Blockchain, a widely utilized distributed ledger technology, faces the scalability challenge. State sharding has emerged as a promising solution for addressing this challenge. However, conventional state allocation solutions often face two major obstacles: a high ratio of cross-shard transactions and an unbalanced workload distribution, due to their reliance on a simple and fixed assignment of states to shards. The former increases the overall workload on the system, while the latter reduces resource utilization. Both factors significantly impact system performance. Moreover, our key observation is that the collection of smart contract transactions can be represented as a hypergraph network by analyzing their characteristics. Therefore, this study proposes HyperChain, a novel dynamic state sharding protocol that integrates a hypergraph partition algorithm. HyperChain aims to reduce the ratio of cross-shard transactions and balance workload distribution, thereby achieving improved throughput and reduced transaction latency in smart contract blockchain systems. Our experiments demonstrate that the proposed HyperChain exhibits superior performance than other solutions in terms of cross-shard transaction ratio, workload balance, throughput, and transaction latency.
R. Hanumantharaju, Shreenath Kn, Sowmya BJ, Srinivasa Kg
Intrusion detection is a familiar phrase in the information and network security domain. An Intrusion Detection System (IDS) is a device or software that will keep track of the networks, for unlawful movements, and policy breaches that arise within the network. There are different forms of IDS, Host Intrusion Detection System (HIDS) helps in identifying unauthorized activities on the host, Network Intrusion Detection System (NIDS) helps in identifying attacks in the network, whereas Distributed Intrusion Detection System (DIDS) consists of multiple IDS over a large area of network where individual IDS communicates with each other or with the central the authorized central server. The proposed work has a three-layered architecture for DIDS for securing data sharing among different IDS. The bottom layer uses multiple IDS, the fog layer is supported with Blockchain functionality, and the cloud service at the upper layer stores required data permanently for future analysis. The fog computing-based architecture for DIDS tries to implement the application in a scalable and trustless environment using distributed ledger technology. The evaluation of the proposed work is carried out for fog, cloud, and integrated fog-cloud with the Blockchain functionality and without Blockchain functionality in measuring performance metrics related to throughput, service latency, response time, block creation time, and block execution time.
Due to the immutability of blockchain, the integration with big-data systems creates limitations on redundancy, scalability, cost, and latency. Additionally, large amounts of invaluable data result in the waste of energy and storage resources. As a result, the demand for data deletion possibilities in blockchain has risen over the last decade. Although several prior studies have introduced methods to address data modification features in blockchain, most of the proposed systems need shorter deletion delays and security requirements. This study proposes a novel blockchain architecture called Unlichain that provides data-modification features within public blockchain architecture. To achieve this goal, Unlichain employed a new indexing technique that defines the deletion time for predefined lifetime data. The indexing technique also enables the deletion possibility for unknown lifetime data. Unlichain employs a new metadata verification consensus among full and meta nodes to avoid delays and extra storage usage. Moreover, Unlichain motivates network nodes to include more transactions in a new block, which motivates nodes to scan for expired data during block mining. The evaluations proved that Unlichain architecture successfully enables instant data deletion while the existing solutions suffer from block dependency issues. Additionally, storage usage is reduced by up to 10%.
Sogolsadat Mansouri, Vodelina Samatova, Nodirbek Korchiev, Kemafor Anyanwu
Blockchains are distributed ledger platforms that were originally envisioned for implementing digital assets and cryptocurrencies such as BITCOIN. Mainstream blockchain platforms such as Ethereumand Hyperledgersupport both "native" transactional behavior i.e., transferring cryptocurrency assets, as well as, other types of transactional behavior relevant to an emerging class of applications called decentralized applications or DApps. However, "non-native" transactional behavior is achieved in terms of user-defined programs, commonly referred to as smart contracts. Unfortunately, smart contracts have several known limitations, including the burden on both implementor and contract consumers, being prone to financially-costly errors, higher cost of execution, and overall difficulty with concurrency optimization. Further, there is a lack of standardization with respect to implementation. Consequently, this contributes to the difficulty of enabling interoperability across blockchains. In this paper, we propose an ontology DeMaTO for modeling transactional behavior on blockchains as a foundation for extending blockchain transaction primitives. As an application context, we focus on marketplace transactions because marketplaces are one of the most popular categories of DApps, i.e., decentralized marketplaces. This modeling of transactional behavior complements the modeling supported by existing ontologies that focus on the infrastructure layer. We illustrate how DeMaTO can be used in blockchain transaction modeling and its value with respect to blockchain queryability and transaction validation.
Distributed ledger technologies (DLTs) have attracted significant attention in the last few years. They gained a noticeable momentum, particularly after the introduction of blockchains as a basic building block for the development of new cryptocurrencies and tokens. This opportunity opened up new research directions to support the modern economy with numerous possibilities to redesign and innovate the market in accordance with the digital revolution we are witnessing. However, these technologies are yet to prove in practice their capability to match all the dependability and security requirements imposed in the economic and banking sector. In this chapter, we will provide an overview of the technical features of DLTs (and of blockchains in particular), outlining their potential impact in the economic field. We will first introduce the reader to their definition from a technical point of view, illustrate its core mechanisms and the guarantees they provide, and describe how these features are realised in a decentralised way. Finally, we will draw opportunities and challenges stemming from the adoption of this technology.
Filip Rezabek, Kilian Glas, Richard von Seck, Achraf Aroua · 6 authors
The recent developments and research in distributed ledger technologies and blockchain have contributed to the increasing adoption of distributed systems. To collect relevant insights into systems' behavior, we observe many evaluation frameworks focusing mainly on the system under test throughput. However, these frameworks often need more comprehensiveness and generality, particularly in adopting a distributed applications' cross-layer approach. This work analyses in detail the requirements for distributed systems assessment. We summarize these findings into a structured methodology and experimentation framework called METHODA. Our approach emphasizes setting up and assessing a broader spectrum of distributed systems and addresses a notable research gap. We showcase the effectiveness of the framework by evaluating four distinct systems and their interaction, leveraging a diverse set of eight carefully selected metrics and 12 essential parameters. Through experimentation and analysis we demonstrate the framework's capabilities to provide valuable insights across various use cases. For instance, we identify that a combination of Trusted Execution Environments with threshold signature scheme FROST introduces minimal overhead on the performance with average latency around \SI{40}{\ms}. We showcase an emulation of realistic systems behavior, e.g., Maximal Extractable Value is possible and could be used to further model such dynamics. The METHODA framework enables a deeper understanding of distributed systems and is a powerful tool for researchers and practitioners navigating the complex landscape of modern computing infrastructures.
Andrei C. Azevedo, Eder J. Scheid, Muriel Figueredo Franco, Lisandro Zambenedetti Granville
Besides the main blockchain use-case of exchanging cryptocurrencies, Distributed Applications (DApps) can also be developed on top of such a technology. However, due to the size of popular blockchains and price, testing these DApps in a real-world environment becomes challenging. Thus, blockchain emulators were proposed to address such as issue. This paper presents the experience of emulating an Ethereum network using a Docker-based lightweight testbed developed for Software Defined Networks (SDN).
Blockchain technology has gained popularity in various applications, including finance transactions and beyond. However, developing blockchain application systems is challenging due to stringent quality requirements, such as performance, scalability, and security. Software architecture plays a critical role in realizing key quality requirements. Nonetheless, little work has been performed on software architectures for blockchain applications since blockchain application development is still a new field. This paper proposes twelve architectural patterns for blockchain application software architectures based on 400 cross-industry real-world applications available on the Internet. We determine the key components of each application guided by a blockchain application taxonomy we developed. We then identify typical architectural patterns from the interactions of these components guided by well-known software patterns, such as peer-to-peer, layered, pipe-filter, and access control. Based on the roles of these patterns, we organize them into four architectural views comprising four structural, two interactional, four transactional, and two security patterns. We describe each pattern in detail using a standard form and demonstrate the patterns through a real-world blockchain application. The use of patterns can be valuable in addressing blockchain’s unique challenges, but creativity remains essential in crafting innovative solutions. Mixing architectural patterns according to varying requirements can help developers communicate effectively.
In recent years, blockchain has developed rapidly and achieved great success in a variety of industries. However, the current shortcomings of blockchain in terms of low throughput and slow transaction confirmation have led to the difficulty of implementing and using blockchain in some highly concurrent scenarios. In this regard, blockchain technology based on DAG was born. DAG is characterized by high concurrency and high throughput due to its unique data structure, and its combination with blockchain can break the blockchain throughput bottleneck. In this regard, a DAG-based blockchain consensus algorithm is proposed to fully order all blocks, provide the total order and effectively improve the throughput of the blockchain using the division of subgraphs. The new proposed consensus algorithm is experimentally demonstrated to have significant improvement in data throughput, and it is found that SgDAG has 79 times higher throughput than Bitcoin, 36.9 times higher than Ethereum, and 5.5 times higher than IOTA, with high throughput and can use smart contracts
Blockchain technology realizes information traceability by constructing chain network structure; Through distributed storage and consensus mechanism, each transaction can be verified and shared. Hyperledger Fabric has the characteristics of deep encryption, convenient expansion, flexible deployment and pluggability, and provides a modular distributed ledger platform for the needs of different applications. Combining the blockchain technology with the storage and sharing requirements of railway engineering data and drawing information, this paper first introduces the related concepts of blockchain technology, Hyperledger Fabric and critical algorithms and puts forward a Coverage Tag Validation (CTV) for the storage of railway engineering data and drawing information, which can improve the query efficiency and optimize the results, and provide some reference for future research.
Bo Li, Hanwen Zhang, Chenhao Jiang, Zhongcheng Li · 5 authors
With the emergence of various application scenarios, various chains have been developed to meet their requirements. Among them, chains with fixed block intervals (fixed chains for short) occupy an increasingly significant position. Performance has always been a key bottleneck of blockchains and modeling for them is the most common method for performance analysis. But til now, few models for fixed chains exist and they are not precise and applicable enough. This paper proposes a model for fixed chains via the bulk-service queuing theory, which can reflect the real scenario more precisely and apply to the high load. We consider the continuous time and the transaction (TX for short) pool with limited capacity and reflect the chains’ features of fixed intervals and empty blocks to improve accuracy and applicability. We give an expression for three significant measurements: the average confirmation delay of TXs, the blockchain throughput, and the TX rejection rate. We use Ethereum to validate our model. And moreover, we use the model for analysis to assist designers in operating chains.
Jongbeen Han, Yunhyeong Seo, Sangjin Lee, Sunggon Kim · 5 authors
A blockchain is designed to establish consistent and reliable agreements in an untrusted and decentralized environment. In addition, the blockchain enables transaction processing and the creation of smart contracts. It empowers end users to execute contracts without any intermediate entities. However, there are some issues when it comes to retrieving information, such as the state and history of smart contracts and regular transactions in the blockchain. For example, in a smart contract, user-defined data structures can be used to recall the state of the smart contract for a range query, which can decrease the general performance. In addition, an external database can be required to retrieve regular transactions for range queries, which increases management costs. To achieve this, we propose a new scheme that enables SQL query operations to retrieve a smart contract and regular transaction information within the blockchain system. To achieve this, we combine an embedded relational database with an Ethereum-based blockchain system to provide the SQL query. It enables range queries on smart contracts without requiring user-defined data structures and decreases management costs for regular transactions without any external database. We implement the proposed blockchain system on quorum, which is an Ethereum-based blockchain system. Also, we evaluate the proposed system using a synthetic benchmark. The performance of retrieving smart contract data is improved by up to approximately 22×, with low memory usage compared with the existing system. Moreover, the proposed system demonstrates a similar search performance to the existing system, even when considering external databases in regular transactions.
This paper explores the potential for improving blockchain performance through the implementation of an adaptive consensus machine. Blockchains, as immutable distributed ledgers, have found applications in various domains such as cryptocurrency, supply chains, healthcare, and more. The two main types of blockchains are permissionless and permissioned, each with its own advantages and limitations. The proposal suggests monitoring transaction metrics on the blockchain to enable the adaptive machine to adjust operational parameters of the consensus protocol or even switch to a different consensus strategy. This autonomic approach aims to enhance the overall performance of the blockchain by utilizing self-defined policies and goals. The paper discusses the use of off-chain structures for recording transactions and the trade-offs between latency and cost. Furthermore, it highlights the potential improvements that can be achieved by adapting classic consensus algorithms in permissioned blockchains. By incorporating adaptive and autonomic techniques, blockchain platforms can achieve enhanced efficiency and performance.
A Blockchain is a decentralized and distributed digital ledger that is used to record transactions and it is secured through cryptographic techniques. It is expected that Blockchain Technology (BCT) will continue to grow exhilaratingly and become indispensable in the architecture of distributed systems. Scaling up BCT is a never-ending race among researchers. When the number of transactions, blocks, or nodes increase, it causes severe scalability problems and stymies the thriving distributed ecosystem. In this paper, the Confederation model is used to make a scalable blockchain system with full atomicity, ensuring that updates are immediately transferred to all nodes, even in cross-zone transactions. The proposed system is flexible and can be easily administered to control network congestion and asymmetric distribution of nodes. The scalability of the proposed system is outperformed as compared to traditional Blockchain.
While blockchain is a secure and tamper-proof registry, it is not well-suited for storing large amounts of data due to its limited storage capacity and high cost. Additionally, storing data on a blockchain can lead to scalability issues and slow down the network. Therefore, it is generally not recommended to store large amounts of data on a blockchain. This paper proposes a solution to transmit data to smart contracts without compromising security with a single point of failure, using a bounty hunting mechanism to ensure fair concurrency between oracles retrieving data on an IPFS database. The proposed solution has been implemented as a prototype and its feasibility has been demonstrated through experiments.
Early open blockchain designs face low throughput, high latency, and prohibitive costs for setting up a full node. New designs improve this with innovative mechanisms for handling transactions and the blockchain state, often assuming locality properties in the workload of transactions. Temporal locality allows efficient space management such as light nodes or snapshot-based bootstrap. Disjoint access parallelism, which depends on spatial locality, enables parallel processing of non-conflicting transactions. We analyze locality properties and their interplay in the largest transactional workload available to date, that of Ethereum. Our results show that, although transactions generally display good locality, a minority of accounts are responsible for caching- or parallelism-unfriendliness, calling for specific identification and handling in future blockchain designs.
A blockchain provides decentralization and trustlessness features for the Industrial Internet of Things (IIoT), which expands the application scenarios of IIoT. To address the problem that blockchains cannot actively obtain off-chain data, the blockchain oracle is proposed as a bridge between the blockchain and external data. However, the existing oracle schemes make it difficult to solve the problem of low quality of service caused by frequent data changes and heterogeneous devices in IIoT, and the current oracle node selection schemes are difficult to balance security and quality of service. To tackle these problems, this paper proposes a secure and reliable oracle scheme that can obtain high-quality off-chain data. Specifically, we first design an oracle node selection algorithm based on a Verifiable Random Function (VRF) and reputation mechanism to securely select high-quality nodes. Second, we propose a data filtering algorithm based on a sliding window to further improve the consistency of the collected data. We verify the security of the proposed scheme through security analysis. The experimental results show that the proposed scheme can effectively select high-quality nodes, reduce data differences, and improve the quality of service of the oracle. In the oracle network with malicious nodes accounting for 10%, the data accuracy rate is increased by about 4%, and the data variance is reduced by about 45% on average.
Yuanfang Chi, Haihan Duan, Wei Cai, Z. Jane Wang · 5 authors
Parallel Web3 metaverses play a vital role in preventing monopolistic markets and fostering fair and profound user experiences. Meanwhile, ensuring interconnections and interoperability among these metaverses is crucial, allowing users to seamlessly transition between different Web3 environments while maintaining their digital identities and assets. In this tutorial paper, we provide an overview of the significance and current landscape of interoperability in parallel metaverses. Furthermore, we identify key challenges in achieving interoperability in parallel Web3 metaverses within the blockchain industry, including the technical complexities and practical business considerations. Then, we suggest that decentralized knowledge inference can be used as a potential solution for facilitating knowledge sharing among parallel metaverses. Finally, we outline the technical and economic approaches of decentralized knowledge inference to inspire future research in this field.
In Bitcoin Core (BTC), there exists an upper limit of the block size around 1MB, which causes the Bitcoin scalability problem that severely limits transaction processing capacity.On the other hand, Bitcoin SV (BSV) forked from BTC is known to eliminate this limit.In BSV, the size of mined blocks is generally not uniform, but a mixture of various different sizes.Block miners in BSV can get more transaction fees as a reward, while there is a risk that the success rate of block mining decreases because it has to take a longer time to verify all the transactions in the block.For this reason, the selection of block size depends on mining strategy of each miner.To the best of our knowledge, there has been no detailed report on how each miner selects a block size.In this paper, we firstly formulated the Bitcoin scalability problem using a mathematical model of transaction processing capacity.Then, we investigated the probability distributions of block size in both Scaling Test Network (STN) and Mainnet of BSV.As a result, we found that the aggregate block size distribution in STN follows an exponential distribution, while that in the Mainnet follows a power-law distribution whose exponent is around one.We demonstrated a theoretical explanation of the difference between two distributions in the STN and Mainnet with a unified manner based on an underlying incentive mechanism.
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Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
In this paper, we propose GreenCoin – an energy-efficient cryptocurrency system with mining protocols designed to favor locations with relatively higher availability of renewable energy. Traditionally, crypto coin mining involves solving complex mathematical problems by high-end computing devices consuming an enormous amount of electricity, thus adversely affecting net carbon emissions. To reduce cost and emissions, GreenCoin uses a modified proof of stake (PoS) consensus algorithm, which itself is more energy efficient compared to other state-of-the-art methods. Our modified PoS algorithm, called Green PoS (GPoS), allows GreenCoin to favor nodes (with reward and privilege) located in regions with higher availability of renewable energy. We present a detailed system architecture of GreenCoin and explain the operating method of GPoS. We also provide results from empirical studies demonstrating the renewable energy-aware approach of GreenCoin.
Ahmad J. Alkhodair, Saraju P. Mohanty, Elias Kougianos
The most essential component of every Distributed Ledger Technology (DLT) is the Consensus Algorithm (CA), which enables users to reach a consensus in a decentralized and distributed manner. Numerous CA exist, but their viability for particular applications varies, making their trade-offs a crucial factor to consider when implementing DLT in a specific field. This article provided a comprehensive analysis of the various consensus algorithms used in distributed ledger technologies (DLT) and blockchain networks. We cover an extensive array of thirty consensus algorithms. Eleven attributes including hardware requirements, pre-trust level, tolerance level, and more, were used to generate a series of comparison tables evaluating these consensus algorithms. In addition, we discuss DLT classifications, the categories of certain consensus algorithms, and provide examples of authentication-focused and data-storage-focused DLTs. In addition, we analyze the pros and cons of particular consensus algorithms, such as Nominated Proof of Stake (NPoS), Bonded Proof of Stake (BPoS), and Avalanche. In conclusion, we discuss the applicability of these consensus algorithms to various Cyber Physical System (CPS) use cases, including supply chain management, intelligent transportation systems, and smart healthcare.
Guzmán Llambías, Bruno Bradach, Juan J. Nogueira, Laura González · 5 authors
Blockchain is a distributed ledger technology (DLT) to manage data in a decentralised way. During the last years, interoperability has become one of the main challenges within blockchain research as blockchains increasingly require integration between each other. Indeed, blockchains work by design in silos of information as interoperability is not a native feature. The main efforts in the field are focused on blockchains, such as Bitcoin and Ethereum. However, interoperability in DLT remains as an almost untouched area of work as they introduce additional requirements focusing on privacy and identity. Although there are some interoperability solutions for DLT, they are either high-level design proposals not providing concrete implementations or focus on interoperability issues between business applications and blockchain platforms. In this paper we propose a gateway-based platform-to-platform interoperability solution for DLT, which comprises a detailed solution design and a reference implementation. The proposal was assessed through the development of a social security case scenario and the evaluation through two interoperability frameworks. A reference implementation was built using two DLT: Hyperledger Fabric and Corda. The experimental results shows that it is possible to achieve technical interoperability between two heterogeneous DLT platforms using a gateway-based interoperability solution, relaxing decentralisation, data privacy, identity and authorisation management properties.
We develop a general and practical framework to address the problem of the optimal design of dynamic fee mechanisms for multiple blockchain resources. Our framework allows to compute policies that optimally trade-off between adjusting resource prices to handle persistent demand shifts versus being robust to local noise in the observed block demand. In the general case with more than one resource, our optimal policies correctly handle cross-effects (complementarity and substitutability) in resource demands. We also show how these cross-effects can be used to inform resource design, i.e. combining resources into bundles that have low demand-side cross-effects can yield simpler and more efficient price-update rules. Our framework is also practical, we demonstrate how it can be used to refine or inform the design of heuristic fee update rules such as EIP-1559 or EIP-4844 with two case studies. We then estimate a uni-dimensional version of our model using real market data from the Ethereum blockchain and empirically compare the performance of our optimal policies to EIP-1559.