Despite its promising potential, scalability issues have hindered the widespread adoption of blockchain applications. Existing blockchain systems incur high communication and computation costs, resulting in poor throughput. Furthermore, they do not provide flexible scalability to match the dynamic changes in user transaction demand. In this paper, we present PuffChain, a dynamic scaling blockchain system that can dynamically scale up the transaction throughput when there is a surge of user demand while automatically scaling down upon the drop of user demand. We decouple the functionalities of blockchain nodes into three roles: packers that pack transactions into blocks, proposers that propose blocks for consensus, and validators that validate blocks. The number of packers is dynamically adjusted according to user transaction demand, achieving dynamic scalability. Proposers and validators use a three-phase consensus protocol with filters to maximize appending valid transactions while discarding invalid ones. By decoupling these functions, PuffChain enables adaptive scaling and optimized consensus efficiency. We also develop a theoretical model to analyze PuffChain's throughput and derive the optimal parameters to achieve maximal effective throughput. Extensive experiments on Amazon EC2 clusters demonstrate that PuffChain achieves a throughput of 6061 transactions per second with 100 nodes, highlighting its potential for real-world applications.
Jun Wook Heo, Gowri Ramachandran, Ali Dorri, Raja Jurdak
Blockchain offers immutability, transparency, and security in a decentralised way for many applications, including finance, supply chain, and the Internet of Things (IoT). Due to its popularity and widespread adoption, it has started to process an enormous number of transactions, placing an ever-growing demand for storage. As the technology gains more popularity, the storage requirements of blockchain will increase, necessitating storage optimisation solutions. Proposed solutions for blockchain storage efficiency range from reducing the degree of data replication to redacting or compressing data. Each of these storage optimisation categories involves a complex interplay with the timing of blockchain data processing and mining, yet no existing survey analyses these dimensions. This article surveys the state-of-the-art blockchain storage optimisations and categorises them into replication-based, redaction-based, and content-based optimisations. Replication-based optimisations focus on reducing duplication of blockchain data shared among participants after committing data on the blockchain ledger. Redaction-based optimisations allow users to modify or delete data already committed on the ledger in various ways, while content-based optimisations compress data before or after committing it to the ledger. We analyse and evaluate these solutions in the aspects of security, decentralisation, and scalability. We present the advantages and disadvantages of the existing blockchain storage optimisations and comprehensively compare them. Additionally, we discuss the opportunities and challenges for future work to optimise blockchain storage.
Mindaugas Juodis, Ernestas Filatovas, Remigijus Paulavičius
The decentralization paradigm has made blockchain one of the most disruptive technologies today. When evaluating the level of decentralization, the key metric for most public blockchain networks is the degree of decentralization of the resources responsible for determining who generates the blocks. In turn, it facilitates a greater understanding of both security and scalability on a blockchain. This work provides an overview of the current state-of-the-art on wealth decentralization, which has not yet received the attention it deserves. We collect data, calculate various wealth decentralization metrics, and compare our results with research on the same methodology. As the amount of data for various blockchains increases rapidly, it is helpful to have techniques to aggregate data for statistical analysis. We introduce and provide conservative estimates of decentralized group metrics based on the reduced data and compare them with full-data measurements. Our research considers both the Layer 1 blockchains of Bitcoin and Ethereum, along with Layer 2 blockchains such as Arbitrum, Optimism, and Polygon.
Yang Feng, Zongya Ding, Linpeng Jia, Yi Sun · 5 authors
In the Interplanetary File System (IPFS), consumers can help each other protect data against hardware failures and improve data availability through replication. While previous replication methods in peer-to-peer (P2P) networks can be used to increase data availability in the IPFS network, they are either hostile to peers with limited availability, preventing them from achieving adequate data availability, or lack flexibility. An ideal replication method should optimize data availability in a manner equitable to all peers while providing flexibility. To achieve this goal, this paper introduces a blockchain-based file replication mechanism. Leveraging the non-tamperable and traceable nature of blockchain technology, our mechanism achieves secure storage and trustworthy query of peers’ information used in the file replication process. Unlike most earlier methods, our mechanism employs an Arweave-inspired file replication algorithm that prioritizes the less available files within the system for replication until all files’ availabilities are optimized. Replicating files according to predefined system-wide cooperation rules like this not only limits the selfishness of peers but also facilitates timely adjustments in response to changes in the P2P system. In addition, our mechanism also uses smart contracts to judge and exclude dishonest peers, thereby fostering honest cooperation among peers without involving any third party.
Jie Xu, Yulong Ming, Zihan Wu, Cong Wang · 5 authors
Recent advances in cryptocurrencies have sparked significant interest in blockchain technology. However, scalability issues remain a major challenge for wide adoption of blockchains. Sharding is a promising approach to scale blockchains, but existing sharding-based blockchains fail to achieve expected performance gains due to limitations in cross-shard transaction processing. In this paper, we propose X-shard, a blockchain system that optimizes cross-shard transaction processing, achieving high effective throughput and low processing latency. First, we allocate transactions to shards based on historical transaction patterns to minimize cross-shard transactions. Second, we take an optimistic strategy to process cross-shard transactions in parallel as sub-transactions within input shards, thereby accelerating transaction processing. Finally, we employ a cross-shard commit protocol with threshold signatures to reduce communication overhead. We implement and deploy X-shard on Amazon EC2 clusters. Experimental results validate our theoretical analysis and show that as the number of shards increases, X-shard achieves nearly linear scaling in effective throughput and decreases in transaction processing latency.
Recently, blockchain-based IoT solutions have been proposed that address trust limitation by maintaining data consistency, immutability, and chronology in IoT environments. However, IoT ecosystems are resource-constrained and have low bandwidth and finite computing power of sensor nodes. Thus, the inclusion of blockchain requires an effective policy design regarding consensus and smart contract environments in heterogeneous IoT applications. Recent studies have presented blockchain as a potential solution in IoT, but an effective view of consensus and smart contract design to meet the end application requirements is an open problem. Motivated by the same, the survey presents the integration of suitable low-powered consensus protocols and smart contract design to assess and validate the blockchain-IoT ecosystems. We discuss the key blockchain concepts and present the scalability and performance issues of consensus protocols to support IoT. Further, we discuss smart contract vulnerabilities and blockchain attacks. Open issues and future directions are presented, supported through a case study of low-powered consensus protocol design in the blockchain- IoT ecosystem. The survey intends to drive novel solutions for future consensus and safe, smart contract designs to support applicative IoT ecosyst
Immutability has always been a core attribute of blockchain to ensure a trusted public ledger. However, in recent years, many malicious actions on blockchain have raised controversy over strict immutability. As a practical matter, it is necessary to design redactable blockchain protocols in some cases. Previous studies have proposed methods to implement redaction features in permissionless blockchains. However, in these protocols, parties can refuse to accept redacted blocks without affecting their mining. It makes these protocols lack feasibility in practice. In this paper, we present Chainknot, a redactable blockchain protocol with forced synchronization. We use the incentives of permissionless blockchain to effectively facilitate the review of a redaction proposal, and design a novel blockchain structure that ensures the acceptance of modified blocks by parties. In addition, we present instantiations of Chainknot on the PoW-based and PoS-based blockchain systems, with further improvements for efficiency and security, respectively. The experimental results show that the additional latency our protocol imposes on the original immutable blockchain system is negligible (less than 4%).
In the dynamic digital epoch, this exploration delves into the impact of technologies on decentralization, unraveling blockchain, AI, and IoT. It dissects their transformative influence on power structures, economic paradigms, and global interactions. From the transparency of blockchain to the decision-making of AI and the symphony orchestrated by IoT, the chapter explores technologies shaping a new decentralized reality. Blockchain disrupts traditional finance, extending its impact to healthcare and supply chain management. The intersection of AI and blockchain enhances security and governance. IoT transforms industries, ushering in real-time data exchange and automation. The chapter explores deglobalization, examining how digital platforms empower local entrepreneurship and decentralized digital identity systems enhance national security. Challenges, including security concerns and inclusive access, demand astute navigation, improved collaboration, and proactive governance. The chapter concludes with a call for collective wisdom and ethical stewardship to shape a decentralized future.
This paper addresses the continuously increasing storage demands challenge faced by blockchain networks, with a particular focus on Ethereum. We propose a novel framework that divides the network into consensus nodes, which inherit Ethereum characteristics, and storage nodes responsible for storing Merkle Patricia Trie (MPT) nodes. This design aims to reduce the storage load on individual nodes by distributing MPT nodes based on their key values. Our approach maintains network security and data integrity while easing the storage burden through a distributed storage mechanism. Key to our work is the dynamic adjustment of storage load across an expandable network of storage nodes. We validate our framework through practical experiments, involving modifications to the go-ethereum source code and testing with authentic Ethereum block data. The results confirm that our work not only mitigates storage issues but also enhances synchronization efficiency.
Li Lin, Jiapeng Wu, Zhi Zhou, Jin Zhao · 6 authors
Computing Power Networking (CPN) represents a transformative paradigm in distributed computing, harnessing the collective capabilities of edge servers dispersed across diverse geographical locations. CPN’s core strengths lie in its ability to accelerate data processing, diminish latency, and scale efficiently, rendering it particularly apt for real-time applications and the Internet of Things. When coupled with blockchain technology, CPN extends its potential by facilitating secure and transparent allocation and trading of computing resources, bolstering data integrity and reliability. However, current research at the intersection of CPN and blockchain primarily focuses on framework development and technology integration, often overlooking the challenge of delivering dependable computing services, especially in the presence of potentially unreliable nodes. To tackle this issue, we introduce a reputation-enhanced resource trading framework, designed to ensure equitable and trustworthy computing power transactions. We establish a decentralized reputation model, capable of accurately assessing node behavior over extended periods. Additionally, we present three optimization mechanisms for reputation updates, accounting for transaction history, quality of service, and transaction amount. Furthermore, our work introduces a reputation-enhanced consensus mechanism within the trading system, strategically employing incentives to motivate participants to deliver high-quality services, thereby increasing their rewards. Simultaneously, it effectively mitigates wealth inequality among resource providers of varying sizes. To validate our approach, we develop a prototype system and conduct performance evaluations, which affirm the superiority of our system in enhancing reputation and delivering robust economic features.
Summary Bitcoin is a Blockchain‐based network in which thousands of nodes are directly connected and communicate via a gossip‐based flooding protocol. Mined blocks are propagated to all participating nodes in the network through a CBR (compact block relay) protocol developed to reduce the block propagation delay. However, propagation delay persists. The relay time between nodes must be measured and analyzed to determine the cause of the delay and provide solutions for reducing block propagation time. Previously, we measured the relay time and investigated the cause of the delay. According to the findings of the previous study, the delay of the relay time occurs when assembling compact blocks, depending on whether transactions are requested. In this paper, we find the reasons for requesting transactions. The reasons are due to the transaction propagation method and the characteristics of the transaction itself. We propose a solution based on this. It is a method of reducing probability of requesting transactions by using the compact block's “PREFILLEDTXN” to send the transactions expected to be requested with the block. The probability of requesting is reduced by up to 67% when transactions that have just entered the memory pool are propagated by PREFILLEDTXN. The block relay time is reduced by up to 44% as a result. Finally, this research reduces block relay time between nodes.
Systems that integrate distributed databases and existing blockchain platforms have recently emerged, which conveniently leverage their respective strengths to build efficient, secure, and usable data sharing and collaboration environments for different organizations. However, the performance of such systems can be limited by the native blockchain platforms due to the high latency of transactions. In this paper, we present CoralDB, a bottom-up fully redesigned hybrid system of blockchain and database, aimed at enabling untrusted organizations to collaborate and share data efficiently and securely at the database level. The storage layer of CoralDB ensures data security and system throughput through key modules such as customized block structure, consensus mechanism, and transaction pool. On top of the storage layer, a database layer is introduced, which extends the blockchain of the storage layer by incorporating connection pools, collaborative tables, and query interfaces, to enhance the usability and efficiency of data collaboration and sharing. Extensive experimental results demonstrate that CoralDB provides security assurances at the level of blockchain and enables efficient decentralized data collaboration and sharing.
Md Arif Hassan, Cong T. Nguyen, Chi-Hieu Nguyen, Dinh Thai Hoang · 6 authors
Web 3.0 is the third generation of the World Wide Web (WWW), concentrating on the critical concepts of decentralization, availability, and increasing client usability. Although Web 3.0 is undoubtedly an essential component of the future Internet, it currently faces critical challenges, including decentralized data collection and management. To overcome these challenges, blockchain has emerged as one of the core technologies for the future development of Web 3.0. In this paper, we propose a novel blockchain-based information management framework, namely Smart Blockchain-based Web (SBW), to manage information in Web 3.0 effectively, enhance the security and privacy of users’ data, bring additional profits, and incentivize users to contribute information to the websites. Particularly, SBW utilizes blockchain technology and smart contracts to manage the decentralized data collection process for Web 3.0 effectively. Moreover, in this framework, we develop an effective consensus mechanism based on Proof-of-Stake (PoS) to reward the user’s information contribution and conduct game theoretical analysis to analyze the user’s behavior in the considered system. Additionally, we conduct simulations to assess the performance of SBW and investigate the impact of critical parameters on information contribution. The findings confirm our theoretical analysis and demonstrate that our proposed consensus mechanism can incentivize the nodes and users to contribute more information to our systems.
Summary The lack of interoperability between blockchains is a primary barrier to adopting the technology. Blockchains suffer from vendor lock‐ins as users cannot easily move their assets between blockchains. To resolve this issue, we propose a cross‐chain decentralized asset transfer protocol for blockchains without involving any intermediaries. Cross‐chain transactions can be efficiently executed using our proposed protocol without including any centralized third party. Most of the existing asset transfer solutions neglect the transaction finality guarantees; however, the protocol presented in this paper keeps track of transaction finality, providing transaction irreversibility guarantees and preventing assets from being lost in the transfer process. The reference implementation for the proposed protocol consists of smart contracts and a Web API for carrying out the cross‐chain transfer of assets. The proposed protocol is experimentally validated for the transfer of assets between Ethereum and Binance testnets. The performance testing shows that the cost of the proposed protocol is acceptable.
Ehtisham Ul Haque, Adil Shah, Jawaid Iqbal, Syed Sajid Ullah · 6 authors
Abstract Recent research has focused on applying blockchain technology to solve security-related problems in Internet of Things (IoT) networks. However, the inherent scalability issues of blockchain technology become apparent in the presence of a vast number of IoT devices and the substantial data generated by these networks. Therefore, in this paper, we use a lightweight consensus algorithm to cater to these problems. We propose a scalable blockchain-based framework for managing IoT data, catering to a large number of devices. This framework utilizes the Delegated Proof of Stake (DPoS) consensus algorithm to ensure enhanced performance and efficiency in resource-constrained IoT networks. DPoS being a lightweight consensus algorithm leverages a selected number of elected delegates to validate and confirm transactions, thus mitigating the performance and efficiency degradation in the blockchain-based IoT networks. In this paper, we implemented an Interplanetary File System (IPFS) for distributed storage, and Docker to evaluate the network’s performance in terms of throughput, latency, and resource utilization. We divided our analysis into four parts: Latency, throughput, resource utilization, and file upload time and speed in distributed storage evaluation. Our empirical findings demonstrate that our framework exhibits low latency, measuring less than 0.976 milliseconds. The proposed technique outperforms Proof of Stake (PoS), representing a state-of-the-art consensus technique. We also demonstrate that the proposed approach is useful in IoT applications where low latency or resource efficiency is required.
Fueled by the growing popularity of proof-of-stake blockchains, there has been increasing interest and progress in permissioned consensus protocols, which could provide a simpler alternative to existing protocols, such as Paxos and PBFT. In particular, the recently proposed Streamlet protocol provides a surprisingly simple and streamlined consensus approach, which crystallizes years of research in simplifying and improving classical consensus protocols. While the simplicity of Streamlet is a major accomplishment, the protocol lacks certain practical features, such as supporting a stable block proposer, and it makes strong assumptions, such as synchronized clocks and the implicit echoing of all messages. Most importantly, it requires sending $O(N^3)$ messages per block in a network of $N$ nodes, which poses a significant challenge to its application in larger networks. To address these limitations, we introduce Pipelet, a practical streamlined consensus protocol. Pipelet employs the same block-finalization rule as Streamlet, but attains state-of-the-art performance in terms of communication complexity and provides features that are crucial for practical applications, such as clock synchronization and stable block proposers. At the same time, Pipelet retains the simplicity of Streamlet, which presents significant practical advantages, such as ease of implementation and verification.
The global seafood industry has various issues, including fraud, opacity, and inefficient payment mechanisms throughout its supply chain. The paper suggests a novel way of transforming payment processes based on Blockchain Technology (BT) and Non-Fungible Tokens (NFTs). This transformative approach is designed to revolutionize the way payment transactions are handled within the seafood industry. Our proposed framework combines Blockchain Technology (BT) for traceability and authenticity of seafood products with smart contracts for automated, secure payments across the supply chain. When certain criteria are satisfied, such as successful delivery or adherence to quality standards, smart contracts activate, assuring efficiency and transparency. Furthermore, our proposed framework provides consumers with real-time access to seafood product details, promoting sustainability and ethical choices while deterring fraud and supporting responsible fishing practices. Finally, we analyzed the practicality and effectiveness of our framework using JMeter, gaining essential insights into its capabilities and scalability. With this knowledge, we can optimize the framework for real-world use.
Sharding is one of the most promising technologies for significantly increasing blockchain transaction throughput. However, as the number of shards increases, the ratio of cross-shard transactions in existing blockchain sharding protocols gradually approaches 100%. Since cross-shard transactions consume many times more resources than intra-shard transactions, the processing overhead of cross-shard transactions already accounts for the majority of the total overhead of the sharding system. There is a very large gap between the transaction throughput of the sharding system and its theoretical upper limit. In this article, we propose Estuary, a novel low cross-shard blockchain sharding protocol. Taking the state model as an entry point, Estuary designs a multi-level state model and state splitting and aggregation mechanism. It decouples the identity and quantity of state units, enabling transactions between users to be completed within one shard. Only when the state quantity for all shards of a user is insufficient a small number of cross-shard transactions are required. On this basis, we propose a community overlap propagation algorithm for sharding. It defines the users’ belonging coefficients of each shard and optimizes the state distribution so that the state distribution can better match the transaction characteristics between users. Finally, we develop an analysis framework for the sharding protocol and experiment with real Bitcoin transactions. The evaluation results show that compared to the state-of-the-art sharding protocol, Estuary reduces the ratio of cross-shard transactions by 88.54% and achieves more than 1.85 times the throughput improvement (92.98% of the theoretical upper limit).
In the realm of the Internet of Things (IoT), in-tegrating blockchain technology has brought about significant enhancements in security and transparency. Nevertheless, the union of these two domains grapples with persistent challenges in performance and scalability. A dilemma confronts developers and researchers: the intricate interplay between security, scalability, and performance in various consensus protocols tailored for implementing blockchain within loT ecosystems. This research paper proposes an innovative consensus protocol to tackle these challenges while striking an optimal equilibrium among these tripartite factors. Central to this proposal is introducing a hybrid architectural framework that bridges the world of loT devices and cloud service providers via distinct regional entities, all united in the objective of consensus through a novel voting mechanism hinged on reputationbased mechanisms. The core of this voting mechanism is a dynamic ensemble of nodes, each endowed with unique roles - encompassing ordinary nodes, verifiers, and assemblers. The protocol employs a random selection mechanism through a verifiable random function (VRF) to designate assem-blers, ensuring a level playing field. At the heart of the reputation model lies an analysis of region-specific traffic patterns, granting privileges to nodes that demonstrate trustworthy behaviour and high rates of request fulfillment. Extending this framework is an incentive mechanism designed to maintain the network's organic and dynamic allocation of roles. Simulation results benchmarked against Ethereum provide results of the ReVo consensus protocol for latency and transaction throughput. This paper also analyses the protocol working through a novel use case of Taxi Providers and Taxi Ride Consumer Services. Index Terms-Blockchain, Consensus Algorithm, Reputation, Internet Of things, Hybrid blockchain, Voting.
This study presents a series of structured and adaptive processes aimed at tracking and verifying transactions recorded on the blockchain. Permissioned blockchains are employed across diverse enterprises for various purposes, including data recording, management, the utilization of blockchain services, and authentication. However, the processes of data tracking and transactions incur substantial resource and time expenditure. Furthermore, there is potential for information asymmetry within the blockchain ledger due to data breach attacks. Consequently, we propose a contract structured as a hash chain to mitigate resource and time consumption in the tracking and verification processes by organizing transaction hash values and content in a hash chain format based on cryptography. We generate a hash chain for the recorded transactions along the process line and expedite the tracking and verification process by navigating the relevant hash chain. This approach achieves faster and more accurate tracking procedures compared to conventional transaction tracking processes, simultaneously maintaining data symmetry within the blockchain ledger. We conduct a comparative analysis of a contract-based hash-chain-employing structure and two contracts related to tracking in terms of tracking time, CPU usage, and network traffic, among other metrics. The findings suggest that structuring transaction data in the form of a hash chain significantly enhances the efficiency and integrity of the data-tracking and verification processes. Consequently, in this study, we advocate for the adoption of contracts based on the hash chain format when leveraging the blockchain for tracking and verification purposes across various institutions.
Sharding technology can address the throughput and scalability limitations that arise when single-chain blockchain are applied in the Internet of Things (IoT). However, existing sharding solutions focus on addressing issues like malicious nodes clustering and cross-shard transactions. Existing sharding solutions cannot adapt to the performance disparities of edge nodes and the characteristic of three-dimensional data queries in building IoT. This leads to problems such as shard overheating and inefficient data query efficiency. This paper proposes a dual-layer architecture called S-DAG, which combines sharded blockchain and DAG blockchain. The sharded blockchain processes transactions within the building IoT, while the DAG blockchain stores block headers from the sharded network. By designing an Adaptive Balancing Load Algorithm (ABLA) for periodic network sharding, nodes are divided based on their load performance values to prevent the aggregation of low-load performance nodes and the resulting issue of shard overheating. By combining the characteristics of the KD tree and Merkle tree, a block structure known as 3D-Merkle tree is designed to support three-dimensional data queries, enhancing the efficiency of three-dimensional data queries in building IoT. By deploying and conducting simulation experiments on various physical devices, we have verified the effectiveness of the solution proposed in this paper. The results indicate that, compared to other solutions, the proposed solution is better suited for building IoT data management. ABLA is effective in preventing shard overheating issue, and the 3D-Merkle tree significantly enhances data query efficiency.