Blockchain Papers

Divesh Sarkar, Manish Sarkar

No abstract is available for this record.

Adarsh Chandra Nigam, Ruby Chanda

The emergence of Web 3.0, built upon blockchain technology, signals a paradigm shift toward decentralized applications and token economies. Digital-native millennials and Gen Z consumers demand hyper-personalization, convenience, and sustainability from brands, influencing a transition toward innovative approaches to customer engagement within the Web 3.0 landscape. Web 3.0 wallets play a crucial role in digital asset management, offering enhanced control and security to users. Many enterprises are expected to embrace Web 3.0, blending centralized services with decentralized applications to meet diverse business needs shortly. This transition is driven by Web 3.0’s unique capabilities, benefiting consumers and enterprises alike. However, the academic literature has limited awareness and scientific clarity regarding Web 3.0 and cryptocurrency integration. This chapter critically reviews cryptocurrency integration in the Web 3.0 ecosystem, delving into real-world case studies of successful projects and exploring opportunities, challenges, and future directions. In the Web 3.0 ecosystem, transactions are predominantly conducted using cryptocurrencies on decentralized blockchains, diverging from traditional fiat currencies issued by governments. The convergence of conventional finance and decentralized finance (DeFi) represents a pivotal moment in the evolution of the blockchain industry, promising to unlock new opportunities for financial inclusion and innovation. The regulatory challenges, scalability issues, and seamless integration of traditional finance and DeFi are poised to reshape the future of finance and foster a more transparent and accessible financial ecosystem.

Nagendra Harish Jamithireddy

The rise of decentralized finance (DeFi) technologies allows businesses to rethink financial processes centered around traditional centralized systems. However, direct on-chain integration with legacy platforms such as SAP incurs latency, cost, and compliance conflicts that are seldom aligned with the needs of enterprise-scale finance. This research proposes and assesses a hybrid architecture that integrates on-chain smart contract execution with off-chain approval and validation logic to enable secure, scalable, and auditable fintech payment processing within SAP environments. The architecture utilizes SAP FI transaction triggers such as FB60 or F110 to instigate payment workflows which are executed in part by blockchain nodes utilizing secure asynchronous handlers while retaining regulatory bounding and state finality within SAP.A testbed which simulated over 100,000 transactions per hour was set up on Quorum, Hyperledger Besu and Polygon Edge blockchains. The hybrid model was proven to outperform fully on-chain and legacy SAP models in transaction throughput, fault tolerance, and audit traceability by a significant margin. Latencies were also reduced by an average of 47% when compared to full-chain setups. The hybrid model was able to retain audit finality in the ledger and had a 94.8% success rate of settlement under Byzantine fault injections exerts while enduring sustained cross-system fault tolerance. Security layers placed on both chains and off-chain components block 98% of simulated attack vectors in the transaction path. In addition, the attack simulations showed over 37% reduced CPU resource consumption in hybrid mode compared to full-chain validated configurations. The results support the hybrid model's capacity to enable high trust decentralized financial operations within SAP while increasing structural performance, resilience, governance capabilities of the system.

Xu Long, Yishun Wang, Xiaoqi Li

As blockchain technology advances, Ethereum based gambling decentralized applications (DApps) represent a new paradigm in online gambling. This paper examines the concepts, principles, implementation, and prospects of Ethereum based gambling DApps. First, we outline the concept and operational principles of gambling DApps. These DApps are blockchain based online lottery platforms. They utilize smart contracts to manage the entire lottery process, including issuance, betting, drawing, and prize distribution. Being decentralized, lottery DApps operate without central oversight, unlike traditional lotteries. This ensures fairness and eliminates control by any single entity. Automated smart contract execution further reduces management costs, increases profitability, and enhances game transparency and credibility. Next, we analyze an existing Ethereum based gambling DApp, detailing its technical principles, implementation, operational status, vulnerabilities, and potential solutions. We then elaborate on the implementation of lottery DApps. Smart contracts automate the entire lottery process including betting, drawing, and prize distribution. Although developing lottery DApps requires technical expertise, the expanding Ethereum ecosystem provides growing tools and frameworks, lowering development barriers. Finally, we discuss current limitations and prospects of lottery DApps. As blockchain technology and smart contracts evolve, lottery DApps are positioned to significantly transform the online lottery industry. Advantages like decentralization, automation, and transparency will likely drive broader future adoption.

Bo Ning

This research paper is a study of creating a blockchain-based system that would make data more secure and consistent in the decentralized information computing system. By pursuing qualitative exploratory research methodology, the study combines the findings of eight adaptively designed interviews with blockchain developers, enterprise IT managers, legal practitioners, and academic researchers. Thematic analysis disclosed five major dimensions defining secure blockchain architecture: Security Mechanisms, Scalability, Governance, Regulatory Compliance and Privacy & Confidentiality. Results indicate the need to focus on strong cryptographical protection, optimization, adaptive governance, legal alignment, and privacy-preserving protocols, including zero-knowledge proofs. Technical and institutional obstacles were identified by the stake holders, and it was noted that a balanced and modular framework that has capability of satisfying various operational and regulatory requirements is sought. This research adds a conceptual model informed by stakeholders and advises a simulation and implementation trial as the next stage to examine the applicability of the model in practice. The results present both theoretical and practical advice on the design of safe, scalable, and regulatory-compliant architectures of blockchain environments in distributed systems.

Blake Regalia, Benjamin Adams

The greatest advantage that Web3 applications offer over Web 2.0 is the evolution of the data access layer. Opaque, centralized services that compelled trust from users are replaced by trustless, decentralized systems of smart contracts. However, the public nature of blockchain-based databases, on which smart contracts transact, has typically presented a challenge for applications that depend on data privacy or that rely on participants having incomplete information. This has changed with the introduction of confidential smart contract networks that encrypt the memory state of active contracts as well as their databases stored on-chain. With confidentiality, contracts can more readily implement novel interaction mechanisms that were previously infeasible. Meanwhile, in both Web 2.0 and Web3 applications, the user interface continues to play a crucial role in translating user intent into actionable requests. In many cases, developers have shifted intelligence and autonomy onto the client, leveraging web technologies for computation, graphics, and networking. Web3’s reliance on such frontends has revealed a pain point though, namely that decentralized applications are not accessible to end users without a persistent host serving the web application. Here we introduce the Non-Fungible Program (NFP) model for developing self-contained frontend applications that are distributed via blockchain, powered by web technology, backed by encrypted databases, and controlled by confidential smart contracts. Access to frontend code, as well as backend services, is controlled and guaranteed by smart contracts according to the NFT ownership model, eliminating the need for a separate host. By extension, NFP applications bring interactivity to token owners and enable new functionalities—such as authorization mechanisms for oracles, supplementary web services, and overlay networks—in a secure manner. In addition to releasing an open-source software development kit for building NFPs, we demonstrate the utility of NFPs with an interactive Bayesian game implemented on Secret Network.

Ravindra J. Lawande, Sudhir B. Lande

One of the main concerns in blockchain (BC) systems is throughput growth. To solve this issue, several improvements and a new gossip algorithm are put forth; however, they are inevitably limited by the message synchronization latency of the underlying peer-to-peer (P2P) network. The current gossip algorithms still have certain drawbacks, such as high latency, low throughput, energy waste, and higher network connection requirements. A very effective BC gossip algorithm is necessary to reduce delivery latency and boost transaction throughput for BC systems. All transactions and activities are centrally stored in the distributed ledger, or BC. Bitcoin and other public blockchains emphasize decentralization, which necessitates high throughput and increases communication costs. Consequently, the hyperledger fabric BC technology employs the joint-graph based delegated practical byzantine fault tolerance (JG-DPBFT) consensus mechanism. The enhanced gossip algorithm (IGA) is used to finish consensus authentication and information exchange. NS-3 is used to implement the JG-DPBFT protocol, and its performance is assessed by contrasting it with other approaches. Consequently, the testing results demonstrated that the JG-DPBFT outperformed the current techniques in terms of throughput and latency.

Luigi Vigneri, Darcy Camargo, Olivia Saa, Andrew Cullen

The rapid advancements in distributed ledger technology (DLT) have produced novel systems combining high throughput, low latency and smart contract programmability. However, designing robust incentives schemes for such advanced protocols remains a critical challenge. Weaknesses in existing incentives schemes, particularly in reward distribution and incentive alignment, can hinder protocol adoption and long-term sustainability. In this paper, we propose a unified framework for comprehensive analysis of a wide range of DLTs. Our framework extends existing methodologies for studying transaction fee mechanisms by incorporating reward distribution among multiple actors involved in the consensus process, addressing critical gaps in the literature. We introduce a categorisation of incentive mechanisms and apply the above framework to the modern consensus protocols of Sui and IOTA, offering comparisons with more ‘traditional’ systems including Ethereum and Bitcoin.

Anshul Wagh, Mangal Singhal, Rachana Patil

The conventional space title industry is overwhelmed by centralized recorders that force tall recharging expenses, limit possession rights, and show security vulnerabilities due to single focuses of disappointment.This paper presents Domyn, a decentralized space title commercial center leveraging blockchain innovation and NFTs (Non-Fungible Tokens) to empower genuine possession of advanced spaces.Built on the Ethereum blockchain, Domyn utilizes ERC-721 keen contracts to tokenize space names, permitting clients to mint, purchase, offer, and exchange proprietorship without mediators.Furthermore, IPFS (InterPlanetary Record Framework) guarantees decentralized capacity, making the framework censorship-resistant and tamper-proof [8].Through an in-depth investigation of its design, exchange stream, and savvy contract execution, we illustrate Domyn's capacity to supply security, straightforwardness, and productivity compared to conventional space enlistment centers.The paper assist presents execution measurements, test case comes about, and a security assessment to approve the viability of the proposed framework.We moreover investigate future upgrades, counting Layer 2 scaling arrangements and multi-chain interoperability, to progress gas proficiency and selection.

Tetiana Yarotska, Oleksandr Yakushenko

Introduction. Cryptocurrencies are gaining popularity among individuals, businesses, and financial institutions. They are used for various purposes, particularly to pay for goods and services. Selling goods and services for cryptocurrencies can help companies attract new customers, increase sales, expand market share, and more. This article explores whether cryptocurrencies today function as a means of payment similar to fiat money, and examines the risks faced by companies that accept cryptocurrencies for goods and services. While cryptocurrencies are approaching the fulfillment of the economic functions of money, they have not yet fully reached this level. Nonetheless, in many countries, cryptocurrencies can be used to pay for goods or services, exchanged for other currencies, and more. In Ukraine, some companies sell household appliances, tickets, fuel, and other goods and services for cryptocurrencies. Problem Statement. Cryptocurrency developers emphasize that it is an alternative, private form of digital money that is not issued by national governments or controlled by financial intermediaries such as banks. The National Bank of Ukraine notes that the complex legal nature of cryptocurrencies prevents them from being recognized as cash, foreign currency, electronic money, securities, or a monetary surrogate. Cryptocurrencies offer certain advantages over traditional money, such as reducing transaction costs. However, transactions involving cryptocurrencies also carry inherent risks. Purpose. The study identifies the main approaches to organizing the sale of goods and services for cryptocurrencies. Additionally, the article aims to identify the risks associated with the sale of goods and services for cryptocurrencies and outline ways to minimize these risks. Materials and methods. We employed various research methods, including historical and legal methods, which involve the study of the legislative framework surrounding cryptocurrency transactions, as well as the empirical method, which investigates different practices of selling goods and services for cryptocurrencies. This approach also helps in identifying the risks companies face when engaging in such activities. One of the primary risks associated with cryptocurrency transactions is significant fluctuations in their exchange rates, which can result in economic losses in the event of a sharp devaluation. To better understand the nature of the risks associated with using cryptocurrencies, we conducted a statistical analysis of fluctuations in the Bitcoin exchange rate and built a correlation model with other market indicators, such as the Nasdaq Composite index and the exchange price of silver, for the period from March 1, 2012, to February 29, 2024. Using the Group Method of Data Handling (GMDH), we identified a connection between Bitcoin’s value fluctuations and market indicators that differ in terms of technological orientation (Nasdaq Composite) and investment risk (silver). Results. More and more countries are legalizing cryptocurrencies. In Ukraine, however, legislation regarding cryptocurrencies is still in development, and the sale of goods and services for cryptocurrencies is treated similarly to barter agreements. Depending on market characteristics and the specifics of their business, sellers of goods and services choose between directly selling for cryptocurrencies or using third-party intermediaries. This raises the question of what risks sellers face when accepting cryptocurrencies and how to mitigate or reduce those risks, such as the risk of sharp devaluation. Our model reveals a connection between Bitcoin’s exchange rate and other market indicators, such as the Nasdaq Composite index and the price of silver. However, the potential risks associated with using cryptocurrencies as a means of payment warrant further exploration. The lack of a clear regulatory framework and consistent definitions also introduces uncertainty in cryptocurrency operations. In practice, varying definitions of cryptocurrencies can create additional risks, particularly regarding the taxation of income received in cryptocurrency. Therefore, selling goods and services via intermediaries and converting cryptocurrency into fiat money can help mitigate legal, financial, and tax risks for companies. Additionally, gove

Barbara Guidi, Andrea Michienzi, Leonardo Pasquale

The InterPlanetary File System (IPFS) is among the most well-known distributed file systems applied in Web3 applications, where data storage is involved. Non-Fungible Tokens (NFTs) represent one of the main scenarios in which distributed content sharing is enacted via IPFS. Generally, NFTs are created, sold and bought via so-called marketplaces, easing the technical difficulties. They play a crucial role during the sale of NFTs because they act as intermediaries between users and underlying technologies. In this paper, we evaluate the impact of NFT marketplaces on the availability of NFT resources in the IPFS network. We focus on the relationship between resources and marketplaces, trying to understand whether access to some of the resources related to NFTs is transparent and consistent with the information present in the contract. We selected $\mathbf{1 0}$ collections and 3 NFTs for each collection and monitored these assets on IPFS. For the monitoring phase, we deployed our node and requested providers of the assets every six hours for two weeks. Our analysis shows that IPFS does not guarantee high availability and marketplaces refer to copies of NFTs, thus violating the integrity and security guaranteed by NFTs and IPFS.

Chuan Zhang, Zhi Yu, Zhe Peng, Mingyang Zhao · 6 authors

Nowadays, checkpoints have been proven to be an effective solution to ensure slashability in proof-of-stake (PoS) consensus, and Tas et al.'s cutting-edge solution in S&P 2023 is a typical example. Unfortunately, despite progress, hour-level transaction delays and annually around 10 K dollar checkpoint costs make existing related solutions still unacceptable in realworld PoS applications. In this paper, we propose SecPoS, a slashable PoS consensus with second-level transaction delays and one-time checkpoint costs. To achieve these design goals, we draw inspiration from Pixel+ signatures and chameleon hash functions to design a novel bilateral blockchain structure, achieving twoblock transaction finalization via only uploading the first block of our chain as checkpoints. Next, considering practical application requirements, we address a series of following challenges, such as bilateral immutability, blockchain forks, determination of the main chain, and malicious attacks from PoS members. In detail, we propose two constructions of SecPoS, i.e., SecPoS – A and SecPoS – B. SecPoS – A and SecPoS – B have a tradeoff between transaction delays and block numbers packed in an epoch. Compatible with most existing one-way blockchains, we implement and outsource a prototype SecPoS to facilitate research11https://github.com/Academic-Paper-Codes/SecPoS-Consensus, and prove the security of SecPoS. Experiments on this prototype show that SecPoS – A and SecPoS – B require around 5s and 100s transaction delays, respectively, and both require 2 dollars one-time checkpoint costs.

Matthieu Pigaglio, Onur Ascigil, Michał Król, Sergi Reñé · 9 authors

Layer-2 protocols can assist Ethereum's limited throughput, but globally broadcasting layer-2 data limits their scalability. The Danksharding evolution of Ethereum aims to support the selective distribution of layer-2 data, whose availability in the network is verified using randomized data availability sampling (DAS). Integrating DAS into Ethereum's consensus process is challenging, as pieces of layer-2 data must be disseminated and sampled within four seconds of the beginning of each consensus slot. No existing solution can support dissemination and sampling under such strict time bounds. We propose PANDAS, a practical approach to integrate DAS with Ethereum under Danksharding's requirements without modifying its protocols for consensus and node discovery. PANDAS disseminates layer-2 data and samples its availability using lightweight, direct exchanges. Its design accounts for message loss, node failures, and unresponsive participants while anticipating the need to scale out the Ethereum network. Our evaluation of PANDAS's prototype in a 1,000-node cluster and simulations for up to 20,000 peers shows that it allows layer-2 data dissemination and sampling under planetary-scale latencies within the 4-second deadline.

Christian Nii Aflah Cobblah, Qi Xia, Jianbin Gao

As data-driven applications and user demands grow, managing content delivery in Named Data Networking (NDN) has become more challenging. Traditional caching methods struggle to scale in dynamic and decentralized environments where content popularity changes and collaboration among routers is needed. This paper introduces a decentralized collaborative caching framework for NDN, combining Multi-Agent Deep Reinforcement Learning (MADRL) and blockchain technology. MADRL enables routers to autonomously adjust caching strategies based on local states and interactions with neighboring routers, improving cache hit rates and reducing retrieval costs. Blockchain technology ensures fair and transparent rewards through a cryptocurrency-based token system, incentivizing collaboration and minimizing free-riding risks. The framework also integrates Delegated Proof of Stake (DPoS) for efficient, secure validation of caching actions. Simulations demonstrate that the approach significantly enhances caching efficiency, reduces latency, and improves scalability, addressing the challenges of dynamic decentralized environments.

VENKATARATHNAM KORUKONDA, Rohita Yamaganti

The emergence of decentralized file-sharing platforms has introduced new challenges in ensuring secure data transmission, preserving node reputation, and preventing unauthorized access. This study presents an advanced peerto-peer (P2P) file-sharing system that integrates encrypted communication channels with blockchain-based consensus mechanisms to strengthen data confidentiality and trust evaluation. By employing protocols such as Proof-of-Work (PoW) and Proof-of-Stake (PoS), the proposed architecture establishes a tamper-resistant and verifiable ledger of interactions. Cryptographic techniques are used to protect data in transit and maintain privacy-preserving trust scores without revealing user identities. The system's reputation module continuously aggregates behavioural metrics, adjusting trust values through dynamic weighting and anomaly detection. Experimental evaluation demonstrates that this approach achieves high resilience against Sybil and eavesdropping attacks while preserving the integrity and confidentiality of shared content. The proposed model offers a scalable and secure foundation for next-generation decentralized file-sharing systems.

Nipun Sharma, Swati Sharma, Kumud Kumari, C. Komalavalli · 6 authors

The Inter Planetary File System (IPFS) is a decentralized, peer-to-peer file storage and sharing protocol designed to make the web faster, more open, and resilient. It allows users to store and share files in a distributed network without relying on central servers, similar to a BitTorrent-based approach, but with a few unique optimization features. In contrast to traditional HTTP, which fetches data from a single location (typically a server), IPFS retrieves data from multiple nodes holding the content. This can improve access speeds and ensure availability even if some nodes go offline. In this paper we discuss, the evolution of IPFS, key features, prime applications and future challenges. The results and concluding sections discuss the potential application areas and uniqueness offered by the storage related blockchain projects. An estimated of 10 billion USD is the market capitalization of the storage projects across top rankers which is estimated to rise exponentially over the next decade.

Іван Пархоменко, Roman Ohiievych

The paper presents a novel approach to enhancing the crypto-economic resilience of decentralized networks by employing a mechanism of Random Time Challenge Tokens (RTCT). Contemporary consensus mechanisms (Proof-of-Work, Proof-of-Stake, Proof-of-Burn) and their ability to deter 51% attacks and Sybil attacks are analyzed. It is shown that classical approaches secure the network by imposing substantial economic barriers to attackers – for example, miners are forced to invest in hardware and electricity, raising the cost of a 51% attack to a prohibitively high level. However, vulnerabilities remain: attackers can rent computational resources or exploit under-active validators. The proposed RTCT mechanism involves generating random cryptographic challenges at unpredictable time intervals, which network nodes must answer with a cryptographically verifiable token, followed by burning of that token. This process creates unpredictable load and continuous costs for network participants, significantly increasing the economic cost of attacks. The RTCT process is mathematically formalized and the dependence of attack cost on the challenge complexity parameter m is evaluated. The results confirm that as complexity m increases, an attack requires exponentially higher expenditures, making the network more resilient. The advantages and potential drawbacks of the RTCT approach are discussed, as well as possible directions for further research, including optimizing challenge frequency and integrating RTCT with existing consensus protocols.

Bongani Mawhayi, Johnny Botha, Louise Leenen

The investigation of cryptocurrency crimes is still in its infancy with no standardised process or methodology to follow. This paper describes research that forms part of a broader project led by the second author (Botha, et al., 2025). The broader project’s aim is to develop a methodology to follow when conducting cryptocurrency crime investigations. One of the steps in the proposed methodology is web scraping. The authors of this paper present a detailed exploration of web scraping techniques within the broader context of the proposed investigation methodology. In this paper, the focus is on developing a well-structured methodology for scraping social media platforms and online forums to gather data related to fraudulent activities; the goal is to find posts that include references to the wallet address of interest. This exploration uses an iterative approach; for every new cryptocurrency wallet address discovered or revealed through on-chain analysis, a parallel path is followed by scraping the Internet. If a mention of the cryptocurrency address should be discovered it is considered to be a key finding, creating a pivot point in the investigation. From a pivot point, further open-source intelligence (OSINT) techniques will be applied, though this aspect falls beyond the scope of this paper. If no relevant information or link is found, the scraping path will not be pursued, and the investigation proceeds with on-chain analysis to identify additional wallet addresses. Additionally, challenges encountered in web scraping, such as handling platform restrictions, ensuring data accuracy, and managing large volumes of data, are addressed. The goal of the proposed methodology is to enhance data extraction and analysis efficiency contributing to the proposed methodology for investigating cryptocurrency scams.

Qin Wang, Shiping Chen

Blockchain has been widely recognized as a trusted computing paradigm underpinning Decentralized Applications (DApps). However, low performance and poor scalability of the existing mainstream blockchain designs and implementations render their prospects unattainable, so-called trilemma . Directed Acyclic Graph (DAG) emerged as an alternative blockchain architecture to address the performance and scalability issue. However, the capacity and feasibility of DAG-based blockchain systems still remain of concern, due to a lack of open source implementations and convincing published experimental results. In this article, we propose a DAG-based blockchain, named 3D-DAG , to greatly improve the scalability and performance without compromising security. The system addresses the trilemma of decentralization, scalability, and security. Technically, our 3D-DAG consists of two layers of chains: DAGchain and mainchain . The DAGchain organizes the transactions in DAG topology, without having to solve the forks. They select a small group of validators from a large number of miners to make up the committee for consensus procedures. The design of DAGchain improves scalability by enabling parallel transaction processing. Based on that, the mainchain plays the role of checkpoint, periodically packaging and recording received transactions from DAGchain for finality. We also provide a prototype implementation with detailed evaluations. Experimental results show our 3D-DAG can meet the performance (a peak value of \(9.82\times 10^{4}\) TPS) that is expected by DApps in the context of Web3.

Sergii Grybniak, Igor Mazurok, Yevhen Leonchyk, Alisa Vorokhta · 5 authors

The emergence of Web3 technology has revolutionized numerous sectors, including gaming. Web3 gaming represents a paradigm shift in the gaming industry with the incorporation of Distributed Ledger Technology (DLT), Decentralized Finance (DeFi), and Non-Fungible Tokens (NFTs) into game development and operations. The Waterfall platform was originally created as a high-speed, high-performance network focused on financial applications. However, a number of unique features of this platform provide interesting opportunities for developing gaming applications. In this article, we consider these features and discuss how they can be adapted to solve the pressing issues of Web3 gaming.

Adnan Imeri, Oussama Gharsallaoui, Thierry Grandjean, Uwe Roth

The rapid evolution of data management in decentralized environments requires innovative solutions to ensure security, accessibility, and efficiency. This paper presents a scientific approach for secure data management in swarmedge computing. The approach leverages DAO, smart contracts, and IPFS to enhance data availability, security, and privacy. It addresses key challenges in integrating off-chain data with blockchain ecosystems. The exploitability of the oracles for data tokenization, smart contracts for metadata mapping and data files based on metadata, and access control are significant contributions from the scientific approach. The proposed approach presents an advanced decentralized, smart contract-driven data management system, integrating non-fungible tokens (NFTs) for data ownership and access rights.

Matthieu Bettinger

Résilience à la collusion dans les mécanismes de places de marché décentralisées Les places de marché décentralisées dans le Web3 cherchent à protéger leurs utilisateurs contre la censure, les biais et les points de défaillance uniques qui peuvent exister dans leurs homologues centralisés. Pourtant, certains mécanismes ont tendance à rester centralisés, par exemple le moteur de recherche permettant de découvrir de nouvelles ressources sur le marché. De telles vulnérabilités ont été exploitées sur des places de marché décentralisées ces dernières années : il est d'autant plus essentiel de fournir des mécanismes de protection. Dans cette thèse, nous proposons des protocoles pour assurer la fiabilité et l'équité des mécanismes des places de marché, notamment par la résilience à la collusion d'acteurs malveillants. Tout d'abord, pour traiter la sélection décentralisée d'un sous-ensemble de participants parmi une population comprenant des acteurs malveillant, nous proposons un protocole basé sur la blockchain pour éviter que les acteurs malveillants n'influencent la sélection à leur avantage. Ensuite, en considérant des ensembles de participants sélectionnés qui travailleront ensemble sur des tâches dans une place de marché décentralisée de ressources cloud, dans un environnement sans accès à des informations fiables ou non confidentielles, nous présentons un mécanisme d'incitation qui punit ou récompense collectivement les participants aux tâches en fonction du résultat de leurs tâches. Nous décrivons et évaluons également la manière d'atteindre un taux de réussite cible des tâches de la place de marché : l'algorithme que nous proposons est capable d'atteindre les objectifs définis et de réduire par 5 à 10 fois le taux d'échec par rapport à un système sans protection. Par ailleurs, nous montrons comment les fournisseurs du moteur de recherche d'une place de marché décentralisée peuvent favoriser un sous-ensemble d'utilisateurs du moteur de recherche. Nous protégeons ces moteurs de recherche avec notre protocole COoL-TEE, qui permet aux utilisateurs honnêtes d'éviter les fournisseurs malveillants de ce moteur de recherche, qui retardent de manière sélective les réponses au profit des utilisateurs qui les soudoient. Les utilisateurs honnêtes collaborent avec des environnements d'exécution de confiance (Trusted Execution Environment, TEE) au sein des machines hôtes des fournisseurs du moteur de recherche, afin de sélectionner des fournisseurs proches, rapides et honnêtes. A partir de simulations d'utilisateurs envoyant des requêtes depuis le monde entier à des fournisseurs géo-distribués hébergés dans des centres de données, nous illustrons comment COoL-TEE réduit l'avantage des utilisateurs malveillants à un niveau proche d'un scénario sans attaques. Enfin, de nombreux protocoles traditionnels et basés sur les TEEs requièrent des mesures temporelles fiables pour leur logique d'exécution, y compris COoL-TEE. Cependant, des attaquants qui contrôlent le système d'exploitation sont capables d'attaquer la perception du temps du TEE et, par conséquent, de manipuler les protocoles utilisant les mesures temporelles fournies. Nous contribuons une implémentation publique du protocole d'état-de-l'art Triad, dont le code source est fermé, et nous menons des attaques sur celui-ci de manière empirique. Sa calibration peut être manipulée pour affecter la vitesse d'horloge perçue par le TEE. En outre, les attaques sur une machine compromise peuvent se propager aux machines honnêtes participant au protocole de temps de confiance de Triad. Nous discutons comment atténuer ces vulnérabilités afin d'améliorer la résilience contre de telles attaques.

Bettinger, Matthieu

Decentralized marketplaces in Web3 aim to protect against censorship, bias, and single points of failure that may exist in their centralized counterparts. Still, some mechanisms tend to remain centralized, for example the search mechanism that enables discovery of new assets in the market. Such vulnerabilities have been exploited in live marketplaces in recent years: it is all the more essential to provide protection mechanisms. In this thesis, we propose protocols to uphold the reliability and fairness of marketplace mechanisms, notably through resilience against colluding malicious actors. First, to address decentralized selection of a subset of participants among a population comprising malicious actors, we contribute a blockchain-based protocol to avoid malicious actors swaying selection to their benefit. Then, considering selected sets of participants that will work together on tasks in a decentralized computing marketplace, in an environment with no access to trustworthy or non-confidential monitoring information, we present an incentive mechanism that collectively punishes or rewards task participants based on the outcome of their tasks. We also describe and evaluate how to meet a target success rate for the marketplace's tasks: our proposed algorithm is able to meet such targets and to reduce the failure rate by 5 to 10 times compared to an unprotected system. Additionally, we show how providers of a marketplace's search mechanism can favor a subset of search consumers, granting them an unfair advantage in accessing information about the most recent state of the market. We protect decentralized marketplaces' search with our protocol COoL-TEE, which enables honest search consumers to avoid malicious search providers, who selectively delay responses to benefit colluding consumers. Honest consumers collaborate with Trusted Execution Environments (TEEs) inside the host providers, in order to select close, fast, and honest providers. Using simulations of consumers sending search requests from around the globe to geo-distributed providers hosted in datacenters, we illustrate how COoL-TEE reduces malicious advantage close to a scenario without attacks. Finally, many TEE and traditional protocols rely on trustworthy time measurements for their execution logic, including COoL-TEE. However, attackers controlling the operating system are capable of attacking the TEE's time perception and, in turn, of manipulating the protocols depending on the timestamps. We contribute a public implementation of the state-of-the-art but closed-source protocol Triad and empirically showcase attacks. Calibration can be manipulated to affect the TEE's perceived clock speed. Furthermore, attacks on a compromised machine could propagate to honest machines participating in Triad's trusted time protocol. We discuss mitigations to these vulnerabilities for higher resilience against such attacks.

Giamouridis, George, Kang, Boojoong, Aniello, Leonardo

The Domain Name System (DNS) is the backbone of the Internet, but remains highly centralised, creating<br/>risks related to censorship, surveillance, and single points of failure. While much of the focus has been on<br/>securing and decentralising DNS as a whole, recursive resolvers continue to rely on central infrastructure.<br/>This paper proposes a decentralised DNS resolver architecture that replaces traditional recursive resolvers<br/>with a decentralised alternative. The system uses the Chord protocol and distributed ledger technology<br/>(DLT) to distribute DNS resolution across a network of cooperating nodes, without altering existing<br/>zone authority structures. We present the key components of the architecture, including peer discovery,<br/>query routing, caching, updating and trust handling, and we analyse how this architecture overcomes<br/>the previously mentioned limitations.