Yaodong Huang, Jiarui Zhang, Jun Duan, Bin Xiao · 6 authors
Edge devices with sensing, storage, and communication resources are penetrating our daily lives. These resources make it possible for edge devices to conduct data transactions (e.g., micro-payments, micro-access control). The blockchain technology can be used to ensure transaction unmodifiable and undeniable. In this paper, we propose a blockchain system that adapts to the limitations of edge devices. The new blockchain system can fairly and efficiently allocate storage resources on edge devices, which makes it scalable. We find the optimal peer nodes for transaction data storage and propose a recent block storage allocation scheme for quick retrieval of missing blocks. We develop data migration algorithms to dynamically reallocate data and block storage to adapt topology changes in the network. The proposed blockchain system can also reach consensus with low energy consumption in edge devices with a new Proof of Stake mechanism. Extensive simulations show that our proposed blockchain system works efficiently in edge environments. On average, the new system uses 18.4 percent less time and consumes 87 percent less battery power when compared with traditional blockchain systems.
Internet of Things (IoT) networks are typically composed of many sensors and actuators. The operation controls for robots in smart factories or drones produce a massive volume of data that requires high reliability. A blockchain architecture can be used to build highly reliable IoT networks. The shared ledger and open data validation among users guarantee extremely high data security. However, current blockchain technology has limitations for its overall application across IoT networks. Because general permission-less blockchain networks typically target high-performance network nodes with sufficient computing power, a blockchain node with low computing power and memory, such as an IoT sensor/actuator, cannot operate in a blockchain as a fully functional node. A lightweight blockchain provides practical blockchain availability over IoT networks. We propose essential operational advances to develop a lightweight blockchain over IoT networks. A dynamic network configuration enforced by deep clustering provides ad-hoc flexibility for IoT network environments. The proposed graph neural network technique enhances the efficiency of dApp (distributed application) spreading across IoT networks. In addition, the proposed blockchain technology is highly implementable in software because it adopts the Hyperledger development environment. Directly embedding the proposed blockchain middleware platform in small computing devices proves the practicability of the proposed methods.
Mobile app markets are emerging with the popularity of smartphones. However, they fall short in several aspects, including no transparent app listing, no world-wide app access, and even insecure app downloading. To address these problems, we propose a novel blockchain-based gateway, AGChain, to bridge end users and app markets so that existing app markets could still provide services while users enjoy permanent, distributed, and secure app delegation from AGChain. To this end, we identify two previously under-estimated challenges and propose mechanisms to significantly reduce gas costs in our smart contract and make IPFS (Inter-planetary File System) based file storage really distributed. We also address three AGChain-specific system challenges to make it secure and sustainable. We have implemented an AGChain prototype (https://www.agchain.ltd/) on Ethereum. The evaluation shows that it achieves security and decentralization with minimal gas costs and reasonable performance.
The popularity of smartphones has led to the growth of mobile app markets, creating a need for enhanced transparency, global access, and secure downloading. This paper introduces AGChain, a blockchain-based gateway that enables trustworthy app delegation within existing markets. AGChain ensures that markets can continue providing services while users benefit from permanent, distributed, and secure app delegation. During its development, we address two key challenges: significantly reducing smart contract gas costs and enabling fully distributed IPFS-based file storage. Additionally, we tackle three system issues related to security and sustainability. We have implemented a prototype of AGChain on Ethereum and Polygon blockchains, achieving effective security and decentralization with a minimal gas cost of around 0.002 USD per app upload (no cost for app download). The system also exhibits reasonable performance with an average overhead of 12%.
Online social networks (OSN) are becoming more important in people's daily life, however, all popular OSNs are centralized, and this raises a series of security, privacy and management issues. A decentralized architecture based on blockchain technology provides the ability to solve above issues. In this paper, an OSN service is developed based on blockchain technology in order to make it operate decentralized. Large volume of data normally required low-security requirements can be stored in Interplanetary Filesystem (IPFS) to make data decentralized. A decentralized autonomous organization is developed for user autonomy, users can self-manage the OSN in a democratic way.
As the development of smart cities, energy management systems have been changing from centralized management systems to distributed energy management systems for better energy efficiency. In the distributed energy management systems, while producing the energy from distributed users, there can be two types of users such that 1) users who have surplus energy generations and 2) users who lack energy generations compared to their demands. In this paper, to alleviate such imbalance of energy generation between distributed users, a peer to peer (P2P) based energy trading platform is proposed. Specifically, blockchain is one of emerging solutions in which transactions can be made reliably to achieve P2P transactions without any centralized broker intervention. Correspondingly, we implement the P2P energy trading platform under Ethereum's smart contract for reliable trading. The energy generated from distributed users at the proposed platform can be traded by utilizing the characteristics of Decentralize Application. Specifically, we provide the details of implementations of the proposed platform, which includes both hardware platform and software platform. Further, we establish a web page and an mobile application for monitoring the transaction information such as transaction details and energy prices, which can enhance users' accessibility. Finally, the demonstration of process of energy trading via web interface is represented.
Blockchain is a distributed ledger technology operating on top of the peer-to-peer (P2P) network, and the variety of Blockchain deployments have been observed in both public and private manners. In Blockchain, the information dissemination among Blockchain nodes relies on the one-to-all-the-others broadcast mechanism over the P2P network. The underlying network topology introduces a significant impact on the performance of information dissemination in the Blockchain P2P network as well as the effectiveness and stability of Blockchain operation as a consequence. When a private blockchain is deployed in a controlled environment, it is crucial to understand the effect of underlying network topology on Blockchain performance and operational effectiveness. This paper simulates various well-known network topologies, including Hypercube, Torus, Fat-Tree, and Scale-Free as an underlying network of the Blockchain, giving more focus on controlled environments such as Data Center Network (DCN). We comparatively evaluate the performance of each network topology based on both Blockchain and network aspects. The evaluation results show that Hypercube performs the best among the topologies being assessed, especially in information propagation delay and resilience against adverse situations.
Electronic voting systems have several necessarily requirements, such as anonymity that others cannot link voters with votes, the fairness that votes should not be leaked before the tally, and the accuracy that eligible voters' votes should be counted correctly. There have been proposed various methods to realize the requirements. Some of them require anonymous communication paths as necessary elements to satisfy the anonymity requirement for a practical electronic voting system. Cruz et al. proposed an electronic voting system that does not need anonymous communication paths, using Bitcoin, a cryptographic currency, as a distributed database. However, Bitcoin is a system in which all data are disclosed, and anyone can check what exchanges a person of a certain ID (Bitcoin address) has done. It is possible to reveal which voter made what vote, and hence(anonymity is not satisfied. In this paper, we propose a method to solve the above problem by using Bitcoin mixing. We propose an electronic voting system using Zerocoin, a variant of Bitcoin, as a database, in which zero knowledge proof is used instead of blind signature for mixing.
Advances in mobile computing have paved the way for new types of distributed applications that can be executed solely by mobile devices on device-to-device (D2D) ecosystems (e.g., crowdsensing). Sophisticated applications, like cryptocurrencies, need distributed ledgers to function. Distributed ledgers, such as blockchains and directed acyclic graphs (DAGs), employ consensus protocols to add data in the form of blocks. However, such protocols are designed for resourceful devices that are interconnected via the Internet. Moreover, existing distributed ledgers are not deployable to D2D ecosystems since their storage needs are continuously increasing. In this work, we introduce and analyse Mneme, a DAG-based distributed ledger that can be maintained solely by mobile devices. Mneme utilizes two novel consensus protocols: Proof-of-Context (PoC) and Proof-of-Equivalence (PoE). PoC employs users' context to add data on Mneme. PoE is executed periodically to summarize data and produce equivalent blocks that require less storage. We analyze Mneme's security and justify the ability of PoC and PoE to guarantee the characteristics of distributed ledgers: persistence and liveness. Furthermore, we analyze potential attacks from malicious users and prove that the probability of a successful attack is inversely proportional to the square of the number of mobile users who maintain Mneme.
Decentralized application (DAPP), replacing traditional business logic and data access layer with block chain, is a new form of Internet service. Testing DAPP requires large-scale distributed systems. Performing experiments in a real system is costly and difficult. This article carefully analyses the process of block generation and synchronization and explains the reasons for the low efficiency of block chain system simulation. We incorporate fuzzy rule based model for enhancing the logging system in blockchain. Rules based on fuzzy are utilized inside system of fuzzy logic to obtain outcome on basis of input variables. The data of Ethereum and Bitcoin proves that the block generation interval conforms to the exponential distribution, and the real PoW calculation can be replaced with random numbers. Both block verification and network propagation processes have latency, which can be simulated with asynchronous messaging. Based on the above analysis, this article proposes a high-performance simulation method based on event-driven model, which is suitable for describing the communication and synchronization behave our of block chain networks. The method can effectively describe the block generation, the synchronization process between nodes, and supports different equity proof forms. Using this method, the performance of the PoW systemis tested. Under the ecs.c6.xlargeinstance,the simulation running speed reaches 782 times of actual system. Further experiments show that this method can be efficiently used in larger-scale networks and is an effective tool for DAPP developing and testing.
With the booming of smart grid, The ubiquitously deployed smart meters constitutes an energy internet of things. This paper develops a novel blockchain-based transactive energy management system for IoT-aided smart homes. We consider a holistic set of options for smart homes to participate in transactive energy. Smart homes can interact with the grid to perform vertical transactions, e.g., feeding in extra solar energy to the grid and providing demand response service to alleviate the grid load. Smart homes can also interact with peer users to perform horizontal transactions, e.g., peer-to-peer energy trading. However, conventional transactive energy management method suffers from the drawbacks of low efficiency, privacy leakage, and single-point failure. To address these challenges, we develop a privacy-preserving distributed algorithm that enables users to optimally manage their energy usages in parallel via the smart contract on the blockchain. Further, we design an efficient blockchain system tailored for IoT devices and develop the smart contract to support the holistic transactive energy management system. Finally, we evaluate the feasibility and performance of the blockchain-based transactive energy management system through extensive simulations and experiments. The results show that the blockchain-based transactive energy management system is feasible on practical IoT devices and reduces the overall cost by 25%.
Muhammad Anas Imtiaz, David Starobinski, Ari Trachtenberg, Nabeel Younis
Efficient and reliable propagation of blocks is vital to the scalability of the Bitcoin network. As a result, several schemes, such as the compact block protocol (BIP 152), have been proposed over the last few years to speed up the block propagation. Even so, we provide experimental evidence that (i) the vast majority (97%) of Bitcoin nodes exhibit only intermittent network connectivity (i.e., churn), and (ii) this churn results in significant number of unsuccessful compact blocks, roughly three times the statistic for continuously connected nodes. We conduct experiments on the Bitcoin network that show that churn results in a roughly five fold increase in block propagation time (i.e., 566.89 ms vs. 109.31 ms) on average. To effect our analysis, we develop a statistical model for churn, based on empirical network data, and use this model to actuate live test nodes on the Bitcoin network. The performance of the system is measured within a novel framework that we developed for logging the internal behavior of a Bitcoin node, and which we share for public use. Finally, to mitigate the problem of missing transactions in churning nodes, we propose and implement into Bitcoin Core a new synchronization protocol, dubbed MempoolSync. Our measurements show that churning nodes implementing MempoolSync experience significantly better performance than standard nodes not implementing MempoolSync, including average block propagation delay reduced by over 50%.
Recommendation system is widely used to predict users' interests and provide targeted products for them, which effectively facilitates users in the era of big data where information overload problem is prevalent. Unfortunately, massive data closely related to users' privacy is in high demand to produce more accurate predictions. In this case, the collection and transmission of such data is communication costly; to process and analyze such data is of high possibility to compromise users' privacy. In this paper, we propose a privacy-preserving recommendation mechanism based on blockchain, which well addresses these problems. Leveraging the inherent advantages of blockchain, we establish a completely distributed model mitigating the risk of privacy disclosure caused by central data storage. Moreover, we combine Inter-Planetary File System with blockchain to greatly improve the communication efficiency. We also introduce local sensitive hashing and local differential privacy into proposed mechanism to reduce the computation load and provide a strong privacy guarantee. The experimental results demonstrate that the proposed mechanism shows better performance on privacy preservation while maintaining desirable recommendation accuracy when compared with the baseline.
Blockchain technology is characterized by decentralization, traceability and tamper resistance. A decentralized application (Dapp) refers to a blockchain-based application deployed on Ethereum platform, with the aim to facilitate decentralized smart contracts and to prosper the blockchain ecosystem. In this paper, an in-depth analysis for the current decentralized applications is performed to reveal the structure and development situation of blockchain ecosystem. With a better understanding of the blockchain ecosystem, insights can be obtained for the Dapp developers as well as for the potential blockchain adopters. Furthermore, guidelines and suggestions are provided to inspire the business applications based on blockchain.
Big data applications put significant latency and throughput demands on distributed storage systems. Meeting these demands requires storage systems to use a significant amount of infrastructure resources, such as network capacity and storage devices. Resource demands largely depend on the workloads and can vary significantly over time. Moreover, demand hotspots can move rapidly between different infrastructure locations. \n \nExisting storage systems are largely infrastructure-oblivious as they are designed to support a broad range of hardware and deployment scenarios. Most only use basic configuration information about the infrastructure to make important placement and routing decisions. In the case of cloud-based storage systems, cloud services have their own infrastructure-specific limitations, such as minimum request sizes and maximum number of concurrent requests. By ignoring infrastructure-specific details, these storage systems are unable to react to resource demand changes and may have additional inefficiencies from performing redundant network operations. As a result, provisioning enough resources for these systems to address all possible workloads and scenarios would be cost prohibitive. \n \nThis thesis studies the performance problems in commonly used distributed storage systems and introduces novel infrastructure-aware design methods to improve their performance. First, it addresses the problem of slow reads due to network congestion that is induced by disjoint replica and path selection. Selecting a read replica separately from the network path can perform poorly if all paths to the pre-selected endpoints are congested. Second, this thesis looks at scalability limitations of consensus protocols that are commonly used in geo-distributed key value stores and distributed ledgers. Due to their network-oblivious designs, existing protocols redundantly communicate over highly oversubscribed WAN links, which poorly utilize network resources and limits consistent replication at large scale. Finally, this thesis addresses the need for a cloud-specific realtime storage system for capital market use cases. Public cloud infrastructures provide feature-rich and cost-effective storage services. However, existing realtime timeseries databases are not built to take advantage of cloud storage services. Therefore, they do not effectively utilize cloud services to provide high performance while minimizing deployment cost. \n \nThis thesis presents three systems that address these problems by using infrastructure-aware design methods. Our performance evaluation of these systems shows that infrastructure-aware design is highly effective in improving the performance of large scale distributed storage systems.
With advancements in connected technology, the number of ambitious applications involving Internet of Things (IoT) are drastically growing. This increases concerns related to security, scalability, and interoperability of IoT. As the network of connected devices grows, decentralized technologies become inevitable. Within this trend towards decentralization, distributed ledger technology (for instance IOTA) will be a significant driving force. IOTA is an innovative distributed ledger technology targeted towards low power devices, where energy efficiency is a high priority. Public research regarding security threats against IOTA especially denial-of-service (DoS) is essentially non-existent. In this paper we focus on exploring a DoS attack against IOTA. The proposed attack methodology takes advantage of the lack of fees along with the ability to transfer minuscule amounts. By sending many conflicting transactions as it results in a high number of re-attachments. The high number of re-attachments threatens IOTA's suitability for the IoT sphere. The implications of such attack, as well as the future of this issue in terms of the planned removal of the centralized coordinator are discussed.
Houshyar Honar Pajooh, Mohammad A. Rashid, Fakhrul Alam, Serge Demidenko
Providing security and privacy to the Internet of Things (IoT) networks while achieving it with minimum performance requirements is an open research challenge. Blockchain technology, as a distributed and decentralized ledger, is a potential solution to tackle the limitations of the current peer-to-peer IoT networks. This paper presents the development of an integrated IoT system implementing the permissioned blockchain Hyperledger Fabric (HLF) to secure the edge computing devices by employing a local authentication process. In addition, the proposed model provides traceability for the data generated by the IoT devices. The presented solution also addresses the IoT systems' scalability challenges, the processing power and storage issues of the IoT edge devices in the blockchain network. A set of built-in queries is leveraged by smart-contracts technology to define the rules and conditions. The paper validates the performance of the proposed model with practical implementation by measuring performance metrics such as transaction throughput and latency, resource consumption, and network use. The results show that the proposed platform with the HLF implementation is promising for the security of resource-constrained IoT devices and is scalable for deployment in various IoT scenarios.
In recent years, the application range of blockchain has become more and more extensive. This paper proposed a volunteer computing system design based on the blockchain. This system takes advantage of the decentralized, persistent and auditable characteristics of the blockchain to solve the scalability and single point of failure problem under the traditional centralized C/S framework and provides a certain traceability for volunteer calculations. Increased scalability implies that the system can accommodate more computing jobs and participants. Solving the single-point failure problem implies that the volunteer computing system can provide researchers with longer-term and more stable computing resources. The traceability implies that anyone can view the blockchain to understand which volunteers have participated in every computing work in history and the adoption of the results provided by each volunteer. At the same time, with the help of the persistence and auditability of the blockchain, the authenticity of history can be ensured. This paper studies the C/S framework volunteer computing as well as blockchain, and proposes a framework for volunteer computing based on the blockchain. Then discussed its pros and cons in terms of feasibility, scalability, security, authenticity, traceability etc.
Pooja Gupta, Volkan Dedeoglu, Salil S. Kanhere, Raja Jurdak
The unprecedented rate of IoT adoption presents an opportunity for device owners to trade their IoT data with interested buyers. A blockchain-enabled data marketplace can democratize the trading of private IoT data by empowering data owners to choose what they want to share and with whom. However, some properties of IoT make it difficult to trade the generated data in conventional centralized markets. This research focuses on developing a marketplace framework to address design challenges imposed by IoT characteristics, such as limited resource and computational capabilities, mobility, data privacy and reselling issues. We propose a three-tiered framework to effectively tackle these challenges from elemental, functional and managerial aspects.
Off-chain is a common approach to deal with the scalability problem of blockchain networks. It enables users to execute multiple payments without committing each of them to the blockchain by relying on predefined payment channels. A pair of users can employ a payment even without a direct channel between them, via routing the payment through off-chain channels involving other intermediate users. Users together with the off-chain channels form a graph, known as the off-chain network topology. The off-chain topology and the payment characteristics affect network performance such as the average number of intermediate users a payment is routed through, the amount of fees, or channel capacities needed to successfully route payments. In this paper, we study two basic problems in off-chain network design. First, efficiently mapping users to an off-chain topology with a known structure. Second, constructing a topology of a bounded number of channels that can serve well users with associated payments. We design algorithms for both problems and evaluate them based on real data from Raiden, the off-chain extension for Ethereum.
Blockchain is a revolutionary technology that has been underlying behind many cryptocurrencies for many years. Due to the scalability issue, this decentralized system lags behind the centralized currency systems, and cannot be adopted by other platforms though it has a lot of unique features. This paper is motivated due to the lack of enough scalability on the existing blockchain technologies. A theoretical method is proposed in this paper to increase throughput and reduce storage dependencies. A distributed storage system IPFS is used to bypass the storing liabilities and to increase throughput. The dual-blockchain method serves the core features of the blockchain by adding the references of the main block into the ledger in place of the original block. The analysis shows that our proposed method can achieve up to 25.8 times greater throughput and almost 1685 times lesser ledger size compared to Bitcoin Core.