Consensus algorithms are applied in the context of distributed computer systems to improve their fault tolerance. The explosive development of distributed ledger technology following the proposal of âBitcoinâ led to a sharp increase in research activity in this area. Specifically, public and permissionless networks require robust leader selection strategies resistant to Sybil attacks in which malicious attackers present bogus identities to induce byzantine faults. Our goal is to analyse the entire breadth of works in this area systematically, thereby uncovering trends and research directions regarding Sybil attack resistance in todayâs blockchain systems to benefit the designs of the future. Through a systematic literature review, we condense an immense set of research records (N = 21,799) to a relevant subset (N = 483). We categorise these mechanisms by their Sybil attack resistance characteristics, leader selection methodology, and incentive scheme. Mechanisms with strong Sybil attack resistance commonly adopt the principles underlying âProof-of-Workâ or âProof-of-Stakeâ while mechanisms with limited resistance often use reputation systems or physical world linking. We find that only a few fundamental paradigms exist that can resist Sybil attacks in a permissionless setting but discover numerous innovative mechanisms that can deliver weaker protection in system scenarios with smaller attack surfaces.
The rapid development of artificial intelligence has pushed the Internet of Things (IoT) into a new stage. Facing with the explosive growth of data and the higher quality of service required by users, edge computing and caching are regarded as promising solutions. However, the resources in edge nodes (ENs) are not inexhaustible. In this paper, we propose an incentive-aware blockchain-assisted intelligent edge caching and computation offloading scheme for IoT, which is dedicated to providing a secure and intelligent solution for collaborative ENs in resource optimization and controls. Specifically, we jointly optimize offloading and caching decisions as well as computing and communication resources allocation to minimize the total cost for tasks completion in the EN. Furthermore, a blockchain incentive and contribution co-aware federated deep reinforcement learning algorithm is designed to solve this optimization problem. In this algorithm, we construct an incentive-aware blockchain-assisted collaboration mechanism which operates during local training, with the aim to strengthen the willingness of ENs to participate in collaboration with security guarantee. Meanwhile, a contribution-based federated aggregation method is developed, in which the aggregation weights of EN gradients are based on their contributions, thereby improving the training effect. Finally, compared with other baseline schemes, the numerical results prove that our scheme has an efficient optimization utility of resources with significant advantages in total cost reduction and caching performance.
Christian Pulmano, Maria Regina Justina E. Estuar, Marlene M. De Leon, Hans Calvin Tan · 6 authors
The Philippinesâ ICT agenda to promote participatory e-Governance, industry and countryside development, and ICT user protection and information security can be addressed by Blockchain. This study used Hyperledger Fabric to develop a Blockchain network for a secured and validated system for issuing, distributing, and sharing digital credentials. For the initial prototype, the network was tested on two use cases: national identification system and academic credentials. Chaincodes were developed for each type of digital credential and deployed into designated Channels in the network. Initial results show that a Blockchain-based system using the Hyperledger Fabric framework is feasible for developing a secure digital credential platform. The current architecture can support the implementation of the initial use cases and can also accommodate the addition of new use cases in the future. The current iteration of our work provides the groundwork for developing a production-level ready platform. Future work for this study includes the development of the end-user web application where users can interact with the network and initiate transactions. The deployment of the Blockchain network may pave the way toward decentralized e-Participatory governance.
Blockchains can provide integrity and authenticity, but their limited storage capacity can be a challenge when it comes to storing large amounts of data. To address this issue, off-chain storage solutions such as the InterPlanetary File System (IPFS) can be utilized. This has led to the emergence of various applications that utilize both blockchain and IPFS. After reviewing a large body of literature utilizing blockchain and IPFS, we found that the coordinated interaction between blockchain and IPFS can help solve many problems and provide many research opportunities. Therefore, this survey paper aims to introduce the interaction mechanism between blockchain and IPFS. We first provide a general overview and comparison of different P2P data networks to help understand why IPFS is suitable as the storage layer for blockchains. Subsequently, we use select applications that leverage blockchain and IPFS to show how the mechanism works and explore new developments in this area. Specifically, we identify research areas and provide a qualitative comparison of these different applications. From the comparison, we derive research goals related to the interaction mechanism between blockchain and IPFS.
Multimedia networking is the area of study associated with the delivery of heterogeneous data including, but not limited to, imagery, video, audio, and interactive content. Multimedia and communication network researchers have continually struggled to devise solutions for addressing the three core challenges in multimedia delivery: security, reliability, and performance. Solutions to these challenges typically exist in a spectrum of compromises achieving gains in one aspect at the cost of one or more of the others. Networked videogames represent the pinnacle of multimedia presented in a real-time interactive format. Continual improvements to multimedia delivery have led to tools such as buffering, redundant coupling of low-resolution alternative data streams, congestion avoidance, and forced in-order delivery of best-effort service; however, videogames cannot afford to pay the latency tax of these solutions in their current state. The Secure Multi-Channel Internet Memory Information Control (S-MIMIC) protocol was developed as a novel solution to address these challenges by leveraging recent developments in blockchain and distributed ledger technology. Multiple algorithms were developed within the S-MIMIC protocol to perform create, read, update, and delete (CRUD) interactions via distributed ledger and blockchain technologies. Performance of the the S-MIMIC protocol was evaluated by porting its capabilities into an open source First-Person Shooter (FPS) videogame developed within the Unity3D game engine. SMIMIC efficacy was evaluated across the dimensions of confidentiality, integrity, availability and read/write performance. Though performance evaluation of the S-MIMIC focused on implementation within videogames, this protocol may be used to augment data delivery in multiple industries to include: medical information, legal documents, financial transactions, and many other applications that require security, reliability and performance guarantees.
With the improvement of people's awareness of environmental protection, electric vehicles (EVs) are becoming more and more popular, and the issue of vehicle to grid (V2G) energy trading is also put on the agenda. To protect the security and privacy of EVs when they trade energy with the grid, many scholars have introduced the emerging blockchain technology. However, there are few studies on the blockchain consensus algorithm for the EVs charging scenario, while the consensus is exactly the core technology in blockchain for reaching agreement in distributed systems, which to some extent determines the efficiency of V2G. Therefore, aiming at the above scenario, this paper proposes two low-complexity consensus algorithms, namely (PBFT-enabled RAFT) PRAFT and (RAFT-enable PBFT) RPBFT, which are combined the typical blockchain consensus PBFT and RAFT, and can be respectively applied to two EVs charging scenarios. In our V2G model, charging piles (CPs) and charging stations (CSs) will participate in the blockchain consensus as nodes. Through theoretical analysis and simulation, and compared with other methods, these two consensus algorithms have high scalability, low communication complexity, low storage overhead, high throughput, and low latency. Meanwhile they can also avoid the risk of Byzantine leader in RAFT. Finally, we demonstrate the two consensus algorithms in a real charging scenario, which show their transaction latency and energy consumption can well adapt to the EVs charging scenario in V2G networks.
Andrea Nanetti, Paola Benussi, Andrea Erboso, Dusit Niyato
To commemorate the 700 years since Marco Poloâs death (1324â2024), the State Archive of Venice, the National Library of Saint Mark, and the Veneto Institute of Sciences, Humanities and Arts (IVSLA) are curating and editing a diplomatic codex (CDP) of documents relevant to the study of the historical figure of Marco Polo (1254â1324). IVSLA will publish the CDP as a prestigious and traditional book, and the Engineering Historical Memory initiative will publish it online. This paper presents and discusses how the CDP is exploring the use of blockchain technology among parties who might not necessarily trust each other (i.e., authors and readers) to 1) launch ongoing participatory editing by entrusting multiple users with the task of promoting substantiated modifications to critical editions of archival documents and 2) share the digital assetâs history while duplicating and reusing archival documentsâ digital reproductions. Thus, the online CDP can be construed as a practice-led research project exploring the disruption of making a critical edition of archival documents using highly participatory research powered by blockchain and distributed ledger technology.
Several unique characteristics of Internet of Things (IoT) devices, such as distributed deployment and limited storage, make it challenging for standard centralized access control systems to enable access control in todayâs large-scale IoT ecosystem. To solve these challenges, this study presents an IoT access control system called Ether-IoT based on the Ethereum Blockchain (BC) infrastructure with Attribute-Based Access Control (ABAC). Access Contract (AC), Cache Contract (CC), Device Contract (DC), and Policy Contract (PC) are the four central smart contracts (SCs) that are included in the proposed system. CC offers a way to save user characteristics in a local cache system to avoid delays during transactions between BC and IoT devices. AC is the fundamental program users typically need to run to build an access control technique. DC offers a means for storing the resource data created by devices and a method for querying that data. PC offers administrative settings to handle ABAC policies on usersâ behalf. Ether-IoT, combined with ABAC and the BC, enables IoT access control management that is decentralized, fine-grained and dynamically scalable. This research gives a real-world case study to illustrate the suggested frameworkâs implementation. In the end, a simulation experiment is performed to evaluate the systemâs performance. To ensure data integrity in dispersed systems, the results show that Ether-IoT can sustain high throughput in contexts with a large number of requests.
Different from âreadâ based Web1 and âread-writeâ based Web2, âread-write-ownâ based Web3 is proposed as a typical user-centric internet to open the new generation of World Wide Web, which is expected to not allow the power to rest with a few big internet companies. Generally, Web3 is decentralized and semantic depending on user behavior, and thus the zero-trust architecture should be created initially. To hasten its arrival, a comprehensive discussion on its architecture and enabling technologies is inspired. Specifically, to access Web3, it is essential to study how to establish an identity management system. Meanwhile, for resource description and data verification, it is necessary to set up decentralized identifiers (DID), and link the data to identifiers in the form of DID document. In particular, a decentralized network operating system is an indispensable underlying technology for Web3, incorporating concepts such as decentralization and user-driven philosophy. Therefore, the corresponding technologies for the operating system such as blockchain and distributed ledger technology should be further studied and developed. Moreover, in order to reduce the consensus cost, a large-scale incentive mechanism is also the basis of long-term sustainability, which can attract and motivate distributed players to participate in the maintenance of Web3. Last but not the least, Web3 is built on a physical infrastructure relying on communication, networking, storage and computing, which is crucial to establishing an effective and secure Web3. This encourages us to study communication, networking, storage and computing in Web3, as well as the specific requirements of running Web3.
Blockchain technology has emerged as a promising solution to secure and decentralized platforms. However, blockchain technology has high computational requirements, latency, and low throughput, particularly for single or multi-query processing. Lightweight blockchain has emerged as a solution to overcome these problems. It addresses performance and efficiency issues and can provide convenience in the query process. This paper proposed a novel high-performance data structure for multi-query processing based on a lightweight blockchain, namely Multi-State Merkle Patricia Trie (MSMPT). MSMPT combines Merkle Patricia Trie (MPT) based indexing and linked-list storage to achieve high performance. MPT has been used on the Ethereum network with a Key-Value database approach. The key field in this proposal is used as crucial user data. The value field is changed to the head of the linked list, and the following data elements will store a summary of the data based on the specified category. In this paper, a blockchain simulator was built to discover the performance of the proposed systems. This simulator will simulate creating blocks in a blockchain network using existing and modified blockchain data structures. The blocks created will be compared using the query process from the conventional and proposed systems. The experimental findings demonstrate that MSMPT outperforms existing blockchain-based data structures by requiring only about one millisecond in query processing performance and less than 500 bytes of additional storage. The MSMPT provides a promising solution for efficient and scalable data management in lightweight blockchain, particularly for multi-query processing.
Saminur Islam, Mohammad Jaminur Islam, Mahmud Hossain, Shahid Noor · 6 authors
Recently, Blockchain-based applications have become immensely popular because of limited reliance on a single entity, unlike a centralized system. However, reaching a consensus among blockchain networks is a challenging and vital aspect of blockchain-based applications. There are various types of blockchain networks for different kinds of application scenarios. Among all of them, the consensus algorithm is the most crucial part of reaching an agreement in the complex blockchain network. Over the years, researchers have focused on dealing with the challenges like distributed computing, storage, transaction speed, security, validity, interoperability, and many more. However, only some of them are appropriate for all domains. Therefore, this paper presents an extensive study of different types of consensus protocols used in existing blockchain solutions with the strength and limitations of each algorithm. We also provide an inherent comparison among different algorithms to understand consensus protocol selection better. Moreover, we investigate operational and interoperability issues in existing blockchain-based applications to understand challenges and provide recommendations for future developers.
Distributed filesystem architectures use commodity hardware to store data on a large scale with maximum consistency and availability. Blockchain makes it possible to store information that can never be tampered with and incentivizes a traditional decentralized storage system. This project aimed to implement a decentralized filesystem that leverages the blockchain to keep a record of all the transactions on it. A conventional filesystem viz. GFS [1] or HDFS [2] uses designated servers owned by their organization to store the data and are governed by a master service. This project aimed at removing a single point of failure and makes use of participating usersâ machines to store data. The implemented file system uses a distributed hash table to evenly store data on multiple machines and efficiently look up, track, maintain, and persist the data. The data stored on the file system is made easily and readily accessible to a user ensuring its soundness. Finally using smart contracts enabled incentives and increased the integrity and reliability of storing data by recording all the transactions. The project functions autonomously by coordinating multiple participant machines in the network to store data and monetize unused storage space on the machines. It supports the basic functionalities of a filesystem which include storing, deletion, and reading a file as desired. The filesystemâs performance was tested with files of different sizes and a variable number of nodes. The current file system is able to store files as big as 100 MB within 12 seconds and 300 MB in less than 25 seconds. This is significantly faster than Storj [3] which nearly takes more than a minute for a similar operation. The tests also provided observations on the average gas consumed during transactions.
For more than a decade, Bitcoin has gained as much adoption as it has received criticism. Fundamentally, Bitcoin is under fire for the high carbon footprint that results from the energy-intensive proof-of-work (PoW) consensus algorithm. There is a trend however for Bitcoin mining to adopt a trajectory toward achieving carbon-negative status, notably due to the adoption of methane-based mining and mining-based flexible load response (FLR) to complement variable renewable energy (VRE) generation. Miners and electricity sellers may increase their profitability not only by taking advantage of excess energy, but also by selling green tokens to buyers interested in greening their portfolios. Nevertheless, a proper ''green Bitcoin'' accounting system requires a standard framework for the accreditation of sustainable bitcoin holdings. The proper way to build such a framework remains contested. In this paper, we survey the different sustainable Bitcoin accounting systems. Analyzing the various alternatives, we suggest a path forward.
Bitcoin uses an unspent transaction output (UTXO) model for coin circulation, which is similar to the banknotes. The transaction history is publicly available and allows to trace cryptocurrency flows. Different users merge transactions into a single bigger one to tangle flows. The merged transaction is called a shared send mixer (SSM). One can try to find the original subtransactionsâsolve an untangling problem. Based on the number of untanglings and their size, one extracts additional information about coin circulation. Theoretical analysis of the untangling problem is known from the literature. The paper aims to collect statistics of the SSM usage by transaction type for Bitcoin blockchain. We propose an algorithm to solve the problem, prove its correctness, and provide a source code. We applied the algorithm to the Bitcoin historical data. 15% transactions are SSM, and 90% of them allow unique untangling. The future work is an algorithm application to other UTXO systems and the results adaptation to an address grouping.
Open access
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Tayyaba Noreen, Qiufen Xia, Muhammad Zeeshan Haider
In the past decade, blockchain has emerged as a promising solution for building secure distributed ledgers and has attracted significant attention. However, current blockchain systems suffer from limited throughput, poor scalability, and high latency. Due to limitations in consensus mechanisms, especially in managing node identities, blockchain is often considered unsuitable for applications such as the Internet of Things (IoT). This paper proposes the Advanced DAG-based Ranking (ADR) protocol to enhance blockchain scalability and throughput. ADR employs a directed acyclic graph (DAG) structure where nodes are positioned based on their rankings. Unlike traditional chains, ADR allows honest nodes to write blocks and verify transactions using a DAG-based topology. The protocol follows a three-step approach to secure the network against double-spending and enhance performance. First, it verifies nodes using their public and private keys before granting entry. Second, it builds an advanced DAG ledger enabling block production and transaction validation. Third, a ranking algorithm filters out malicious nodes, ranks the remaining nodes based on performance, and arranges them topologically. This process increases throughput and ensures robust scalability. We evaluated ADR on Amazon EC2 clusters with over 100 nodes, including scenarios with injected malicious nodes. Simulation results demonstrate that ADR significantly improves transaction throughput and network liveness compared to existing DAG-based blockchains such as IOTA and ByteBall, making it well-suited for IoT applications.
Blockchain-based decentralized applications (DApp) draw more attention with the increasing development and wide application of blockchain technologies. A wealth of funds are invested into the crowd-funding of various types of DApp. As reported in August 2022, there are more than 5,000 DApps with more than 1.67 million daily Unique Active Wallets (users). However, the definition, architectures, and classifications of the DApps are still not cleared up till now. This survey aims to provide a comprehensive overview of DApps for further research. First, the definitions and typical architectures of DApps are presented. Then we collect 3,118 popular DApps and categorize them into different types, and summarize their typical advantages and challenges. Finally, we provide an overview of the recent research problems of DApps from the perspectives of economics, security, and performance and then figure out promising research opportunities in the future.
The accomplishment of blockchain has increased the focus on the various applications for simplifying the confidentiality and transaction sanctuary using the decentralized architecture via consensus mechanisms between different internet of things (IoT) nodes in daily increasing societal areas. The growth of blockchain lasted to grow and used to do compare technologies. The major shortcomings of blockchain is the lack of scalability in modern application settings. Holochain technology vends itself as a âthinkingâ exterior to blocks, and it is a peer-to-peer disseminated ledger technology. It works contrarily compared to the blockchain, and it offers an exclusive value in the existing market. IoT devices are continuously used in distributed environments, in various smart applications. The peer-to-peer IoT networks, connected to smart agricultural systems are exposed to the security issues. Specifically, the personal data of agricultural land records need protection against unauthorized access and eradicate corruption in land transactions. The Blockchain offers a possible solution based on distributed ledger, but it has scalability issues due to high storage and processing requirements with growing network size. Also data is not locally stored in a Blockchain. This paper studies the conventions of holochain technology, its architecture and challenges, and critical mechanisms of holochain applications. We also analyze the numerous models utilized for the implementation of protected transactions. We discuss an agent centric framework with distributed hash table for secured applications.
Blockchains are a new approach to creating distributed networks that were first introduced in 2008. It allows the formation of peer-to-peer networks based on consensus, forming chains from accepted blocks without requiring a central authority or centralized controller. A prominent application of this technology is its use in decentralized storage systems. Individuals in decentralized storage networks rent unused hardware storage space to other individuals. A decentralized network utilizing end-to-end encryption eliminates the risk of data loss associated with centralized data control by enabling clients to transmit their files securely. The storage providers must prove that they have kept unaltered files in this network for this time. Many studies have been conducted in this specific domain, most targeting storage capacity and efficiency, but a security, integrity and privacy loophole need to be addressed. This paper presents an overview of blockchain-based storage systems and how they work, followed by a comparison with cloud-based storage networks and a survey of various decentralized storage networks like SIA, File coin, and Storj available on the market. Next, we discuss the advantages and disadvantages of blockchain-based storage. In our final discussion, we examine the security problems of decentralized storage networks and explore potential solutions and research directions for the future.
This paper presents an architectural overview and detailed design of the Krypton network, the first decentralized search engine built on Web3 principles. Krypton leverages blockchain technology, token-driven incentives, and privacy-focused features to revolutionize internet search. The proposed solution incorporates distributed storage, decentralized web crawling and indexing, a consensus mechanism, open-source search algorithms, and a privacy-focused search experience. Krypton introduces the novel concept of Proof of Learning, a machine learning protocol embedded in the search engine to facilitate the discovery of decentralized platforms and enable direct peer-to-peer networking. The system also employs decentralized cloud technologies (validators in the PoS blockchain) to promote enhanced decentralization and encryption, paving the way for a more secure and equitable internet.