Powered by a number of smart devices distributed throughout the whole network, the Internet of Things (IoT) is supposed to provide services computing for massive data from devices. Fog computing, an extension of cloud-based IoT-oriented solutions, has emerged with requirements for distribution and decentralization. In this respect, the conjunction with Blockchain provides a natural solution for decentralization, as well as potentially helps fog computing overcome some deficiencies such as security and privacy then consequently expand the application scope of IoT. However, one of the key challenges of blockchain's integration with fog computing is scalability. To end this, this work proposes Groupchain, a novel scalable public blockchain of a two-chain structure suitable for fog computing of IoT services computing. Groupchain employs the leader group to collectively commit blocks for highertransaction efficiency and introduces bonus and deposit into the incentive mechanism to supervise behaviors of members in the leader group. Our security analysis shows that Groupchain retains the security of Bitcoin-like blockchain and enhances defense against attacks such as double-spend and selfish mining. We implement a prototype of Groupchain and conducted experiments. The experimental results demonstrate that Groupchain achieves optimization on transaction throughput and confirmation latency which are argued in Bitcoin.
Zakwan Jaroucheh, Baraq Ghaleb, William J Buchanan
The proof-of-work consensus protocol suffers from two main limitations: waste of energy and offering only probabilistic guarantees about the status of the blockchain. This paper introduces SklCoin, a new Byzantine consensus protocol and its corresponding software architecture. This protocol leverages two ideas: 1) the proof-of-stake concept to dynamically form stake proportionate consensus groups that represent block miners (stakeholders), and 2) scalable collective signing to efficiently commit transactions irreversibly. SklCoin has immediate finality characteristic where all miners instantly agree on the validity of blocks. In addition, SklCoin supports high transaction rate because of its fast miner election mechanism.
Blockchain-based cryptocurrencies received a lot of attention recently for their applications in many domains. IoT domain is one of such applications, which can utilize cryptocur-rencies for micro payments without compromising their payment privacy. However, long confirmation times of transactions and relatively high fees hinder the adoption of cryptoccurency based micro-payments. The payment channel networks is one of the proposed solutions to address these issue where nodes establish payment channels among themselves without writing on blockchain. IoT devices can benefit from such payment networks as long as they are capable of sustaining their overhead. Payment channel networks pose unique characteristics as far as the routing problem is concerned. Specifically, they should stay balanced to have a sustainable network for maintaining payments for longer times, which is crucial for IoT devices once they are deployed.In this paper, we present a payment channel network design that aims to keep the channels balanced by using a common weight policy across the network. We additionally propose using multi-point connections to nodes for each IoT device for unbalanced payment scenarios. The experiment results show that we can keep the channels in the network more equally balanced compared to the minimal fee approach. In addition, multiple connections from IoT devices to nodes increase the success ratio significantly.
Cai Wen-jun, Wei Jiang, Ke Xie, Yan Zhu · 6 authors
The energy blockchain is a distributed Internet protocol for energy transactions between nodes in power systems. The consensus algorithm is the core component of the energy blockchain and has an essential impact on its application. At present, in the implementation of the energy blockchain, there are problems such as low transaction throughput (transactions per second) and high latency, which cannot meet the application requirements of real-time processing transactions in the energy field. To this end, according to the analysis of conventional blockchain consensus algorithm and traditional practical Byzantine fault tolerance algorithm, a dynamic-reputation practical Byzantine fault tolerance algorithm for the energy blockchain is proposed. The dynamic-reputation practical Byzantine fault tolerance algorithm adopts a credit-based consortium node consensus election method. The monitoring node divides the remaining nodes into two types of nodes according to the reputation value: the consensus node and the secondary node, which, respectively, participate in different stages of the block generation process, and dynamically update the consensus nodes with low reputation ratings. By constructing the experimental platform simulation, the test results verify the effectiveness of the dynamic-reputation practical Byzantine fault tolerance algorithm. Compared with the algorithm of the fabric platform, the dynamic-reputation practical Byzantine fault tolerance algorithm improves the transaction processing speed and is suitable for the blockchain application in the energy field.
The interoperability across multiple or many blockchains would play a critical role in the forthcoming blockchain-based data management paradigm. In particular, how to ensure the ACID properties of those transactions across an arbitrary number of blockchains remains an open problem in both academic and industry: Existing solutions either work for only two blockchains or requires a centralized component, neither of which would meet the scalability requirement in practice. This short paper shares our vision and some early results toward scalable cross-blockchain transactions. Specifically, we design two distributed commit protocols and, both analytically and experimentally, demonstrate their effectiveness.
Philipp Frauenthaler, Marten Sigwart, Christof Spanring, Stefan Schulte
Current blockchain technologies provide very limited means of interoperability. In particular, solutions enabling blockchains to verify the existence of data on other blockchains are either very costly or are not fully decentralized. To overcome these limitations, we introduce Testimonium, a novel blockchain relay scheme that applies a validation-on-demand pattern and the on-chain execution of Simplified Payment Verifications to enable the verification of data across blockchains while remaining fully decentralized. Evaluating the scheme for Ethereum-based blockchains shows that Testimonium achieves a cost reduction of up to 92% over existing solutions. As such, the scheme lays a strong foundation for generic blockchain interoperability. For instance, it enables the development of an atomic-commit protocol for distributed transactions across blockchains.
Envisioned to be the future of secured distributed systems, blockchain networks have received increasing attention from both the industry and academia in recent years. However, blockchain mining processes demand high hardware costs and consume a vast amount of energy (studies have shown that the amount of energy consumed in Bitcoin mining is almost the same as the electricity used in Ireland). To address the high mining cost problem of blockchain networks, in this paper, we propose a blockchain mining resources allocation algorithm to reduce the mining cost in PoW-based (proof-of-work-based) blockchain networks. We first propose an analytical queueing model for general blockchain networks. In our queueing model, transactions arrive randomly to the queue and are served in a batch manner with unknown service rate probability distribution and agnostic to any priority mechanism. Then, we leverage the Lyapunov optimization techniques to propose a dynamic mining resources allocation algorithm (DMRA), which is parameterized by a tuning parameter $K \gt 0$. We show that our algorithm achieves an $[O(1/ K),O(K)]$ cost-optimality-gap-vs-delay tradeoff. Our simulation results also demonstrate the effectiveness of DMRA in reducing mining costs.
Mengting Liu, Yinglei Teng, F. Richard Yu, Victor C. M. Leung · 5 authors
The boom of video streaming industry has resulted in the increasing demands for transcoding services from heterogeneous users. Recent advances of blockchain technology allow some startups to realize decentralized collaborative transcoding through device-to-device (D2D) networks, where a group of transcoders are selected to perform transcoding cooperatively. For the blockchain-enabled D2D transcoding systems, it's imperative to jointly design transcoder selection, task scheduling and resource allocation schemes in order to provide efficient and trustworthy transcoding services. In this paper, viewing the involved multi-dimensional complex factors and channel fluctuation, we propose a novel deep reinforcement learning (DRL) based transcoder selection framework for blockchain enabled D2D transcoding systems where both the platform dynamics and channel statistics are captured. To reduce the action space size, we adopt a two-stage decision approach to first select the transcoders through a normal DRL based framework and then obtain the optimal task scheduling, power control, and resource allocation scheme by solving a stochastic optimization problem with the constrained stochastic successive convex approximation (CSSCA) approach. Simulation results show that our proposed framework can achieve high transcoding revenue while meeting the quality of service (QoS) requirements, and it can well handle dynamic cases.
Fog computing is an emerging paradigm in provisioning computing and storage resources for the Internet-of-Things (IoT) devices. In a fog computing system, all devices can offload their data or computationally intensive tasks to nearby fog nodes, instead of to the distant cloud. As compared with cloud computing, fog computing can significantly reduce the transmission delay between IoT devices and computing servers. However, the current fog system is rather susceptible to malicious attacks. To increase the security level, we propose to partition the fog system into fog node clusters (FNCs), with fog nodes (FNs) in one cluster sharing the same access control list (ACL) which is protected by a blockchain. Generating blockchains requires tremendous computing power and can rapidly drain the computing capacities of FNs. In this article, we first customize the blockchain for FNC to reduce the required computing power consumption and storage spaces. Second, a new scheme is designed for the blockchain-based FNC (BFNC) to recover ACL automatically. In addition, we propose a heuristic algorithm to reduce the time to acquire hash values of blocks by computing cooperatively with all available devices. The simulation results have demonstrated that using the cooperative computing strategy can reduce the time of computing a block hash than noncooperative strategies.
Purpose The purpose of this paper is to assist records managers and information governance professionals to understand the challenges presented by their organization’s use of blockchain distributed ledger technology (DLT). Design/methodology/approach An extensive literature review was conducted, which revealed a multitude of articles based on research into blockchain DLT, most written from the technology perspective. This paper differs in that it applies a records management lens to an analysis of the records created, registered or stored on a blockchain. A six-stage blockchain records consideration model is provided to illustrate examples of the records management challenges presented by the implementation of blockchain DLT. Questions are posed and recommendations are made to aid the reader in developing a blockchain DLT records management and information governance strategy. Findings Because there is no one universal configuration for a blockchain DLT solution, each implementation must be analyzed to understand the resultant records management and information governance challenges. A series of questions that should be asked and answered can not only help records management and information governance professionals adapt their policies and practices to the technology but also provide a basis for discussion with those designing the blockchain DLT solutions so they can include records management features in their designs. Originality/value This paper contributes an original analysis of the implications of the adoption of Blockchain DLT for records management and information governance programs through the lens of a six-stage Blockchain Records Consideration Model.
In next-generation computing, the role of cloud, internet and smart devices will be capacious. Nowadays we all are familiar with the word smart. This word is used a number of times in our daily life. The Internet of Things (IoT) will produce remarkable different kinds of information from different resources. It can store big data in the cloud. The fog computing acts as an interface between cloud and IoT. The extension of fog in this framework works on physical things under IoT. The IoT devices are called fog nodes, they can have accessed anywhere within the range of the network. The blockchain is a novel approach to record the transactions in a sequence securely. Developing a new blockchains based middleware framework in the architecture of the Internet of Things is one of the critical issues of wireless networking where resolving such an issue would result in constant growth in the use and popularity of IoT. The proposed research creates a framework for providing the middleware framework in the internet of smart devices network for the internet of things using blockchains technology. Our main contribution links a new study that integrates blockchains to the Internet of things and provides communication security to the internet of smart devices.
Tayebeh Rajab, Mohammad Hossein Manshaei, Mohammad Dakhilalian, Murtuza Jadliwala · 5 authors
Bitcoin's single leader consensus protocol (Nakamoto consensus) suffers from significant transaction throughput and network scalability issues due to the computational requirements of it Proof-of-Work (PoW) based leader selection strategy. To overcome this, committee-based approaches (e.g., Elastico) that partition the outstanding transaction set into shards and (randomly) select multiple committees to process these transactions in parallel have been proposed and have become very popular. However, by design these committee or shard-based blockchain solutions are easily vulnerable to the Sybil attacks, where an adversary can easily compromise/manipulate the consensus protocol if it has enough computational power to generate multiple Sybil committee members (by generating multiple valid node identifiers). Despite the straightforward nature of these attacks, they have not been systematically analyzed. In this paper, we fill this research gap by modelling and analyzing Sybil attacks in a representative and popular shard-based protocol called Elastico. We show that the PoW technique used for identifier or ID generation in the initial phase of the protocol is vulnerable to Sybil attacks, and a node with high hash-power can generate enough Sybil IDs to successfully compromise Elastico. We analytically derive conditions for two different categories of Sybil attacks and perform numerical simulations to validate our theoretical results under different network and protocol parameters.
Yueyue Dai, Du Xu, Ke Zhang, Sabita Maharjan · 5 authors
Vehicular Edge Computing (VEC) is a promising paradigm to enable huge amount of data and multimedia content to be cached in proximity to vehicles. However, high mobility of vehicles and dynamic wireless channel condition make it challenge to design an optimal content caching policy. Further, with much sensitive personal information, vehicles may be not willing to caching their contents to an untrusted caching provider. Deep Reinforcement Learning (DRL) is an emerging technique to solve the problem with high-dimensional and time-varying features. Permission blockchain is able to establish a secure and decentralized peer-to-peer transaction environment. In this paper, we integrate DRL and permissioned blockchain into vehicular networks for intelligent and secure content caching. We first propose a blockchain empowered distributed content caching framework where vehicles perform content caching and base stations maintain the permissioned blockchain. Then, we exploit the advanced DRL approach to design an optimal content caching scheme with taking mobility into account. Finally, we propose a new block verifier selection method, Proof-of-Utility (PoU), to accelerate block verification process. Security analysis shows that our proposed blockchain empowered content caching can achieve security and privacy protection. Numerical results based on a real dataset from Uber indicate that the DRL-inspired content caching scheme significantly outperforms two benchmark policies.
The use of Internet of Things (IoT) has introduced genuine concerns regarding data security and its privacy when data are in collection, exchange, and use. Meanwhile, blockchain offers a distributed and encrypted ledger designed to allow the creation of immutable and tamper-proof records of data at different locations. While blockchain may enhance IoT with innate security, data integrity, and autonomous governance, IoT data management and its allocation in blockchain still remain an architectural concern. In this article, we propose a novel context-aware mechanism for on-chain data allocation in IoT-blockchain systems. Specifically, we design a data controller based on fuzzy logic to calculate the Rating of Allocation (RoA) value of each data request considering multiple context parameters, i.e., data, network, and quality and decide its on-chain allocation. Furthermore, we illustrate how the design and realization of the mechanism lead to refinements of two commonly used IoT-blockchain architectural styles (i.e., blockchain-based cloud and fog). To demonstrate the effectiveness of our approach, we instantiate the data allocation mechanism in the blockchain-based cloud and fog architectures and evaluate their performance using FogBus. We also compare the efficacy of our approach to the existing decision-making mechanisms through the deployment of a real-world healthcare application. The experimental results suggest that the realization of the data allocation mechanism improves network usage, latency, and blockchain storage and reduces energy consumption.
Tasos Bakogiannis, Ioannis Mytilinis, Katerina Doka, Georgios Goumas
Cloud computing offerings traditionally originate from a handful of large and well established providers, which monopolize the market, preventing small players and individuals from having a share. As a result, the few, blindly and perforce trusted entities define the prices and manage to gain a significant competitive advantage by exploiting the knowledge derived by users’ data and computations. To tackle this monopoly and empower the democratization and full decentralization of the cloud computing market, we present CloudAgora, a platform that enables any potential resource provider, ranging from individuals to large companies, to monetize idle resources competing on equal terms, and allows any cloud consumer to enjoy access to low-cost storage and computation without having to trust any central authority. The key enabler of the platform is Blockchain technology, which is used to record commitment policies through the use of smart contracts, publicly verify off-chain services, both storage and computation related, and trigger automatic micropayments. On one hand, cloud consumers have the chance to request storage or compute resources, upload data, and outsource task processing over remote, fully distributed infrastructures. Although such infrastructures cannot be a priori trusted, CloudAgora offers mechanisms to ensure the verifiable validity of the outsourced storage and computation, discourage potential providers from behaving maliciously, and incentivize participants to play fair. On the other hand, providers are able to participate in auctions, placing bids for storage or computation tasks, serve requests, and offer validity proofs upon request. Our prototype is built as a Dapp on top of Ethereum and is available as an open source project.
The traditional method of blockchain retrieval is to search the “Block File” in sequence from the “tail” to the “head” of the blockchain, which always takes a lot of time. How to reduce the retrieval time has been a hot issue in blockchain research. This paper proposes a fast retrieval method for the Multi-Transaction Mode Consortium Blockchain (MTMCB). Firstly, we create a “User Set” and “Block Name Set” cached in Redis. Then, according to the transaction participants and “Block Name Set”, we can get the relevant “Block Name List”, and quickly obtain the corresponding block files. On this basis, in order to meet the needs of rapid retrieval in large-scale systems, an improved retrieval algorithm based on a B+-tree data structure is proposed. Firstly, the block file information is put into different ordered sets according to the transaction participants, and the B+-tree index is established to quickly get the information of relevant block files by participants. Experimental results show that the improved method of Redis cache retrieval in this paper can greatly increase the efficiency of blockchain retrieval, and can settle some crucial problem in the blockchain application and popularization.
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.
Blockchain technology can be extensively applied in diverse services, including online micro-payments, supply chain tracking, digital forensics, health-care record sharing, and insurance payments. Extending the technology to the Internet of things (IoT), we can obtain a verifiable and traceable IoT network. Emerging research in IoT applications exploits blockchain technology to record transaction data, optimize current system performance, or construct next-generation systems, which can provide additional security, automatic transaction management, decentralized platforms, offline-to-online data verification, and so on. In this article, we conduct a systematic survey of the key components of IoT blockchain and examine a number of popular blockchain applications. In particular, we first give an architecture overview of popular IoT-blockchain systems by analyzing their network structures and protocols. Then, we discuss variant consensus protocols for IoT blockchains, and make comparisons among different consensus algorithms. Finally, we analyze the traffic model for P2P and blockchain systems and provide several metrics. We also provide a suitable traffic model for IoT-blockchain systems to illustrate network traffic distribution.
Justin J. Ochoa, Gomanth Bere, Indrasena R. Aenugu, Taesic Kim · 5 authors
Blockchain-as-a-Service is an emerging blockchain-based platform service that can potentially contribute to the advancement of contemporary power and energy systems in cyber-physical environment, such as battery energy storage systems (BESSs). This paper explores how the blockchain technology that can be applied toward a next-generation BESS by managing critical activities and tasks including security, supply chain, health monitoring, data sharing, and energy transactions. Specifically, it is expected that the blockchain technology can lead to the advancement of BESSs by offering security enhancements as compared to applications that rely on a traditional-based approach without blockchain technology.
Ikechukwu Dimobi, Manisa Pipattanasomporn, Saifur Rahman
The changing nature of the energy grid has prompted innovative solutions to incoming challenges. In a distribution system with microgrids, residents with distributed energy resources (DERs) and interactive devices can interact with one another and the grid to exchange energy. Blockchain-based transactive energy could dynamically align active grid elements to incentivize demand-side energy resource investment and energy efficient behavior. This work models a blockchain-in-the-loop framework and simulates it using a Hyperledger Fabric blockchain network and the transactive energy simulation platform (TESP). Blockchain smart contracts are used to coordinate a microgrid market. Three market coordination schemes are compared, namely two auction-less schemes and one simple auction scheme, in a 30 home microgrid with different DER penetration levels. Results show that the auction-less scheme is more beneficial to community residents if the energy mix within the microgrid is diverse.
Marco Savi, Daniele Santoro, Katarzyna Di Meo, Daniele Pizzolli · 9 authors
This demonstration aims at showcasing an initial version of the DECENTER Brokerage Platform, which leverages an Ethereum blockchain to enable resource federation among different Fog Computing infrastructures. We consider a scenario where an Italian Infrastructure Provider wants to seamlessly extend its pool of resources to get access to an IP camera located in Korea, so that it can deploy an application to locally perform text recognition from a live video stream.