This paper presents a new blockchain network simulator that uses bitcoin's original reference implementation as its main application. The proposed simulator leverages the use of lightweight virtualization technology to build a fine tuned local testing network. To enable fast simulation of a large scale network without disabling mining service, the simulator can adjust the bitcoin mining difficulty level to below the default minimum value. In order to assess the performance of blockchain under different network conditions, the simulator allows to define different network topologies, and integrates Linux kernel traffic control (tc) tool to apply distinct delay or packet loss on the network nodes. Moreover, to validate the efficiency of our simulator we conduct a set of experiments and study the impact of the computation power and network delay on the network's consistency in terms of number of forks and mining revenues. The impact of applying different mining difficulty levels is also studied and the block time as well as fork occurrences are evaluated. Furthermore, a comprehensive survey and taxonomy of existing blockchain simulators are provided along with a discussion justifying the need of new simulator. As part of our contribution, we have made the simulator available on Github (https://github.com/noureddinel/core-bitcoin-net-simulator) for the community to use and improve it.
Salma Shalaby, Alaa Awad Abdellatif, Abdulla Al‐Ali, Amr Mohamed · 6 authors
Blockchain is a distributed secure ledger that eliminates the need for centralized authority to store data. The centralized approach has several limitations as it is a Single-Point-of-Failure and a third-party might be needed. Blockchain, on the other hand, provides decentralized, secure and trustless framework that eliminates the need for a third party and enhances fault tolerance. In this paper, we investigate the potentials of customizing the behavior of Blockchain network based on the applications' requirements. In particular, we conduct several experiments to evaluate the performance of the Hyperledger Fabric (HLF) - a permissioned blockchain framework. Seven different scenarios were tested to depict the Blockchain behavior in terms of end-to-end transaction latency and network throughput. Moreover, in these scenarios, the impact of different parameters, such as the batch-timeout, batch size, and number of endorsing peers, has been studied.
We present eclipse attacks on Ethereum nodes that exploit the peer-to-peer network used for neighbor discovery. Our attacks can be launched using only two hosts, each with a single IP address. Our eclipse attacker monopolizes all of the victim’s incoming and outgoing connections, thus isolating the victim from the rest of its peers in the network. The attacker can then filter the victim’s view of the blockchain, or co-opt the victim’s computing power as part of more sophisticated attacks. We argue that these eclipse-attack vulnerabilities result from Ethereum’s adoption of the Kademlia peer-to-peer protocol, and present countermeasures that both harden the network against eclipse attacks and cause it to behave differently from the traditional Kademlia protocol. Several of our countermeasures have been incorporated in the Ethereum geth 1.8 client released on February 14, 2018.
In many typical application scenarios, it is necessary to revoke the incorrect account operations caused by user mis-operation, financial fraud, illegal hacking, etc. Unfortunately, users often blur the lines between the concept of "transaction state revocable" and "business status revocable", which result in revocable transaction not universally supported in blockchain systems at present. In this work, we propose GateChain , a blockchain that support revocable transaction model (RTM) on distributed ledger. Specifically, based on the state-of-the-art blockchain technologies, GateChain can safely withdraw the account status change operations by leveraging an improved account model and extra designed transaction types. On that basis, GateChain exploit the characteristics of functional completeness, easy to deployment and lower complexity.
The aim of this paper is to understand whether Distributed Ledger\nTechnologies (DLTs) are ready to support complex services, such as those\nrelated to Intelligent Transportation Systems (ITS). In smart transportation\nservices, a huge amount of sensed data is generated by a multitude of vehicles.\nWhile DLTs provide very interesting features, such as immutability,\ntraceability and verifiability of data, some doubts on the scalability and\nresponsiveness of these technologies appear to be well-founded. We propose an\narchitecture for ITS that resorts to DLT features. Moreover, we provide\nexperimental results of a real test-bed over IOTA, a promising DLT for IoT.\nResults clearly show that, while the viability of the proposal cannot be\nrejected, further work is needed on the responsiveness of DLT infrastructures.\n
In recent years, blockchain technology has received unparalleled attention from academia, industry, and governments all around the world. It is considered a technological breakthrough anticipated to disrupt several application domains. This has resulted in a plethora of blockchain systems for various purposes. However, many of these blockchain systems suffer from serious shortcomings related to their performance and security, which need to be addressed before any wide-scale adoption can be achieved. A crucial component of any blockchain system is its underlying consensus algorithm, which in many ways, determines its performance and security. Therefore, to address the limitations of different blockchain systems, several existing as well novel consensus algorithms have been introduced. A systematic analysis of these algorithms will help to understand how and why any particular blockchain performs the way it functions. However, the existing studies of consensus algorithms are not comprehensive. Those studies have incomplete discussions on the properties of the algorithms and fail to analyse several major blockchain consensus algorithms in terms of their scopes. This article fills this gap by analysing a wide range of consensus algorithms using a comprehensive taxonomy of properties and by examining the implications of different issues still prevalent in consensus algorithms in detail. The result of the analysis is presented in tabular formats, which provides a visual illustration of these algorithms in a meaningful way. We have also analysed more than hundred top crypto-currencies belonging to different categories of consensus algorithms to understand their properties and to implicate different trends in these crypto-currencies. Finally, we have presented a decision tree of algorithms to be used as a tool to test the suitability of consensus algorithms under different criteria.
Traditional public distributed ledgers have not been able to scale-out well and work efficiently. Sharding is deemed as a promising way to solve this problem. By partitioning all nodes into small committees and letting them work in parallel, we can significantly lower the amount of communication and computation, reduce the overhead on each node's storage, as well as enhance the throughput of the distributed ledger. Existing sharding-based protocols still suffer from several serious drawbacks. The first thing is that all non-faulty nodes must connect well with each other, which demands a huge number of communication channels in the network. Moreover, previous protocols have faced great loss in efficiency in the case where the honesty of each committee's leader is in question. At the same time, no explicit incentive is provided for nodes to actively participate in the protocol. We present CycLedger, a scalable and secure parallel protocol for distributed ledger via sharding. Our protocol selects a leader and a partial set for each committee, who are in charge of maintaining intra-shard consensus and communicating with other committees, to reduce the amortized complexity of communication, computation, and storage on all nodes. We introduce a novel semi-commitment scheme between committees and a recovery procedure to prevent the system from crashing even when leaders of committees are malicious. To add incentive for the network, we use the concept of reputation, which measures each node's trusty computing power. As nodes with a higher reputation receive more rewards, there is an encouragement for nodes with strong computing ability to work honestly to gain reputation. In this way, we strike out a new path to establish scalability, security, and incentive for the sharding-based distributed ledger.
Internet of Things (IoT) refers to the concept of enabling Internet connectivity and associated services to nontraditional computers formed by integrating essential computing and communication capability to physical things for everyday usage. Security and privacy are two of the major challenges in IoT. The essential security requirements of IoT cannot be ensured by the existing security frameworks due to the constraints in CPU, memory, and energy resources of the IoT devices. Also, the centralized security architectures are not suitable for IoT because they are subjected to single point of attacks. Defending against targeted attacks on centralized resources is expensive. Therefore, the security architecture for IoT needs to be decentralized and designed to meet the limitations in resources. Blockchain is a decentralized security framework suitable for a variety of applications. However, blockchain in its original form is not suitable for IoT, due to its high-computational complexity and low scalability. In this article, we propose a sliding window blockchain (SWBC) architecture that modifies the traditional blockchain architecture to suit IoT applications. The proposed SWBC uses previous $(n-1)$ blocks to form the next block hash with limited difficulty in proof-of-work (PoW). The performance of SWBC is analyzed on a real-time data stream generated from a smart home testbed. The results show that the proposed blockchain architecture increases security and minimizes memory overhead while consuming fewer resources.
Bitcoin-NG is among the first blockchain protocols to approach the \emph{near-optimal} throughput by decoupling blockchain operation into two planes: leader election and transaction serialization. Its decoupling idea has inspired a new generation of high-performance blockchain protocols. However, the existing incentive analysis of Bitcoin-NG has several limitations. First, the impact of network capacity is ignored. Second, an integrated incentive analysis that jointly considers both key blocks and microblocks is still missing. In this paper, we aim to address these two limitations. First, we propose a new incentive analysis that takes the network capacity into account, showing that Bitcoin-NG can still maintain incentive compatibility against the microblock mining attack even under limited network capacity. Second, we leverage a Markov decision process (MDP) to jointly analyze the incentive of both key blocks and microblocks, showing that the selfish mining revenue of Bitcoin-NG is a little higher than that in Bitcoin only when the selfish miner controls more than 35\% of the mining power. We hope that our in-depth incentive analysis for Bitcoin-NG can shed some light on the mechanism design and incentive analysis of next-generation blockchain protocols.
The massive redundant data storage and communication in network 4.0 environments have issues of low integrity, high cost, and easy tampering. To address these issues, in this article, a secure data storage and recovery scheme in the blockchain-based network is proposed by improving the decentration, tampering-proof, real-time monitoring, and management of storage systems, as such design supports the dynamic storage, fast repair, and update of distributed data in the data storage system of industrial nodes. A local regenerative code technology is used to repair and store data between failed nodes while ensuring the privacy of user data. That is, as the data stored are found to be damaged, multiple local repair groups constructed by vector code can simultaneously yet efficiently repair multiple distributed data storage nodes. Based on the unique chain storage structure, such as data consensus mechanism and smart contract, the storage structure of blockchain distributed coding not only quickly repair the nearby local regenerative codes in the blockchain but also reduce the resource overhead in the data storage process of industrial nodes. Experimental results show that the proposed scheme improves the repair rate of multinode data by 9% and data storage rate increased by 8.6%, indicating to be promising with good security and real-time performance.
Samiur Khan, Md. Al-Amin, Hrittik Hossain, Nawshad Noor · 5 authors
Blockchain has been a latest trend and many of its applications show promising results in terms of transactions, validations, finances etc. and recently it has become an apple of eye for the tech industry and investors. The concept of decentralized application (commonly known as dApp) and the blockchain platform itself can help to reform many unresolved solutions for the betterment of services and generate new opportunities for the developers to focus on creating applications in a decentralized environment with ease. The adaptation of blockchain technology through dApps is increasing drastically; thus opportunity for the developers and entrepreneurs are growing rapidly. Considering the impactful revolution of dApps, the developer communities are getting more interest to the dApps development tools, frameworks and platforms. This paper is presenting a comprehensive study on some popular blockchain powered decentralized or distributed dApp platforms. In this paper we made analysis of these platforms based on different factors and parameters. This analysis provides an impactful direction to the developer and enterprise community in adopting of the development platform.
Blockchain has emerged as a promising technology that can guarantee data consistency and integrity among distributed participants. It has been used in many applications of the Internet of Things (IoT). However, since IoT applications often introduce a massive number of devices into blockchain systems, the efficiency of the blockchain becomes a serious problem. In this article, we analyze the key factors affecting the efficiency of blockchain. Unlike most existing solutions that handle this from the computing perspective, we consider the problem from the communication perspective. In particular, we propose a coordinated satellite-terrestrial network to create efficient blockchains. We also derive a network scheduling strategy for the proposed architecture. Simulation results demonstrate that the proposed system can support blockchains for higher efficiency. Moreover, several open research issues and design challenges will be discussed.
The interoperability across multiple blockchains would play a critical role in future blockchain-based data management paradigm. Existing techniques either work only for two blockchains or requires a centralized component to govern the cross-blockchain transaction execution, neither of which would meet the scalability requirement. This paper proposes a new distributed commit protocol, namely \textit{cross-blockchain transaction} (CBT), for conducting transactions across an arbitrary number of blockchains without any centralized component. The key idea of CBT is to extend the two-phase commit protocol with a heartbeat mechanism to ensure the liveness of CBT without introducing additional nodes or blockchains. We have implemented CBT and compared it to the state-of-the-art protocols, demonstrating CBT's low overhead (3.6\% between two blockchains, less than $1\%$ among 32 or more blockchains) and high scalability (linear scalability on up to 64-blockchain transactions). In addition, we developed a graphic user interface for users to virtually monitor the status of the cross-blockchain transactions.
Although our communities are paying extensive attention to the blockchain technology, it is still far away from realistic applications. Thus, this red-hot technology could be understood and employed for visual applications. Authors focus on online videos that collect sufficient user clicks owning to the high demand every day. When people watch the videos of TV drama episodes in an online website, they often need to exactly organise the playlists in ascending or descending order. However, video websites such as YouTube can't provide this service due to multiple reasons. This chapter creates a private blockchain for these video websites and applies Merkle tree to store the sorted videos in the chain. A sorted playlist has been created in the video website. Getting out of the box of video search so as to provide a quick video ranking solution is authors' main task. Sorting results are evaluated by using edit distance.
Junho Jeong, Donghyo Kim, Yangsun Lee, Jin‐Woo Jung · 5 authors
Nowadays, social inequality is an important social problem. Donations are one of the many ways to improve social inequality. Donation is largely divided into sponsorship by individuals such as corporations and public administration. In the individual sponsorship, it is common to donate to a donation organization and to support the aid recipients by donation organization. Many people are reluctant to support to this donation because of the lack of transparency. In addition, many donation organizations lack transparent and formal administration due to lack of working capital. Therefore, this paper proposes a method to enhance personal transparency by enhancing the transparency of donation organizations and protecting the privacy of sponsors using blockchain that is a Hyperledger fabric. And We implement a blockchain network for the proposed system.
Blockchain technology has been used in many fields such as data management, cloud computing and Internet of Things with the features of decentralization, transparency and immutability. In order to study the performance of a blockchain system with a light-load traffic, we establish a discrete-time non-exhaustive vacation queue with batch service and gated service. In this model, we regard transaction initiation, mining processing and block verification as arrival, vacation and service period, respectively. By using an embedded Markov chain method and a regeneration cycle approach, we derive the average response time of transactions. Experiment results with analysis and simulation show that the average response time of transactions is impacted by the arrival rate of transactions. Finally, we study the Nash equilibrium behavior and the socially optimal behavior of transactions, and present a pricing policy for transactions to maximize the social profit.
Blockchain system is affected by many factors with the rapid development of technology. In order to study the blockchain system more realistically, the processes of transaction consensus and transaction storage are simulated in this paper, and factors such as interference factors, impatience phenomena of transactions and fault repairable conditions of the system during the service process are considered. Vacation queueing model with negative customers, impatient customers, repairable fault and two-phase service that customers can select sever in the first service is established. Using the matrix-geometric solution method, the expressions of the average confirmation time of transactions and other performance measures are given. The parameters of the system are obtained based on the statistics of the blockchain transaction data. The influence of each parameter on the performance measures of blockchain system is analyzed by using MATLAB software. The equilibrium reception rate is discussed by constructing the revenue function of the system, and equilibrium numerical results are obtained.