Blockchain is the backbone technology behind crypto-currency and Bitcoin. By concept, Blockchain is a distributed database where transactions are recorded in an incorruptible and non-modifiable manner. Currently, Blockchain technology is envisioned as a powerful framework for open-access networks, decentralized information processing and sharing systems, etc. This review is motivated due to the lack of an extensive survey on the existing decentralized consensus mechanisms in Blockchain technology. So in this paper, an in-depth review of the distributed consensus mechanisms has been presented. In addition to this, a comparative analysis of the consensus protocols based on the type of Blockchain is also demonstrated.
Beom Suk Lee, Jae Song, Sung Jun Moon, In Hwan Park · 5 authors
We consider blockchain architectures for P2P energy trading of surpluses and demands between prosumers and consumers in the neighborhood without any intermediaries. We identify key elements comprising the P2P energy trading platform based on blockchain. The software architecture of our energy trading platform is provided with example codes. We build smart contracts on Ethereum for determination of trading price as well as matching between prosumers and consumers in such a way to balance the surpluses and the demands. At the start of each trading period, the prosumers and consumers send their respective amounts of surplus or demand. And the smart contract for price determination automatically evaluates the price in a predetermined way to balance surplus and demand within the neighborhood. Another smart contract performs matching between prosumers and consumers using this price. Authenticated and private messaging called `whisper' is employed for prosumers and DSO(Distributed System Operator)s to notify injection of surplus energy to the DSO and verify the ownership of the injected energy. Each participant interacts with Ethereum virtual machine through web server built with Node.js, Web3.js and Geth. We build a small experimental setup with 4 Raspberry-Pis in a private Ethereum network to provide proof-of-concept for our blockchain based P2P trading architecture between neighbors.
Chol Hyun Park, Ivanrey Mejia Barlongo, Yoohwan Kim
In the recent decade, self-consumption and local renewable energy communities are growing, especially in California, North Carolina, Arizona and Nevada. In these communities, approximately twenty percent of electricity comes from solar generation. However, what happens if a household generates more than what they consume? In most cases, the excess energy would go back to the grid with little to no compensation given by the energy utility. In today's market, there are countless homeowners who would like to profit from their own PV system. Unfortunately, there is no energy marketplace that would allow homeowners to sell or purchase energy to and from their neighbors. Luckily with blockchain, this idea becomes a reality. With the use of distributed ledger technology, it is possible to perform energy transactions in near-real time from a prosumer to consumer without the need of a central authority. Our thesis suggests ways to handle the facilitation of energy transactions using an Ethereum blockchain system in an effortless and efficient way.
Internet of Things (IoT) is an emerging technology that have been attracting significant attention from diverse application domains ranging from smart homes, smart cities to smart healthcare and manufacturing. Especially in smart city context, IoT devices play a significant role since the city of the future is an interconnected one, where distributed devices communicate with one another, constantly exchanging streams of real time data. However, the fundamental challenge on deploying such technology is the inherent limitations on IoT device's computational power, network connectivity, energy consumption, which in turn hinders secure deployment. The introduction of Blockchain technology for digital cash offers a promising data security scheme for IoT applications in trust-less environments. Blockchain promises an elegant approach for secure information dissemination, machine-to-machine micro-transactions, and access control in a smart city context for IoT devices. However, the computational and storage requirements for original Blockchain model presents difficulties for IoT deployment. In this paper, we propose an experimental lightweight distributed ledger for IoT devices, TangoChain, utilizing a directed acyclic graph as underlying ledger data structure. We discuss the rationale behind our design approach, then present our in-progress proof-ofconcept prototype implementation details, and highlight the potentials for secure IoT device deployments in a smart city context.
Blockchain – a distributed and public database of transactions – has become a platform for decentralized applications. Despite its increasing popularity, blockchain technology faces a scalability problem: the throughput does not scale with the increasing network size. Thus, in this paper, we propose a scalable blockchain protocol to solve the scalability problem. The proposed method was designed based on a proof of stake (PoS) consensus protocol and a sharding protocol. Instead of transactions being processed by the whole network, the sharding protocol is employed to divide unconfirmed transactions into transaction shards and to divide the network into network shards. The network shards process the transaction shards in parallel to produce middle blocks. Middle blocks are then combined into a final BLOCK in a timestamp recorded on the blockchain. Experiments were performed in a simulation network consisting of 100 Amazon EC2 instances. The latency of the proposed method was approximately 27 s and the maximum throughput achieved was 36 transactions per second for a network containing 100 nodes. The results of the experiments indicate that the throughput of the proposed protocol increases with the network size. This confirms the scalability of the proposed protocol.
Wireless power transfer is a promising approach to charge low-power IoT devices for energy replenishment. However, energy attacks from malicious IoT devices can result in significant energy loss to energy transmitters. In this article, we propose a new distributed and secure wireless power transfer architecture by utilizing blockchain. The proposed architecture includes two planes: the energy plane and blockchain plane. We further abstract three types of traffic flows, transaction flow, consensus flow and coin flow, to provide a profound insight into the workflow of blockchain. Furthermore, to obtain the optimal amount of transferred energy in the energy plane, and to resolve high operational overhead of the consensus process in the blockchain plane, we develop a contract theory based wireless power transfer scheme and a DPoS based lightweight consensus scheme, and design an efficient wireless power transfer mechanism by combining the two schemes. Illustrative results demonstrate that our proposed schemes offer significant energy loss reduction with moderate operational overhead.
James Kempf, Sambit Nayak, Remi Robert, Jim Feng · 9 authors
In this paper, we describe a virtual services marketplace, called Nubo, designed to connect buyers of virtual services (or tenants) with providers of those services on a cloud computing platform. The marketplace is implemented as a collection of distributed microservices along with a marketplace portal that runs as a Web application. The heart of Nubo is the Saranyu tenant and service management microservice. Saranyu is a decentralized application (dApp) built on top of the J.P. Morgan Quorum blockchain. Tenant and service accounts are represented as static (nonnegotiable) smart contracts written in the Solidity language. Quorum provides a tamper evident and tamper resistant distributed ledger, whereby multiple cloud and service providers can co-operate to provide service resources to tenants in a trustworthy fashion. Services offer resources consisting of a collection of attributes describing what the tenant can consume, and tenants subscribe to service resources through the Nubo Marketplace portal. The Service Manager microservice provides multitenant support for containerized services built for deployment and orchestration using Docker that were originally not designed to be managed through Saranyu. We discuss our design goals for Nubo, describe the overall architecture, discuss some details on how Saranyu uses the blockchain and smart contracts, and provide comprehensive performance and scalability data measured on the Saranyu REST API. The results indicate Saranyu is competitive with published results for comparable operations on the Havana release of OpenStack Keystone, but Saranyu provides a much richer collection of tenant and service management functionality than Keystone.
Ajay Kumar Shrestha, Ralph Deters, Julita Vassileva
The tremendous technological advancement in the last few decades has brought many enterprises to collaborate in a better way while making intelligent decisions. The use of Information Technology tools in obtaining data of people's everyday life from various autonomous data sources allowing unrestricted access to user data has emerged as an important practical issue and has given rise to legal implications. Various innovative models for data sharing and management have privacy and centrality issues. To alleviate these limitations, we have incorporated blockchain in user modeling. In this paper, we constructed a decentralized data sharing architecture with MultiChain blockchain in the travel domain, which is also applicable to other similar domains including education, health, and sports. Businesses that operate in the tourism industries including travel and tour agencies, hotels and resorts, shopping malls are connected to the MultiChain and they share their user profile data via stream in the MultiChain. The paper presents the hotel booking service for an imaginary hotel as one of the enterprise nodes, which collects user profile data with proper validation and will allow users to decide which of their data to be shared thus ensuring user control over their data and the preservation of privacy. The data from the repository is converted into an open data format while sharing via stream in the blockchain so that other enterprise nodes, after receiving the data, can easily convert them and store into their own repositories. The paper presents an evaluation of the performance of the model by measuring the latency and memory consumption with three test scenarios that mostly affect the user experience. The node responded quickly in all of these cases.
Blockchain is a technology that can ensure data integrity in a distributed network, and it is actively applied in various fields. Recently, blockchain is gaining attention due to combining with the Internet of Things (IoT) technology in the industrial field. Moreover, many researchers have proposed the Industrial IoT (IIoT) architecture with blockchain for data integrity and efficient management. The IIoT network consists of many heterogeneous devices (e.g., sensors, actuators, and programmable logic controllers (PLC)) with resources-constrained, and the availability of the network must be preferentially considered. Therefore, applying the existed blockchain technology is still challenging. There are some results about the technique of constructing blockchain lightly to solve this challenge. However, in these results, the analysis in perspective of cryptographic performance (area, throughput, and power consumption) has not been considered sufficiently, or only focused on the architecture of the blockchain network. The blockchain technology is based on cryptographic techniques, and the main part is a cryptographic hash function. Therefore, if we construct the blockchain-based IIoT architecture, we have to consider the performance of the hash function. Many lightweight hash functions have been proposed recently for the resource-constrained environment, and it can also be used to the blockchain. Therefore, in this paper, we analyze the considerations of lightweight blockchain for IIoT. Also, we conduct an analysis of lightweight hash for blockchain, and propose a new lightweight hash-based blockchain architecture that can change the hash algorithm used for mining adjust to network traffic.
Zoltán Lux, Felix Beierle, Sebastian Zickau, Sebastian Göndör
Self-sovereign Identity (SSI) powered by distributed ledger technologies enables more flexible and faster digital identification workflows, while at the same time limiting the control and influence of central authorities. However, a global identity solution must be able to handle myriad credential types from millions of issuing organizations. As metadata about types of digital credentials is readable by everyone on the public permissioned ledger with Hyperledger Indy, anyone could find relevant and trusted credential types for their use cases by looking at the records on the blockchain. To this date, no efficient full-text search mechanism exists that would allow users to search for credential types in a simple and efficient fashion tightly integrated into their applications. In this work, we propose a full-text search framework based on the publicly available metadata on the Hyperledger Indy ledger for retrieving matching credential types. The proposed solution is able to find credential types based on textual input from the user by using a full-text search engine and maintaining a local copy of the ledger. Thus, we do not need to rely on information about credentials coming from a very large candidate pool of third parties we would need to trust, such as the website of a company displaying its own identifier and a list of issued credentials. We have also proven the feasiblity of the concept by implementing and evaluating a prototype of the full-text credential metadata search service.
Payment channel networks (PCNs) are viewed as one of the most promising scalability solutions for cryptocurrencies today. Roughly, PCNs are networks where each node represents a user and each directed, weighted edge represents funds escrowed on a blockchain; these funds can be transacted only between the endpoints of the edge. Users efficiently transmit funds from node A to B by relaying them over a path connecting A to B, as long as each edge in the path contains enough balance (escrowed funds) to support the transaction. Whenever a transaction succeeds, the edge weights are updated accordingly. In deployed PCNs, channel balances (i.e., edge weights) are not revealed to users for privacy reasons; users know only the initial weights at time 0. Hence, when routing transactions, users typically first guess a path, then check if it supports the transaction. This guess-and-check process dramatically reduces the success rate of transactions. At the other extreme, knowing full channel balances can give substantial improvements in transaction success rate at the expense of privacy. In this work, we ask whether a network can reveal noisy channel balances to trade off privacy for utility. We show fundamental limits on such a tradeoff, and propose noise mechanisms that achieve the fundamental limit for a general class of graph topologies. Our results suggest that in practice, PCNs should operate either in the low-privacy or low-utility regime; it is not possible to get large gains in utility by giving up a little privacy, or large gains in privacy by sacrificing a little utility.
Blockchain technology has been increasingly used for decentralizing cloud-based Internet of Things (IoT) architectures to address limitations faced by centralized systems. While many existing efforts are successful in decentralization with multiple servers (i.e., full nodes) to handle faulty nodes, an important issue has arisen that external clients have to rely on a relay node to communicate with the full nodes in the blockchain. Compromization of such relay nodes may result in a security breach and even a blockage of IoT sensors from the network. In this article, we propose blockchain-based decentralized IoT management systems for censorship resistance, which include a “diffusion” function to deliver all messages from sensors to all full nodes and an augmented consensus protocol to check data losses, replicate processing outcome, and facilitate opportunistic outcome delivery. We also leverage public key aggregation to reduce communication complexity and signature verification. The experimental results from proof-of-concept implementation and deployment in a real distributed environment show the feasibility and effectiveness in achieving censorship resistance.
Abstract Blockchain is a key technology that enables cryptocurrencies such as Bitcoin, Litecoin, etc. In recent years, researchers have ventured into tapping the potential of blockchain‐based ecosystems beyond cryptocurrencies. This paper explores the convergence of blockchain with the Internet of things (IoT) and its improved versions like software‐defined network (SDN)–based IoT, which are upcoming technologies in the area. This paper gives a brief description of the IoT and its challenges, especially the security aspects. It also discusses how blockchain concept can further resolve these challenges on the SDN‐based IoT platform. This paper first discussed the evolution of conventional IoT to the SDN‐based IoT, which can resolve many drawbacks of a conventional IoT system. Also, it is focused on how the concept of blockchain can be converged with SDN‐based IoT system to further improve its security aspects. Although the convergence of these different technologies has resulted into many advantages, many associated challenges still remain. This paper highlighted these challenges and opportunities to discover many other research issues that need to be resolved. The details of current literature on the same issue has also been highlighted in this paper.
Xiang Fu, Wang Huaimin, Shi Peichang, Xue Ouyang · 5 authors
Summary The blockchain is a distributed ledger that records all transactions and operations in a shared manner. Public blockchains such as Bitcoin realize decentralization at the cost of mining overhead, which is not suitable for real‐life scenarios requiring high throughput. Techniques such as the consortium blockchain improve efficiency through partial decentralization. However, the consensus algorithms used in the existing state‐of‐the‐art consortium blockchains face many challenges when dealing with commercial applications. For example, the high communication overhead hinders the scalability of PBFT‐based consensus algorithms even though they are efficient at small scale. Hashgraph, one of the most popular Directed Acyclic Graph‐based (DAG‐based) consensus algorithms, achieves good performance in scalability; however, it does not allow users' dynamic participation. To deal with these challenges, we propose Jointgraph, a Byzantine fault‐tolerance consensus algorithm for consortium blockchains based on DAG. In Jointgraph, transactions are packed into events and validated by no less than 2/3 of all members. A supervisor is introduced in our design, who monitors member behaviors and improves consensus efficiency. Simulation results demonstrate that Jointgraph outperforms Hashgraph in both throughput and latency.