Blockchain has become one of the most demanding technologies of the decade. Blockchain is a decentralised digital record of information stored in a form of blocks in a chain of blocks called blockchain. It is totally dependent on the addition of new block in its chain. At a single time, there are a number of blocks ready to be added in the blockchain; choosing one valid block from this number of blocks is a complex and most important part of blockchain architecture. As we know that blockchain is a non-centralised system, it has peer-to-peer network in which blocks are added one by one to the chain of blocks only when a consensus is reached amongst the participants of the network. This paper presents a theory summarising of some consensus algorithm used in public, private and consortium blockchain technology along with pros and cons of each algorithms.
In order to reduce the cost of grid dispatching and increase the transparency of energy transactions, the distributed energy transaction model based on blockchain is constructed. At the same time, in order to improve the high communication overhead and low throughput of the traditional PBFT algorithm in the consortium blockchain, an efficient Byzantine fault‐tolerant consensus mechanism (DE‐BFT) for the energy blockchain is designed. The algorithm improves from two aspect: node election and main chain consensus. In the stage of node election, the model uses a health score evaluation and a verifiable random function to improve the security and randomness of node selection. In the stage of main chain consensus, the efficient data consistency interaction protocol decreases the complexity of the communications between nodes, down to a constant term level from exponential one. The result shows that, compared with other consensus algorithm, the DE‐BFT algorithm performs better in terms of consensus delay, communication overhead, throughput, and consensus node reliability.
Blockchain technology is a promising resource management architecture due to its ability of building trust in a decentralized transaction. Block mining participants, i.e. miners, are incentivized with reward for successfully mining blocks. Unfortunately, solving the proof-of-work puzzle consumes substantial computing powers during the mining period, which greatly challenges miners. Mobile devices also fail to participate in mining because of limited resource. To solve these issues, we are motivated to propose a mining framework of alleviating miner’s computation-intensive mining burdens, as well as enabling mobile devices’ participation. Depending on the proposed model, miners are capable of offloading their computation-intensive tasks to the edge cloud and mobile devices. The interactions among them formulate a muti-leader multi-follower Stackelberg game. We achieve the Subgame Perfect Equilibrium (SPE) in the game, which guarantees three types of participants to realize profit maximization. Simulation results demonstrate the effectiveness of the proposed model.
Haoran Qiu, Tao Ji, Shixiong Zhao, Xusheng Chen · 7 authors
Numerous blockchain systems with various consensus protocols have emerged to achieve high transaction rates (2$\sim$10K tps). However, their underlying P2P network primitives constrain further improvements due to two problems (i) high message redundancy and (ii) long broadcast convergence time. The first problem is caused by the excessive robustness of the dominant broadcast approach Gossip. All state-of-the-art blockchain systems only tolerate 20-50% node failure while Gossip can withstand up to 90%. The reason for (ii) is that existing broadcast topologies ignore geographical distances among nodes and incur paths with unnecessarily high latency. We presentFRing, a geography-based P2P overlay network for fast and robust broadcast in blockchain systems.FRinghas three main features: sufficient robustness, low message redundancy, and fast convergence. To reduce convergence time,FRingforms the network topology by considering geographical proximity. A novel broadcast algorithm based onFRingtopology is proposed to lower message redundancy while maintaining sufficient robustness. One major challenge is to eliminate the risk of topology inference by traffic pattern analysis.FRingleverages Intel SGX to guarantee nodes’ behavior integrity and incorporates pattern obfuscation to prevent traffic pattern analysis. The evaluation shows thatFRingimproved the throughput of EOS by 220% and Hyperledger Fabric by 210%.
The blockchain nexus with energy transactions in the distributed energy-trading arena successfully achieved a decentralized transaction and increased security. With the elimination of a third-party middle man, an electronic app is introduced to achieve decentralization and aid transactive communications. Observing the internet-of-things (IoT) intense protocols in the transactive communications amongst blockchain participants, however, leads to transaction time delay with associated uncertainty. This paper integrates the practical byzantine fault tolerance (pBFT) algorithm with the private Hyperledger Sawtooth blockchain network (P) to achieve a P-pBFT algorithm. The P-pBFT achieved a combined two-step transaction latency optimization (minimization) amongst the blockchain participants in the distributed energy generation (DEG) ecosystem. Through their combined feature extraction, further minimization is achieved by simulating the resulting transaction model derived from the integration. Subsequently, an optimization method is proposed to achieve the shortest transaction time given transaction constraints based on participants’ comfort. Thus, the ratio of node population to the transaction size and the choice of constraints can be regulated at the participants’ convenience to achieve minimum transaction time. Hence, the benefit of deciding the transaction time is achieved thereby eliminating the undesired characteristic uncertainty.
In this chapter, we will work on measuring the impact of mining digital coins by mobile on the main resources of the phone, by means of experiments conducted on iOS devices and Android devices. The experiments were conducted within four scenarios, which are as follows: A. Measuring the impact of cryptocurrency mining on the main resources of the phone when the mining program is running in the foreground of the system while keeping the phone screen active. B. Measuring the impact of cryptocurrency mining on mobile resources when the mining program is running in the foreground of the system and keeping the screen idle. C. Measuring the impact of cryptocurrency mining on the main resources of the mobile while the mining program is running in the background and keeping the mobile screen active. D. Measuring the impact of cryptocurrency mining on the main sources of the mobile while the mining program is running in the background and keeping the mobile screen in the login mode. This is to determine the effects resulting from the mining process on mobile resources, such as high CPU usage, high temperature, battery power consumption, and high temperature, in addition to the increase in RAM consumption, clarifying the results for each experiment, which are reflected in the mobile performance and functions. In addition, a fair use policy must be provided, and the experiments could suggest one. For both iOS and Android devices, the results will help to control and analyze the programs installed on the mobile to ensure that the user does not fall victim to malicious programs that use the mobile resources in the mining process and consume them without the knowledge or consent of the user.
Md. Tayeen Khan, Md. Nozib Ud Dowla, Fardin Ahmed Niloy
The popularity of renewable energy is increasing due to its cost effectiveness. However, not everyone can generate and fulfill their energy demand, so energy trading is necessary. Current solutions are centralised and charged at a high fee for energy trading as they have a monopoly in the market. Energy trading requires the storage, verification, and sharing of data related to the trade while keeping records tamper-proof. Traditional database solutions are centralised and susceptible to data tempering. In our proposed scheme, we aim to solve those problems with the help of blockchain technology by storing data on blockchain and verifying transactions with the PoA consensus algorithm for faster processing. We tested our scheme against the Ethereum network and found that our scheme has a significant improvement in cost and processing. In the future, with the help of machine learning, pricing for each transaction can be optimised.
The research on the governing blockchain by blockchain supervision system is an important development trend of blockchain technology. In this system there is a supervisory blockchain managing and governing the supervised blockchain based on blockchain technology, results in a uniquely cross-blockchain demand to consensus mechanism for solving the trust problem between supervisory blockchain and supervised blockchain. To solve this problem, this paper proposes a cross-blockchain consensus mechanism based on smart contract and a set of smart contracts endorse the cross-blockchain consensus. New consensus mechanism called Proof-of-Endorse-Contracts (PoEC) consensus, which firstly transfers the consensus reached in supervisory blockchain to supervised blockchain by supervisory nodes, then packages the supervisory block in supervisory blockchain and transmits it to the smart contract deployed in the supervised blockchain, finally miners in supervised blockchain will execute and package the new block according to the status of the smart contract. The core part of the consensus mechanism is Endorse Contracts which designed and implemented by us and verified the effectiveness through experiments. PoEC consensus mechanism and Endorse Contracts support the supervised blockchain to join the governing blockchain by blockchain system without changing the original consensus mechanism, which has the advantages of low cost, high scalability and being able to cross-blockchain. This paper proves that our method can provide a feasible cross-blockchain governance scheme for the field of blockchain governance.
In this paper, we have proposed the intimate environment of multiblockchain optimization algorithm using big data inquiry to mend the effectiveness of association query handling among numerous multihoming blockchains by implementing the big data system. This technique adds semantic evidences to the old‐styled multiblockchain prototype and constructs a semantic model of multiblockchain that delivers a foundation for linking queries among the various blockchain multihoming system in big data. On the base of this model, distributed databases have index arrangement, and a linking index arrangement is proposed among the numerous blockchains, with several attributes linked to these blockchains employed to improve the efficacy of linking calculation. Besides, the communication cost is d for data communication. On this foundation, a multichain linking enquiry algorithm based on optimization is anticipated to progress the productivity of multiblockchain connection queries. To conclude, two genuine big data community sets of data are used to conduct experiments on. The associating index arrangement among blockchains is unchanging and is equated with the old‐styled direct linking inquiry operation. The multiblockchain linking query method of optimization shortens the probe processing procedure. It acquires the query outcomes directly by retrieving the linking index, sinking the local calculating ability, system overhead, and illuminating query efficacy.
The blockchain technology promises innovation by moving away from conventional centralized architectures, where trust is placed in a small number of actors, to a decentralized environment where a collection of actors must work together to maintain consensus in the overall system. Blockchain offers security and pseudo-anonymity to its adopters, through the use of various cryptographic methods. While much attention has focused on creating new applications that make use of this technology, equal importance must be given to studying naturally occurring phenomena in existing blockchain ecosystems and mitigating their effects where harmful. In this dissertation, we develop a novel open-source log-to-file system that provides the ability to record information relevant to events as they take place in live blockchain networks. Specifically, our open-source software facilitates in-situ measurements on full nodes in the live Bitcoin and Bitcoin Cash blockchain networks. This measurement framework sheds new light on many phenomena that were previously unknown or scarcely studied. First, we examine the presence and impact of churn, namely nodes joining and leaving, on the behavior of the Bitcoin network. Our data analysis over a two-month period shows that a large number of Bitcoin nodes churn at least once. We perform statistical distribution fitting to this churn and emulate it in our measurement nodes to evaluate the impact of churn on the performance of the Bitcoin protocol. From our experiments, we find that blocks received by churning nodes experience as much as five times larger propagation delay than those received by non-churning nodes. We introduce and evaluate a novel synchronization scheme to mitigate such effects on the performance of the protocol. Our empirical evaluation shows that blocks received by churning nodes that synchronize their mempools with peers have roughly half the delay in propagation experienced by those that do not synchronize their mempools. We next evaluate and compare the performance of three block relay protocols, namely the default protocol, and the more recent compact block and Graphene protocols. This evaluation is conducted over full nodes running the Bitcoin Unlimited client (which is used in conjunction with the Bitcoin Cash network). We find that in most scenarios, the Graphene block relay protocol outperforms the other two in terms of the block propagation delay and the amount of total communication associated with block relay. An exception is when nodes churn frequently and spend a significant fraction of time off the network, in which case the compact block relay protocol performs best. In-depth analyses reveal subtle inefficiencies of the protocols. Thus, in the case of frequent churns, the Graphene block relay protocol performs as many as two extra round-trips of communication to recover information necessary to reconstruct blocks. Likewise, an inspection of the compact block relay protocol indicates that the full transactions included in the initial block message are either unnecessary or insufficient for the successful reconstruction of blocks. Finally, we investigate the occurrence of orphan transactions which are those whose parental income sources are missing at the time that they are processed. These transactions typically languish in a local buffer until they are evicted or all their parents are discovered, at which point they may be propagated further. Our data reveals that slightly less than half of orphan transactions end up being included in the blockchain. Surprisingly, orphan transactions tend to have fewer parents on average than non-orphan transactions, and their missing parents have a lower fee, a larger size, and a lower transaction fee per byte than all other received transactions. Moreover, the network overhead incurred by these orphan transactions can be significant when using the default orphan memory pool size (i.e., 100 transactions), although this overhead can be made negligible if the pool size is simply increased to 1,000 transactions. In summary, this dissertation demonstrates the importance of characterizing the inner behavior of the peer-to-peer network underlying a blockchain. While our results primarily focus on the Bitcoin network and its variants, this work provides foundations that should prove useful for studying and characterizing other blockchains.
With the growing maturity of blockchain technology, its peer-to-peer model and fully duplicated data storage pattern enable blockchain to act as a distributed ledger in untrustworthy environments. Blockchain storage has also become a research hotspot in industry, finance, and academia due to its security, and its unique data storage management model is gradually becoming a key technology to play its value in various fields’ applications. However, with the increasing amount of data written into the blockchain, the blockchain system faces many problems in its actual implementation of the application, such as high storage space occupation, low data flexibility and availability, low retrieval efficiency, poor scalability, etc. To improve the above problems, this paper combines off-chain storage technology and de-duplication technology to optimize the blockchain storage model. Firstly, this paper adopts the double-chain model to reduce the data storage of the major chain system, which stores a small amount of primary data and supervises the vice chain through an Application Programming Interface (API). The vice chain stores a large number of copies of data as well as non-transactional data. Our model divides the vice chain storage system into two layers, including a storage layer and a processing layer. In the processing layer, deduplication technology is applied to reduce the redundancy of vice chain data. Our double-chain storage model with high scalability enhances data flexibility, is more suitable as a distributed storage system, and performs well in data retrieval.
Yustus Eko Oktian, Thi-Thu-Huong Le, Uk Jo, Howon Kim
Bandwidth trading procedures can be made to incentivize users to sell their needless traffic and indirectly reduce the probability of traffic congestion. However, implementation of bandwidth trading is opex-heavy from Internet Service Provider (ISP) perspective, while on the other hand, users also do not trust network executions from the ISP due to its heavily centralized control. These issues hinder the applicability of bandwidth trading and become our motivation to propose this paper. Our bandwidth-trading framework utilize software-defined networking (SDN) and blockchain. SDN automates the bandwidth trading executions from the ISP side and reduces the opex. Meanwhile, the smart contract is a trusted platform for building a trading marketplace where buyers, sellers, and SDN controllers can negotiate the trading terms. Once the trading is executed, SDN controllers generate proof of trading that must be submitted to the smart contract as proof of provisioning. We implement our works using Ethereum and POX SDN controllers, and the results prove that it can provide a seamless bandwidth trading experience with reasonable overhead. Furthermore, by committing to our framework, bandwidth trading can be executed fairly and securely because all previous provisioning can be cross-checked through the provided proof-of-trading.
The rapid advancement in the area of the Internet of Vehicles (IoV) has provided numerous\ncomforts to users due to its capability to support vehicles with wireless data communication. The\nexchange of information among vehicle nodes is critical due to the rapid and changing topologies,\nhigh mobility of nodes, and unpredictable network conditions. Finding a single trusted entity to\nstore and distribute messages among vehicle nodes is also a challenging task. IoV is exposed to\nvarious security and privacy threats such as hijacking and unauthorized location tracking of smart\nvehicles. Traceability is an increasingly important aspect of vehicular communication to detect and\npenalize malicious nodes. Moreover, achieving both privacy and traceability can also be a challenging\ntask. To address these challenges, this paper presents a blockchain-based efficient, secure, and\nanonymous conditional privacy-preserving and authentication mechanism for IoV networks. This\nsolution is based on blockchain to allow vehicle nodes with mechanisms to become anonymous and\ntake control of their data during the data communication and voting process. The proposed secure\nscheme provides conditional privacy to the users and the vehicles. To ensure anonymity, traceability,\nand unlinkability of data sharing among vehicles, we utilize Hyperledger Fabric to establish the\nblockchain. The proposed scheme fulfills the requirement to analyze different algorithms and\nschemes which are adopted for blockchain technology for a decentralized, secure, efficient, private,\nand traceable system. The proposed scheme examines and evaluates different consensus algorithms\nused in the blockchain and anonymization techniques to preserve privacy. This study also proposes\na reputation-based voting system for Hyperledger Fabric to ensure a secure and reliable leader\nselection process in its consensus algorithm. The proposed scheme is evaluated with the existing\nstate-of-the-art schemes and achieves better results.
In the last era the number of internet-connected devices surpassed the human population. IoT integration rate into human world equals at least five times the rate of electricity and telephony. Currently in 2020 the number of IoT devices is around 50 billion smart objects. This great invasion to our live requires extensive efforts for controlling and securing those devices. BlockChain (BC) is a distributed write-only ledger that eliminates the need for third party in securing and verifying transactions between peers. BC is considered the most powerful technique for securing transactions between IoT devices. In this work, a robust and scalable blockchain-based security framework for IoT is proposed. This framework comprises clients, device gateways, and administrators. IoT devices access BC through gateways. Ethereum BlockChain is utilized in addition to Ethereum smart contracts for enforcing a set of rules defined by the system administrator. Finally metrics that fulfill both efficiency and effectiveness of the proposed framework are introduced. In the results section, the proposed work provides robust and scalable security framework for the IoT devices under different attack probabilities in addition to satisfying the conditions of lightweight, transparency, and timeliness.
As a decentralized database technology, blockchain is increasingly being applied to smart grids. This paper proposes a blockchain-based smart microgrid power transaction model. The model realizes the power dispatching between users and agents in the microgrid through two-way auctions and point-to-point transactions and optimizes energy allocation through market regulation. And based on the Ethereum private chain, it ensures the openness, transparency, safety, and reliability of transactions. The simulation results show that the open and reliable features of the blockchain improve the efficiency of power dispatching, and verify the feasibility and effectiveness of the model.
Blockchain has been regarded as a trusted carrier for distributed data storage. With large volumes of valuable data stored on blockchain, data query has become a major requirement. However, the existing blockchains do not provide efficient query functionality because of their deep-rooted chain structure. Blockchain database is a new direction that constructs index on top of blockchain to provide rich query functionalities. The existing works are either insecure because the query process separates from the blockchain consensus, or inscalable because all the data needs to be stored in the block. In this paper, we propose a novel semantic blockchain database called MSTDB. We design a hybrid on/off chain blockchain storage architecture in which the majority of blockchain storage is offloaded to the off-chain storage and a novel index structure named Merkle Semantic Trie (MST) is designed to be a secure and semantic bridge between on- and off-chain. Based on MST, MSTDB provides a variety of semantic query functions including multi-keyword query, range query, Top-K query, and cross-chain query. To improve the performance further, we design some index compression and query preprocessing techniques for MSTDB. Extensive experiments demonstrate the effectiveness and efficiency of our blockchain database.