Aicha Fatrah, Said El Kafhali, Abdelkrim Haqiq, Khaled Salah
Blockchain is becoming the missing puzzle to solve many digital services problems these days. In this paper, we propose a design and implementation of a Blockchain-based voting system that can be used in national elections. In the paper, we argue that our Blockchain-based voting system is more secure, reliable and it has the ability to protect voter privacy which will help boost the number of voters and their trust in the electoral system as well as reducing considerably the cost of national elections.
Said El Kafhali, Chorouk Chahir, Mohamed Hanini, Khaled Salah
In this paper, we propose a novel architecture that utilizes features of Blockchain, fog computing, and cloud computing to manage IoT data. Blockchain allows to have a distributed peer-to-peer network in which non-trusting participants can interact with each other without a trusted intermediary or third party. We evaluate how this mechanism works to face the challenges of IoT with respect to multiple accessibility to IoT devises. We consider a Blockchain architecture in presence of edge computing layer. With fog or fog computing, the sensitive data can be analyzed locally instead of sending it to the cloud for analysis. Edge nodes can also keep track and control of the IoT devices that collect, analyze and store data. We show that this control can be better executed when Software Defined Network (SDN) and Network Functions Virtualization (NFV) are integrated into our process for optimal resource management. In this paper, we present our system architecture with a detailed description of the different interactions. We remark that the integration of Blockchain, IoT, and edge computing when coupled with SDN and NFV-enabled cloud infrastructure can bring to more superior and efficient platform for accessing, managing, and processing the huge influx of IoT data.
Yackolley Amoussou-Guenou, Antonella Del Pozzo, Maria Potop-Butucaru, Sara Tucci-Piergiovanni
Committee-based blockchains are among the most popular alternatives of proof-of-work based blockchains, such as Bitcoin. They provide strong consistency (no fork) under classical assumptions, and avoid using energy-consuming mechanisms to add new blocks in the blockchain. For each block, these blockchains use a committee that executes Byzantine-fault tolerant distributed consensus to decide the next block they will add in the blockchain. Unlike Bitcoin, where there is only one creator per block with high probability, in committee-based blockchain any block is cooperatively created. In order to incentivize committee members to participate to the creation of new blocks rewarding schemes have to be designed. In this paper, we study the fairness of rewarding in committee-based blockchains and we provide necessary and sufficient conditions on the system communication under which it is possible to have a fair reward mechanism.
Information overload is a phenomenon of our days due to the unprecedented penetration of information and communication technologies (ICT) in our daily lives. As a result, people often end up with more options than they can process to choose from and therefore may opt for choices which do not fit best to their preferences. To address these issues, recommender systems (RSs) were proposed and have gained a lot of interest from the research community and industry. However, privacy is a big concern in these systems. While decentralized recommenders can protect privacy, they lack the needed efficiency to be widely adopted. In this article, we use blockchain as the backbone of a decentralized RS, managing to equip it with a broad set of features while simultaneously, preserving user's privacy. We introduce a new architecture, based on decentralized locality sensitive hashing classification as well as a set of recommendation methods, according to how data are managed by users. Extensive experimental results illustrate the performance and efficacy of our approach compared with state-of-the-art methods. In addition, a discussion about its benefits and opportunities provides ground for further research.
Summary In recent decades, newly emerging mobile applications and services are becoming increasingly resource hungry and computation intensive. Portable size mobile devices fall short in providing such services. Cloud computing has been a core computation technology to provide visualized resources in a scalable way for mobile services. However, the unpredictable network transmission latency makes cloud computing not efficient enough for time‐sensitive mobile services, which requires major changes in underlying computing platform. Mobile edge computing is widely known as one of the novel technologies has emerged in recent years to address this issue. For being impractical to construct huge edge cloud in network edge, edge clouds can still be overloaded in rush time. Offloading to near‐user facilities using device‐to‐device (D2D) or other technologies becomes an augmentation approach. However, how to manage the facilities/resources effectively become a new issue. In this paper, we proposed a resource management scheme named BCEdge based on blockchain in D2D‐assisted mobile edge computing. BCEdge is a reliable scheme that operates in a distributed way to relieve the load of edge clouds. We illustrate the advantages and technical details of BCEdge using flow charts and interaction charts. The experiment results validate the effectiveness of our scheme. Finally, we discuss the possible future extensions.
Known as a distributed ledger, blockchain is becoming prevalent due to its decentralization, traceability and tamper resistance. Particularly, permissioned blockchain such as Hyperledger Fabric shows great application prospects as the infrastructure of IoT security, credit management, etc. Many cloud platforms like AWS, Azure, Oracle and IBM cloud currently provide blockchain as a service, in which tenants can quickly build permissioned blockchain and run smart contract based applications. However, the transactions throughput and scalability in the permissioned blockchain are not ideal, despite many optimization efforts in consensus protocol and parallel chain. Existing solutions still reveals some limitations like excessive CPU scheduling, inefficient block broadcast and high latency of initial blocks synchronization when new nodes join blockchain network. Inspired by the emerging RDMA (Remote Direct Memory Access) network, we propose BoR, an RDMA-based permissioned blockchain framework. By offloading the block transfer transaction into RDMA NICs, it can increase block broadcast speed and reduce block sync delay. We exploit the RDMA primitives to redesign the block synchronization protocol and accelerate DPoS (Delegated Proof of Stake) consensus process for higher throughput and lower latency in kernel-bypass manner. As demonstrated in our evaluation with different workloads, BoR with lower CPU utilization significantly outperforms the state-of-the-art EoS blockchain.
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
The microgrid trading market can effectively solve the problem of in-situ consumption of distributed energy and reduce the impact of distributed generation (DG) on the grid. However, the traditional microgrid trading model has some shortcomings, such as high operation cost and poor security. Therefore, in this paper, a microgrid market trading model was developed using consortium blockchain technology and Nash game equilibrium theory. Firstly, blockchain container is used to authenticate the users who want to participate in the transaction. Then, the pricing system collects and integrates transaction requests submitted by users, then formulates transaction pricing strategy of microgrid using Nash equilibrium theory. Finally, the price, trading volume, and user information are submitted to the blockchain container for transaction matching to achieve the transaction. After the transaction is completed, its related information is recorded in the hyperledger and the dispatch system is called. The scene simulation was implemented on Fabric 1.1 platform and the results analyzed. Results show that the trading model proposed in this paper greatly reduces the cost of electricity purchase and improves the benefits of electricity sales. Besides, the model is far more capable of handling transactions than the models based on Bitcoin and Ethereum.
Georgios Birmpas, Ηλίας Κουτσουπιάς, Philip Lazos, Francisco J. Marmolejo-Cossío
Bitcoin is a decentralised digital currency that serves as an alternative to existing transaction systems based on an external central authority for security. Although Bitcoin has many desirable properties, one of its fundamental shortcomings is its inability to process transactions at high rates. To address this challenge, many subsequent protocols either modify the rules of block acceptance (longest chain rule) and reward, or alter the graphical structure of the public ledger from a tree to a directed acyclic graph (DAG). Motivated by these approaches, we introduce a new general framework that captures ledger growth for a large class of DAG-based implementations. With this in hand, and by assuming honest miner behaviour, we (experimentally) explore how different DAG-based protocols perform in terms of fairness, i.e., if the block reward of a miner is proportional to their hash power, as well as efficiency, i.e. what proportion of user transactions a ledger deems valid after a certain length of time. Our results demonstrate fundamental structural limits on how well DAG-based ledger protocols cope with a high transaction load. More specifically, we show that even in a scenario where every miner on the system is honest in terms of when they publish blocks, what they point to, and what transactions each block contains, fairness and efficiency of the ledger can break down at specific hash rates if miners have differing levels of connectivity to the P2P network sustaining the protocol.
In this paper, we propose coded Merkle tree (CMT), a novel hash accumulator that offers a constant-cost protection against data availability attacks in blockchains, even if the majority of the network nodes are malicious. A CMT is constructed using a family of sparse erasure codes on each layer, and is recovered by iteratively applying a peeling-decoding technique that enables a compact proof for data availability attack on any layer. Our algorithm enables any node to verify the full availability of any data block generated by the system by just downloading a $Θ(1)$ byte block hash commitment and randomly sampling $Θ(\log b)$ bytes, where $b$ is the size of the data block. With the help of only one connected honest node in the system, our method also allows any node to verify any tampering of the coded Merkle tree by just downloading $Θ(\log b)$ bytes. We provide a modular library for CMT in Rust and Python and demonstrate its efficacy inside the Parity Bitcoin client.
In blockchain, delivering block data, especially delivering all historical blocks to a new node, will cost lots of bandwidth consumption. This cost may dissuade nodes from sharing their blocks to new or rejoined peer. In this paper, we present some incentive schemes for this kind of data sharing behaviour. In our design, node participating in delivering their storage data to their peers can get some rewards from the node who request the data. We adopt coin-locking strategy to discourage dishonest behaviour in the sharing process. Nodes need not put a large deposit to big data sharing since the data sharing process can be divided into smaller ones, and micropayment channel is set to accelerate the speed of during each small transmitting process. We give a theoretical analysis of our mechanism and discuss its practical application of data sharing in some mainstream cryptocurrencies and blockchains in IoT industry.
Yustus Eko Oktian, Elizabeth Nathania Witanto, Sandra Kumi, Sang-Gon Lee
In general shared internet service, the ISP shares a static bandwidth resource pool to multiple customers in the same neighborhood area. The users' internet speed wavers when the number of customers accessing the same resource is increasing. The issue becomes problematic during peak hours. Many customers are expected to use the limited bandwidth simultaneously, thus deteriorating the overall user experiences. The ISP is subject to blame when such incidents happen; the customers claim the ISP breaks the Service Level Agreement by providing lower internet speed than the one the ISP marketed. It is a dilemma for the ISP, increasing the bandwidth resource pool may solve the problem. However, when the peak hours period is over, the additional bandwidth becomes useless, thereby generating the over-allocation problem. In this paper, we propose the use of blockchain and SDN to provide agile network bandwidth management for the ISP in the form of three use cases: Bandwidth on Demand, Selling Bandwidth, and Real-Time Pricing. We argue that using these proposed use cases, the ISP can serve the customer fairly, while also generating more appealing economics to compete in the modern market.
Yueyue Dai, Du Xu, Ke Zhang, Sabita Maharjan · 5 authors
Vehicular Edge Computing (VEC) is a promising paradigm to enable huge amount of multimedia content to be cached in proximity to vehicles. Since vehicles are equipped with a certain amount of caching resource, they can be regarded as edge nodes to expand the caching capacity of the network edge. However, with much sensitive personal information, vehicles may be not willing to cache their content to an untrusted vehicle. Permission blockchain has the potential to address such an issue. In this paper, we utilize permissioned blockchain to design a secure content caching scheme between vehicles. Since high mobility of vehicles makes a dynamic caching environment, we exploit deep reinforcement learning approach to design the content caching scheme. Moreover, we propose a new block verifier selection metric, Proof-of-Utility (PoU), to enable a lightweight permissioned blockchain. Security analysis shows that our proposed blockchain empowered content caching can achieve security and privacy protection. Numerical results based on the Uber dataset indicate the DRL-inspired content caching scheme significantly outperforms two benchmark policies.
Peer to peer energy trading (P2P ET) is expected to be one of the key elements of the next generation power systems. Existing centralized grid systems face several challenges to support P2P ET such as single point of failure, communication overhead, security and privacy problems. Blockchain based P2P ET has been suggested by many researchers as a possible solution to the aforementioned problems. In this paper, we propose P2P ET architecture that allows performing secure energy trading without compromising system efficiency. The proposed architecture consists of three layers: Blockchain layer, Off-Blockchain communication layer and Physical layer. We describe the components of each layer along with interactions that exist between them to achieve the overall objectives. Moreover, we explain how the proposed architecture can achieve a better performance.
The past decade has witnessed an explosive growth in cryptocurrencies, but the blockchain-based cryptocurrencies have also raised many concerns, among which a crucial one is the scalability issue. Suffering from the large overhead of global consensus and security assurance, even the leading cryptocurrencies can only handle up to tens of transactions per second, which largely limits their applications in real-world scenarios. Among many proposals to improve the cryptocurrency scalability, one of the most promising and mature solutions is the payment channel network (PCN), which offers the off-chain settlement of transactions with minimal involvement of expensive blockchain operations. However, transaction failures may occur due to external attacks or unexpected conditions, e.g., an uncooperative user becoming unresponsive. In this paper, we present a distributed robust payment routing protocol RobustPay to resist transaction failures, which achieves robustness, efficiency and distributedness. Moreover, we modify the original HTLC protocol and adapt it to the robust payment routing protocol.
In the fourth industrial revolution, blockchain is one of the popular technologies. There are many benefits such as decentralization, persistency and security. A blockchain network can be public or private. Among them, the private blockchain model is applied to the business model. It can be a consortium of networks and is efficiently handled using smart contracts. However, there are many problems in applying the blockchain technology to various environments. One of the concerns is that it does not provide enough performance for many transactions [1]. This paper focuses on improving the performance of Hyperledger Fabric which is reported to be the fastest private blockchain platform [2]. Fabric has various component such as chaincode(smart-contract), endorsing peer, ordering service and committing peer. We propose two optimization method about endorsing peer and ordering service. Firstly, we have improved the procedure of read transactions by distinguishing between read and write transactions in the endorsement phase. We achieved 60% better performance than original read transaction processing. Secondly, we create a new consensus protocol without using an external project. We decreased latency by 80% through ordering service optimization. By combining two optimizations, we improved the overall latency and throughput performance by 20%.
Md. Ashraf Uddin, Andrew Stranieri, Iqbal Gondal, Venki Balasubramanian
Blockchain emerging for healthcare provides a secure, decentralized and patient driven record management system. However, the storage of data generated from IoT devices in remote patient management applications requires a fast consensus mechanism. In this paper, we propose a lightweight consensus mechanism and a decentralized patient software agent to control a remote patient monitoring (RPM) system. The decentralized RPM architecture includes devices at three levels; 1) Body Area Sensor Network- medical sensors typically on or in patient's body transmitting data to a Smartphone, 2) Fog/Edge, and 3) Cloud. We propose that a Patient Agent(PA) software replicated on the Smartphone, Fog and Cloud servers processes medical data to ensure reliable, secure and private communication. Performance analysis has been conducted to demonstrate the feasibility of the proposed Blockchain leveraged, distributed Patient Agent controlled remote patient monitoring system.
Blockchain technology aims to maintain a consistent ledger which is kept by the nodes of the system in a distributed manner. To achieve this goal, a consensus protocol needs to be employed for the nodes to process the block data and exchange their validation opinions. A variety of consensus protocols have been proposed for different application scenarios. In this paper, we propose a framework of categorizing consensus protocols based on the number, role and selection of nodes to be involved in the validation and ordering procedure. We also identify several possible new directions of consensus protocol design for future blockchain applications.
Denis Rangelov, Nikolay Tcholtchev, Philipp Lämmel, Ina Schieferdecker
In recent years the emergence of the Ethereum Blockchain has introduced a new alternative perspective on how web applications can be build. More precisely, the Ethereum Blockchain allows the development of applications, where programming code can be executed in a decentralized manner with no restrictions imposed by a central authority. However, as it is the case with many emerging technologies, there is a fair amount of trade-offs that have to be considered when this technology is used as a platform for implementing decentralized applications. In this work we present two architectural designs for building decentralized applications (DApps) based on the Ethereum Blockchain technology. Within this context, we discuss the inherent strengths and weaknesses of each of the architectural designs as well as the set of challenges that we faced during the development process.
Christos Profentzas, Magnus Almgren, Olaf Landsiedel
For any distributed system, and especially for the Internet of Things, recording interactions between devices is essential. At first glance, blockchains seem to be suitable for storing these interactions, as they allow multiple parties to share a distributed ledger. However, at a closer look, blockchains require heavy computations, large memory capacity, and always-on communication to the cloud; these are three properties that are challenging for IoT devices with limited resources. In this paper, we present IoTLogBlock to address these challenges. IoTLogBlock connects resource-constrained IoT devices to the blockchain, and it consists of three building blocks jointly enabling recording transactions: a lightweight contract signing protocol, a blockchain network, and a smart contract. The contract signing protocol allows devices to interact locally to perform transactions, even if no communication to the cloud and the blockchain exists at that moment. At a later time, devices forward the stored transactions to the blockchain, where a smart contract ultimately verifies the transactions. We evaluate our design on low-power devices and quantify the performance in terms of memory, computation, and energy consumption. Our results show that a constrained device can create and sign a transaction within 3 s on average. Finally, we expose the devices to network scenarios with edge connections ranging from 10 s to over 2 h.
Matteo Varvello, Iñigo Querejeta Azurmendi, Antonio Nappa, Panagiotis N. Papadopoulos · 6 authors
Distributed Virtual Private Networks (dVPNs) are new VPN solutions aiming to solve the trust-privacy concern of a VPN's central authority by leveraging a distributed architecture. In this paper, we first review the existing dVPN ecosystem and debate on its privacy requirements. Then, we present VPN0, a dVPN with strong privacy guarantees and minimal performance impact on its users. VPN0 guarantees that a dVPN node only carries traffic it has "whitelisted", without revealing its whitelist or knowing the traffic it tunnels. This is achieved via three main innovations. First, an attestation mechanism which leverages TLS to certify a user visit to a specific domain. Second, a zero knowledge proof to certify that some incoming traffic is authorized, e.g., falls in a node's whitelist, without disclosing the target domain. Third, a dynamic chain of VPN tunnels to both increase privacy and guarantee service continuation while traffic certification is in place. The paper demonstrates VPN0 functioning when integrated with several production systems, namely BitTorrent DHT and ProtonVPN.
Iman Vakilinia, Shahin Vakilinia, Shahriar Badsha, Engin Arslan · 5 authors
Blockchain technology has provided a solid system to develop incentivization algorithms using the smart contract. Blockchain applies the distributed ledger to store transaction histories, and the information is stored across a network of computers instead of on a single server. This facilitates the development of a new set of applications such as distributed file storage systems where users can rent out their storage in return for a premium. The distributed file storage systems provide more privacy and security compared to the centralized storage models as there is no need to have a trusted party. New schemes have been developed for distributed file storage systems on top of the blockchain platform, however, the problem of task/service allocation in these models have not been studied before. In this paper, we study the task/service allocation in the distributed file storage systems considering the challenge of computation cost. First, we formalize the problem of task/service allocation in a decentralized storage network, and then we discuss different approaches to allocate storage tasks to storage servers in an efficient manner. Moreover, we study the benefits of the cooperation (a.k.a pooling) in the storage and retrieval markets of distributed storage networks. The evaluation results show the benefit of our proposed pooling based approach in storage and retrieval markets.