Caixiang Fan, Changyuan Lin, Hamzeh Khazaei, Petr Musı́lek
In this work, we present a set of comprehensive experimental studies on Hyperledger Besu in private blockchain. We aim to exhibit its performance characteristics in terms of transaction throughput, latency, resource utilization, and scalability, from the application perspective by adding a load balancer middleware. We have carefully designed a set of comparative experiments and judiciously selected typical parameters, including transaction send rate, network size, node flavor, load balancing, consensus, and block time. In particular, three proof of authority consensus algorithms, Clique, IBFT 2.0, and QBFT, are investigated. Through extensive experimental evaluations using the Hyperledger Caliper benchmark tool, we analyze how these parameters impact the performance of a private Besu blockchain. Our studies reveal several interesting findings: 1) Blockchain parameters, e.g., block time and block size, are the most significant factors in determining Besu performance; 2) The performance of Besu is bottlenecked by transaction execution and blockchain state updates, which are determined by parameters such as node computation power, transaction complexity, and load balancing; 3) A Besu network with QBFT consensus can scale up to 14 validators without noticeable performance loss. Our findings shed some light on further performance improvement of Hyperledger Besu. The identified bottlenecks and root cause analysis provide insightful suggestions for blockchain practitioners to build performant enterprise applications.
Thomas Lavaur, Jérôme Lacan, Caroline Ponzoni Carvalho Chanel
The Internet of Things includes all connected objects from small embedded systems with low computational power and storage capacities to efficient ones, as well as moving objects like drones and autonomous vehicles. The concept of Internet of Everything expands upon this idea by adding people, data and processing. The adoption of such systems is exploding and becoming ever more significant, bringing with it questions related to the security and the privacy of these objects. A natural solution to data integrity, confidentiality and single point of failure vulnerability is the use of blockchains. Blockchains can be used as an immutable data layer for storing information, avoiding single point of failure vulnerability via decentralization and providing strong security and cryptographic tools for IoE. However, the adoption of blockchain technology in such heterogeneous systems containing light devices presents several challenges and practical issues that need to be overcome. Indeed, most of the solutions proposed to adapt blockchains to devices with low resources confront difficulty in maintaining decentralization or security. The most interesting are probably the Layer 2 solutions, which build offchain systems strongly connected to the blockchain. Among these, zk-rollup is a promising new generation of Layer 2/off-chain schemes that can remove the last obstacles to blockchain adoption in IoT, or more generally, in IoE. By increasing the scalability and enabling rule customization while preserving the same security as the Layer 1 blockchain, zk-rollups overcome restrictions on the use of blockchains for IoE. Despite their promises illustrated by recent systems proposed by startups and private companies, very few scientific publications explaining or applying this barely-known technology have been published, especially for non-financial systems. In this context, the objective of our paper is to fill this gap for IoE systems in two steps. We first propose a synthetic review of recent proposals to improve scalability including onchain (consensus, blockchain organization, …) and offchain (sidechain, rollups) solutions and we demonstrate that zk-rollups are the most promising ones. In a second step, we focus on IoE by describing several interesting features (scalability, dynamicity, data management, …) that are illustrated with various general IoE use cases.
Due ecosystem, it is common for new blockchains to fork or partially reuse the code of classic blockchains. For example, the popular Dogecoin, Litecoin, Binance BSC, and Polygon are all variants of Bitcoin/Ethereum. These “forked” blockchains thus could encounter similar vulnerabilities that are propagated from Bitcoin/Ethereum during forking or subsequently commit fetching. In this paper, we conduct a systematic study of detecting and investigating the propagated vulnerabilities in forked blockchain projects. To facilitate this study, we propose BlockScope, a novel tool that can effectively and efficiently detect multiple types of cloned vulnerabilities given an input of existing Bitcoin/Ethereum security patches. Specifically, BlockScope adopts similarity-based code match and designs a new way of calculating code similarity to cover all the syntax-wide variant (i.e., Type-1, Type-2, and Type-3) clones. Moreover, BlockScope automatically extracts and leverages the contexts of patch code to narrow down the search scope and locate only potentially relevant code for comparison. Our evaluation shows that BlockScope achieves good precision and high recall both at 91.8% (1.8 times higher recall than that in the state-of-the-art ReDeBug while with close precision). BlockScope allows us to discover 101 previously unknown vulnerabilities in 13 out of the 16 forked projects of Bitcoin and Ethereum, including 16 from Dogecoin, 6 from Litecoin, 1 from Binance BSC, and 4 from Optimism. We have reported all the vulnerabilities to their developers; 40 of them have been patched or accepted, 66 were acknowledged or under pending, and only 4 were rejected. We further investigate the propagation and patching processes of discovered vulnerabilities, and reveal three types of vulnerability propagation from source to forked projects, as well as the long delay (mostly over 200 days) for releasing patches in Bitcoin forks (vs. ∼100 days for Ethereum forks).
Purpose Sharding of blockchains consists of partitioning a blockchain network into several sub-networks called “shards,” each shard processing and storing disjoint sets of transactions in parallel. Sharding has recently been applied to public blockchains to improve scalability through parallelism. The throughput of sharded blockchain is optimized when the workload among the shards is approximately the same. The purpose of this paper is to investigate the problem of balancing workload of account-based blockchains such as Ethereum. Design/methodology/approach Two known consensus-based distributed load-balancing algorithms have been adapted to sharded blockchains. These algorithms migrate accounts across shards to balance transaction processing times. Two methods to predict transaction processing times are proposed. Findings The authors identify some challenging aspects for solving the load-balancing problem in sharded blockchains. Experiments conducted with Ethereum transactions show that the two load-balancing algorithms are challenged by accounts often created to process a single transaction to optimize anonymity, while existing accounts sparsely generate transactions. Originality/value Tests in this work have been conducted on transactions originating from a blockchain platform rather than using artificially generated data distributions. They show the specificity of the load-balancing problem for sharded blockchains, which were hidden in artificial data sets.
S. Viannis Murphy Caxton, K. Naveen, R. Karthik, S. Sathya Bama
Non-Fungible Token (NFT) is a program similar to cryptocurrency that runs on blockchain. Due to its recent popularity, the user count increases every day. NFT, a relatively new technology compared to cryptocurrency brings many new terms and complicated user flows. The study was conducted to explore the motives of new NFT users, to identify the usability issues in those platforms that tend to be a barrier and to suggest relevant design approaches that help new users freely use the platform. A survey was conducted to identify the understanding of NFTs among various user groups. Further, usability testing and heuristic evaluation were carried out for the top 2 popular NFT marketplaces. The results show that the NFT platforms need more usability improvements, especially for first-time users. Based on the findings, relevant user-centered design approaches are suggested and are expected to improve the usability of the NFT platforms.
Accounting Information System (AIS), which is the foundation of any enterprise resource planning (ERP) system, is often built as centralized system. The technologies that allow the Internet-of-Value, which is built on five aspects that are network, algorithms, distributed ledger, transfers, and assets, are based on blockchain. Cryptography and consensus protocols boost the blockchain platform implementation, acting as a deterrent to cyber-attacks and hacks. Blockchain platforms foster innovation among supply chain participants, resulting in ecosystem development. Traditional business processes have been severely disrupted by blockchains since apps and transactions that previously required centralized structures or trusted third-parties to authenticate them may now function in a decentralized manner with the same level of assurance. Because a blockchain split in AIS may easily lead to double-spending attacks, reducing the likelihood of a split has become a very important and difficult research subject. Reduced block relay time between the nodes can minimize the block propagation time of all nodes, resulting in better Bitcoin performance. In this paper, three problems were addressed on transaction and block propagation mechanisms in order to reduce the likelihood of a split. A novel algorithm for blockchain is proposed to reduce the total propagation delay in AIS transactions. Numerical results reveal that, the proposed algorithm performs better and reduce the transaction delay in AIS as compared with existing methods.
Ertem Nusret Tas, David Tse, Fangyu Gai, Sreeram Kannan · 6 authors
Bitcoin is the most secure blockchain in the world, supported by the immense hash power of its Proof-of-Work miners. Proof-of-Stake chains are energy-efficient, have fast finality but face several security issues: susceptibility to non-slashable long-range safety attacks, low liveness resilience and difficulty to bootstrap from low token valuation. We show that these security issues are inherent in any PoS chain without an external trusted source, and propose a new protocol, Babylon, where an off-the-shelf PoS protocol checkpoints onto Bitcoin to resolve these issues. An impossibility result justifies the optimality of Babylon. A use case of Babylon is to reduce the stake withdrawal delay: our experimental results show that this delay can be reduced from weeks in existing PoS chains to less than 5 hours using Babylon, at a transaction cost of less than 10K USD per annum for posting the checkpoints onto Bitcoin.
Blockchain is a distributed ledger technology that has recently gained widespread popularity. Many industries have started to implement blockchain solutions for their application and services. Blockchain provides immutability, privacy, security, and transparency. There is no central authority to validate and verify the transactions, still, every transaction in the Blockchain is considered secure and verified. This is made possible by the use of a consensus algorithm which is a core part of any Blockchain network. Different consensus algorithms exist and the selection of appropriate consensus algorithms can affect the performance of the blockchain. This paper presents a pattern for one of the most commonly used blockchain consensus algorithms, which is the Proof of Stake (PoS) algorithm. This pattern describes its architecture, including its structure and dynamics.
Electric Vehicles (EVs), as well as the number of applications for their management, are rapidly increasing due to the fact that Internet of Vehicles (IoV) becomes more informative and industrialized. According to the literature, IoV requires decentralization towards the energy Demand Response (DR) management, with secure energy trading, efficient charging scheduling, and incentives for making the drivers to participate. Blockchain and Distributed Ledger Technologies (DLTs) can be used to enable a foundational environment to support DR management. However, and to the best of our knowledge, none of the existing research works discussed in the literature adopts a holistic approach to address them. As such there is a demand for exploring a unified blockchain-based framework for distributed DR management. Therefore, the aim of this work is focused on the blockchain adoption in IoV-assisted smart cities. More specifically, we propose a blockchain based approach, to be used for building a secure and user-centric DR management framework. Our proposition aims to address the DRP in IoV through charging scheduling based on the generation of EV driving profiles, and optimal Vehicle-to-Vehicle/Grid (V2V | V2G) energy trading.
Smart contracts provide the means to stipulate rules of interaction between mutually distrustful organizations. They encode contractual agreements on the basis of source code, which else need to be contractualized in natural language. While the mediation of contractual agreements via smart contracts is seamless in theory, it requires that the conditions of an interaction are accurately made available in the blockchain. Time is a prominent such condition. In the paper at hand, we empirically measure the consistency of a smart contract to yield equal results on the basis of the time of an interaction and its potentially inaccurate representation in the blockchain. We propose a novel metric called execution accuracy to measure this consistency. We specifically measure the execution accuracy of a time intervalconstrained smart contract that executes distinct logic within and without some constraint interval. We run experiments for the local Ganache and Quorum and the public Görli and Rinkeby Ethereum blockchains. Our experiments confirm our intuition that execution accuracy decreases near interval bounds. The novelty of our proposed metric resides in its capacity to quantify this decrease. We demonstrate how time constraints can be effectively stipulated on the basis of execution accuracy measurements.
Mohammad Hossein Tabatabaei, Roman Vitenberg, Narasimha Raghavan Veeraragavan
The explosive advent of the blockchain technology has led to hundreds of blockchain systems in the industry, thousands of academic papers published over the last few years, and an even larger number of new initiatives and projects. Despite the emerging consolidation efforts, the area remains highly turbulent without systematization, educational materials, or cross-system comparative analysis. In this paper, we provide a systematic and comprehensive study of four popular yet widely different blockchain systems: Bitcoin, Ethereum, Hyperledger Fabric, and IOTA. The study is presented as a cross-system comparison, which is organized by clearly identified aspects: definitions, roles of the participants, entities, and the characteristics and design of each of the commonly used layers in the cross-system blockchain architecture. Our exploration goes deeper compared to what is currently available in academic surveys and tutorials. For example, we provide the first extensive coverage of the storage layer in Ethereum and the most comprehensive explanation of the consensus protocol in IOTA. The exposition is due to the consolidation of fragmented information gathered from white and yellow papers, academic publications, blogs, developer documentation, communication with the developers, as well as additional analysis gleaned from the source code. We hope that this survey will help the readers gain in-depth understanding of the design principles behind blockchain systems and contribute towards systematization of the area.
With the rapid rise of digital currency in recent years, blockchain technology has now gradually entered the public's field of vision. Bitcoin, as the first application of blockchain, is self-evidently hot. Among them, Consensus algorithm plays a crucial role in blockchain technology, and consensus algorithm as the core can directly affect the merits and demerits of the blockchain system. Therefore, different consensus algorithms are adopted for different blockchain systems, and different consensus algorithms have their own advantages and disadvantages. This paper introduces the most mainstream blockchain consensus algorithms in detail, reveals the characteristics of various algorithms, compares them in three aspects such as security, limitation, and decentralization degree, and summarizes the advantages and disadvantages of each. For higher efficiency, potential optimization schemes of various mainstream consensus algorithms proposed by researchers are also presented in, so that later researchers and developers can gain insight into designing and learning consensus algorithms and clarify future research directions as a way, so as to promote the development and application of blockchain technology.
Original Equipment Manufacturers (OEMs) need to collaborate within and outside their organizations to improve product quality and time to market. However, legacy systems built over decades using different technology stacks make information sharing and maintaining consistency challenging. Distributed ledger technologies (DLTs) can improve efficiency and provide trust, thus helping to achieve a more streamlined and unified collaboration infrastructure. However, most of the work done is theoretical or conceptual and lacks implementation. This paper elaborates on architecture and implementing a proof of concept (POC) of blockchain-based interoperability and data sharing system that allows OEMs to collaborate seamlessly and share information in real-time.
Adel Albshri, Ali Alzubaidi, Bakri Awaji, Ellis Solaiman
Recently, distributed ledger technologies like blockchain have been proliferating and have attracted interest from the academic community, government, and industry. A wide range of blockchain solutions has been introduced, such as Bitcoin, Ethereum, and Hyperledger technologies in the literature. However, tools for evaluating these solutions and their applications are still lacking, limiting the exploration of their potentiality and associated challenges/limitations. That is, experimenting with real blockchain networks usually requires a solid budget; and thus, sophisticated blockchain simulators can facilitate designing and evaluating solutions before the actual implementation stage. The quality of such simulators depends on several factors such as usability, reliability, provided capabilities, and supported features. This paper aims to provide a systemic mapping review of blockchain simulators focusing on these quality factors. This paper also sheds light on the configuration parameters (inputs) and produced metrics (outputs) supported by each simulator. Furthermore, it investigates which metrics supported by each simulator are scientifically validated/evaluated. Moreover, code quality comparison is carried out to assess the source code of the covered simulators. The results reveal that no simulator fully covers the wide operational range of features and capabilities of existing blockchain technologies. However, several promising efforts exist in the domain of blockchain simulation with interesting and useful features. Finally, we discuss the subject of blockchain simulation and provide our insight into the matter.
For any distributed system, consensus plays a pivotal role in holding together the whole system. This is true not just for any blockchain (BC) peer-to-peer (P2P) Network but also for Cloud Computing where the Leader Election Problem is solved by the use of various consensus algorithms. No “one” consensus algorithm is universal or perfect. Depending upon the type of BC employed and the use case of the BC, there may be a consensus algorithm that would help the system reach optimum functioning without compromising the integrity of the system. While proof of work (PoW) [ 2 ] became the first Consensus Mechanism to be used in BC, there have been many consensus algorithms to date. These are mechanisms which help the P2P network of a BC arrive at a decision. The decision taken most often is who is going to add the next block on the BC. This decision is crucial because if there exists a malicious entity in the network who gets in charge of the chain, then it would be detrimental to the overall functioning of the network. The chapter discusses the following consensus algorithms-PoW [ 2 ], proof of stake, delegated proof of stake, Byzantine fault tolerance (BFT), Crash Fault Tolerance, Hashgraph Consensus Algorithm, Proof of Elapsed Time, and Proof of Authority (PoA). The pros of the consensus algorithms and main drawbacks against implementation such as low throughput and excessive consumption of bandwidth have been discussed as well. A comparative analysis of the aforementioned algorithms with a major focus on use cases has been done to help understand how such mechanisms may be used for designing solutions which surpass the initial application of cryptocurrency and delve into real-world solutions in the fields including but not limited to the Internet of Things (IoT) and big data.
Abstract:The DApp (Decentralised application) being developed enables easy verification of credentials by storing the certificates on Ethereum blockchain network using IPFS (Inter Planetary File System) which is a distributed file system, thereby making the information stored immutable and secure. The website is being developed in three phases. In the first phase, the college enrolls students and uploads their credentials on the Ethereum blockchain. In the second phase, students can view their credentials and access requests sent by companies. In the third phase, companies can send access requests to students whose credentials they want to verify. Once the students accept the access requests, companies can view and verify the certificates.
Sharding is a promising approach to high-performance blockchains and has been extensively explored in academia recently. However, sharding also introduces cross-shard transactions, which require expensive inter-shard coordination to ensure state consistency. Such transactions significantly limit the performance of sharded blockchains.
Margarita Capretto, Martín Ceresa, Antonio Fernández Anta, Antonio Russo · 5 authors
Blockchain technologies are facing a scalability challenge, which must be overcome to guarantee a wider adoption of the technology. This scalability issue is mostly caused by the use of consensus algorithms to guarantee the total order of the chain of blocks (and of the operations within each block). However, total order is often overkilling, since important advanced applications of smart-contracts do not require a total order of all the operations. Hence, if a more relaxed partial order (instead of a total order) is allowed under certain safety conditions, a much higher scalability can be achieved. In this paper, we propose a distributed concurrent data type, called Setchain, that allows implementing this partial order and increases significantly blockchain scalability. A Setchain implements a grow-only set object whose elements are not totally ordered, unlike conventional blockchain operations. When convenient, the Setchain allows forcing a synchronization barrier that assigns permanently an epoch number to a subset of the latest elements added. With the Setchain, operations in the same epoch are not ordered, while operations in different epochs are. We present different Byzantine-tolerant implementations of Setchain, prove their correctness and report on an empirical evaluation of a direct implementation. Our results show that Setchain is orders of magnitude faster than consensus-based ledgers to implement grow-only sets with epoch synchronization. Since the Setchain barriers can be synchronized with block consolidation, Setchain objects can be used as a sidechain to implement many smart contract solutions with much faster operations than on basic blockchains.
Pedro Henrique F. S. Oliveira, Daniel Muller Rezende, Heder S. Bernardino, Saulo Moraes Villela · 5 authors
One of the main events that involve the world economy in 2022 is the conflict between Russia and Ukraine. This event offers a rare opportunity to analyze how events of this magnitude can reflect the use of cryptocurrencies. This work aims to investigate the behavior of accounts and their transactions on the Ethereum cryptocurrency during this event. To this end, we collected all transactions that occurred two weeks before and two weeks after the beginning of the conflict, organized into two groups: the collection of the accounts involved in these transactions and the subset of these ones that interacted with a service in Ethereum, called Flashbots Auction. We modeled temporal graphs where each node represents an account, and each edge represents a transaction between two accounts. Then, we analyzed the behavior of these accounts with graph metrics for both groups during each observed week. The results showed changes in the behavior and activity of users and their accounts, as well as variations in the daily volume of transactions.
Focusing on the business alliance scenario in blockchains, this paper proposes a new consensus mechanism named proof of rest (PoR) and strong smart contracts. The block structure and logic of PoR consensus are described. And a consortium blockchain system supporting strong smart contracts is designed. We modify the difficulty value algorithm based on proof of work (PoW) and add adjustable parameters. The longer a node rests after creating a block, the less difficult it is to create another new block, hence the term PoR. The penalty for slack nodes, the joining and quitting of nodes, and the adjustment of the expected block creation time can all be accomplished using the strong smart contracts, so the consortium blockchain can realize self-renewal.
At the technical level, the goal of Interledger is to provide an architecture and a minimal set of protocols to enable interoperability between any value transfer systems. The Interledger protocol is a protocol for inter-blockchain payments which can also accommodate FIAT currencies. To understand how it is possible to achieve this goal, several aspects of the technology require a deeper analysis. For this reason, in our journey to become knowledgeable and active contributors we decided to create our own test-bed on our premises. By doing so, we noticed that some aspects are well documented but we found that others might need more attention and clarification. Despite a large community effort, the task to keep information on a fast evolving software ecosystem up-to-date is tedious and not always the main priority for such a project. The purpose of this tutorial is to guide, through several examples and hands-on activities, community members who want to engage at different levels. The tutorial consolidates all the relevant information from generating a simple payment to ultimately creating a test-bed with the Interledger protocol suite between Ripple and other distributed ledger technologies.
Blockchain genuinely has the power to revolutionise the energy market mechanism by introducing smart PPAs (purchase power agreements), smart micro grids, and REC certificates. By converting energy resources into digital commodities that can be exchanged on a blockchain, new investment and trading possibilities that allow new players to join easily and encourage innovations will be enabled. It may also contribute to a shift driven by the organisation to address the issue of last mile connectivity. While recent grid developments have broadened the use of advanced control techniques, the next-generation grid requires technology that makes it simpler to connect distributed energy services (DERs) for users who both acquire and sell power seamlessly. This chapter will present a case study of a blockchain-based optimization paradigm and framework for crowd-sourced operations.