Decentralization is essential when trust and performance must not depend on a single organization. Distributed Ledger Technologies (DLTs) and Decentralized Hash Tables (DHTs) are examples where the DLT is useful for transactional events, and the DHT is useful for large-scale data storage. The combination of these two technologies can meet many challenges. The blockchain is a DLT with immutable history protected by cryptographic signatures in data blocks. Identification is an essential issue traditionally provided by centralized trust anchors. Self-sovereign identities (SSIs) are proposed decentralized models where users can control and manage their identities with the help of DHT. However, slowness is a challenge among decentralized identification systems because of many connections and requests among participants. In this article, we focus on decentralized identification by DLT and DHT, where users can control their information and store biometrics. We survey some existing alternatives and address the performance challenge by comparing different decentralized identification technologies based on execution time and throughput. We show that the DHT and machine learning model (BioIPFS) performs better than other solutions such as uPort, ShoCard, and BBID.
This research letter considers the approach to managing a collection of business process models using the ideas of Blockchain and Directed Acyclic Graph structures. It is expected to make shared web resources more secure and transparent using this approach when managing cross-enterprise collections of business process models.
Alessia Antelmi, Giuseppe D’Ambrosio, Andrea Petta, Luigi Serra · 5 authors
The amount of accessible computational devices over the Internet offers an enormous but latent computational power. Nonetheless, the complexity of orchestrating and managing such devices requires dedicated architectures and tools and hinders the exploitation of this vast processing capacity. Over the last years, the paradigm of (Browser-based) Volunteer Computing emerged as a unique approach to harnessing such computational capabilities, leveraging the idea of voluntarily offering resources. This article proposes VFuse, a groundbreaking architecture to exploit the Browser-based Volunteer Computing paradigm via a ready-to-access volunteer network. VFuse offers a modern multi-language programming environment for developing scientific workflows usingWebAssembly technology without requiring the user any local installation or configuration. We equipped our architecture with a secure and transparent rewarding mechanism based on blockchain technology (Ethereum) and distributed P2P file system (IPFS). Further, the use of Non-Fungible Tokens provides a unique, secure, and transparent methodology for recognizing the users’ participation in the network.We developed a prototype of the proposed architecture and four example applications implemented with our system. All code and examples are publicly available on GitHub.
Léo Besançon, Catarina Ferreira da Silva, Parisa Ghodous, Jean-Patrick Gelas
Decentralized Applications, or DApps, provide distributed trusted applications that use blockchains. They are often composed of several services, such as transaction scalability protocols, decentralized storage and distributed computing solutions. In order to help formalize these applications, facilitate their development and improve their interoperability, we propose a novel blockchain Ontology focused on the concepts involving DApps. This ontology extends the existing EthOn ontology. It defines several key concepts related to DApps development, as well as the relations between these concepts. It features the formalization of known use cases and design patterns of blockchain technology through blockchain patterns. We use Semantic Web Rule language (SWRL) in order to define rules that express constraints on the formalized concepts. We then execute an inference engine and obtain new constraints on the properties of a defined DApp, such as its cost, based on the DApp characteristics and the services it uses. For illustration we show the inference of constraints between the Ethereum blockchain and its sidechain Polygon. We apply our research work in the field of blockchain video games. This application shows how to use the ontology to model DApps, and can be adapted to other fields.
Decentralized applications (DApps) gained traction in the context of the blockchain technology. Ethereum is currently the public blockchain that backs the largest amount of the existing DApps. Onboarding new users to Ethereum DApps is a notoriously hard issue to solve. This is mainly caused by lack of cryptocurrency ownership, needed for transaction fees. Several meta-transaction patterns emerged for decoupling users from paying these fees. However, such solutions are mostly offered via off-chain, often paid relayer services and do not fully address the security issues present in the meta-transaction path. In this paper, we introduce a new meta-transaction architecture that makes use of the Intel Software Guard Extensions (SGX). Unlike other solutions, our approach would offer the possibility to deploy a fee-free Ethereum DApp on a web server that can directly relay meta-transactions to the Ethereum network while having essential security guarantees integrated by design.
Ammar Battah, Mohammad Madine, Ibrar Yaqoob, Khaled Salah · 6 authors
The demand for high-quality Artificial Intelligence (AI) models is ever-increasing in this digital era. However, most of the existing methods leveraged for managing the ownership, trading, and access of AI models fall short of providing traceability, transparency, audit, security, and trustful features. In this paper, we propose a solution based on blockchain and Non-fungible Tokens (NFTs) to manage ownership rights and exchange of AI models in a transparent, traceable, auditable, secure, and trustworthy manner. Smart contracts are employed to enforce ownership, ease of access, and exchange policies for the unique NFT linked to an AI model. We use decentralized storage of the InterPlanetary File System (IPFS) and proxy re-encryption oracles to securely fetch, store, and share data related to AI models. We present algorithms along with their implementation, testing, and validation details. The proposed solution is evaluated using cost and security analyses to show its affordability and resiliency against security threats and attacks. All smart contract codes are made publicly available on GitHub.
Sebastian Müller, Andreas Penzkofer, Nikita Polyanskii, Jonas Theis · 6 authors
We introduce the theoretical foundations of the Tangle 2.0, a probabilistic leaderless consensus protocol based on a directed acyclic graph (DAG) called the Tangle. The Tangle naturally succeeds the blockchain as its next evolutionary step as it offers features suited to establish more efficient and scalable distributed ledger solutions. Consensus is no longer found in the longest chain but on the heaviest DAG, where PoW is replaced by a stake- or reputation-based weight function. The DAG structure and the underlying Reality-based UTXO Ledger allow parallel validation of transactions without the need for total ordering. Moreover, it enables the removal of the intermediary of miners and validators, allowing a pure two-step process that follows the \emph{propose-vote} paradigm at the node level and not at the validator level. We propose a framework to analyse liveness and safety under different communication and adversary models. This allows providing impossibility results in some edge cases and in the asynchronous communication model. We provide formal proof of the security of the protocol assuming a common random coin.
Trust management systems often use registries to authenticate data, or form trust decisions. Examples are revocation registries and trust status lists. By introducing distributed ledgers (DLs), it is also possible to create decentralized registries. A verifier then queries a node of the respective ledger, e.g., to retrieve trust status information during the verification of a credential. While this ensures trustworthy information, the process requires the verifier to be online and the ledger node available. Additionally, the connection from the verifier to the registry poses a privacy issue, as it leaks information about the user's behavior. In this paper, we resolve these issues by extending existing ledger APIs to support results that are trustworthy even in an offline setting. We do this by introducing attestations of the ledger's state, issued by ledger nodes, aggregatable into a collective attestation by all nodes. This attestation enables a user to prove the provenance of DL-based data to an offline verifier. Our approach is generic. So once deployed it serves as a basis for any use case with an offline verifier. We also provide an implementation for the Ethereum stack and evaluate it, demonstrating the practicability of our approach.
We present a new stochastic model for the evolution of Directed Acyclic Graphs (DAG)-based distributed ledgers (DL), under the presence of heterogeneous delay. This model is used to analyse the performance metrics of the DL, showing in particular that the number of unapproved messages does not diverge to infinity, even under the presence of delay. We propose an analysis based on conveniently defined sets, as well as an alternative drift-based analysis. The former allows to get a bound on the number of unapproved messages, while the latter, through a simpler analysis, allows to probe the existence of such bound. For particular scenarios, we are able to derive the expected value of the drift of unapproved messages, through a Markov process-based approach. State-of-the-art mathematical models trying to capture the impact of delays on the performance of such DLs rely on some particular simplifications. In contrast, through our model, we are able to analytically derive similar performance guarantees, in a more realistic setup. In particular, we focus on IOTA foundation's tangle, while our results can be extended to other DAG-based distributed ledgers. We compare our results to results obtained in a real testbed, showing good accordance between them.
Piero Fraternali, Sergio Luis Herrera González, Matteo Frigerio, Mattia Righetti
Distributed Ledger Technology (DLT) is one of the most durable results of virtual currencies, which goes beyond the financial sector and impacts business applications in general. Developers can empower their solutions with DLT capabilities to attain such benefits as decentralization, transparency, non-repudiability of actions and security and immutability of data assets, to the price of integrating a distributed ledger framework into their software architecture. Model-Driven Development (MDD) is the discipline that advocates the use of abstract models and of code generation to reduce the application development and integration effort by delegating repetitive coding to an automated model-to-code transformation engine. In this paper, we explore the suitability of MDD to support the development of hybrid applications that integrate centralized database and distributed ledger architectures and describe a prototypical tool capable of generating the implementation artefacts starting from a high-level model of the application and its architecture.
The development of Web3 — a stack of decentralised technologies underpinned by blockchains — isn’t simply a technical or financing challenge, it is also a problem of innovation and entrepreneurial discovery. In this paper we apply the lens of user innovation toolkit theory to the development of Web3. Toolkits are an organizational design solution to an innovation problem with sticky and local information. Our aim is to explore how toolkits theory applies to Web3 innovation, proposing that Web3 innovation is being organized through toolkits (e.g., blockchains, token standards, DAO frameworks) that enable efficient organization of sticky information to facilitate innovation. The contribution of this paper is the first application of toolkits theory to Web3, reframing its development as a problem of entrepreneurship and innovation in the context of distributed information. We provide implications for the role of developers as user innovators, the economic problem of emergent toolkit stacking, and the design of toolkit business models.
A group of researchers, builders and activists came together to discuss platform cooperativism and the intersection with the web3 movement. We touched on some of the key takeaways from the history of cooperatives that can be applied to developing new internet platforms and protocols, as well as the challenges platform cooperatives face scaling alternative models of ownership and control. Consequently, we investigated how developers and emerging internet companies might learn from the shared history of cooperatives and how, in practice, they can construct systems that respect cooperative ideals.
Quinten Stokkink, Can Umut Ileri, Dick Epema, Johan Pouwelse
Web3 is emerging as the new Internet-interaction model that facilitates direct collaboration between strangers without a need for prior trust between network participants and without central authorities. However, one of its shortcomings is the lack of a defense mechanism against the ability of a single user to generate a surplus of identities, known as the Sybil attack. Web3 has a Sybil attack problem because it uses peer sampling to establish connections between users. We evaluate the promising but underexplored direction of Sybil avoidance using network latency measurements, according to which two identities with equal latencies are suspected to be operated from the same node, and thus are likely Sybils. Network latency measurements have two desirable properties: they are only malleable by attackers by adding latency, and they do not require any trust between network participants. Our basic SybilSys mechanism avoids Sybil attackers using only network latency measurements if attackers do not actively exploit their malleability. We present an enhanced version of SybilSys that protects against targeted attacks using a variant of the flow correlation attack, which we name TrafficJamTrigger. We show how the message flows of Round-Trip Time measurements can be used to expose attack patterns and we propose and evaluate six classifiers to recognize these patterns. Our experiments show, through both emulation and real-world deployment, that enhanced SybilSys can serve a fundamental role for Web3, effectively establishing connections to real users even in the face of networks consisting of 99% Sybils.
Ahto Buldas, Dirk Draheim, Mike Gault, Märt Saarepera
Abstract The Web3 vision takes blockchain disintermediation to a next level by making it ubiquitous, encompassing not only payments and financial services but also digital identities, data and business models. Recently, Web3 has gained massive attention by major analysts such as Gartner, Forrester, Forbes Technology Council and the Harvard Business Review. Albeit the current enthusiasm about Web3, we are lost in a state of confusion about what Web3 actually is – or could be. In this paper, we take an engineering approach. We discuss a potential foundation of Web3 in terms of fundamental components, architectural principles and a Web3 design space. We conclude that, from an engineering viewpoint, the Web3 can be characterized as the integration of digital rights exchange into the (application layer) internet protocols. Finally, on the basis of these findings, we discuss the Alphabill platform as a Web3 enabling technology.
Many cross-organization cooperation applications of blockchain-based distributed ledger technologies (DLT) do not aim at innovation at the cooperation pattern level: essentially the same ''business'' is conducted by the parties, but this time without a central party to be trusted with bookkeeping. The migration to DLT is expected to have a negative performance impact, but some DLTs, such as Hyperledger Fabric, are accepted to be much better suited performance-wise to such use cases than others. However, with the somewhat surprising, but ongoing absence of application-level performance benchmarks for DLTs, cross-DLT comparison for "classic" workloads and the evaluation of the performance impact of "blockchainification" is still ill-supported. We present the design and Hyperledger Caliper-based open implementation of a full port of the classic TPC-C benchmark to Hyperledger Fabric, complete with a structured approach for transforming the original database schema to a smart contract data model. Initial measurements about the workload characteristics that will affect the design of large-scale performance evaluations are also included.
Andrea De Salve, Andrea Lisi, Paolo Mori, Laura Ricci
Decentralized Applications have become of paramount importance, especially thanks to the widespread adoption of blockchains, such as Ethereum and EOS.IO, which are two of the most known platforms where such applications can be executed. Even if the goal of Ethereum and EOS.IO is very similar, the two projects have distinct capabilities and properties. For example, they use different consensus algorithms, different languages to program smart contracts, and allocate and manage on-chain resources in different ways. In this paper, we perform in-depth analysis of the models used by EOS.IO blockchain to manage its resources (i.e., ram, cpu and network bandwidth). For this purpose, we instantiate an EOS.IO-based Decentralized Application (DApp) implementing a Decentralized Rating Framework and we measure its resource requirements. Finally, we evaluate and compare the cost in fees required for running the DApp under three different resource management models provided by EOS.IO, which are the staking, rex, and power up models.
Muntadher Sallal, Gareth Owenson, Dawood Salman, Mo Adda
Bitcoin is a digital currency based on a peer-to-peer network to propagate and verify transactions. Bitcoin is gaining wider adoption than any previous crypto-currency. However, the mechanism of peers randomly choosing logical neighbours without any knowledge about the underlying physical topology can cause a delay overhead in information propagation which makes the system vulnerable to double spend attacks. Aiming at alleviating the propagation delay problem, this paper introduces a proximity-aware extension to the current Bitcoin protocol, named Master Node Based Clustering (MNBC). The ultimate purpose of the proposed protocol, which is based on how clusters are formulated and how nodes can define their membership, is to improve the information propagation delay in the Bitcoin network. In the MNBC protocol , physical internet connectivity increases as well as the number of hops between nodes decreases through assigning nodes to be responsible for maintaining clusters based on physical Internet proximity. Furthermore, a reputation-based blockchain protocol is integrated with MNBC protocol in order to securely assign a master node for every cluster. We validate our proposed methods through a set of simulation experiments and the findings show how the proposed methods run and their impact in optimising the transaction propagation delay.
Bitcoin was proposed as an alternative to a centralized trust-based financial system in 2008 which uses distributed ledger called blockchain as the underlying technology. Bitcoin uses a peer-to-peer network without a third trusted party but still maintained trust in the network. The consensus mechanisms do the task of trust-building by executing certain algorithms to bring consensus to the peer nodes of the network. The consensus mechanism used in bitcoin is Proof of Work which involves a massive computation of hashes to validate a block and add it to the blockchain. As the applicability of blockchain increased, the computation-heavy consensus mechanisms were not suitable for real-time transactions. And so, there is a need for a new efficient and high throughput consensus mechanism. This paper proposes a new consensus mechanism using a scope index to mine a new block. This consensus mechanism deals with forking conditions, and the presence of malicious nodes in the network is also studied and compared with other consensus mechanisms.
Online file management systems enable cooperatively editing and sharing. However, due to the cost of communication and storage infrastructures, traditional online file management services, e.g., Google Drive and OneDrive, usually provide limited storage space and relatively low download speed for free users. To achieve better performance, ordinary users have to purchase their expensive services. Moreover, these file management systems are based on centralized architecture and bear the privacy leakage risk, because users’ personal files are stored and controlled by their servers. To address the above problems, we propose a peer-to-peer (P2P) file management system based on IPFS and Hyperledger Fabric, named as FileWallet, which can serve as a personal wallet for individual users or organizations to store and share their files in a secure manner. In FileWallet, the users form a P2P network and a Fabric network, where P2P network builds the connections and distributed storage network and the Fabric network sustains consistent blockchain ledgers to record file operation related transactions. In our FileWallet, the storage and communication costs are mitigated in the decentralized design, and the file owner can fully control the access permission of the file to preserve the file privacy. The design of the system architecture, main functionalities, and system implementations are presented in this paper. The performance of the system is evaluated through experiments, and the experimental results show its wide applicability and scalability.
Anwar Said, Muhammad Umar Janjua, Saeed‐Ul Hassan, Zeeshan Muzammal · 8 authors
Ethereum, the second-largest cryptocurrency after Bitcoin, has attracted wide attention in the last few years and accumulated significant transaction records. However, the underlying Ethereum network structure is still relatively unexplored. Also, very few attempts have been made to perform link predictability on the Ethereum transactions network. This paper presents a Detailed Analysis of the Ethereum Network on Transaction Behavior, Community Structure, and Link Prediction (DANET) framework to investigate various valuable aspects of the Ethereum network. Specifically, we explore the change in wealth distribution and accumulation on Ethereum Featured Transactional Network (EFTN) and further study its community structure. We further hunt for a suitable link predictability model on EFTN by employing state-of-the-art Variational Graph Auto-Encoders. The link prediction experimental results demonstrate the superiority of outstanding prediction accuracy on Ethereum networks. Moreover, the statistic usages of the Ethereum network are visualized and summarized through the experiments allowing us to formulate conjectures on the current use of this technology and future development.