A Practical Byzantine Fault Tolerance (PBFT) is a consensus algorithm deployed in a consortium blockchain that connects a group of related participants. This type of blockchain suits the implementation of the Building Information Modeling (BIM) information exchange with few participants. However, when much more participants are involved in the BIM information exchange, the PBFT algorithm, which inherently requires intensive communications among participating nodes, has limitations in terms of scalability and performance. The proposed solution for a multi-layer BFT hypothesizes that multi-layer BFT reduces communication complexity. However, having more layers will introduce more latency. Therefore, in this paper, Double-Layer Byzantine Fault Tolerance (DLBFT) is proposed to improve the blockchain scalability and performance of BIM information exchange. This study shows a double-layer network structure of nodes that can be built with each node on the first layer, which connects and forms a group with several nodes on the second layer. This network runs the Byzantine Fault Tolerance algorithm to reach a consensus. Instead of having one node send messages to all the nodes in the peer-to-peer network, one node only sends messages to a limited number of nodes on Layer 1 and up to three nodes in each corresponding group in Layer 2 in a hierarchical network. The DLBFT algorithm has been shown to reduce the required number of messages exchanged among nodes by 84% and the time to reach a consensus by 70%, thus improving blockchain scalability. Further research is required if more than one party is involved in multi-BIM projects.
Andrei Constantinescu, Diana Ghinea, Lioba Heimbach, Zilin Wang · 5 authors
Traditional blockchain design gives miners or validators full control over transaction ordering, i.e., they can freely choose which transactions to include or exclude, as well as in which order. While not an issue initially, the emergence of decentralized finance has introduced new transaction order dependencies allowing parties in control of the ordering to make a profit by front-running others' transactions. In this work, we present the Decentralized Clock Network, a new approach for achieving fair transaction ordering. Users submit their transactions to the network's clocks, which run an agreement protocol that provides each transaction with a timestamp of receipt which is then used to define the transactions' order. By separating agreement from ordering, our protocol is efficient and has a simpler design compared to other available solutions. Moreover, our protocol brings to the blockchain world the paradigm of asynchronous fallback, where the algorithm operates with stronger fairness guarantees during periods of synchronous use, switching to an asynchronous mode only during times of increased network delay.
Blockchain technology constitutes a paradigm shift in the way we conceive distributed architectures. A Blockchain system lets us build platforms where data are immutable and tamper-proof, with some constraints on the throughput and the amount of memory required to store the ledger. This paper aims to solve the issue of memory and performance requirements developing a multiple Blockchain architecture that mixes the benefits deriving from a public and a private Blockchain. This kind of approach enables small sensors - with memory and performance constraints - to join the network without worrying about the amount of data to store. The development is proposed following a context-aware approach, to make the architecture scalable and easy to use in different scenarios.
Vincent Gramoli, Rachid Guerraoui, Andrei Lebedev, Chris Natoli · 5 authors
With the recent advent of blockchains, we have witnessed a plethora of blockchain proposals. These proposals range from using work to using time, storage or stake in order to select blocks to be appended to the chain. As a drawback it makes it difficult for the application developer to choose the right blockchain to support their applications. In particular, the scalability and performance one can obtain from a specific blockchain is typically unknown. The claimed results are often obtained in isolation by the developers of the blockchain themselves. The experimental conditions corresponding to these results are generally missing and the lack of details make these results irreproducible.
Federico Carrozzino, Marco Fiore, Marina Mongiello
Blockchain technology is a Distributed Ledger Technology mainly used to store information in an immutable and secure way, but scalability and throughput issues are major challenges. Integration of the NoSQL paradigm within a Blockchain pipeline enhances throughput and scalability, and it can handle both on-chain and off-chain data. This work aims to study which approaches are currently used to integrate a NoSQL database in a Blockchain architecture, how the advantages of both technologies can be exploited to enhance the system's capabilities, and to propose a novel hybrid architecture that mixes Blockchain and NoSQL characteristics.
Blockchain enables peer-to-peer transactions in cyberspace without a trusted third party. The rapid growth of Ethereum and smart contract blockchains generally calls for well-designed Transaction Fee Mechanisms (TFMs) to allocate limited storage and computation resources. However, existing research on TFMs must consider the waiting time for transactions, which is essential for computer security and economic efficiency. Integrating data from the Ethereum blockchain and memory pool (mempool), we explore how two types of events affect transaction latency. First, we apply regression discontinuity design (RDD) to study the causal inference of the Merge, the most recent significant upgrade of Ethereum. Our results show that the Merge significantly reduces the long waiting time, network loads, and market congestion. In addition, we verify our results' robustness by inspecting other compounding factors, such as censorship and unobserved delays of transactions via private changes. Second, examining three major protocol changes during the merge, we identify block interval shortening as the most plausible cause for our empirical results. Furthermore, in a mathematical model, we show block interval as a unique mechanism design choice for EIP1559 TFM to achieve better security and efficiency, generally applicable to the market congestion caused by demand surges. Finally, we apply time series analysis to research the interaction of Non-Fungible token (NFT) drops and market congestion using Facebook Prophet, an open-source algorithm for generating time-series models. Our study identified NFT drops as a unique source of market congestion -- holiday effects -- beyond trend and season effects. Finally, we envision three future research directions of TFM.
Jesús Rosa-Bilbao, Juan Boubeta-Puig, Adrian Rutle
Internet of Things (IoT) is made up of millions of devices generating large amounts of heterogeneous data from multiple sources. These devices can be from multiple manufacturers which makes their use in terms of data acquisition, processing, analysis and actions on these data challenging. Additionally, all these data must be analyzed and correlated in real time for the early detection of situations of interest (complex events) and subsequent decision making. These complex events must be able to automatically trigger decisions and be stored in a secure, immutable and accessible way. In this context, Event-Driven Applications (EDAs) are a solution to meet these needs, however, developing such applications requires vast knowledge in certain technologies. To address these challenges, an EDA is proposed in this paper to integrate Complex Event Processing (CEP) and blockchain through the low-code paradigm. This proposal allows for the development of EDAs in a user-friendly way. These applications make it possible to integrate IoT devices from multiple manufacturers and with different data formats together with CEP technology for complex event detection and blockchain for secure, immutable and accessible event storage. To demonstrate the feasibility, the architecture was applied and evaluated in a case study related to measuring and acting on air quality using IoT devices that measure different pollutants and factors such as temperature, humidity and wind. The results show that the graphically designed EDAs facilitate the real-time analysis of the collected IoT data via a CEP engine, whose outcome is transparently and automatically registered in a blockchain network.
As blockchain protocols exhibit diverse characteristics and performances, it is crucial to decide whether to develop a custom blockchain protocol, select an existing platform, or identify a promising protocol before initiating a blockchain-based service or starting a new business. To assist the general public and business operators in assessing the desirability of each blockchain protocol, various services provide evaluation and ranking services for blockchain projects. However, most of these services rely on qualitative evaluation based on reports provided by the blockchain development team. Therefore, we propose a quantitative evaluation method for blockchain protocols that compares and analyzes the technological status, future development direction, and technological differences of Layer 1 and Layer 2 protocols. Our approach incorporates indicators that are distinct from other services and indicators specific to layer 2 solutions, facilitating a more comprehensive analysis of blockchain protocols. This allows for objective evaluation of protocol performance and mutual comparison between protocols.
Reordering blockchain transactions to manipulate markets profited hackers by hundreds of millions of dollars. Because they rely on State Machine Replication (SMR), blockchains order transactions without preventing hackers from influencing the chosen order. Some order-fair consensus protocols, like Pompē [33], order transactions before agreeing on this order. They are insufficient because a hacker can leverage the lack of triangle inequality among network latencies to observe pending transactions before issuing their own. Other DAG-based protocols, like Fino [24], use commit-reveal to obfuscate transactions, but cannot prevent reordering by a Byzantine leader.In this paper, we present Lyra, a protocol that solves this problem. The key idea is the combination of a commit-reveal protocol to obfuscate transaction payloads, and a leaderless ordered consensus protocol that predicts the order of transactions. Lyra has optimal good-case latency, prevents reordering attacks, and is scalable. Finally, it outperforms the latency of Pompē by up to 2 times and its throughput by up to 7 times on a 100-node network over 3 continents.
Smart Contracts have enabled Distributed Ledger Technologies and Blockchains to execute business logic over decentralized and distributed networks. Consequently, Blockchain technology boosted through Smart Contracts has become increasingly widespread in decentralized finance and industrial applications in recent years. Although Blockchain-based development systems have experienced significant growth in adoption areas, Smart Contract testing is still an immature aspect of the Blockchain development life cycle, even if it is involved in mission-critical financial and non-financial applications. To contribute to remedying this state of affairs, we provide the design guidelines for implementing a Smart Contract testing approach based on log analysis and programming language independence. We thus describe the key aspects of this testing strategy, such as the integration of the Elastic Search (ELK) stack and the feasibility of its use in distributed and decentralized applications.
Farhana Javed, Josep Mangues‐Bafalluy, Engin Zeydan
This poster presents a use case for smart contract-based inter-provider agreements and Service Level Agreement (SLA) monitoring for 6G networks. We use chainlink oracle and InterPlanetary File System (IPFS) to monitor SLA data logs. We also provide experimental evaluations of two approaches: raw data log access in IPFS and chainlink-based log access. To understand the performance and feasibility of the proposed approaches on a public blockchain, the proposed framework is deployed on the Ethereum and Polygon testnets to measure the cost and latency for both approaches. We measure the latency as well as the total cost for comparison purposes. The maximum cost observed for the first approach is ≈ 1.4 USD, and the maximum latency observed with the first approach is ≈4 seconds in the Polygon testnet and 12 ~ 14 seconds in the Ethereum testnet. However, the second approach's latency is 30 ~ 60 seconds.
Blockchain is a decentralized distributed system on which a large number of financial applications have been deployed. The consensus process in it plays an important role, which guarantees that legal transactions on the chain can be executed and recorded fairly and consistently. However, because of Consensus Failure Bugs (CFBs), many blockchain systems do not provide even this basic guarantee. The validity and consistency of blockchain systems rely on the soundness of complex consensus logic implementation. Any bugs which cause the blockchain consensus failure can be crucial.In this work, we introduce Tyr, an open-source tool for detecting CFBs in blockchain systems with a large number of abnormal divergent consensus behaviors. First, we design four oracle detectors to monitor the behaviors of nodes and analyze the violation of consensus properties. To trigger these oracles effectively, Tyr harnesses a behavior divergent model to constantly generate consensus messages and make nodes behave as differently as possible. We implemented and evaluated Tyr on six widely used commercial blockchain consensus systems, including IBM Fabric, WeBank FISCO-BCOS, ConsenSys Quorum, Facebook Diem, Go-Ethereum, and EOS. Compared with the state-of-the-art tools Peach, Fluffy, and Twins, Tyr covers 27.3%, 228.2%, and 297.1% more branches, respectively. Furthermore, Tyr has detected 20 serious previously unknown vulnerabilities, all of which have been repaired by the corresponding maintainers.
Vytautas Tumas, Beltrán Borja Fiz Pontiveros, Christof Ferreira Torres, Radu State
Blockchains are disrupting traditional finance by reducing the number of intermediaries and providing transparency. Blockchains, however, come with their own set of prominent issues. One such challenge is frontrunning. Attackers try to influence the transaction order so that their transaction executes before their victims' transaction. While frontrunning is a well-studied topic on Ethereum, it is unknown whether other blockchains are also susceptible to such attacks. One proposed defence strategy against frontrunning attacks is to randomize the transaction execution order. XRP Ledger is the highest-value blockchain to use such a strategy. Furthermore, it runs a Decentralized Exchange, which provides ample frontrunning opportunities. Therefore, in the context of XRP Ledger, we examine whether randomized transaction order provides sufficient protection against frontrunning. Our results show that the mechanism embedded in the XRP Ledger protocol is insufficient to prevent these attacks. We showcase two strategies to perform frontrunning attacks. The first, “naive” strategy, uses randomly generated accounts, whereas the second uses carefully selected accounts to improve the attack's success. Based on our analysis of the XRP Ledgers' historical data, we estimate that attackers could generate up to approx. 1.4M USD profit over two months, provided they succeeded to frontrun every opportunity.
Secure voting may be a crucial application of blockchain advancement, but guaranteeing the astuteness and protection of voting can be a complex issue. This record proposes a blockchain-based cloud computing appear on the Ethereum Virtual Machine (EVM) trade to address this issue. Our dissidents will utilize savvy contracts to screen vote preparation, but the votes themselves will be put away off-chain in a secure cloud capacity framework. We utilize agreement calculations based on Proof-of-Stake (PoS) measures to guarantee voting preparation choices. This degree guarantees that authorized centers can take part, so to talk, within the preparation of votes, which votes are numbered precisely. Moreover, we propose a novel cryptographic plot that permits for exact numbering of votes whereas ensuring vote mystery. Our appear is outlined to be versatile and successful in arrange to form it reasonable for large-scale voting scenarios. demonstrate. Our comes about show up to supply a flexible and able include for secure voting whereas guaranteeing voting precision and secrecy.
A significant portion of research on distributed ledgers has focused on circumventing the limitations of leader-based blockchains mainly in terms of scalability, decentralization and power consumption. Leaderless architectures based on directed acyclic graphs (DAGs) avoid many of these limitations altogether, but their increased flexibility and performance comes at the cost of increased design complexity, so their potential has remained largely unexplored. Management of write access to these ledgers presents a major challenge because ledger updates may be made in parallel, hence transactions cannot simply be serialised and prioritised according to token fees paid to validators. In this work, we propose an access control scheme for leaderless DAG-based ledgers which is based on consuming credits rather than paying fees in the base token. We outline a general model for this new approach and provide some simulation results showing promising performance boosts.
Rabimba Karanjai, Lei Xu, Nour Diallo, Lin Chen · 5 authors
Function-as-a-service (FaaS) is an emerging computation architecture, which provides high scalability and flexibility. All the existing F aaS systems are owned and managed by a single cloud service provider. While this is not an issue for most existing enterprise applications, such character is not compatible with the decentralization principle of dApp/Web3 applications, more of which are being deployed in the cloud environment. Therefore, there is an urgent need to build a decentralized FaaS, which is managed by multiple cloud service providers and allows a decentralized application to take advantages of FaaS. In this research paper, we propose DeFaaS, a novel system for managing decentralized FaaS using blockchain technology and decentralized API management, where functions are executed on a distributed network of nodes by multi-cloud data centers, rather than on a centralized server. This allows for greater scalability and flexibility, as well as improved security and reliability.
Decentralization promises to remedy the drawbacks of the web by executing decentralized applications (DApps) on blockchains. Unfortunately, modern blockchains cannot support realistic web application workloads mainly due to congestion.We introduce the Smart Redbelly Blockchain (SRBB), a provably correct permissionless blockchain that reduces congestion by (1) avoiding redundant propagation and validations of transactions with Transaction Validation and Propagation Reduction (TVPR) and (2) mitigating the propagation of invalid transactions within blocks by Byzantine nodes with a dedicated Reward-Penalty Mechanism (RPM). Our comparison of SRBB against Algorand, Avalanche, Diem, Ethereum, Quorum, and Solana, using the DIABLO benchmark suite, indicates that SRBB outperforms all these blockchains under real application workloads. Moreover, SRBB is the only blockchain to successfully execute real workloads of NASDAQ and Uber on a DApp without losing transactions. To demonstrate that TVPR and RPM are the causes of the improved performance, we compare SRBB with its naive baseline, which does not contain TVPR and RPM. Our results show that TVPR increases the throughput by 55× and divides the latency by 3.5, while RPM increases the throughput by 7% under flooding attacks. Finally, TVPR helps reduce transaction losses in the normal scenario while RPM goes further and mitigates transaction losses under flooding attacks.
Anwar Sadad, Muazzam A. Khan, Baraq Ghaleb, Fadia Ali Khan · 7 authors
Blockchain (BC) and Information for Operational and Tactical Analysis (IOTA) are distributed ledgers that record a huge number of transactions in multiple places at the same time using decentralized databases. Both BC and IOTA facilitate Internet-of-Things (IoT) by overcoming the issues related to traditional centralized systems, such as privacy, security, resources cost, performance, and transparency. Still, IoT faces the potential challenges of real-time processing, resource management, and storage services. Edge computing (EC) has been introduced to tackle the underlying challenges of IoT by providing real-time processing, resource management, and storage services nearer to IoT devices on the network's edge. To make EC more efficient and effective, solutions using BC and IOTA have been devoted to this area. However, BC and IOTA came with their pitfalls. This survey outlines the pitfalls of BC and IOTA in EC and provides research directions to be investigated further.
Zhongming Yao, Junchang Xin, Kun Hao, Zhiqiong Wang · 5 authors
Blockchain has become increasingly popular for data management in recent years. However, the existing blockchain systems lack efficient semantic queries, particularly keyword queries. To address this issue, we propose a learned-index-based semantic keyword query architecture on blockchain. First, our architecture records data semantics information to support semantic keyword queries. Second, we establish the lookup table index for semantic information among blocks and the block-level recursive model index for blocks to improve the query efficiency. We store the lookup table in the extended block headers to maintain the result’s completeness, and we store recursive model indexes off chain to optimize the maintenance efficiency. Third, we propose a verifiable query algorithm based on our proposed architecture to maintain the result’s correctness. Finally, the experimental results show that combining the lookup table and the learned index effectively improves the query efficiency on blockchain.
Blockchain interoperability promotes value delivery, application expansion, and ecological compatibility across heterogeneous blockchain systems. However, the contract framework and virtual machine construction in these systems are significantly different, and crosschaining becomes a challenging issue for system universality and compatibility. Starting from this problem, in this study, we propose VM-Studio, a crosschain smart contract verification and execution scheme to migrate the virtual machines (VMs) from the origin blockchain to the target blockchain. In our scheme, the migrated VMs are loaded as independent components enclosed in containers. We also design a unified system schedule to enable VM-Studio to allocate transactions into different containers. Loaded with origin blockchain VMs, these containers can accordingly solve crosschain transaction execution and smart contract verification. We implement VM-Studio and evaluate the transaction execution performance in the origin environment with multiple blockchains and the container environment. Experiment results demonstrate that VM-Studio achieves broad universality without compromising the execution performance of original blockchain transactions.
E Chen, Shengdian Wang, Yuqing Fan, Yan Zhu · 5 authors
Usage-based pricing or Pay-as-You-Go is a relatively new SaaS business model that may provide customers the option to pay for only what they use. Yet, it is more challenging to implement than traditional Pay-before-Use subscriptions considering that it need not only realize financial payment on consumption-based behaviors, but also regulate the rights and obligations among the providers, consumers, and platforms in a legal form. To address these challenges, in this article Smart Legal Contract (SLC) is integrated into a service computing platform by introducing a new architecture, called Service as a Smart Contract (SaaSC). On the aspect of service legalization, through combining SaaS and SaaSC, we establish three kinds of terms in SLC-based software subscription contract to support service's registration, discovery and customization, so that a complete transaction procedure can be regulated in terms of service states, transaction process, and interactions among contracting parties. On the aspect of service financialization, we propose a new scheme of service interface declaration in the SLC-based SPESC contract. By automatically executing smart contracts and checking the terms, the pay-as-you-go billing form can be made fine-grained payment after using service interface calls. Moreover, we take weather forecast service as a case to implement and analyze the acquisition, delivery, and contractual payment of software service on Blockchain smart contract. The experimental results demonstrate the feasibility and effectiveness of the proposed SaaS+SaaSC architecture so that it provides a practicable approach for contractual software service.
Blockchain has attracted significant attention in recent years due to its potential to revolutionize various industries by providing trustlessness. To comprehensively examine blockchain systems, this article presents both a macro-level overview on the most popular blockchain systems, and a micro-level analysis on a general blockchain framework and its crucial components. The macro-level exploration provides a big picture on the endeavors made by blockchain professionals over the years to enhance the blockchain performance while the micro-level investigation details the blockchain building blocks for deep technology comprehension. More specifically, this article introduces a general modular blockchain analytic framework that decomposes a blockchain system into interacting modules and then examines the major modules to cover the essential blockchain components of network, consensus, and distributed ledger at the micro-level. The framework as well as the modular analysis jointly build a foundation for designing scalable, flexible, and application-adaptive blockchains that can meet diverse requirements. Additionally, this article explores popular technologies that can be integrated with blockchain to expand functionality and highlights major challenges. Such a study provides critical insights to overcome the obstacles in designing novel blockchain systems and facilitates the further development of blockchain as a digital infrastructure to service new applications.