Blockchain has emerged as a promising technology for enabling decentralized, tamper-evident, and auditable data sharing among multiple untrusted parties. However, practical deployments in distributed computing environments face a persistent trade-off between scalability and privacy. Public blockchain networks often expose transactional metadata, compromising confidentiality, while privacy-preserving blockchainsâsuch as those leveraging zero- knowledge proofs (ZKPs)âtypically suffer from reduced throughput and increased latency due to the computational overhead of proof generation and verification. Similarly, scalability-enhancing techniques like Layer- 2 rollups, sharding, and state channels often provide minimal privacy guarantees, leaving sensitive metadata vulnerable to inference attacks. This paper proposes a privacy-preserving and scalable blockchain architecture designed specifically for secure data sharing in distributed systems, such as federated cloud platforms, healthcare data networks, IoT ecosystems, and inter-bank settlements. The architecture integrates Layer-2 zero- knowledge rollups with a modular Layer-1 settlement layer (Ethereum or Hyperledger Fabric), decentralized storage (IPFS/Filecoin), and fine-grained access control mechanisms. By batching transactions off-chain, generating succinct ZK proofs for validity, and committing only aggregate proofs and state roots to the base chain, the system achieves both confidentiality and high throughput. The architecture is deployed in a Kubernetes-orchestrated environment, enabling horizontal scaling, automated failover, and comprehensive observability through Prometheus, Grafana, and Jaeger. A prototype implementation demonstrates a throughput improvement of up to$5.8 \times$over baseline privacypreserving blockchains, with latency remaining within acceptable limits for distributed applications. Our evaluation framework compares the proposed design against three baselinesâ Layer-1 only, Layer-1 + privacy, and Layer- 1 + scalabilityâand includes metrics such as throughput, latency, cost, privacy efficacy, and fault tolerance. The results indicate that combining privacy-preserving Cryptography with scalable rollup architectures is both feasible and beneficial for real-world distributed systems, offering a compelling pathway toward secure, high-performance blockchain applications.
MegaETH leads the way in blockchain technology. It created the Real-Time Proof of Stake (RTPoS) consensus method. This new approach tackles regular blockchain networks' main speed and scaling issues in regular blockchain networks. It allows fast transaction processing without giving up security or decentralization. Meg+aETH focuses on high output and can handle thousands of transactions per second (TPS). This opens doors for many decentralized apps (dApps) across different fields. A big plus of the Ethereum platform is how MegaETH fits into the Ethereum ecosystem. It uses smart contract features and works well with the Ethereum Virtual Machine (EVM). This compatibility helps the ecosystem grow and brings new ideas by making it easier for more developers to join in. MegaETH also cares about the environment. Its design uses less energy, meaning it has less impact on nature than proof-of-work systems. MegaETH brings together efficiency, security, and the ability to grow. This sets a new bar for real-time blockchain apps. As a result, it speeds up how the economy takes on decentralized solutions. It also lets developers and companies explore new ways to use this technique.
Blockchain is known for being a decentralized ledger with distributed storage. It has changed whole industries across borders by increasing security, transparency, and reliance on intermediaries. Thus, from its initial design for cryptocurrencies like Bitcoin, Blockchain extends its transformative potential for a wide range of fields such as finance, supply chain management, and healthcare. The contribution of this research is an in-depth analysis of blocks, transactions, and consensus mechanisms constituting the anatomy of a blockchain. We have paid particular attention to block-structure research in our work, emphasizing that a block is an indivisible information unit, each containing transactional data and cryptographic hashes that link it to the previous block. One of the most valuable parts of our research consists of an innovative analysis of a consensus mechanism. We explain how different algorithms ensure the validity and sequence of transactions among the network nodes, and review the strengths and weaknesses of algorithms, namely, Proof of Work (PoW), Proof of Stake (PoS), and Delegated Proof of Stake (DPoS). The key highlights in this work are the case studies of well-established blockchain platforms, including Bitcoin and Ethereum. These manifest our insight into their operational efficiencies and mechanisms for security. Further, we demonstrate empirical results on the processing times for transactions and scalabilities of blockchains under different network conditions. Additionally, the challenges of scalability and energy consumption are put forth, for which novel approaches may be proposed for future blockchain development. The study contributes to the further development of blockchain technology by informing future research directions toward solving the existing limitations and exploring new applications within emergent sectors.
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.
The Execute-Order-Validate (EOV) framework has been used to improve the scalability of blockchains by concurrently executing transactions. However, the EOV framework also poses a critical performance issue. Specifically, when multiple transactions access the same data, only one of them can be committed eventually while the others are aborted due to the strong concurrency control restriction. This inefficiency makes the EOV framework far from practicality since there always exist hotspot variables that can be frequently accessed in real-world scenarios, such as the Fungible Token (FT) and Non-Fungible Token (NFT) online marketplace. In this paper, we propose RapidSnail, a novel EOV framework that enables transactions to execute based on the uncommitted data to reduce the transaction abort rate in such scenarios with hotspot variables. We first propose a new read-write set representation and a concurrency execution schedule algorithm in the execution phase to maintain the concurrent efficiency. Then we propose an effect-based conflict graph construction algorithm in the order phase to handle the conflict transactions based on the new read-write set. Finally, we propose a concurrent commitment schedule algorithm to adopt the new read-write set to validate the transactions concurrently in the validation phase. Our experiment results show that RapidSnail increases the throughput by at least 4Ă compared to the state-of-the-art EOV framework under high contention workload. More specifically, RapidSnail reduces the abort rate by 50%, and achieves at least 4Ă speedup in the order phase and 2.94Ă speedup in the validation phase over the existing EOV frameworks.
Ethereum block building has traditionally been approached using greedy algorithms that prioritize transactions with the highest fee per unit of gas. This work proposes an alternative that considers semantic interactions among transactions and operational constraints to define the utility of transaction combinations. Through a utility model that assigns bonuses and penalties to pairs and triples of transactions, we design algorithms capable of constructing blocks more valuable than those obtained by traditional methods. In experiments with 1,000 real transactions extracted from the network, two algorithms were implemented and evaluated, both grounded in a formulation inspired by job scheduling theory: a classic greedy baseline and the proposed heuristic. The base heuristic achieved approximately 86 % of the utility of the greedy approach ($6.78 \times 10^{20}$vs.$7.81 \times 10^{20}$) while including only 23 transactions. The extended version with greedy fill reached up to 120 % of the reference utility ($1.73 \times 10^{21}$), incorporating 268 transactions compared to 212 for the greedy, while maintaining execution times below 2 seconds. These preliminary results demonstrate the feasibility of capturing additional semantic value within time windows compatible with Ethereum block-building intervals, based on isolated experiments with bounded transaction sets.
Directed Acyclic Graph (DAG) based Distributed Ledger Technologies (DLTs) are promising solution for IoT environments, offering scalability and high transaction throughput. Given the resource constraints of IoT Gateways (GWs), which maintain the ledgers, pruning of a ledger is important to prevent its size from increasing beyond the storage capacity of GWs. However, existing methods cannot simultaneously address the scalability and consistency issues for planning and executing the DAG based ledger pruning, consistency preservation, and orphaned transactions. We explore an approach that Storage Nodes (SNs) of the DAG based DLT plan the ledger pruning in an efficient, scalable, and consistent manner, and then GWs execute it. This paper introduces the Consensus based High Consistency Ledger Pruning (CHCLP) Framework, which uses two key techniques: Pruning List Reduction (PLR) and Consensus-based Pruning Mechanism (CPM). PLR aggressively compresses a long list of prunable transactions to the combination of a single transaction called "Adam Point" and the rest encoded as unique bit string paths from the Adam Point. CPM leverages Practical Byzantine Fault Tolerance consensus among SNs to ensure tamper-resistant agreement on the Pruning List (PL) and maintain DAG consistency across GWs. The CHCLP Framework was implemented by extending an existing benchmark DAG based DLT system. The proposed framework reduced the size of a PL by 98%, and the ratio of orphan transactions decreased to 0.5% compared to the benchmark system, which was 10.3%. The CHCLP Framework reduces the storage consumption of GWs in DAG based DLTs to a desirable extent with high consistency, and can drastically improve their scalability and performance.
The proliferation of multi-vendor autonomous systems (MVAS), such as shared warehouses, necessitates robust cooperation frameworks for robotic agents from different vendors. Ensuring operational integrity in these environments is a critical challenge, as the misbehaviour of a single agent can disrupt the entire system. This paper proposes a decentralised framework for secure and trustworthy multi-robot cooperation. Our approach leverages distributed ledger technology (DLT) to create an immutable record of operations and introduces a novel, lightweight Proof of Location (PoL) mechanism. This PoL allows agents to verify task completions both physically and cryptographically with minimal computational overhead. The framework is further strengthened by a real-time, algorithmic trust and reputation system that continuously evaluates agent behaviour. A key advantage over traditional methods is our support for asynchronous verification, which enhances both scalability and efficiency by removing centralised bottlenecks. Extensive simulations in a warehouse setting demonstrate that our framework effectively detects and mitigates malicious activities, thereby improving the security and performance of MVAS. The broader applicability of our approach is further illustrated through a conceptual case study in a smart city parking scenario.
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 blockchainâs 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 Ethereumâs 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.
This paper presents a new method for discovering Connected Things in a universal way. The method is designed to be used in all kinds of networks, from the smallest sensor networks to the largest interconnected cloud networks. The method allows different technologies to identify entities in different ways. It allows for full or partial identification. It does not rely on collecting information into central repositories, whether such repositories reside on central nodes, or are mirrored on distributed nodes, such as in a distributed ledger of blockchain type or similar. Instead, the method presented relies on local governance of local information and interoperability between nodes across the Internet for finding entities.
Tradicionalne metode preverjanja prisotnosti, kot so roÄno beleĆŸenje ali QR kode, so podvrĆŸene manipulaciji in ne zagotavljajo zadostne varnosti ter zasebnosti uporabnikov. Magistrsko delo naslavlja te izzive z razvojem decentraliziranega sistema za preverjanje fiziÄne prisotnosti, ki temelji na tehnologiji verige blokov in niÄelno 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 veÄplatformski uporabniĆĄki vmesniki (spletna in mobilna aplikacija) z razliÄnimi naÄini potrjevanja prisotnosti. Razvita reĆĄitev predstavlja funkcionalen in robusten sistem, ki omogoÄa varno ter transparentno preverjanje prisotnosti brez razkrivanja osebnih podatkov uporabnikov.
Ivan Homoliak, Martin PereĆĄĂni, Marek TamaĆĄkoviÄ, 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 interoperabilityâenabling agents and systems to seamlessly discover each otherâs 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 fĂŒr die Verifikation von Blockchains. Zentralisierte Node-as-a-Service (NaaS)-Anbieter (z.B. Infura oder Alchemy) bieten zwar praktische APIs, schaffen jedoch zusĂ€tzliche VertrauensabhĂ€ngigkeiten und bergen Risiken in Bezug auf Datenschutz und Zensurfreiheit. Ein selbst betriebener Full Node ermöglicht Datenzugang ohne zusĂ€tzliche Vertrauensannahmen, ist fĂŒr die meisten Nutzerinnen und Nutzer jedoch aufgrund des hohen Ressourcenbedarfs kaum praktikabel. Im Gegensatz dazu arbeiten Light Clients deutlich ressourcenschonender, können dafĂŒr den vollstĂ€ndigen Anwendungszustand nicht rekonstruieren. Ein neuer Ansatz, der als Sparse Client (bzw. Partially Stateless Client) bekannt ist, ermöglicht dagegen die verifizierbare Ăberwachung eines Teilzustands der Blockchain, indem ausschlieĂlich jene Transaktionen heruntergeladen, ausgefĂŒhrt und gespeichert werden, die diesen Teilzustand lesen oder verĂ€ndern. Bisher fehlt eine fundierte wissenschaftliche Aufarbeitung: Die einzige verfĂŒgbare Arbeit zu diesem Thema weist deutliche Limitierungen auf und wurde weder implementiert noch umfassend evaluiert. In dieser Arbeit prĂ€sentieren wir zwei Sparse-Client-Protokolle fĂŒr EVM-kompatible Blockchains: Sparseth fĂŒr zustandsbasierte Synchronisation und Eventeth fĂŒr ereignis-basierte Synchronisation. Beide Protokolle ermöglichen es Nutzerinnen und Nutzern, ĂŒberprĂŒfbare Teilmengen der globalen Transaktions- oder Ereignissequenz und des damit verbundenen Zustands zu verwalten, ohne dass zusĂ€tzlicher Validator-Aufwand erforderlich ist. Sparseth nutzt einen InteraktionszĂ€hler, um sicherzustellen, dass keine relevanten Transaktionen ausgelassen werden, wĂ€hrend Eventeth eine kryptographische Hash-Kette einsetzt, um die IntegritĂ€t und VollstĂ€ndigkeit der Ereignisse zu gewĂ€hrleisten. Im Gegensatz zu bestehenden AnsĂ€tzen arbeiten beide Protokolle vollstĂ€ndig auf der AusfĂŒhrungsschicht und sind mit EVM-basierten Blockchains kompatibel. Unsere formale Analyse zeigt, dass beide Protokolle im angenommenen Widersacher-Modell Sicherheit, Liveness und spĂ€rliche GĂŒltigkeit garantieren. Unsere Implementierung in Go demonstriert die praktische Umsetzbarkeit: Event Nodes senken den Bandbreitenbedarf um ĂŒber 95%, Sparse Nodes reduzieren die auszufĂŒhrenden Transaktionen um 92% gegenĂŒber Full Nodes. Die Gas-Kosten steigen um 4-16% fĂŒr typische dApp-Transaktionen, ein Mehraufwand, der sich durch L2-Lösungen und ökonomische Anreize weiter mindern lĂ€sst.
Blockchain consensus protocols must be thoroughly evaluated for security and resilience, but their large scale makes experimental testing in a lab setting challenging. While numerous simulators exist, there is a need for a more general framework that can translate simulation data into useful and comparable metrics. This thesis addresses this gap by adopting CNSim, a simulator developed at York University that introduces a finality-based approach to evaluating consensus networks. To study the Bitcoin protocol, CNSim was enhanced by designing and implementing a novel framework for modeling adversarial behaviors. Specifically, the Majority Attack was implemented to create a detailed simulation for double-spending scenarios. Using this extended simulator, a systematic evaluation was conducted to assess the attack's impact on transaction finality, quantifying how network resilience degrades as malicious hash power increases. The findings provide valuable insights into the practical security limitations of the Bitcoin protocol and successfully demonstrate the utility of a finality-based methodology for analyzing blockchain consensus mechanisms.
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 523â2,500 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 = 2âlog2(n)â + 2 + âlog2(2 + 1/(2Δ))â for Δ = 0.001, and conservative estimates ranging up to 2,500 logical qubits based on comprehensive resource modelsâsignificantly less than the 2,100â2,400 logical qubits es- timated for general elliptic curvesâcurrent systems achieve only âŒ100 logical qubits. IBMâs quantum roadmap projects 500â1,000 logical qubits by 2029, placing the critical threshold within 4â10 years depending on which estimate proves accurate. This timeline collides with the reality that convincing decentralized communities to accept 50% capacity loss and 2â 3Ă fee increases may take 10â15 years in themselves, based on historical governance patterns where even beneficial upgrades required 2â5+ 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 30â50% additional performance degradation due to global verification requirements, heterogeneous hardware, and compounding propagation delays. This methodological limitationâextrapolating from permissioned to permissionless systemsârepresents 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 = 59.2Ă 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 50â60% 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.