As the blockchain technology grows, the scale of the network is becoming huger and huger, which brings us a troublesome question: how to allocate our data into each computer of a blockchain network? For example, we can store our data from one computer, until the memory space filled, and then switch to another, spending a lot of time searching in sole computer. Or we can only put a small amount of data into one computer, resulting in a huge network and plenty of transmission time. In this paper, we compute the cost of all the allocations according to the mathematical model. By studying the formula, we get the solution of balancing the search time and the space occupancy by users' input. Based on the result, we design a data allocation strategy that can decide how many data allocated to an individual computer.
Dumitrel Loghin, Gang Chen, Tien Tuan Anh Dinh, Beng Chin Ooi · 5 authors
Motivated by the massive energy usage of blockchain, on the one hand, and by significant performance improvements in low-power, wimpy systems, on the other hand, we perform an in-depth time-energy analysis of blockchain systems on low-power nodes in comparison to high-performance nodes. We use three low-power systems to represent a wide range of the performance-power spectrum, while covering both x86/64 and ARM architectures. We show that low-end wimpy nodes are struggling to run full-fledged blockchains mainly due to their small and low-bandwidth memory. On the other hand, wimpy systems with balanced performance-to-power ratio achieve reasonable performance while saving significant amounts of energy. For example, Jetson TX2 nodes achieve around 80% and 30% of the throughput of Parity and Hyperledger, respectively, while using 18x and 23x less energy compared to traditional brawny servers with Intel Xeon CPU.
In this paper we propose and analyze a community-driven platform for flexibility provision based on a distributed ledger. We introduce and analyze the platform for the use case of a self-organized decentralized virtual power plant consisting of a local community of individual prosumers with photovoltaic-storages located on a low voltage feeder. Like a virtual power plant, it aggregates small-scale assets and is able to provide ancillary services in the form of active power provision to the electrical power system. However, the decentralized virtual power plant provides a direct flexibility market access of the distributed assets without the need for a third party. Thus, balancing group managers or system operators can directly interact with the distributed assets in an aggregated way without the need for an aggregator. The solution approach uses a heuristic algorithm for the coordination combined with a distributed ledger and democratic consensus within the community. We propose the concept in detail, describe the prototypical implementation based on a consortium Ethereum blockchain and discuss results of the proof-of-concept. Our numerous test runs with up to 20 participants showed that the coordinated flexibility provision, energy sharing and according financial settlement works in practice, but would need an upgrade concerning the smart-meter hardware for an implementation in the field. We analyze the impact of the coordination interval on the community self-sufficiency and determine that one minute intervals are enough to reach 96% of the optimum. We evaluate the storage and communication effort and conclude with suggestions for future improvements and other possible applications of the decentralized platform like aggregated flexibility coordination between balancing group managers and system operators.
Bin Cao, Yixin Li, Lei Zhang, Long Zhang · 7 authors
Blockchain has been regarded as a promising technology for Internet of Things (IoT), since it provides significant solutions for decentralized network which can address trust and security concerns, high maintenance cost problem, etc. The decentralization provided by blockchain can be largely attributed to the use of consensus mechanism, which enables peer-to-peer trading in a distributed manner without the involvement of any third party. This article starts from introducing the basic concept of blockchain and illustrating why consensus mechanism plays an indispensable role in a blockchain enabled IoT system. Then, we discuss the main ideas of two famous consensus mechanisms including Proof of Work (PoW) and Proof of Stake (PoS), and list their limitations in IoT. Next, two mainstream Direct Acyclic Graph (DAG) based consensus mechanisms, i.e., the Tangle and Hashgraph, are reviewed to show why DAG consensus is more suitable for IoT system than PoW and PoS. Potential issues and challenges of DAG based consensus mechanism to be addressed in the future are discussed in the last.
People need a motive to use and maintain a system. In many of the systems we use today, financial rewards and punishments provide a key incentive to participate and abide by the rules. From salaries to traffic tickets, financial motives are often closely tied to a system's viability. Distributed systems such as blockchain also need a mechanism to motivate good behavior. A blockchain must encourage users to maintain the system while preventing a minority of these users from colluding and gaining disproportionate control. Many popular public blockchains use monetary incentives to encourage users to participate and behave appropriately. But these same incentive schemes create more problems than they solve. Mining rewards cause centralization in proof of work chains such as Bitcoin. Validator rewards and punishments invite attacks in proof of stake chains. This paper argues why these incentive schemes are detrimental to blockchain. It also considers a range of other systems-some of which incorporate monetary incentives, some of which do not-to confirm that monetary incentives may be neither necessary nor sufficient for good user behavior.
The benefits of blockchain technology are evident in the banking industry as the underlying technology for cryptocurrencies. Recently, research has been focused on novel, non-cryptocurrency uses of blockchain for other industries such as national defense. Application of these technologies in military use cases requires special consideration of the limitations inherent to tactical military operations, namely the network communication technologies. In this work we explore the performance of blockchain technologies on network environments representative of those available in Department of Defense (DoD) tactical operations. Our experimentation with the Ethereum blockchain on a mobile network emulation reveals a series of verbose blockchain network communication protocols as well as a heavy reliance on Transmission Control Protocol (TCP) for block transfer and synchronization that may limit the effectiveness of blockchain on current DoD mobile ad hoc networks.
Blockchain offers the ability to create distributed databases that can be trusted, even if some actors on the network may be malicious. We consider the problem of reducing the read overhead of a ledger built using blockchains as part of the IDASH 2018 competition. In this scenario, we have multiple nodes granted to access a server. The goal is to store the activity logs of the nodes accessing the server in a secure fashion, using a blockchain-based ledger. To increase search speed, we propose splitting the ledger into groups based on expected search terms, and storing each group on a separate blockchain. By doing so, a search for all records of a specific type is transformed from a linear search on all records, to a linear search on a small subset of records. In our solution, this increases search efficiency by a factor of 8, at the cost of increasing storage overhead by a factor of 4. The system can be adjusted based on what types of searches are expected to reduce this overhead.
Boubakr Nour, Adlen Ksentini, Nicolas Herbaut, Pantelis A. Frangoudis · 5 authors
With advent of 5G, the classical mobile network business model is shifting from a network-operator-oriented business to a more open system with several actors. In this context, the network slice provider will play the role of an intermediate entity between the vertical service provider and the resource provider. To deploy a network slice, the network slice provider will require a brokering mechanism, which allows it to lease resources from different providers in a secure and private way. In this letter, we propose a broker design based on blockchain technology, providing a mechanism that secures and ensures anonymous transactions.
With billions of IoT devices expected in the next few years, their management is an important issue to be resolved and, while being praised in the past decades, the centralized approach of cloud computing may not be adequate at this massive scale. In this context, the introduction of blockchain technology with a distributed approach has raised a lot of hypes in solving this scalability problem. This paper proposes a blockchain-based architecture design for scalable reconfiguration of massive IoT devices. A REST API event-based publish/subscribe mechanism is used to decouple the IoT devices from the blockchain operations for reducing resource utilization. Moreover, smart contracts, reconfiguration workflows are developed to facilitate the blockchain-based update process. To evaluate the feasibility and performance of the proposed architecture, a proof-of-concept testbed has been developed. Experimental results illustrate that the proposed architecture is capable of providing a scalable solution for delivering on-demand configuration changes with a negligible effect on the resource utilization on IoT devices.
Olamide Jogunola, Mohammad Hammoudeh, Bamidele Adebisi, Kelvin Anoh
Blockchain (BC) is becoming a key technology in securing future businesses and economic competition around the world. It is seen as an enabler for trust and security in the growing sharing economy. In this study, we demonstrate the application of BC to energy peer-to-peer (P2P) trading in smart grid. A smart contract for managing trust and transactions is designed and implemented for a use case in energy P2P trading on IBM platform using hyperledger composer. In addition, current challenges that could be faced when implementing BC for securing energy P2P trading are investigated and discussed.
This paper introduces FileTribe, a secure decentralized application for sharing files in closed groups. It employs IPFS, a distributed file system, as its data storage layer, avoiding the pitfalls of centralized storage solutions. Changes to files and group membership are recorded separately on a blockchain, making them irrefutable. A Decentralized Application (Dapp) on top of Ethereum is responsible for user authentication and reaching consensus among group members regarding the state of the group and shared files. File access control is supervised by the members themselves. These features combine to make FileTribe unique in its ability to serve a wide range of safetycritical scenarios, including ones where cloud-based or pure peerto- peer solutions fall short.
Permissioned blockchains have evolved as an alternative to permissionless blockchains for various closed business environments. In this paper, we develop FRChain, a scalable and high-performant consensus protocol for permissioned blockchains, which is resilient to different types of node and network failures. FRChain uses collective signing over multicast trees for block propagation and block validation. The protocol ensures safety and liveness as long as a majority of the nodes can participate in the protocol correctly. Further, we also demonstrate a technique for replacing failed nodes with correct ones. We have implemented and tested FRChain spread across a 5000 node blockchain network over two different data centers - (a) 35 Softlayer Cloud VMs located across Melbourne, Milan and San Jose, (b) Amazon VPC with 30 Amazon EC2 instances spread across Mumbai, Singapore, Tokyo and Frankfurt. Our experiments show that FRChain is scalable in terms of both transaction throughput and network size.
Today, Internet of Things (IoT) technology is applied to everywhere providing tremendous amounts of IoT service such as home control, facility management, and social public services. The GS1, a non-profit international standard organization, standardized an Object Name Service (ONS) which enables users to manage and discover services in the midst of tremendous amounts of service. However, it has a vulnerability in security and fault tolerance of providing service, because the ONS operates based on the DNS protocol. It is weak against data tampering attacks caused by DNS cache poisoning, spoofing, and local DNS cracking. It has a weak fault tolerance from problems with attack or malfunction. In this paper, we propose a BlockONS, which is novel ONS based on a blockchain. It provides a strength in data tampering attacks allowing a fault tolerance for sustainable service. The BlockONS consists of new service data modeling for an off-chain scaling, data tampering validation method, and fault tolerance mechanism. We designed the BlockONS into two parts: a BlockONS Node part to valid data tampering, and a BlockONS Agent part for scaling and fault tolerance. Finally, we implement the BlockONS prototype using a Hyperledger Sawtooth blockchain and intel i5 NUC. We proof the feasibility of the BlockONS by comparing with performance of an existing ONS.
In this paper, we focus on the energy efficiency aware architecture of caching the necessary production messages and the transaction process to support a readable and tamper proof internet of things (IoT). To achieve this, blockchain can provide a reliable distributed storage of the messages, because any changes of the cached messages will break the structure of the blockchain. Specifically, we assume that the access points belonging to different telecom operators collect the messages in the IoT network, wherein multiple servers used for either caching or computing are placed at each access point. We define that the caching servers can be divided into the data loading caches for caching the received wireless IoT data and the data transmission caches for transmitting the IoT data into the blockchain based cloud caching servers. The blocks generated in the data loading caches at each access point will be written into the blockchain based on both the proof-of-work and the capacity of the data loading caches at each access point. Then, we formulate the optimization problem maximizing the system energy efficiency by optimizing the allocation of cache, computation and communication resources by a geometric programming model. By the CVX tool in matlab software, the geometric programming model can be solved effectively. We study the impact of different parameters involved in the blockchain on the system performance, and verify the effectiveness of our proposed energy efficiency aware optimization mechanism in the blockchain based IoT.
Caching and sharing contents among mobile devices via wireless device-to-device (D2D) communications is a promising way to offload data traffic. In order to encourage more content sharing among mobile devices, we propose a blockchain incentive scheme in this paper, where the base station (BS) can allocate computing power to mine blockchain in a period of time and give this mining profit to the mobile devices that share contents with others via D2D communication. In order to maximize the total profit, we develop the caching placement schemes considering different relationships between the allocated computing power and the shared data size. For the linear relationship, we can obtain the closed form expression of the optimal caching scheme and find that the mobile device prefers to cache the popular contents. For the nonlinear relationship, the optimal problem can be effectively solved by difference of convex (DC) programming and the results reveal that the mobile device prefers to caching different contents.
Blockchain can be used to ensure trust in a decentralized environment in which no trusted authority is available. Its original idea is to collect transactions in a block, and to chain the blocks together in such a way that attackers cannot forge the chain if the majority of the network is honest. Since its creation in 2008, blockchain technology has been used broadly in Internet to support decentralized payments, cloud computing, publishing, etc. This work focuses on public permissionless blockchain which neither guards against bad actors nor enforces access control. Named data networking (NDN) uses name-based routing and in-networking caching to support efficient content delivery, making it a promising future Internet architecture as well as a great network technology which can improve blockchain data delivery. Therefore, it is a very necessary task to enable deployment of blockchain applications over NDN. However, NDN is not immediately compatible with typical blockchain, since (permissionless) blockchain applications usually require broadcasting transactions and blocks in real time, which is not supported by the “pull” design of NDN. In this work, we propose BoNDN which enables blockchain applications over NDN. Unlike previous work, BoNDN follows the core design of NDN. We treat each type of blockchain data needed to be broadcast individually. Specifically, we rely on Interest broadcasting to support real-time broadcasting of blockchain transactions, which is small in size and can be brought by an Interest packet. In addition, we propose a subscription-push approach to support broadcasting of blockchain blocks, in which each miner performs subscription, and once a block is generated, the subscribed miner will receive the block.
In Blockchain networks involving multiple applications, the quality of service of an application is affected by the transaction ordering. We study a setting where each application is represented by a node, which might attempt to prioritize its own transactions through including them early in blocks added to the blockchain. A fair block proposal of a node follows a random selection of the transactions among the set of pending transactions the node is aware of. On the contrary, a dishonest node includes more of its transactions at the expense of transactions of other applications. In this work, we propose a toolbox of techniques to enforce such a fair block selection. First, we design an accurate statistical testing for the honesty of a proposal and explain it. Next, we describe a reputation system, documenting honesty of nodes to encourage fairness. Our last technique enforces fair block selection through concise commitments on the set of pending transactions known to a node.
In massive, dynamic and distributed P2P networks like Bitcoin, where thousands of updates occur per second, it is hard to obtain an accurate topology representing the structure of the network as a graph with nodes and links by using the traditional local measurement approaches based on batches, offline data, or on the discovery of the topology around a small set of nodes and then combine them to discover an approximate network topology. All of which present some limitation when applying them on blockchain-based networks. In this paper, we propose a topology discovery system, which performs a real-time data collection and analysis for Bitcoin P2P links with the use of a customized version of the Page-Rank algorithm that assembles incoming nodes information for deeper graph analysis processing. The topology discovery system allows us to gain knowledge on the Bitcoin network size, the network stability in term of well-connected Bitcoin nodes, as well as some data regarding the Bitcoin nodes geolocation.
Michael Herbert Ziegler, Marcel Großmann, Udo R. Krieger
Considering the Internet-of-Things, the blockchain technology has recently become a major focus of research. One of its major drawbacks is given by the poor performance of blockchain systems subject to heavy load. In particular, systems which use Proof-of-Work as leader election strategy are not suitable for an active participation of IoT devices. We propose a new system architecture which uses the Plasma framework to integrate blockchain technology and fog computing and evaluate the performance of its prototype. The Plasma framework has the advantage to provide a scalable hierarchical design based on sidechains and an off-chain scaling strategy which is agnostic with regard to the architecture of the employed root chain.
The past several years have 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. In this paper, we investigate the problem of payment routing in PCNs from an optimization perspective, which is to minimize the transaction fee of a payment path, subject to the timeliness and feasibility constraints. We present an optimal distributed algorithm CheaPay for this problem. Extensive simulations demonstrate that CheaPay significantly outperforms baseline algorithms in terms of the success ratio and the average accepted value.
Muhammad T. Afzal, Khalid Umer, Waqas Amin, Muhammad Naeem · 7 authors
This paper proposes an optimization model for community microgrid. The proposed scheme performs the scheduling of domestic appliances in a community microgrid using renewable energy resources. The objective of the scheme is to minimize the total operating cost in the whole community. The optimization problem is solved using the branch and bound algorithm. Blockchain (BC) technology is introduced for secure implementation of the proposed approach. Machine to machine interaction is facilitated using BC technology. The transaction information/ data is stored in the distributed shared ledger. The smart contract is used to automatically trigger the flow of electricity and the movement of funds once the necessary conditions are met.
Smart Communities seeks to thrive in a context of broadband economy, its engine and reason for being. The success of any community is a function of its economic backbone or the supply chain. A supply chain can be defined as the integration of customers, retailers, distributors and manufacturers. The changing technology has made the survival in commerce highly competitive and price sensitive. Blockchain technology can be the game-changer for decentralizing infrastructure and building a trust layer for business logic. BlockCom is a commerce model based on the emerging technology of blockchain. This paper presents a double auction scheme for energy trading between customers and suppliers. A smart contract implements a distributed algorithm to maximize individual participating profit. Parties bid to smart contract which act as auctioneer for maximizing the profit. Mathematical parameter named credibility score has been created to deal with trust issues in the decentralized network using byzantine fault tolerant mechanism. BlockCom provides a fresh perspective on the concept of supply chain and commerce.
Vysakh Anilkumar, Joseph Antony Joji, Asif Afzal, Reshma Sheik
Blockchain technology has been shining like a star after the introduction and widespread acceptance of the Bitcoin, the very first cryptocurrency in people's everyday lives. At the beginning, Blockchain was used only for monetary transactions but studies have proven that it has many more applications. Blockchain platforms introduce a decentralized mode of control are rapidly being developed in the world on a large scale and their survey along with their characteristics are being discussed in this paper. But since developing Blockchain applications on a Blockchain network are more costly, there is a need for a simulation platform to refine and test the applications before it can be committed to the network There are a huge number of Blockchain simulation platforms available. The real task is to choose one among them that is best suited for decentralised application (DApp) developers. In this paper, a study is made using an E-voting application [7] to compare different Ethereum simulation platforms.