The blockchain establishes trust by maintaining a distributed appending-only ledger, which is widely applied to the nodes lacking trust in the edge environment. However, the full-replication storage mode of blockchain is a big challenge for resource-constrained edge devices. What is worse, system performance is also affected by the large storage overhead. Existing solutions to reduce blockchain storage overhead often require additional security assumptions, lack incentives, or fail to account for resource heterogeneity. To overcome these limitations, we design an auction-based storage resource allocation scheme. Winners are selected to store blocks, taking into account the block preferences of nodes, and the fairness of the system. Nodes are incentivized by implementing fairness and equity in distributed auctions and data transactions through smart contracts. Finally, extensive experiments show 65%–81% savings in storage overhead compared to fully replicated storage.
Joachim Neu, Srivatsan Sridhar, Lei Yang, David Tse
Classic BFT consensus protocols guarantee safety and liveness for all clients if fewer than one-third of replicas are faulty. However, in applications such as high-value payments, some clients may want to prioritize safety over liveness. Flexible consensus allows each client to opt for a higher safety resilience, albeit at the expense of reduced liveness resilience. We present the first construction that allows optimal safety--liveness tradeoff for every client simultaneously. This construction is modular and is realized as an add-on applied on top of an existing consensus protocol. The add-on consists of an additional round of voting and permanent locking done by the replicas, to sidestep a sub-optimal quorum-intersection-based constraint present in previous solutions. We adapt our construction to the existing Ethereum protocol to derive optimal flexible confirmation rules that clients can adopt unilaterally without requiring system-wide changes. This is possible because existing Ethereum protocol features can double as the extra voting and locking. We demonstrate an implementation using Ethereum's consensus API.
Soosan Naderi Mighan, Jelena Mišić, Vojislav B. Mišić, Xiaolin Chang
In this paper, we analyze the performance of Ethereum data distribution network using a probabilistic model which allows accurate modeling of data propagation but also of forking, which happens when the blockchain maintained by the network temporarily splits into multiple versions due to a disagreement over the validity of a particular block. We also investigate the duration of inconsistent states of the ledger, which refers to the amount of time that the network remains split or partitioned. Finally, we model the block withholding attack and block slowdown attack, and analyze their impact on network performance of the network in terms of quality indicators such as block delivery time, the duration of ledger inconsistency, and forking probability. We also propose countermeasures for the block withholding attack.
The charity organizations in China lack transparency and the supervision to them is difficult to achieve, which has a negative impact on the willingness of the people to donate. Blockchain as an underlying technology of Bitcoin system provides a new solution for the charity system in terms of technology. This paper proposed a charity system based on blockchain technology and expounds the design pattern, architecture and operational process of the platform. Some core functions of the charity platform have been realized and verified on Ethereum in this article. We hope to increase the transparency of charities to enhance the public’s trust in charities and promote the development of philanthropy by blockchain-based charity system.
Lorenzo Gigli, Ivan Zyrianoff, Federico Montori, Cristiano Aguzzi · 6 authors
The Internet of Things (IoT) envisions a global market in which it would be possible to easily get data from IoT devices across the globe. However, the potential of this idea still needs to be unlocked. Centralized architectures fall short due to their lack of transparency and tendency to create silos. On the other hand, blockchain technology enables the creation of distributed and trustworthy systems, but its integration with the IoT is still a matter of research. IoT-based scenarios often employ numerous devices for the same sensing task, which may be heterogeneous and unreliable by purpose. In our vision, IoT applications should rely on data and its quality rather than on single providers. For this purpose, we propose an architecture that enables a decentralized IoT global market in which clients pay for data and device owners are rewarded for providing it. Our solution employs a distributed oracle layer on top of smart contracts powered by a distributed global network of IoT devices. The system supports IoT data source decoupling since the end-user can perform semantic queries bounded to specific locations and data types without specifying the target devices. In addition, it features automatic discovery, interoperability mechanisms, and reputation algorithms for the selection of trustworthy data sources. Our results show that the proposed system is robust and consistently provides quality data, even with multiple malicious data sources.
Blockchain establishes security and trust in mobile ad hoc networks (MANETs). Due to the decentralized and opportunistic communication characteristics of MANETs, hashgraph consensus is more applicable to the MANET-based blockchain. Sharding scales the consensus further through disjoint nodes in multiple shards simultaneously updating ledgers. However, the dynamic addition and deletion of nodes in a shard pose challenges regarding robustness and efficiency. Particularly, the shard is vulnerable to Sybil attacks and targeted attacks, and dishonest gossip reduces the efficiency of hashgraph consensus. Therefore, we proposed a behavior-based sharding hashgraph scheme. First, dishonest behaviors of nodes are recorded in a decentralized blacklist. Gossip information is sent to a reliable neighbor, and gossip information from another reliable neighbor is received. Second, a tree-assisted inter-sharding consensus is proposed to prevent Sybil attacks. The combination of shard recovery and reconfiguration based on node state is devised to prevent targeted attacks. Finally, we conducted the performance evaluation including security analysis and experimental evaluation to reveal the security and efficiency of the proposed scheme.
Ruochen Fang, Xinghua Sun, Jiyun Qiu, Jingjing Liu
Blockchain, as a type of distributed ledger technology, is well-suited for the distribution, sharing, certification, and tracing of information. Therefore, DApps implemented on blockchain have been utilized in various industries, where businesses utilize DApps to achieve reliable information flow and certification across enterprises or within an enterprise. However, DApps are limited by the constraints of the blockchain architecture, which results in issues such as poor performance, limited scalability, difficult maintenance and management, and high development costs. As a result, it is difficult for DApps to replace traditional database models in enterprises. In order to address this issue, we conducted an analysis of the shortcomings of DApps and proposed a novel blockchain service framework based on ordered Hash tree architecture, which provides a consistent and reliable solution for data management in DApps. Our work, through analysis, is capable of resolving or improving the challenges faced by DApps and holds practical applications value.
This paper introduces TeleBTC, a fully decentralized protocol designed to wrap Bitcoin (BTC) on programmable blockchains. The creation of a decentralized wrapped BTC presents challenges due to the non-programmable nature of Bitcoin, making it difficult to custody BTCs in a decentralized way. Existing solutions have addressed this challenge by introducing an external layer of validators who take custody of users' BTCs. However, the security and decentralization of this layer are inferior to the underlying blockchains on which wrapped BTC is built. Moreover, the process of joining or leaving for a validator has become overly complex and expensive. To overcome these limitations, we propose a novel approach that eliminates the need for such an external layer by leveraging the light client bridge protocol. Additionally, we employ economic mechanisms such as incentivization and slashing, resulting in a secure and trust-minimized wrapped BTC solution. With TeleBTC, users can seamlessly transfer their BTC to other blockchains and utilize it within decentralized applications. Furthermore, they can unwrap their TeleBTC and reclaim the native BTC. To address the high costs associated with light client bridges, we present an optimistic approach that minimizes the cost. This approach significantly reduces the operational expenses of running the protocol.
Designing the secure and privacy-protected smart power contract between electricity suppliers and consumers, considered agents, of different microgrids, is a challenging task in the networked- microgrid system. A framework is suggested in which each microgrid implements a heterogeneous or isomorphic blockchain based platform. The blockchain interoperability, inherently, is present in different blockchains implemented by various microgrids. This paper reviews the interoperability issues and smart contract designs in blockchain based systems. The paper proposes new mechanisms to cater blockchain interoperability challenges to facilitate the design of secure and seamless smart contracts among different blockchains of microgrids. A network hub of heterogeneous or isomorphic blockchains of network microgrids has been created. A methodology has been developed to transfer tokens between interoperable blockchains. Distributed identity-based microgrid (DIBM) scheme is incorporated to make the networked microgrid system secure and trustworthy. This paper suggests an effective consensus protocol for cross-chain architecture that improves the tokenization system and smart power contract designs. For simulation purposes, MATLAB and python programming have been used with real-time data of microgrids.
Srivatsan Sridhar, Onur Ascigil, Navin V. Keizer, François Genon · 8 authors
The InterPlanetary File System (IPFS) is currently the largest decentralized storage solution in operation, with thousands of active participants and millions of daily content transfers. IPFS is used as remote data storage for numerous blockchain-based smart contracts, Non-Fungible Tokens (NFT), and decentralized applications. We present a content censorship attack that can be executed with minimal effort and cost, and that prevents the retrieval of any chosen content in the IPFS network. The attack exploits a conceptual issue in a core component of IPFS, the Kademlia Distributed Hash Table (DHT), which is used to resolve content IDs to peer addresses. We provide efficient detection and mitigation mechanisms for this vulnerability. Our mechanisms achieve a 99.6\% detection rate and mitigate 100\% of the detected attacks with minimal signaling and computational overhead. We followed responsible disclosure procedures, and our countermeasures are scheduled for deployment in the future versions of IPFS.
This paper proposes a general and interoperable Web of Things (WoT)-oriented architecture to support a distributed storage application. In particular, the focus is on a distributed ledger service dedicated to machine-to-machine (M2M) transactions occurring in an intelligent ecosystem. For this purpose, the basic functional modules have been characterized and integrated into a comprehensive framework relying on an IOTA approach. Furthermore, a general protocol that is built upon an underlying publish-and-subscribe framework is proposed to support all the application phases. The proposed approach has been validated by a simulation campaign targeting the achievable latency and throughput and, further, by a qualitative analysis of high-level metrics, both pointing out several advantages in terms of interoperability, scalability, and mobility support, together with addressing some constraints affecting service availability and security.
Blockchain technology is extensively used for cryptocurrencies and is considered for industrial applications due to features like decentralization, anonymity, and a tamper-proof history of transactions. However, the well-known blockchain trilemma of being unable to simultaneously meet the properties of decentralization, security, and scalability (DSS) negatively impacts widespread acceptance. Numerous solutions have been put forward in response to this challenge, aiming to increase performance and scalability while retaining the decentralized and trustless aspects. They range from introducing off-chain technologies to changing consensus algorithms and on-chain data structures. One of the most effective methods to accomplish horizontal scalability along with the growing network size could be sharding, which involves dividing the network of nodes into numerous shards or channels. The overhead of repetitive communication, storage, and processing at each node is decreased by this technique. This paper explores various sharding approaches to solve performance issues regarding blockchain. We review recent sharding technologies, including Polkadot, Ethereum Casper, and Cardano Hydra. We discuss the performance challenges of blockchains and provide essential insights into the tradeoffs.
A learning management system (LMS) is a web-based technology developed to improve the learning process in educational institutions. This study addresses the drawbacks of existing LMS by developing DeLMS (Decentralized Learning Management System) and aims to revolutionize the way educational institutions manage and deliver educational content using Ethereum smart contracts and the IPFS (InterPlanetary File System). By leveraging Smart contracts and IPFS cutting-edge technologies, DeLMS provides a secure, transparent and decentralized platform for managing and delivering educational content. The content addressing feature of IPFS eliminates the need for constant requests to centralized servers for the location of files, resulting in faster file transfer and reduced energy consumption. The proposed system has the potential to change the way educational institutions operate, making it more accessible and beneficial for both students and educators.
Domain Name System(DNS) is a crucial component for us to access the Internet. However, it is vulnerable to several attacks such as DNS Cache Poisoning Attack and DNS DDoS Attack. Because of the high security promised by the Blockchain technology, we investigate the domain name systems based on blockchain, and focus on Ethereum Name Service(ENS). In this paper, we propose an ENS-oriented light node in order to solve the Full-node problem which means each participant has to hold a large amount data.
Rongxin Xu, Qiujun Lan, Shiva Raj Pokhrel, Gang Li
The Internet of Things (IoT) and distributed ledger technology (DLT) have significantly changed our daily lives. Due to their distributed operational environment and naturally decentralized applications, the convergence of these two technologies indicates a more lavish arrangement for the future. This article develops a comprehensive survey to investigate and illustrate state-of-the-art DLT for various IoT use cases, from smart homes to autonomous vehicles and smart cities. We develop a novel framework for conducting a systematic and comprehensive review of DLT over the IoT by extending the knowledge graph approach. With relevant insights from this review, we extract innovative and pragmatic techniques to DLT design that enable high-performance, sustainable, and highly scalable IoT systems. Our findings support designing an end-to-end IoT-native DLT architecture for the future that fully coordinates network-assisted functionalities.
Consensus protocol is a key technology enabling blockchain to provide secure and trustful services in wireless networks. However, most previous study on blockchain consensus protocols for wireless networks relies on reliable message transmissions and honest leaders. In practice, wireless blockchains inherently suffer from limited physical resources and unreliable wireless channels due to environmental noises and adversary attacks. This paper studies the design of Byzantine fault tolerant consensus protocol for blockchain in single-hop wireless networks subject to signal-to-noise constraint. For this purpose, we propose a low-latency and reliable Byzantine fault-tolerant consensus protocol LRBP, which incorporates the following three designs: 1) Randomized credit-based block proposer selection, which can prevent adversary corruption and improve the system throughput, 2) Enhanced threshold Boneh-Lynn-Shacham signature based voting mechanism, which can achieve communication-efficient block validity voting by using piggyback-based acknowledgment and criticality-based adaptive channel accessing probability adjustment, and 3) Random linear network coding based batch forwarding, which supports reliable block transmissions. We derive the consensus success probability and consensus time complexity of LRBP. We prove that LRBP simultaneously satisfies the properties of persistence and liveness. It is resistant to the 51% attack, Sybil attack, double-spending attack, and jamming attack. Simulation results show the high efficiency of LRBP as compared with existing work.
Block production in Bitcoin, often referred to as mining, is becoming increasingly industrialized. Many nodes in the network are represented by registered business entities. The concept of Bitcoin as a Service is also pushing the industry to become more customer oriented. Services such as transaction validation, transaction status query or notification, and blockchain data indexing are in high demand among blockchain application providers and users. As service providers, nodes need to distinguish themselves from others and be identifiable. In this article, we introduce an efficient self-established identity system, called Miner ID, to enable nodes to be publicly identifiable. It is based on economic investment and active participation in the blockchain network. Moreover, Miner ID is optional for nodes, and it does not affect the consensus mechanism of the network. We explore use cases including instant transaction confirmation, blockchain attestation, public key infrastructure, and token recovery. Miner ID can also be used for secure communication with applications, services, users and peers.
Blockchains face many challenges in time, among which the ever-growing storage needs for blockchains’ data. In particular, Ethereum is quickly approaching the 1 TB storage limit for a node, what may significantly reduce the candidates able to run an Ethereum fullnode. In this paper, we propose a new synchronization and storage strategy for Ethereum that takes full advantage of the Distributed Hash Table implemented in all clients but left unused. By digging into the history of Ethereum’s synchronization and storage strategies, we justify why such distribution of storage duties among peers makes much sense today. We implemented our solution in the official Ethereum client Geth and validated its smooth operation on a private Ethereum instance. Our solution can save around 60% of the storage of a node (360 GB) which represents a total of 12 PB of data at the network scale, while being fully backward compatible with current clients.
Voting mechanisms play a crucial role in decentralized governance of blockchain systems. Liquid democracy, also known as delegative voting, allows voters to vote directly or delegate their voting power to others, thereby contributing to the resolution of problems such as low voter turnout. In recent years, liquid democracy has been widely adopted by Delegated-Proof-of-Stake (DPoS) blockchains and implemented successfully on platforms with millions of users. However, little is known regarding the characteristics and actual effectiveness of liquid democracy in decentralized governance. This paper explored for the first time the practical implementation of liquid democracy in DPoS blockchain systems. Using actual data collected from two major DPoS blockchains, EOS and Steem, our study compared and evaluated the participation of different types of users of DPoS blockchain systems in liquid democracy, as well as extracting and analyzing the delegation chains and networks formed during the process of liquid democracy within the systems. We believe that the findings of this paper will contribute to further studies on the design and implementation of liquid democracy and other voting mechanisms in decentralized governance.
In recent years, the utilization of fog cloud-based Internet of Things (IoT) applications has been steadily rising due to the exponential growth of data produced by interconnected smart devices. However, cloud providers who are responsible for these IoT applications face two critical problems: 1) how to protect the system from untrusted users and 2) how to allocate processing units to meet the demands with acceptable costs. The fog–cloud blockchain system (FCB), proposed in past research, provides a perfect solution for the former question by integrating Blockchain’s security qualities into the fog–cloud paradigm. In this article, we address the latter question by proposing an improved version of the life-choice-based optimization algorithm (ILCO) to solve the task scheduling for Bag-of-Task applications in the FCB system. Task scheduling is one of the most prominent problems in resource allocation. Our proposed algorithm not only increases the convergence speed but also maintains diversity better, optimizing the FCB’s power, latency, and cost. Under a single-objective problem setting, ILCO outperforms LCO and similar state-of-the-art methods by achieving better results for FCB’s latency and power consumption.
In March 2021, we witnessed a surge in Bitcoin price. The cause seemed to be a tweet by Elon Musk. Are other blockchains as sensitive to social media as Bitcoin? And more precisely, could Ethereum's popularity be explained using social media data? This work aims to explore the determinants of Ethereum's popularity. We use both data from Etherscan to retrieve the relevant historic Ethereum factors, and Twitter data. Our sample consists of data ranging from 2015 to 2022. We use Ordinary Least Squares to assess the relationship between these factors (Ethereum characteristics and Twitter data) and Ethereum's popularity. Our findings show that Ethereum's popularity - translated here by the number of daily new addresses - is related to the following elements: the Ether (ETH) price, the transaction fees, and the polarity of tweets related to Ethereum. The results could have multiple practical implications, for both researchers and practitioners. First of all, we believe that it will enable readers to better understand the technology Ethereum and its stake. Secondly, it will help the community to identify pointers for the anticipation or explanation of the popularity of existing or future platforms. And finally, the results could help in understanding the factors facilitating the design of future platforms.
Web3Recommend is a decentralized Social Recommender System implementation that enables Web3 Platforms on Android to generate recommendations that balance trust and relevance. Generating recommendations in decentralized networks is a non-trivial problem because these networks lack a global perspective due to the absence of a central authority. Further, decentralized networks are prone to Sybil Attacks in which a single malicious user can generate multiple fake or Sybil identities. Web3Recommend relies on a novel graph-based content recommendation design inspired by GraphJet, a recommendation system used in Twitter enhanced with MeritRank, a decentralized reputation scheme that provides Sybil-resistance to the system. By adding MeritRank's decay parameters to the vanilla Social Recommender Systems' personalized SALSA graph algorithm, we can provide theoretical guarantees against Sybil Attacks in the generated recommendations. Similar to GraphJet, we focus on generating real-time recommendations by only acting on recent interactions in the social network, allowing us to cater temporally contextual recommendations while keeping a tight bound on the memory usage in resource-constrained devices, allowing for a seamless user experience. As a proof-of-concept, we integrate our system with MusicDAO, an open-source Web3 music-sharing platform, to generate personalized, real-time recommendations. Thus, we provide the first Sybil-resistant Social Recommender System, allowing real-time recommendations beyond classic user-based collaborative filtering. The system is also rigorously tested with extensive unit and integration tests. Further, our experiments demonstrate the trust-relevance balance of recommendations against multiple adversarial strategies in a test network generated using data from real music platforms.
Yong Eui Kim, Sang‐Min Choi, Dongwoo Lee, Yeong Geon Seo · 5 authors
Personalized recommender systems are used not only in e-commerce companies but also in various web applications. These systems conventionally use collaborative filtering (CF) and content-based filtering approaches. CF operates using memory-based or model-based methods; both methods use a user-item matrix that considers user preferences as items. This matrix denotes information on user preferences, which refers to the user ratings for items. The model-based method exploits the fact that the input matrix is factorized. CF approaches can effectively provide personalized recommendation results to users; however, cold-start problems arise because both these methods depend on the users’ ratings for items to predict users’ preferences. We proposed an approach to alleviate the cold-start problem along with a methodology for utilizing blockchain that can enhance the reliability of the processes of the recommendations. We attempted to predict an average rating for a new item to alleviate item-side cold-start problems. First, we applied the concept of word2vec, treating each user’s item-selection history as a sentence. Then, we derived genre2Vec based on the skip-gram technique and predicted an average rating for a new item by utilizing the vectors and category ratings. We experimentally demonstrated that our approach could generate more accurate results than conventional CF approaches could. We also designed the processes of the recommendation based on the concept of blockchain addressing the smart contract. Based on our approach, we proposed a system that can secure reliability as well as alleviate the cold-start problems in recommender systems.