To overcome the scaling and performance limitations, the Directed Acyclic Graph (DAG) is utilized as the underlying storage model of blockchain systems, which enables concurrent transaction processing and confirmation. However, accompanied by high performance, DAG-based blockchains still suffer from the severe challenge of constrained storage scalability, i.e., expensive storage overhead. Based on an in-depth analysis of the data, we discover that the root cause of storage overhead stems from the considerable data redundancy in the DAG-based blockchains. In this paper, we propose GeckoDAG, a lightweight DAG-based blockchain, whose design consists of two steps. First, we abstract a storage model named Basic from the existing DAG-based blockchain systems, which offers both high performance and security. On top of Basic, we then devise GeckoDAG, which merges previous transactions into Transaction Union (TU) and reduces the data redundancy in TU, thus lowering the storage overhead. To evaluate our design, we implement a prototype of GeckoDAG and conduct various experiments on it. The experimental results demonstrate that GeckoDAG can offer storage scalability while maintaining the security and efficiency of DAG-based blockchains.
Zhuo Xu, Xinyi Luo, Kaiping Xue, David S. L. Wei · 5 authors
The immutability of blockchains is an important security feature, but applications and studies have shown that it poses some problems. For instance, harmful information and vulnerable programs can be permanently stored on public blockchains such as Bitcoin and Ethereum, causing continuous damage. Therefore, researchers proposed the redactable blockchain to delete or modify those harmful data. Existing schemes usually adopt the Chameleon hash function (CHF) to keep the block hash unchanged so that other blocks remain unaffected. However, these schemes suffer from two security problems: (i) (unknown-version) users cannot determine whether a received block is the up-to-date version because different versions have the same hash; and (ii) (lazy-redaction) miners have no motivations to update historical blocks, causing continuous spreading of data which should have been discarded. To solve the problems, we propose SEREDACT, a secure and efficient redactable blockchain protocol with verifiable modification. Specifically, we design a Merkle tree-based verification mechanism with efficient dynamic updating that supports quick version checks and forcible modification updates, and further integrate it with restricted redaction policies to guarantee security. Our security and performance analyses show that SEREDACT has adequate security as a redactable blockchain protocol and retains close efficiency compared with the immutable blockchain.
Daniël Reijsbergen, Aung Htein Maw, Jingchi Zhang, Tien Tuan Anh Dinh · 5 authors
A plethora of different blockchain platforms have emerged in recent years, but many of them operate in silos. As such, there is a need for reliable cross-chain communication to enable blockchain interoperability. Blockchain interoperability is challenging because transactions can typically not be reverted – as such, if one transaction is committed then the protocol must ensure that all related transactions are committed as well. Existing interoperability approaches, e.g., Cosmos and Polkadot, are limited in the sense that they only support interoperability between their own subchains, or require intrusive changes to existing blockchains. To overcome this limitation, we propose PIEChain, a general, Kafka-based cross-chain communication framework. We utilize PIEChain for a practical case study: a cross-chain auction in which users who hold tokens on multiple chains bid for a ticket sold on another chain. PIEChain is the first publicly available, practical implementation of a general framework for cross-chain communication.
Economic transactions in distributed systems are typically atomic operations that exchange resources between two parties. However, these types of transactions are not well-suited for environments where numerous entities contribute to a valuable outcome, such as the Internet of Things or content creation in Web 3.0. In this work, we propose a novel transaction concept called a “value tree” that can involve multiple parties arranged hierarchically. Value trees use smart contracts to enable asynchronous execution, allowing payments to be temporally de-coupled from the underlying resources exchange while providing basic assurances. We describe how we have implemented value trees using smart contracts on the Ethereum blockchain. We demonstrated the use of value trees in the context of named data networking, where all contributors to a successful data delivery are rewarded asynchronously.
Zahra Batool, Sion Israel Sion, Rodrigue Tonga Naha, Kaiwen Zhang
The rise in inflation triggered by the COVID pandemic puts tremendous pressure on low or fixed-income family, who may be unqualified to take loans from banks. As a solution to this, a traditional community-based financial product, i.e., Rotating Savings and Credit Associations (ROSCAs), can bring individuals together to pool resources and provide access to credit. However, ROSCA communities have traditionally been formed by individuals with acquaintances, such as family, neighbors, and friends. To rely solely on these relationships can limit the potential profitability and accessibility of the group. Which subsequently leads to smaller, less diverse groups with limited access to resources and reduced financial outcomes. Therefore, marginalized communities will still be financially excluded. In this paper, we present B-ROSCA (Blockchain-based Rotating Savings and Credit Association), a mechanism to implement smart contract-based collateral to form ROSCAs using social network analysis. We designed a multi-mode and one mode projections-based method to connect the ROSCA members on similar financial situations and life experiences. Furthermore, we incorporate smart contract-based collateralization to increase trust. The members need to provide collateral in the form of cryptocurrency, to secure their contributions and reduce the risk of default. We argue that smart contract-based selective constitution of ROSCA groups has the potential to increase the size and diversity of the group. This leads to greater access to resources and improved financial outcomes for all participants by gaining the trust of people on the ROSCA platform. Moreover, B-ROSCA designed to leverage the improved execution speed of Ethereum 2.0 and the benefits of EIP1559 for more efficient operation.
Abstract Trilemma in blockchain refers to the infamous problem of simultaneously not delivering the three critical aspects of a ledger: security, scalability, and decentralisation. While security and scalability hinder decentralisation, security is jeopardised if the scalability is escalated. This deficiency of not maintaining a balance among these three crucial factors restricts the broader adoption of blockchain technology and cryptocurrencies in the industries. This paper proposes a solution to the blockchain trilemma by implementing a public ledger using The InterPlanetary File System (IPFS) and a newly introduced strategy called the double‐chain technique. The scalability and decentralisation features are guaranteed by the distributed file system of IPFS and the public nature of the blockchain suggested in this study. Although any consensus can be plugged into our system, the proof‐of‐work consensus is utilised to ensure that the security is not compromised while stabilising scalability and decentralisation.
One of the most important features of blockchain protocols is decentralization, as their main contribution is that they formulate a distributed ledger that will be maintained and extended without the need of a trusted party. Bitcoin has been criticized for its tendency to centralization, as very few pools control the majority of the hashing power. Pass et al. proposed FruitChain [PODC 17] and claimed that this blockchain protocol mitigates the formation of pools by reducing the variance of the rewards in the same way as mining pools, but in a fully decentralized fashion. Many follow up papers consider that the problem of centralization in Proof-of- Work (PoW) blockchain systems can be solved via lower rewards' variance, and that in FruitChain the formation of pools is unnecessary. Contrary to the common perception, in this work, we prove that lower variance of the rewards does not eliminate the tendency of the PoW blockchain protocols to centralization; miners have also other incentives to create large pools, and specifically to share the cost of creating the instance they need to solve the PoW puzzle. We abstract the procedures of FruitChain as oracles and assign to each of them a cost. Then, we provide a formal definition of a pool in a blockchain system, and by utilizing the notion of equilibrium with virtual payoffs (EVP) [AFT 21], we prove that there is a completely centralized EVP, where all the parties form a single pool controlled by one party called the pool leader. The pool leader is responsible for creating the instance used for the PoW procedure. To the best of our knowledge, this is the first work that examines the construction of mining pools in the FruitChain system.
Navin V. Keizer, Onur Ascigil, Michał Król, George Pavlou
The Web has become an integral part of life, and over the past decade, it has become increasingly centralised, leading to a number of challenges such as censorship and control, particularly in search engines. Recently, the paradigm of the decentralised Web (DWeb), or Web3, has emerged, which aims to provide decentralised alternatives to current systems with decentralised control, transparency, and openness. In this paper we introduce Ditto, a decentralised search mechanism for DWeb content, based on similarity search. Ditto uses locality sensitive hashing (LSH) to extract similarity signatures and records from content, which are stored on a decentralised index on top of a distributed hash table (DHT). Ditto uniquely supports numerous underlying content networks and types, and supports various use-cases, including keyword-search. Our evaluation shows that our system is feasible and that our search quality, delay, and overhead are comparable to those currently accepted by users of DWeb and search systems.
Lorenzo Petrosino, Giordano Pescetelli, Quirino Fieramosca, Stefano Della Valle · 6 authors
The rapid increase in the number and variety of smart devices connected to the Internet has increased the need to ensure resilience, reliability, and traceability when transferring data within the current Internet of Things (IoT) network. The adoption of Distributed Ledger Technologies (DLT) can provide data with the above-mentioned features, but the low scalability and high cost related to the adoption of classical DLTs, like the blockchains, results in ineffective integration with most of IoT systems. Conversely, other DLTs, DAGs (Directed Acyclic Graph), possess benefits comparable to those of blockchains without presenting most of the limitations that prevent their application in the IoT domain. Therefore we present dRAIN: a distributed Reliable Architecture for IoT Networks. The adoption of this architecture can grant the communication, management, supervision, and updating of distributed IoT devices, guaranteeing the resilience of the system and the reliability and traceability of exchanged data. In order to test the scalability potential and to assess the actual limitation of the proposed architecture, we developed both a physical and virtual (simulated) Proof of Concept. The results of our analysis show adequate execution times for the operations, guaranteeing high levels of security with acceptable performance, and prove the architecture suitable for most IoT applications that do not require to process external data in real-time.
Andrew Cullen, Lianna Zhao, Luigi Vigneri, Robert Shorten
Usability of distributed ledgers is crucial to their mainstream adoption, especially for enterprise applications in which most users do not wish to operate full-node infrastructure. Some attempts have been made to solve the problem of user-node interaction for blockchains in which leaders assemble users’ transactions into blocks, but in the case of leaderless DAG-based ledgers such as IOTA, many of these solutions cannot be applied due to the absence of a shared mempool and the ability of nodes to issue blocks in parallel. In this work, we propose a user-node interaction mechanism for ledgers of this kind that is designed to balance user traffic across nodes and ensure the risk of a user experiencing a poor quality of service is low. Our mechanism involves users selecting nodes to issue their transactions to the ledger based on quality of service indicators advertised by the nodes. Simulation results are presented to illustrate the efficacy of the proposed policies.
The rapid onboarding of renewable generation has led to many difficulties for both generators and the grid due to volatile output and market conditions. Battery energy storage systems have begun to alleviate these issues. However, such systems face many financial challenges in their deployment and operation. This paper demonstrates the use of advanced distributed ledger technology with smart contracts to design a decentralised autonomous organisation (DAO) to manage the investments in these systems and optimise their operations. In this paper, a series of smart contracts have been designed, deployed, and tested to demonstrate the effectiveness of such a DAO framework for battery management. The interconnected smart contracts can manage the financing, governing, and revenue-sharing mechanisms, allowing investors to coordinate investment and vote on the battery energy storage system's operation (charge/float/discharge) for a given period. This interconnected smart contract design implementation demonstrates a novel and effective strategy for managing battery energy storage systems, decreasing barriers to entry for investors, thus, allowing a greater adoption of such technology.
Anton Wahrstätter, Matthew D. Solomon, Ben DiFrancesco, Vitalik Buterin · 5 authors
Stealth addresses represent an approach to enhancing privacy within public and distributed blockchains, such as Ethereum and Bitcoin. Stealth address protocols employ a distinct, randomly generated address for the recipient, thereby concealing interactions between entities. In this study, we introduce BaseSAP, an autonomous base-layer protocol for embedding stealth addresses within the application layer of programmable blockchains. BaseSAP expands upon previous research to develop a modular protocol for executing unlinkable transactions on public blockchains. BaseSAP allows for the development of additional stealth address layers using different cryptographic algorithms on top of the primary implementation, capitalizing on its modularity. To demonstrate the effectiveness of our proposed protocol, we present simulations of an advanced Secp256k1-based dual-key stealth address protocol. This protocol is developed on top of BaseSAP and deployed on the Ethereum test network as the first prototype implementation. Furthermore, we provide cost analyses and underscore potential security ramifications and attack vectors that could affect the privacy of stealth addresses. Our study highlights the flexibility of the BaseSAP protocol and provides insights into the broader implications of stealth address technology in the realm of blockchain privacy.
Abstract The goal of a content delivery network (CDN) is to reduce the content delivery latency to end-users by using distributed cache servers. Nevertheless, it is very expensive to deploy and maintain cache servers in a large-scale. To solve this problem, CDN providers have come up with a new content delivery strategy: allowing end-users's IoT edge devices to share their storage/bandwidth resources. This new edge CDN platform needs to address two core questions: (1) how can we incentivize end users to share IoT devices? (2) how can we facilitate a safe and transparent content transaction environment for end users? In this paper, we introduce SmartSharing, a new content delivery network solution. In smartSharing, the over-the-top (OTT) IoT devices belonging to end-users are used as mini-cache servers. To motivate end users to share the idle devices and storage/bandwidth resources, SmartSharing designs the content delivery schedule and the pricing scheme based on game theory and machine learning algorithms (to be specific, a tailored Expectation-Maximization (EM) algorithm). To facilitate content trading among end users, SmartSharing creates a secure and transparent transaction platform based on smart contracts in Ethereum. In addition, SmartSharing's performance evaluation not only through trace-driven simulations in the real world, but also a prototype using content metadata and the achieved pricing schemes. The evaluation results show that CDN providers, end users and content providers can all benefit from our SmartSharing framework.
Despite their increasing popularity, blockchains still suffer from severe scalability limitations. Recently, Ethereum proposed a novel approach to block validation based on Data Availability Sampling (DAS), that has the potential to improve its transaction per second rate by more than two orders of magnitude. DAS should also significantly reduce per-transaction validation costs. At the same time, DAS introduces new communication patterns in the Ethereum Peer-to-Peer (P2P) network. These drastically increase the amount of exchanged data and impose stringent latency objectives. In this paper, we review the new requirements for P2P networking associated with DAS, discuss open challenges, and identify new research directions.
Athira Jayavarma, Abhijith Rajeev Menon, P. Vyshnav, S. B. Susilkessav · 6 authors
Over these years, there has been an observable effect on the environment due to Global Climatic Change. Scientists all over the world have predicted many of these disasters, and the main reason behind this is the emission of greenhouse gas. The use of fossil fuels to generate electricity contributes significantly to greenhouse gas emissions. If this conventional fossil fuel-based energy is replaced by renewable energy resources like solar energy, wind energy, etc., more than half of the emissions can be curbed. Increasing the usage of renewable sources of energy, mostly photovoltaic devices, and enabling distributed energy services will thereby encourage an energy trading environment among the users. This paper focuses on providing an approach to implement a prototype that integrates a microgrid and blockchain to trade electricity without an intermediary. It comprises of smart contracts and an interface which together forms a microgrid management system creating a peer-to-peer platform for users to trade electricity and thereby contributing towards sustainable and affordable energy.
Web3, decentralized web, is one of the buzz words brought up in the field of IT business as well as IT technology. Data ownership is supposed to be democratized by Web3, which means data is kept at its owner and the availability of the data is controlled and managed by the owner in the world of Web3. One of the mechanisms providing democratization of data ownership is InterPlanetary File System (IPFS) which leaves data as well as its meta data at its owner and only pointers to data are distributed over the network for data sharing. This paper discusses network layer support for IPFS to improve its performance. In particular, we propose to use Information Centric Networking as the network layer of IPFS to speed up data search in IPFS.
Blockchain adopts a chain data structure, and the characteristics of blocks that can only be added and cannot be deleted make the total number of blocks accumulate over time, forcing resource-constrained nodes to become degraded nodes in order to alleviate increasingly severe storage pressure. Degraded nodes only store partial blocks, although improving the scalability of blockchain storage and reducing data redundancy will lead to a decrease in data availability. To address the problem of storage scalability, quantitative research is needed on data availability. Based on a summary of the existing definitions of data availability, we propose a definition of data availability for blockchain. By analyzing the data synchronization process and the transaction lifecycle, key factors affecting data availability were extracted, and a data availability measurement model was constructed based on node types. On this basis, a relationship model linking data availability and storage scalability was constructed to find the range of data redundancy that meets the target data availability. The experimental results indicate that the data availability measurement model for blockchain can measure the data availability levels of different scalable storage schemes. The model of the relationship between data availability and storage scalability can guide the setting of data redundancy in scalable storage schemes.
Due to increasingly widespread electoral corruption, citizens are slowly starting to lose trust in the fairness of democratic elections. The main objective of VoteChain is the elimination of the aspect of trust from the electoral process, in order to make voting more secure, transparent, and easily accessible. This paper proposes and implements a robust system that enhances voting efficiency by creating an electronic platform on top of a distributed Bitcoin Cash blockchain ledger. Blockchain represents a time-stamped series of immutable data records shared across a distributed network. When utilized in the context of voting, it guarantees full anonymity, vote integrity, and a fair, incontrovertible ledger with verifiable election results to all voters. Moreover, the system offers the ability to vote via any Internet-enabled computer or smartphone, dramatically decreasing the overall election organization costs. The system is envisioned as an application that connects to the Bitcoin Cash blockchain network via a custom feature-rich library. After discussing the system's characteristics, design, and underlying technology, this paper presents an example election scenario explaining how VoteChain works in-depth. In the end, the system's possible shortcomings are outlined, along with its prospective evolution and potential improvements that can be implemented.
Xueqiang Yan, Xueli An, Wenxuan Ye, Mingyu Zhao · 6 authors
In conventional mobile communications systems, network services are designed to serve a huge amount of subscribers simultaneously, which is normally called a network-centric design approach. In comparison, this paper aims to investigate the user-centric design approach, which refers to sys-tems that are designed to be user-defined, user-configurable and user-controllable. The user-centric approach allows for dedicated network services to be provided at the granularity of the user. A novel User-Centric Network (UCN) architecture is proposed in this work, which includes key design principles, corresponding network elements as well as procedures. It is envisioned that UCN is distributed in nature by leveraging enabling technologies like Distributed Ledger Technology (DLT) and Distributed Hash Table (DHT). In this way, UCN not only provides extreme customization by offering fine-grained services, but also enables autonomous and trusted data control and privacy protection. A simulation platform is developed to verify the feasibility of the architecture, and to preliminarily evaluate its performance by numerical results in terms of hop count, bandwidth consumption, latency, success ratio and scalability.
The exponential growth of the Internet of Things (IoT) is being witnessed nowadays in different sectors. This makes IoT data communications more complex and harder to manage. Addressing such a challenge using a centralized model is an ineffective approach and would result in security and privacy difficulties. Technologies such as blockchain provide a potential solution to enable secure and effective management of IoT data communication in a distributed and trustless manner. In this paper, a novel lightweight blockchain-centric IoT architecture is proposed to address effective IoT data communication management. It is based on an event-driven smart contract that enables manageable and trustless IoT data exchange using a simple publish/subscribe model. To maintain system complexity and overhead at a minimum, the design of the proposed system relies on a single smart contract. All the system operations that enable effective IoT data communication among the different parties of the system are defined in the smart contract. There is no direct blockchain–IoT-device interaction, making the system more useable in wide IoT deployments incorporating IoT devices with limited computing and energy resources. A practical Ethereum-based implementation of the system was developed with the ability to simulate different IoT setups. The evaluation results demonstrated the feasibility and effectiveness of the proposed architecture. Considering varying-scale and varying-density experimental setups, reliable and secure data communications were achieved with little latency and resource consumption.
In order to propagate transactions and blocks, today’s blockchain systems rely on unstructured peer-to-peer overlay networks. In such networks, broadcast is known to be an inefficient operation in terms of message complexity and overhead. In addition to the impact on the system performance, inefficient or delayed block propagation may have severe consequences regarding security and fairness of the consensus layer. In contrast, the Kadcast protocol is a structured peer-to-peer protocol for block and transaction propagation in blockchain networks. Kadcast utilizes the well-known overlay topology of Kademlia to realize an efficient broadcast operation with tunable overhead. We study the security and privacy of the Kadcast protocol based on probabilistic models and analyze its resilience to packet losses and node failures. Moreover, we evaluate Kadcast’s block delivery performance, broadcast reliability, efficiency, and security based on advanced network simulations. Lastly, we introduce a QUIC-based prototype implementation of the Kadcast protocol and show its merits through deployment in a global-scale cloud-based testbed.
Habib Allah Yajam, Elnaz Ebadi, Mohammad Ali Akhaee
The consensus algorithm is fundamental to the decentralization property of blockchain technology. Developing blockchain networks and consensus algorithms necessitates the analysis of variables on large global-scale networks through experiments. However, conducting experiments on test networks is expensive due to the high cost of necessary infrastructure. In this article, JABS (Just Another Blockchain Simulator), a simulator specifically designed for researching large-scale blockchain consensus algorithms, is introduced. Superior performance in simulating real-world scale blockchain networks compared to other frameworks is demonstrated in this article. JABS is faster, more efficient, and produces accurate results that are comparable to measurements from Bitcoin and Ethereum blockchain networks. JABS' modularity, which allows for the easy substitution of components without changing others, is highlighted. Additionally, JABS aids in the design and evaluation of new consensus algorithms. Improving the CasperFFG consensus algorithm is proposed and its improved performance using JABS is demonstrated.