This paper proposes Atomic Ownership Blockchains (AOB), a novel blockchain architecture designed to address scalability and decentralization challenges in distributed ledger systems. AOB introduces an approach where each atomic object is represented by an independent blockchain, potentially allowing for horizontal scaling and enhanced security. The system stores only ownership transfer records, which may enable parallel transaction processing and improved throughput. By eliminating traditional mining and voting mechanisms, AOB aims to mitigate certain security risks while proposing an implicit consensus mechanism for resolving forks. The AOB architecture could potentially support the digitization of real-world assets and enable decentralized applications involving shared or fractional ownership. This paper presents the theoretical framework of AOB, discussing its potential advantages and outlining areas for future research and empirical validation. Practical implementation and rigorous testing are necessary to fully assess its viability and impact on digital ownership paradigms.
Maxim Jourenko, Mario Larangeira, Kanta Kurazumi, Keisuke Tanaka
Abstract Blockchain-based systems, in particular cryptocurrencies, face a serious limitation: scalability. This holds, especially, in terms of the number of transactions per second. Several alternatives are currently being pursued by both the research and practitioner communities. One venue for exploration is on protocols that do not constantly add transactions on the blockchain and therefore do not consume the blockchain’s resources. This is done using off-chain transactions, i.e. , protocols that minimize the interaction with the blockchain, also commonly known as Layer-2 approaches. This work relates several existing off-chain channel methods, also known as payment and state channels, channel network construction methods, and other components such as channel and network management protocols, e.g. , routing nodes. All these components are crucial to keep the usability of the channel and are often overlooked. In this work, we propose a taxonomy for all the components of Layer-2. We provide extensive coverage of the state-of-the-art protocols available outline their respective approaches, and discuss their advantages and disadvantages.
The increasing prevalence of Maximal Extractable Value (MEV) in blockchain networks has highlighted critical challenges in achieving fair and predictable transaction ordering. On Ethereum, where block builders possess unrestricted control over transaction sequencing, users face significant risks from frontrunning and sandwich attacks, particularly within decentralized finance (DeFi) applications interacting with shared contract states. To address this issue, this paper proposes a hybrid MEV mitigation method employing Lamport-style logical clocks, designed to establish a local causal ordering mechanism within individual smart contracts. The proposed approach equips each smart contract, such as a decentralized exchange liquidity pool, with a local logical timestamp counter. Transactions submitted to the contract carry logical timestamps, enabling the enforcement of a causally consistent execution order. A key benefit of this method is that it does not necessitate alterations to Ethereum’s global consensus mechanism, thus ensuring compatibility with the current Ethereum ecosystem, as well as rollups and modular app-chain architectures. The study details the protocol design, explores various implementation strategies for both on-chain and off-chain execution environments, and addresses resilience against adversarial attempts such as timestamp manipulation and denial-of-service attacks. The primary advantage of this approach lies in its effectiveness in mitigating intra-contract MEV extraction by strictly controlling transaction reordering for conflicting state interactions, while preserving concurrency for non-conflicting transactions. Findings indicate that the use of local Lamport clocks provides a practical, low-overhead solution for MEV-sensitive applications, including decentralized exchanges and rollup sequencing systems.
The Monty-Hall (parameterized strategist-host) Theorem along with a constructive proof is presented, by solving the corresponding Monty-Hall Problem, wherein the host plays a parameterized strategy on the guest. It establishes the limits on the range of values for the probability of winning the prize. Eight extreme strategies (corresponding to the set of extreme values for the three perturbation parameters) have been well characterized. It is shown that there does not exist any strategy wherein a switched-choice will always (irrespective of the placement of the prize and irrespective of the initial-choice of the guest) lead to an enhancement in the chances of winning the prize. The classical Monty-Hall Problem is a special case with zero-value for each of the three perturbation parameters. This paper is an attempt to correct the errors (of long-standing historical significance) in the application of statistical methodology in solving the classical Monty-Hall Problem - one of them being the erroneous use of conditional probabilities for updating the knowledge to facilitate the decision-making by the guest, based on the information about a losing-choice, which itself is dependent on the initial-choice of the guest. Similar scenarios in data science, machine learning & artificial intelligence can have serious far-reaching consequences.
Tradicionalne metode preverjanja prisotnosti, kot so ročno beleženje ali QR kode, so podvržene manipulaciji in ne zagotavljajo zadostne varnosti ter zasebnosti uporabnikov. Magistrsko delo naslavlja te izzive z razvojem decentraliziranega sistema za preverjanje fizične prisotnosti, ki temelji na tehnologiji verige blokov in ničelno spoznavnih dokazih (zk-SNARK). Sistem integrira ZoKrates ogrodje za generiranje zasebnih dokazov, geolokacijsko verifikacijo z GPS koordinatami, Ethereum pametne pogodbe ter hibridni pristop k shranjevanju podatkov. Implementirani so bili večplatformski uporabniški vmesniki (spletna in mobilna aplikacija) z različnimi načini potrjevanja prisotnosti. Razvita rešitev predstavlja funkcionalen in robusten sistem, ki omogoča varno ter transparentno preverjanje prisotnosti brez razkrivanja osebnih podatkov uporabnikov.
Ivan Homoliak, Martin Perešíni, Marek Tamaškovič, Timotej Ponek · 6 authors
Proof-of-Stake (PoS) consensus protocols often face a trade-off between performance and security. Protocols that preelect leaders for subsequent rounds are vulnerable to Denial-of-Service (DoS) attacks, which can disrupt the network and compromise liveness. In this work, we present PoS-CoPOR, a single-chain PoS consensus protocol that mitigates this vulnerability by integrating a native onion routing mechanism into the consensus protocol itself. PoS-CoPOR combines stake-weighted probabilistic leader election with an anonymization layer that conceals the network identity of the next block proposer. This approach prevents targeted DoS attacks on leaders before they produce a block, thus enhancing network resilience. We implemented and evaluated PoS-CoPOR, demonstrating its ability to achieve a throughput of up to $110 \mathrm{tx} / \mathrm{s}$ with 6 nodes, even with the overhead of the anonymization layer. The results show that native anonymization can provide robust DoS resistance with only a modest impact on performance, offering a solution to build secure and scalable PoS blockchains.
Aniket P. Kakde, Karan M. Bhoyar, Muhammad Aiman Shad, Prof. Sudesh A. Bachwani
Autonomous agents powered by Large Language Models (LLMs) require reliable and standardized frameworks to connect tools, exchange contextual information, and synchronize tasks across diverse systems. Despite growing interest in such agents, current integration with external tools remains disjointed. Developers often have to manually create interfaces, handle authentication protocols, and navigate incompatible function-calling standards across platforms. To overcome these limitations and promote the evolution of agentic AI, it is critical to establish standardized communication protocols that ensure interoperability—enabling agents and systems to seamlessly discover each other’s capabilities, share data, and coordinate operations. This paper explores a structured overview of emerging communication standards for agents, focusing on the Model Context Protocol (MCP), Agent Communication Protocol (ACP), Agent-to-Agent Protocol (A2A), and Agent Network Protocol (ANP). MCP utilizes a JSON-RPC based client-server architecture to enable secure execution of tools and well-typed data transfer. ACP introduces a REST-compliant message structure with support for asynchronous streaming and multipart formats, facilitating rich, multimodal agent outputs.A2A enables agents to delegate tasks peer-to-peer using capability-rich Agent Cards, enabling scalable and distributed workflows across organizations. ANP facilitates agent discovery and secure collaboration in open networks, leveraging decentralized identifiers (DIDs) and semantic graphs based on JSON-LD.
Proof-of-stake blockchains require consensus protocols that support Dynamic Availability and Reconfiguration (so-called DAR setting), where the former means that the consensus protocol should remain live even if a large number of nodes temporarily crash, and the latter means it should be possible to change the set of operating nodes over time. State-of-the-art protocols for the DAR setting, such as Ethereum, Cardano's Ouroboros, or Snow White, require unrealistic additional assumptions, such as social consensus, or that key evolution is performed even while nodes are not participating. In this paper, we identify the necessary and sufficient adversarial condition under which consensus can be achieved in the DAR setting without additional assumptions. We then introduce a new and realistic additional assumption: honest nodes dispose of their cryptographic keys the moment they express intent to exit from the set of operating nodes. To add reconfiguration to any dynamically available consensus protocol, we provide a bootstrapping gadget that is particularly simple and efficient in the common optimistic case of few reconfigurations and no double-spending attempts.
Moderne Blockchains verarbeiten mittlerweile Zehntausende Transaktionen pro Sekunde. Mit steigendem Durchsatz wachsen jedoch auch die Anforderungen für die Verifikation von Blockchains. Zentralisierte Node-as-a-Service (NaaS)-Anbieter (z.B. Infura oder Alchemy) bieten zwar praktische APIs, schaffen jedoch zusätzliche Vertrauensabhängigkeiten und bergen Risiken in Bezug auf Datenschutz und Zensurfreiheit. Ein selbst betriebener Full Node ermöglicht Datenzugang ohne zusätzliche Vertrauensannahmen, ist für die meisten Nutzerinnen und Nutzer jedoch aufgrund des hohen Ressourcenbedarfs kaum praktikabel. Im Gegensatz dazu arbeiten Light Clients deutlich ressourcenschonender, können dafür den vollständigen Anwendungszustand nicht rekonstruieren. Ein neuer Ansatz, der als Sparse Client (bzw. Partially Stateless Client) bekannt ist, ermöglicht dagegen die verifizierbare Überwachung eines Teilzustands der Blockchain, indem ausschließlich jene Transaktionen heruntergeladen, ausgeführt und gespeichert werden, die diesen Teilzustand lesen oder verändern. Bisher fehlt eine fundierte wissenschaftliche Aufarbeitung: Die einzige verfügbare Arbeit zu diesem Thema weist deutliche Limitierungen auf und wurde weder implementiert noch umfassend evaluiert. In dieser Arbeit präsentieren wir zwei Sparse-Client-Protokolle für EVM-kompatible Blockchains: Sparseth für zustandsbasierte Synchronisation und Eventeth für ereignis-basierte Synchronisation. Beide Protokolle ermöglichen es Nutzerinnen und Nutzern, überprüfbare Teilmengen der globalen Transaktions- oder Ereignissequenz und des damit verbundenen Zustands zu verwalten, ohne dass zusätzlicher Validator-Aufwand erforderlich ist. Sparseth nutzt einen Interaktionszähler, um sicherzustellen, dass keine relevanten Transaktionen ausgelassen werden, während Eventeth eine kryptographische Hash-Kette einsetzt, um die Integrität und Vollständigkeit der Ereignisse zu gewährleisten. Im Gegensatz zu bestehenden Ansätzen arbeiten beide Protokolle vollständig auf der Ausführungsschicht und sind mit EVM-basierten Blockchains kompatibel. Unsere formale Analyse zeigt, dass beide Protokolle im angenommenen Widersacher-Modell Sicherheit, Liveness und spärliche Gültigkeit garantieren. Unsere Implementierung in Go demonstriert die praktische Umsetzbarkeit: Event Nodes senken den Bandbreitenbedarf um über 95%, Sparse Nodes reduzieren die auszuführenden Transaktionen um 92% gegenüber Full Nodes. Die Gas-Kosten steigen um 4-16% für typische dApp-Transaktionen, ein Mehraufwand, der sich durch L2-Lösungen und ökonomische Anreize weiter mindern lässt.
The transition to post-quantum cryptography poses an unprecedented challenge for Bitcoin and Ethereum, as it involves implementing a defensive downgrade that imposes immediate, severe costs with no tangible benefits. While quantum computers capable of breaking secp256k1 require between 523–2,500 logical qubits, with the author deriving 523 logical qubits as an algorithmic lower bound (not inclusive of arithmetic and ancilla qubits) for a canonical Shor/phase-estimation circuit using the formula QL = 2⌈log2(n)⌉ + 2 + ⌈log2(2 + 1/(2ε))⌉ for ε = 0.001, and conservative estimates ranging up to 2,500 logical qubits based on comprehensive resource models—significantly less than the 2,100–2,400 logical qubits es- timated for general elliptic curves—current systems achieve only ∼100 logical qubits. IBM’s quantum roadmap projects 500–1,000 logical qubits by 2029, placing the critical threshold within 4–10 years depending on which estimate proves accurate. This timeline collides with the reality that convincing decentralized communities to accept 50% capacity loss and 2– 3× fee increases may take 10–15 years in themselves, based on historical governance patterns where even beneficial upgrades required 2–5+ years. Current testnet implementations on per- missioned systems show measurable performance degradation. Critically, this data comes from fundamentally different architectures than permissionless networks, which will likely experience 30–50% additional performance degradation due to global verification requirements, heterogeneous hardware, and compounding propagation delays. This methodological limitation—extrapolating from permissioned to permissionless systems—represents a critical infrastructure failure that introduces massive uncertainty into migration planning. Com- pounding this challenge, secp256k1 is not officially approved by NIST under FIPS 186-5 or SP 800-186, creating additional regulatory vulnerabilities. Beyond transient impacts, PQC creates permanent state bloat, with quantum-resistant accounts requiring 59 times more storage (1,952 bytes / 33 bytes = 59.2× for ML-DSA-65), thereby accelerating centralization- tion. This paper presents a comprehensive framework acknowledging these harsh realities. While we propose specific BIP/EIP implementations and optimization strategies that might achieve 50–60% capacity retention, we recognize that the quantum threat timeline may now be shorter than even the minimum viable migration period. Unlike beneficial upgrades like SegWit (which took 20 months for activation and 5+ years for 50% adoption despite offering improvements), PQC migration is a purely defensive measure imposing only costs. The stark reality: blockchain communities must choose between accepting immediate emergency action or facing quantum vulnerability by 2029.
Sharding has emerged as a critical solution to address the scalability challenges faced by blockchain networks, enabling them to achieve higher transaction throughput, reduced latency, and optimized resource usage. This paper investigates the advancements, methodologies, and adoption potential of sharding in the context of Hedera, a distributed ledger technology known for its unique Gossip about Gossip protocol and asynchronous Byzantine Fault Tolerance (ABFT). We explore various academic and industrial sharding techniques, emphasizing their benefits and trade-offs. Building on these insights, we propose a hybrid sharding solution for Hedera that partitions the network into local and global committees, facilitating efficient cross-shard transactions and ensuring robust security through dynamic reconfiguration. Our analysis highlights significant reductions in storage and communication overhead, improved scalability, and enhanced fault tolerance, demonstrating the feasibility and advantages of integrating sharding into Hedera's architecture.
Namrata Marium Chacko, V G Narendra, Mamatha Balachandra, T Manoj
Blockchain technology has seen a rapid pace of development and expanded application domains swiftly due to the rising demand for decentralized trust, transparency, and integrity. The consensus algorithm plays a critical role in ensuring trust, immutability and governance of the decentralized network. However, traditional consensus face challenges such as high energy consumption, low scalability, security, and fault tolerance. Researchers have been investigating Lightweight Consensus to overcome these challenges. Lightweight Consensus is a mechanism that enables a more efficient and scalable blockchain system while ensuring security and immutability. This work uses the Systematic Literature Review method to comprehend Lightweight Consensus. 127 studies were grouped based on application specific network, and an in-depth analysis was done on the characteristics of the consensus. A novel taxonomy of Lightweight Consensus based on the agreement method and round propagation is proposed. Various parameters that needed consideration for a Lightweight Consensus are also analyzed. Finally, the study makes recommendations for future research on Lightweight Consensus in blockchain, emphasizing the importance of more empirical investigations and real-world implementations. This study offers a comprehensive overview of the current research landscape on lightweight consensus in blockchain, shedding light on its potential impact on the evolution of blockchain technology. It also serves as a valuable guide for researchers, helping them identify the most suitable consensus features for specific application domains with unique requirements.
In recent years, blockchain consensus mechanisms have evolved significantly from the original proof-of-work design, transitioning towards more efficient and scalable alternatives. This paper presents a comprehensive review and analysis framework for blockchain consensus mechanisms based on a systematic examination of 200+ publications. We categorize consensus mechanisms into four performance-oriented groups: high throughput, strong security, low energy, and flexible scaling, each addressing specific trade-offs in the blockchain trilemma of decentralization, security, and scalability. Through quantitative metrics including transactions per second, energy consumption, fault tolerance, and communication complexity, we evaluate mainstream mechanisms. Our findings reveal that no single consensus mechanism optimally satisfies all performance requirements, with each design involving explicit trade-offs. This paper provides researchers and practitioners with a structured framework for understanding these trade-offs and selecting appropriate consensus mechanisms for specific application contexts. Finally, we discussed future development trends, as well as regulatory and ethical considerations.
The InterPlanetary File System (IPFS) has been successfully established as the de facto standard for decentralized data storage in the emerging Web3. Despite its decentralized nature, IPFS nodes, as well as IPFS content providers, have converged to centralization in large public clouds. Centralization introduces BGP routing-based attacks, such as passive interception and BGP hijacking, as potential threats. Although this attack vector has been investigated for many other Web3 protocols, such as Bitcoin and Ethereum, to the best of our knowledge, it has not been analyzed for the IPFS network. In our work, we bridge this gap and demonstrate that BGP routing attacks can be effectively leveraged to censor content in IPFS. For the analysis, we collected 3,000 content blocks called CIDs and conducted a simulation of BGP hijacking and passive interception against them. We find that a single malicious AS can censor 75% of the IPFS content for more than 57% of all requester nodes. Furthermore, we show that even with a small set of only 62 hijacked prefixes, 70% of the full attack effectiveness can already be reached. We further propose and validate countermeasures based on global collaborative content replication among all nodes in the IPFS network, together with additional robust backup content provider nodes that are well-hardened against BGP hijacking. We hope this work raises awareness about the threat BGP routing-based attacks pose to IPFS and triggers further efforts to harden the live IPFS network against them.
Ethereum enables the creation and execution of decentralized applications through smart contracts, that are compiled to Ethereum Virtual Machine (EVM) bytecode. Once deployed in the blockchain, the bytecode is immutable; hence, ensuring that smart contracts are bug-free before their deployment is of utmost importance. A crucial preliminary step for any effective static analysis of EVM bytecode is the extraction of the control-flow graph (CFG): this presents significant challenges due to potentially statically unknown jump destinations. In this paper we present a novel approach, based on Abstract Interpretation, aiming to build a sound CFG from EVM bytecode smart contracts. Our analysis, which is implemented in our static analyzer EVMLiSA, is based on a parametric abstract domain that approximates concrete execution stacks at each program point as an l -sized set of abstract stacks of maximal height h ; the results of the analysis are then used to resolve the jump destinations at jump nodes. Furthermore, EVMLiSA includes a checker for reentrancy detection, working on the constructed CFG. Our experiments show that, by fine-tuning the analysis parameters, EVMLiSA is able to build sound CFGs for all real-world smart contracts in the considered benchmark suite. Moreover, EVMLiSA successfully detects all reentrancy vulnerabilities in EVM bytecode smart contracts, while producing a small number of false positives.
Andrea Esposito, Francesco Rossi, Marco Bernardo, Francesco Fabris · 5 authors
Algorand is a scalable and secure permissionless blockchain that achieves proof-of-stake consensus via cryptographic self-sortition and binary Byzantine agreement. In this paper we present a process algebraic model of the Algorand consensus protocol with the aim of enabling formal verification. Our model captures the behavior of participants in terms of the structured alternation of consensus steps toward a committee-based agreement. We validate the correctness of the protocol in the absence of adversaries and then extend our model to assess the influence of coordinated malicious nodes that can force the commit of an empty block instead of the proposed one. The adversarial scenario is analyzed through an equivalence-checking-based noninterference framework that we have implemented in the CADP verification toolkit. In addition to highlighting both the robustness and the limitations of the Algorand protocol under adversarial assumptions, this work illustrates the added value of using formal methods for the analysis of consensus algorithms within blockchains.
This paper presents a framework for analyzing and modeling validator behavior in dynamic consensus protocols. A discrete state-based model is proposed in order to represent four key validator states: majority, non-faulty minority, faulty minority, and non-validator, enabling systematic behavioral analysis through three complementary metrics: Jensen-Shannon Divergence (JSD) for entropy-based behavioral differences, the Bhattacharyya Coefficient for distribution similarity, and Wasserstein distance for state transition costs. To identify coherent validator groups and detect outliers, an HDBSCAN (Hierarchical Density-Based Spatial Clustering of Applications with Noise) clustering is used since it is well-suited for detecting clusters in data with varying densities. Using JSD-based similarity measures in HDBSCAN, transient convergence patterns and stable behavioral clusters are uncovered, even in decentralized networks with diverse fault conditions. Simulation results on a 50-node network demonstrate the framework’s effectiveness, providing insights into system dynamics and offering tools for validator selection, fault detection, and stability monitoring in distributed ledger systems. This approach is particularly relevant, as consensus protocols evolve beyond traditional PBFT (Practical Byzantine Fault Tolerance) implementations, combining theoretical metrics with clustering techniques to enhance consensus robustness.
Meihua Xiao, Y. P. Xu, Yongtuo Zhang, Ke Yang · 6 authors
Smart contracts, as a critical application of blockchain technology, significantly enhance its programmability and scalability, offering broad application prospects. However, frequent security incidents have resulted in substantial economic losses and diminished user trust, making security issues a key challenge for further development. Since smart contracts cannot be modified after deployment, flaws in their design or implementation may lead to severe consequences. Therefore, rigorous pre-deployment verification of their correctness is particularly crucial. This paper explores the symmetry in control flows and state transitions of Solidity smart contracts and leverages this inherent structural symmetry to develop a normalized state transition model based on a finite state machine. The FSM model is subsequently formalized into a Promela model with the Spin model checker. By integrating manually defined Linear Temporal Logic formulas with those generated by Smart Pulse, the Promela model is formally verified in Spin to ensure the correctness and security of smart contracts. This approach establishes a systematic verification framework, providing effective support to enhance the reliability and security of smart contracts.
Siamak Abdi, Giuseppe Di Fatta, Atta Badii, Giancarlo Fortino
Blockchain is a distributed ledger technology that has applications in many domains such as cryptocurrency, smart contracts, supply chain management, and many others. Distributed consensus is a fundamental component of blockchain systems that enables secure, precise, and tamper-proof verification of data without relying on central authorities. Existing consensus protocols, nevertheless, suffer from drawbacks, some of which are related to scalability, resource consumption, and fault tolerance. We introduce Blockchain Epidemic Consensus Protocol (BECP), a novel fully decentralised consensus protocol for blockchain networks at a large scale. BECP follows epidemic communication principles, without fixed roles like validators or leaders, and achieves probabilistic convergence, efficient message dissemination, and tolerance to message delays. We provide an extensive experimental comparison of BECP against classic protocols like PAXOS, RAFT, and PBFT, and newer epidemic-based protocols like Avalanche and Snowman. The findings indicate that BECP provides desirable gains in throughput, consensus latency, and substantial message-passing efficiency compared to existing epidemic-based approaches, validating its usability as an effective and scalable approach for next-generation blockchain systems.
Data marketplace are rapidly gaining traction as critical components of the modern data economy. However, traditional centralized marketplaces suffer from inherent challenges such as data leakage, lack of user control and single points of failure. To address these limitations, we propose Versatile Peer Network (VePran) – a decentralized data market place built on the Web3 suite of technologies. VePraN is designed to be modular, scalable and aligned with open standards, ensuring broad interoperability and future extensibility. Leveraging the InterPlanetary File System for persistent storage and blockchain for identity and ownership management, the platform offers a robust infrastructure that enhances data security and provenance. Unlike existing buyer centric solutions, VePraN adopts a seller oriented approach, empowering data owners with greater autonomy, fair exchange and control over their data assets. In addition to enabling secure data exchange, the platform facilitates the trading of machine learning models, expanding its utility in AI driven ecosystems. Verification mechanisms such as Merkle roots and Non- Fungible Tokens are employed to ensure data integrity and authenticity. This paper presents the architecture and implementation of VePraN as a foundational step toward a more equitable and resilient data exchange system.
Blockchain consensus algorithms face trade-offs between performance, security, decentralization, and energy efficiency. Proof-of-Work (PoW) ensures strong security but is energy-intensive. Proof-of-Stake (PoS) is efficient but may risk centralization. Byzantine Fault Tolerance (BFT) offers low latency but lacks scalability. This paper proposes an Adaptive Hybrid Consensus (AHC) algorithm that dynamically integrates PoW, PoS, and BFT elements. The AHC mechanism is designed for general-purpose blockchain environments and can adapt to real-time network conditions. AHC is a promising solution for next-generation blockchain systems as it has the potential to significantly improve latency, throughput, and energy consumption [13][14].