in digital health, smart energy, asset tracking and smart transportation. As Blockchain networks evolve to industrial deployments with large numbers of geographically distributed nodes, the block transfer and processing delays arise as a critical issue which may create greater potential for forks and vulnerability to adversarial attacks. Motivated by these issues, we develop stochastic network models to capture the Blockchain evolution and dynamics and analyze the impact of the block dissemination delay and hashing power of the member nodes on Blockchain performance in terms of the overall block generation rate and required computational power for launching a successful attack. The results provide useful insight in crucial design issues, e.g., how to adjust the `difficulty-of-work' in the presence of delay so as to achieve a target block generation rate or appropriate level of immunity from adversarial attacks. We employ a combination of analytical calculations and simulation experiments to investigate both stationary and transient performance features, and demonstrate close agreement with measurements on a wide-area network testbed running the Ethereum protocol.
With the success of Bitcoin, the technique behind it, Blockchain, is catching massive attention recently. Blockchain is a collection of several techniques like cryptology, P2P and distributed consensus protocol. The main idea of Blockchain is that nodes in the network keep the same distributed ledger. Because of this immutable ledger, a trusted bridge is built among parties without fully trust. Blockchain can be used in variety of areas, especially in financial fields, like supply chain management, cross-border payment and global bank settlement. Meanwhile, we can observe that mobile network is growing rapidly and nibbling the PC market. However, the current public Blockchain applications like Bitcoin or Ethereum require the nodes to store the whole ledger which exceeds the capacity of the mobile devices. Thus, we need to develop a blockchain platform to support mobile devices. In this demo, we introduce Jupiter, a mobile-based Blockchain platform which provides a novel concept called consensus unit (CU) to alleviate the storage problem of mobile. We present the system architecture and demonstrate several CU scenarios via Jupiter.