Christian Delgado‐von‐Eitzen, Luis Anido, María Ruiz‐Molina, Manuel J. Fernández Iglesias
ABSTRACT Introduction The popularization of blockchain‐based applications made evident a critical challenge, namely the inherent isolation of these decentralized systems, akin to the disconnected and technologically diverse local area networks of the 1970s. This lack of interoperability limits the potential for widespread adoption and innovation in the blockchain space. While various initiatives aim to bridge this gap, many remain nascent. Methods This article addresses this issue by proposing a robust architecture and practical implementation to interconnect two Ethereum‐based blockchains, enabling seamless smart contract interactions across these chains, and facilitating the exchange of complex information beyond mere token transfers. Results Our work explores the emerging landscape of inter‐blockchain communication, highlighting their current maturity and potential, and providing insights on how to overcome the technical hurdles associated with these protocols, particularly in the context of transmitting complex data and executing cross‐chain function calls. Additionally, we illustrate with a case study the challenges posed by linking private blockchains with public ones, ensuring secure and efficient data exchange. Conclusion This article aims to inspire blockchain researchers and practitioners, presenting a foundational framework for enhancing blockchain interoperability, including detailed, practical steps for its implementation. By laying the groundwork for more connected blockchain ecosystems, we intend to support the continued evolution and widespread adoption of blockchain technology.
Hamra Afzaal, Nazir Ahmad Zafar, Aqsa Tehseen, Shaheen Kousar
Ethereum 2.0 Beacon Chain has adopted the Proof of Stake (PoS) consensus mechanism to significantly advance the security, scalability, and decentralization of blockchain technology. It has played an integral role in organizing validator operations and addressing scalability issues. The Beacon Chain’s rewards and penalty system incentivizes honest behavior and penalizes dishonest actors inside the network. Ensuring the correctness of this mechanism is paramount for guaranteeing the system’s integrity. Therefore, this work formally verifies the rewards and penalty mechanism in the Beacon Chain using model checking, a formal methods-based technique. The formal specification of the rewards and penalties processes and several other epoch operations are described using the Communicating Sequential Programs (CSP#) language. The properties for rewards and penalties procedures are specified with Linear Temporal Logic (LTL). The Process Analysis Toolkit (PAT) model checker is utilized for verifying the formal model against the properties. The PAT model checker takes the specified formal model as input and determines whether the properties are satisfied or violated. The properties are examined in terms of verification time, visited states, total transitions, and memory utilization.
In this paper, we provide an overview of a specific, but rather popular type of blockchain scaling solutions, which are usually referred to as Layer 2 blockchains.These solutions depend on the rollup scaling strategy.First, they all create batches of transactions known as rollups.Second, there are two primary approaches to rollup verifications.One approach is referred to as optimistic rollup, where it is assumed that fraudulent transactions rarely occur and should it happen, then some nodes could raise a challenge, which would lead to the resolution of the problem.The interaction between the asserter and the challenger is referred to as interactive fraud proof.The other approach is a conservative approach, where every rollup batch is associated with a validity proof.For all practical purposes, Ethereum is used as the Layer 1 blockchain because it is the first and only large-scale public blockchain that supports Turing-complete smart contracts.These Layer 2 blockchains typically deploy at least two smart contracts on the Layer 1 blockchain, one to receive rollups from the Layer 2 blockchain, and the other to verify the rollup batch.Furthermore, we provide technical details of two Layer 2 blockchains (i.e., Arbitrum and Optimism) that use the optimistic rollup mechanism, and two Layer 2 blockchains (i.e., Polygon and Starknet) that use validity rollup mechanism.Finally, we analyze the Layer 2 blockchain solutions in the framework of the blockchain trilemma theory.We show that all Layer 2 scaling solutions trade decentralization for better scalability.
Over the last few decades, a large body of research was carried out covering Byzantine Fault Tolerance (BFT) systems. This research has brought forward new techniques, including but not limited, for ordering operations (Abraham et al., 2018; Buchman, 2016; Guo et al., 2020; Bessani et al., 2014; Duan et al., 2018) and state transfer (Bessani et al., 2013; Distler, 2021 , Eischer et al., 2019 ), on networks that suffer from byzantine faults. More recently, the ongoing research on distributed ledgers re-ignited the interest on BFT, due to its high throughput when compared to other alternatives of byzantine consensus ( Vukolić, 2016 ). In this paper we present three contributions covering several aspects, including modular and extensible framework design and implementation, system optimization through development of better networking alternatives, a greater use of parallelism, several ordering protocol improvements and extensive comparative assessment of previous state-of-the-art approaches. First, we introduce Atlas, an open-source modular BFT framework that aims to support the research and development of highly efficient BFT protocols, by decoupling traditionally entangled sub-protocols, e.g., consensus primitive from the execution (Bessani et al., 2014), and deferment of log management to replicated services from state transfer. Atlas allows to further provide modules that can be re-used across different BFT approaches, such as deterministic and probabilistic/randomized models. Second, we present FeBFT, a new BFT implementation developed upon Atlas that combines pre-existing proven ideas from PBFTs, namely its 3-phase consensus and view-change protocol. This base approach is then extended with novel optimizations of the protocol, namely, multi-leader proposals (Stathakopoulou et al., 2019), multi-instance consensus execution (Stathakopoulou et al., 2022; Behl et al., 2015), and configurable batching solution that allow us to reduce the latency while improving throughput at the same time. Third, we offer a comprehensive evaluation amongst our work and other state-of-the-art BFT-SMR implementations, namely, Atlas ( Anon, 2024a ) with FeBFT (Official febft repository 2024), BFT-SMaRt (Bessani et al., 2014) and Themis (Rüsch et al., 2019). With these contributions, we aim to lay the ground work to: (i) improve reusability and hence productivity in BFT(-SMR) development; (ii) increase system safety, performance, scalability and reduce recovery time with the optimizations proposed; (iii) draw insights on the bottlenecks preventing order-of-magnitude improvements in BFT processing from a system’s perspective; and lastly, (iv) improve reproducibility between different BFT (sub-)protocols by allowing for true apples-to-apples comparisons. • Atlas, an open-source, modular BFT framework designed to support the efficient development of BFT protocols by separating traditionally intertwined sub-protocols and allowing for reusable modules across different BFT approaches. • FeBFT, introduces a novel BFT implementation leveraging the Atlas framework, which boosts protocol efficiency via multi-leader proposals and multi-instance consensus execution. It incorporates a batching solution designed to scale with network throughput, prioritizing this over network latency while maintaining the configurability to be tuned for low latency if needed. • Focusing on the essential need for reproducibility in scientific evaluation, Atlas provides a critical framework for accurate comparisons between different protocols. By offering a modular and reusable architecture, it significantly reduces the workload for system researchers in developing and testing implementations. This approach ensures a true apple-to-apple comparison, enabling a more precise and reliable assessment of protocol performance and efficacy. • And lastly, a comprehensive evaluation comparison with two well-known BFT-SMR (deterministic) implementations, namely, BTF-SMaRt and Themis, against FeBFT, our PBFT implementation that uses Atlas.
In database applications involving sensitive data, the dual imperatives of data confidentiality and provable (verifiable) query processing are important. This paper introduces PoneglyphDB, a database system that leverages non-interactive zero-knowledge proofs (ZKP) to support both confidentiality and provability. Unlike traditional databases, PoneglyphDB enhances confidentiality by ensuring that raw data remains exclusively with the host, while also enabling verifying the correctness of query responses by providing proofs to clients. The main innovation in this paper is proposing efficient ZKP designs (called circuits) for basic operations in SQL query processing. These basic operation circuits are then combined to form ZKP circuits for larger, more complex queries. PoneglyphDB's circuits are carefully designed to be efficient by utilizing advances in cryptography such as PLONKish-based circuits, recursive proof composition techniques, and designing with low-order polynomial constraints. We demonstrate the performance of PoneglyphDB with the standard TPC-H benchmark. Our experimental results show that PoneglyphDB can efficiently achieve both confidentiality and provability, outperforming existing state-of-the-art ZKP methods.
Chon Kit Lao, Sophie Zhou, Luyao Zhang, Fan Zhang · 5 authors
Blockchain systems such as Bitcoin and Ethereum have limitations in efficiency, resulting in an inability to immediately confirm all transactions, leading to extended periods of transactions residing in the mempool. We refer to these transactions as “long latency trans- actions” and this paper explores the issue of resource utilization in- efficiencies issues from these transactions. Utilizing the Geth client, the study quantifies the impact of these transactions on Ethereum’s resource consumption, which encompassing three crucial metrics: computational power, memory storage, and network bandwidth. Furthermore, this study also identifies three primary factors con- tributing to long latency transactions: low gas prices, long block processing times, and future-index transactions. Through empirical analysis, this study offers insights into the transaction-handling mechanisms in Ethereum. The implications of our findings aim to contribute to the enhancement of resource efficiency within the Ethereum blockchain ecosystem.
The consensus protocol is a crucial element of blockchain technology that guarantees all participants agree on the same data values and follow the same direction, even in the presence of defective components. This research project has identified a problem that affects both users of blockchain technologies and investors in cryptocurrencies. The question of whether current blockchain platforms are truly decentralized has been raised by the blockchain community over the years. The most popular blockchains use Proof of Work (PoW), Proof of Stake (PoS), or a combination of both, but both systems have limitations in terms of decentralization. Several alternative consensus protocols have emerged recently, but none have achieved total decentralization or welcomed any level user to be the next miner or forger.Therefore, true decentralization of a blockchain system is more challenging as most of the popular consensus protocols were invented to accommodate decentralization but eventually, driven by the centralization of power. This research study proposes a truly decentralized consensus protocol that is capable to avoid the centralization of power even in the future regardless of the number of network participants. The protocol also makes sure it avoids the use of specialized hardware resources, decreases the level of energy consumption, and encourages network activities. Additionally, the new consensus protocol offers a more democratic and fair approach to blockchain consensus.Furthermore, the implemented solution underwent comprehensive testing to ascertain its level of decentralization. Considering the lack of a suitable metric for evaluating the practical extent of decentralization achieved by a blockchain system, this study adopted a set of requirements delineated in a prior investigation. Based on this assessment, it was determined that the solution has successfully attained genuine decentralization. Moreover, the test results demonstrate that the solution has achieved enhancement in terms of security and performance, thereby ensuring its effectiveness in circumventing the need for specialized hardware and reducing energy consumption.
Francesco D’Amato, Roberto Saltini, Thuy-An Tran, Luca Zanolini
Gasper, the consensus protocol currently employed by Ethereum, typically requires 64 to 95 slots -- the units of time during which a new chain extending the previous one by one block is proposed and voted -- to finalize. This means that under ideal conditions -- where the network is synchronous, and all chain proposers, along with more than two-thirds of the validators, behave as dictated by the protocol -- proposers construct blocks on a non-finalized chain that extends at least 64 blocks. This exposes a significant portion of the blockchain to potential reorganizations during changes in network conditions, such as periods of asynchrony. Specifically, this finalization delay heightens the network's exposure to Maximum Extractable Value (MEV) exploits, which could undermine the network's integrity. Furthermore, the extended finalization period forces users to balance the trade-off between economic security and transaction speed. To address these issues and speed up finality, we introduce a partially synchronous finality gadget, which we combine with two dynamically available consensus protocols -- synchronous protocols that ensure safety and liveness even with fluctuating validator participation levels. This integration results in secure ebb-and-flow protocols [SP 2021], achieving finality within three slots after a proposal and realizing 3-slot finality.
This report presents the results of a PhD thesis focused on the creation of a decentralised and autonomous identity structure. This structure allows users not only to store their identities, but also to generate them autonomously, without the need for a trusted third party or an external validation structure. To implement this concept, the 3BI-ECC framework, a network system based on blockchain and the cryptographic advantages of elliptic curves, has been designed to establish a decentralised consortium network of self-generated identities. In addition, a new blockchain structure called NestedChain was created, which allows two types of information to be stored simultaneously: the identity of users through smart contracts and the certification elements of the network. The Nested-C protocol has also been developed, a new consensus protocol that improves the efficiency and security of storing transactions on the blockchain. In addition, solutions are proposed to preserve the integrity of the information in each smart contract and in its transactions with the theoretical scheme. This research aims to create decentralised environments where each user controls their information on the network, protecting both their identity and the privacy of their data, thus promoting user autonomy in the digital environment.
Blockchain technology has revolutionized decentralized systems by enabling secure, transparent, and tamper-resistant data management. Central to blockchain functionality is the consensus mechanism, which ensures agreement among distributed nodes. This paper presents a comprehensive review of cryptographic solutions underpinning various blockchain consensus protocols. We analyze the role of cryptographic primitives such as hash functions, digital signatures, zero-knowledge proofs, and threshold cryptography in enhancing security and efficiency of consensus algorithms like Proof of Work (PoW), Proof of Stake (PoS), and Practical Byzantine Fault Tolerance (PBFT). The review highlights strengths, limitations, and emerging trends in cryptographic techniques addressing scalability, privacy, and resistance to adversarial attacks. Finally, we discuss future research directions toward integrating advanced cryptography with blockchain consensus to improve trustworthiness and performance.
A. Jabbari, Gowri Ramachandran, Sidra Malik, Raja Jurdak
In the current digital landscape, supply chains have transformed into complex networks driven by the Internet of Things (IoT), necessitating enhanced data sharing and processing capabilities to ensure traceability and transparency. Leveraging Blockchain technology in IoT applications advances reliability and transparency in near-real-time insight extraction processes. However, it raises significant concerns regarding data privacy. Existing privacy-preserving approaches often rely on Smart Contracts for automation and Zero Knowledge Proofs (ZKP) for privacy. However, apart from being inflexible in adopting system changes while effectively protecting data confidentiality, these approaches introduce significant computational expenses and overheads that make them impractical for dynamic supply chain environments. To address these challenges, we propose ZK-DPPS, a framework that ensures zero-knowledge communications without the need for traditional ZKPs. In ZK-DPPS, privacy is preserved through a combination of Fully Homomorphic Encryption (FHE) for computations and Secure Multi-Party Computations (SMPC) for key reconstruction. To ensure that the raw data remains private throughout the entire process, we use FHE to execute computations directly on encrypted data. The "zero-knowledge" aspect of ZK-DPPS refers to the system's ability to process and share data insights without exposing sensitive information, thus offering a practical and efficient alternative to ZKP-based methods. We demonstrate the efficacy of ZK-DPPS through a simulated supply chain scenario, showcasing its ability to tackle the dual challenges of privacy preservation and computational trust in decentralised environments.
The adoption of smart contracts in decentralized blockchain-based applications enables reliable and certified audits. These audits allow the extraction of valuable information from blockchains, which can be used to reconstruct the execution of the application and facilitate advanced analyses. One of the most commonly used techniques in this context is process mining, which leverages event logs to trace and accurately represent the process execution of applications. However, extracting execution data from blockchains poses significant challenges, and the current methodologies developed have some limitations. Most approaches are tailored to specific use cases, requiring that analysis techniques are defined during the smart contract’s development. Other techniques are applied a posteriori, relying on blockchain events that often lack a standardized format. This absence of standardization requires complex processing steps to correlate logs with the executed actions and such approaches are not universally applicable to all smart contracts on the blockchain , further limiting their scope. Lastly, none of the existing techniques can extract information from event logs embedded in internal transactions of smart contracts. To address these limitations, we propose EveLog an application-agnostic methodology that can be applied to any EVM-compatible application without predefined constraints. Its primary goal is to extract information from smart contracts, capturing both public and internal transactions, and organizing the results into a structured XES event log. The EveLog methodology consists of five key steps: (i) extraction of data from smart contract transactions, (ii) decoding raw data, (iii) selection of sorting criteria, (iv) construction of traces, and (v) generation of the XES event log. EveLog has been implemented in a client–server application and tested on existing solutions, specifically the CryptoKitties application, a blockchain-based game on the Ethereum blockchain. The study was conducted using 12,996 blocks, including over 8000 real transactions from the Ethereum mainnet.
Zachary Painter, Christina Peterson, Victor Cook, Damian Dechev
Blockchain networks use consensus mechanisms so that participants can exchange transactions without the need to rely on a trusted third party. Consensus mechanisms using Proof of Work burn significant energy to select a block miner, and this delay limits performance. Other consensus mechanisms such as Proof of Stake or Practical Byzantine Fault Tolerance still designate a single validator to append a block to the chain, preventing blocks from being built and published in parallel. In this article, we introduce a new consensus mechanism, Proof of Descriptor, enabling clients to work together to publish blockchain transactions using a descriptor object which stores information on the cooperative parallel execution of transactions. Proof of Descriptor consensus allows commutative transactions to be mined concurrently. It does not require a single leader to append transactions to the ledger, enabling clients to cooperate on publishing transactions. We also propose a novel graph-based ledger with multiple entry points to facilitate the scalability of Proof of Descriptor, as well as a secure hashing scheme to resist long-range attacks. We demonstrate that our approach is as secure as related works with respect to a malicious leader, 51% attack, and other known blockchain vulnerabilities. Furthermore, our experimental evaluation shows that our approach scales with the size of the network, experiencing up to a 4 \(\times\) improvement in throughput over the fastest sequential blockchain, Solana .
Viktor Valaštín, Dušan Morháč, Kristián Košťál, Ivan Kotuliak
Liquidity is critical for a healthy and thriving blockchain ecosystem, enabling value exchange between participants. However, achieving unified liquidity across heterogeneous blockchain platforms remains challenging due to disparities in architecture, virtual machines, and asset management logic. These disparities force assets to be wrapped into other formats to ensure compatibility with underlying systems, thus fragmenting liquidity into multiple pools. This paper proposes LiquiSpell, a novel protocol that aims to unify liquidity across multiple parachains within the Polkadot ecosystem. By leveraging the cross-chain message passing (XCMP), LiquiSpell introduces the concept of a universal transaction that can be constructed to be compatible with any parachain, regardless of its underlying architecture or asset management pallet. This approach overcomes the obstacles posed by the diverse nature of parachains, enabling seamless asset sharing and enhancing cross-chain interoperability. The proposed solution mitigates liquidity fragmentation within the Polkadot ecosystem. It presents a framework that can be extended to other multichain environments outside Polkadot. Ultimately, LiquiSpell aims to foster a thriving ecosystem by facilitating the introduction of new assets and increasing overall liquidity, thereby driving innovation and adoption within the decentralized finance (DeFi) landscape.
Open access
Advanced Data Storage Technologies
Innovative Microfluidic and Catalytic Techniques Innovation
Arijet Sarker, Simeon Wuthier, Jinoh Kim, Jonghyun Kim · 5 authors
Cryptocurrency software implements cryptocurrency operations (including the distributed consensus protocol and peer-to-peer networking) and often involves the open-source community. We design a software assurance scheme for cryptocurrency and advance the cryptocurrency handshaking protocol by providing the verification capability of the Bitcoin software by peers and preventing any potential peer from establishing a connection with modified Bitcoin software. Since we focus on Bitcoin (the most popular cryptocurrency) for implementation and integration, we call our scheme Version++, built on and advancing the current Bitcoin handshaking protocol based on the Version message. Our Version++ protocol providing software assurance is distinguishable from previous research because it is permissionless, distributed, and lightweight for its cryptocurrency application. Our scheme is permissionless since it does not require a centralized trusted authority (unlike the remote software attestation techniques from trusted computing); it is distributed since the peer checks the software assurances of its own peer connections; and it is designed for efficiency/lightweight to support the dynamic nature of the peer connections and large-scale broadcasting in cryptocurrency networking. Utilizing Merkle Tree for the efficiency of the proof verification, we implement and test Version++ on Bitcoin software and conduct experiments in an active Bitcoin node prototype connected to the Bitcoin Mainnet. Our prototype-based performance analyses demonstrate the lightweight design of Version++. The peer-specific verification grows logarithmically with the number of software files in processing time and in storage. Furthermore, the Version++ verification overhead is small compared to the version-verack handshaking process; we measure the overhead to be 0.524% in our local networking environment between virtual machines and between 0.057% and 0.282% (depending on the peer location) in our more realistic cloud-based experiments with remote peer machines.
The coming of Distributed Ledger Technologies (DLTs) and blockchain, in the outlook of new technologiesduring the last decade, entailed a disruption in several spheres, such as the economy field and the identificationof entities and individuals, due to the great possibilities provided to them. Although their first application were cryptocurrencies, DLTs have been assimilated in other settings, suchas their introduction in enterprise-grade systems. The technology itself has been evolving, facing some of itslimitations and accommodating the extension of its potential use cases. SIGMA is conceived to broaden knowledge in two of the most novel aspects of DLTs: Layer-2 networksand decentralized self-sovereign identity. Its goal is to increase expertise in these areas to facilitate theirintegration and exploitation by our surrounding companies.
(English) The advent of the internet, marked by pivotal developments such as the launch of Arpanet and the standardization of HTTP, has irrevocably changed the fabric of modern society. Centralized platforms like Microsoft, Google, Apple, and Amazon have dominated this digital landscape, offering many services ranging from cloud computing to online storage. However, the centralized nature of these services has raised significant concerns regarding user privacy, data integrity, and the potential for censorship. In response to these issues, the open-source community has explored peer-to-peer alternatives, notably in the realm of distributed file systems, ledgers, and blockchain technology. Blockchains, popularized by the emergence of Bitcoin, promote a democratized service model that challenges the centralized status quo. Yet, they are not without their own challenges, including decentralization, security, privacy, and performance. This thesis delves into the nuances of blockchain technology, focusing on Ethereum's transition from Proof of Work (PoW) to Proof of Stake (PoS) and its implications on network hardware requirements, topology, and overall performance. The development of Ethereum serves as a small-scale reflection of the broader ambitions and challenges in transitioning to Decentralized Finance (DeFi) platforms. Despite significant theoretical advancements in consensus mechanisms and scalability solutions, real-world implementations and experimental validations remain sparse. This work aims to bridge this gap by comprehensively analysing Ethereum's PoS transition by examining the interlaced relationships between software logic, hardware configurations, and network dynamics. Through novel measurement models and tools, this thesis contributes to a deeper understanding of how Ethereum's architectural changes impact its ecosystem and its participants' behaviours. Lastly, the research presented in this thesis illustrates the technical and operational challenges facing Ethereum and similar blockchain platforms and proposes a series of contributions that advance the field. This work empirically analyses the future enhancements in blockchain technology by exploring the implications of the network and its topology, to the viability of decentralized validation processes, and the potential for scaling solutions like Data Availability Sampling. The open-source tools and methodologies developed within the thesis scope represent the commitment to transparency and collaboration, which follows the spirit of the decentralized communities it seeks to serve. Through a mix of theoretical exploration and empirical research, this thesis aims to provide a deeper and more detailed understanding of Ethereum PoS' design choices, its capabilities and the limitations this one represents in future steps and upgrades, leading the way for more resilient, scalable, and decentralized digital infrastructures. (Català) L'arribada d'Internet, marcada per avenços fonamentals com el llançament d'Arpanet i l'estandardització de HTTP, ha canviat irrevocablement el teixit de la societat moderna. Les plataformes centralitzades com Microsoft, Google, Apple i Amazon han dominat aquest panorama digital, oferint serveis que van des de la computació al núvol fins a l'emmagatzematge en línia. No obstant això, la naturalesa centralitzada d'aquests serveis ha generat importants preocupacions pel que fa a la privacitat de l'usuari, la integritat de les dades i la possibilitat de censura. En resposta a aquests problemes, la comunitat de codi obert ha explorat alternatives d'igual a igual, especialment en l'àmbit dels sistemes d'arxius distribuïts i la tecnologia blockchain. Les blockchains, popularitzades pel sorgiment de Bitcoin, han proposat fins i tot un model de servei democratitzat que desafia l'statu quo centralitzat. No obstant això, no estan exemptes de desafiaments, incloent la descentralització, la seguretat, la privacitat i el rendiment. Aquesta tesi aprofundeix en les dinàmiques de la tecnologia blockchain, centrant-se en la transició d'Ethereum de Proof of Work (PoW) a Proof of Stake (PoS) i les seves implicacions en els requisits, la topologia de la xarxa i el rendiment general del maquinari. El desenvolupament d'Ethereum serveix com un reflex a petita escala de les ambicions i els desafiaments més amplis en la transició a plataformes de finances descentralitzades (DeFi). Malgrat els importants avenços teòrics en els mecanismes de consens i les solucions d'escalabilitat, les implementacions al món real i les validacions experimentals segueixen sent escasses. Aquesta tesi té com a objectiu tancar aquesta bretxa analitzant exhaustivament la transició PoS d'Ethereum mitjançant l'examen de les relacions entrellaçades entre la lògica del programari, les configuracions de maquinari i la dinàmica de la xarxa. A través de nous models i eines de mesura, aquesta tesi contribueix a una comprensió més profunda de com els canvis arquitectònics d'Ethereum impacten en el seu ecosistema i els comportaments dels seus participants. Per últim, la investigació presentada en aquesta tesi il·lustra els desafiaments tècnics i operatius que enfronten Ethereum i plataformes blockchain similars, i proposa una sèrie de contribucions que esperem serveixin per fer avançar el mon de les blockchains. La tesi analitza empíricament les millores futures en la tecnologia blockchain explorant les implicacions de la xarxa i la seva topologia, la viabilitat dels processos de validació descentralitzats i el potencial per escalar solucions com el mostreig de disponibilitat de dades. Les eines i metodologies de codi obert desenvolupades dins de l'abast de la tesi representen el compromís amb la transparència i la col·laboració, que segueix l'esperit de les comunitats descentralitzades a les que busquem servir. A través d'una combinació d'exploració teòrica i investigació empírica, aquesta tesi té com a objectiu proporcionar una comprensió més profunda i detallada de les opcions de disseny d'Ethereum PoS, les seves capacitats i les limitacions que això representa en futurs passos i actualitzacions, obrint el camí cap a una solució més resilient i escalable per a infraestructures digitals descentralitzades. (Español) La llegada de Internet, marcada por avances fundamentales como el lanzamiento de Arpanet y la estandarización de HTTP, ha cambiado irrevocablemente el tejido de la sociedad moderna. Plataformas centralizadas como Microsoft, Google, Apple y Amazon han dominado este panorama digital, ofreciendo servicios que van desde computación en la nube hasta almacenamiento en línea. Sin embargo, la naturaleza centralizada de estos servicios ha generado importantes preocupaciones con respecto a la privacidad del usuario, la integridad de los datos y la posibilidad de censura. En respuesta a estos problemas, la comunidad de código abierto ha explorado alternativas de igual a igual, especialmente en el ámbito de los sistemas de archivos distribuidos, los libros de contabilidad y la tecnología blockchain. Las blockchains, popularizadas por el surgimiento de Bitcoin, promueven un modelo de servicio democratizado que desafía el status quo centralizado. Sin embargo, no están exentos de desafíos, incluida la descentralización, la seguridad, la privacidad y el rendimiento. Esta tesis profundiza en los matices de la tecnología blockchain, centrándose en la transición de Ethereum de Proof of Work (PoW) a Proof of Stake (PoS) y sus implicaciones en los requisitos, la topología de la red y el rendimiento general del hardware. El desarrollo de Ethereum sirve como un reflejo a pequeña escala de las ambiciones y desafíos más amplios en la transición a plataformas de finanzas descentralizadas (DeFi). A pesar de los importantes avances teóricos en los mecanismos de consenso y las soluciones de escalabilidad, las implementaciones en el mundo real y las validaciones experimentales siguen siendo escasas. Esta tesis tiene como objetivo cerrar esta brecha analizando exhaustivamente la transición PoS de Ethereum mediante el examen de las relaciones entrelazadas entre la lógica del software, las configuraciones de hardware y la dinámica de la red. A través de novedosos modelos y herramientas de medición, esta tesis contribuye a una comprensión más profunda de cómo los cambios arquitectónicos de Ethereum impactan su ecosistema y los comportamientos de sus participantes. Por último, la investigación presentada en esta tesis ilustra los desafíos técnicos y operativos que enfrentan Ethereum y plataformas blockchain similares y propone una serie de contribuciones que hacen avanzar el campo. La tesis analiza empíricamente las mejoras futuras en la tecnología blockchain explorando las implicaciones de la red y su topología, la viabilidad de los procesos de validación descentralizados y el potencial para escalar soluciones como el muestreo de disponibilidad de datos. Las herramientas y metodologías de código abierto desarrolladas dentro del alcance de la tesis representan el compromiso con la transparencia y la colaboración, que sigue el espíritu de las comunidades descentralizadas a las que busca servir. A través de una combinación de exploración teórica e investigación empírica, esta tesis tiene como objetivo proporcionar una comprensión más profunda y detallada de las opciones de diseño de Ethereum PoS, sus capacidades y las limitaciones que esto representa en futuros pasos y actualizaciones, abriendo el camino hacia una solución más resiliente y escalable. e infraestructuras digitales descentralizadas.
Intelligent blockchain is an emerging field that integrates Artificial Intelligence (AI) techniques with blockchain networks, with a particular emphasis on improving the performance of blockchain, especially in cryptocurrencies exchanges. Meanwhile, arbitrage bots are widely deployed and increasing in intelligent blockchain. These bots exploit the characteristics of cryptocurrencies exchanges to engage in frontrunning, generating substantial profits at the expense of ordinary users. In this paper, we address this issue by proposing a more efficient asynchronous Byzantine ordered consensus protocol, which can be used to prevent arbitrage bots from changing the order of the transactions for profits in intelligent blockchain-based cryptocurrencies. Specifically, we present two signal asynchronous common subset protocols, the more optimal one with only constant time complexity. We implement both our protocol and the optimal existing solution Chronos with Go language in the same environment. The experiment results indicate that our protocols achieve a threefold improvement over Chronos in consensus latency and nearly a tenfold increase in throughput.
With the rapid development of Zero-Knowledge Proofs (ZKPs), particularly Succinct Non-Interactive Arguments of Knowledge (SNARKs), benchmarking various ZK tools has become a valuable task. ZK-friendly hash functions, as key algorithms in blockchain, have garnered significant attention. Therefore, comprehensive benchmarking and evaluations of these evolving algorithms in ZK circuits present both promising opportunities and challenges. Additionally, we focus on a popular ZKP application, privacy-preserving transaction protocols, aiming to leverage SNARKs' cost-efficiency through "batch processing" to address high on-chain costs and compliance issues. To this end, we benchmarked three SNARK proving systems and five ZK-friendly hash functions, including our self-developed circuit templates for Poseidon2, Neptune, and GMiMC, on the bn254 curve within the circom-snarkjs framework. We also introduced the role of "sequencer" in our SNARK-based privacy-preserving transaction scheme to enhance efficiency and enable flexible auditing. We conducted privacy and security analyses, as well as implementation and evaluation on Ethereum Virtual Machine (EVM)-compatible chains. The results indicate that Poseidon and Poseidon2 demonstrate superior memory usage and runtime during proof generation under Groth16. Moreover, compared to the baseline, Poseidon2 not only generates proofs faster but also reduces on-chain costs by 73% on EVM chains and nearly 26% on Hedera. Our work provides a benchmark for ZK-friendly hash functions and ZK tools, while also exploring cost efficiency and compliance in ZKP-based privacy-preserving transaction protocols.
Christian Berger, Sadok Ben Toumia, Hans P. Reiser
Novel Byzantine fault-tolerant (BFT) state machine replication protocols improve scalability for their practical use in distributed ledger technology, where hundreds of replicas must reach consensus. Assessing that BFT protocol implementations meet their performance expectations requires careful evaluation. We propose a new methodology using scalable network simulations to predict BFT protocol performance. Our simulation architecture allows for the integration of existing BFT implementations without modification or re-implementation, offering a cost-effective alternative to large-scale cloud experiments. We validate our method by comparing simulation results with real-world cloud deployments, showing that simulations can accurately predict performance at larger scales when network limitations dominate. In our study, we applied this methodology to assess the performance of several “blockchain-generation” BFT protocols, including HotStuff, Kauri, Narwhal & Tusk, and BullShark, under realistic network conditions (with constrained 25 Mbit/s bandwidth) and induced faults. Kauri emerges as the top performer, achieving 6,742 operations per second (op/s) with 128 replicas, outperforming BullShark (2,318 op/s) and Tusk (1,952 op/s). HotStuff, using secp256k1 and BLS signatures, reaches 494 op/s and 707 op/s, respectively, demonstrating the efficiency of BLS-signature aggregation for saving bandwidth. This study demonstrates that state-of-the-art asynchronous BFT protocols can achieve competitive throughput in large-scale, real-world scenarios.
Recent Byzantine Fault-Tolerant (BFT) State Machine Replication (SMR) protocols increasingly focus on scalability and security to meet the growing demand for Distributed Ledger Technology (DLT) applications across various domains. Current BFT consensus algorithms typically require a single leader node to receive and validate votes from the majority process and broadcast the results, a design challenging to scale in large systems. We propose a fast-response consensus algorithm based on improvements to HotStuff, aimed at enhancing transaction ordering speed and overall performance of distributed systems, even in the presence of faulty copies. The algorithm introduces an optimistic response assumption, employs a message aggregation tree to collect and validate votes, and uses a dynamically adjusted threshold mechanism to reduce communication delay and improve message delivery reliability. Additionally, a dynamic channel mechanism and an asynchronous leader multi-round mechanism are introduced to address multiple points of failure in the message aggregation tree structure, minimizing dependence on a single leader. This adaptation can be flexibly applied to real-world system conditions to improve performance and responsiveness. We conduct experimental evaluations to verify the algorithm's effectiveness and superiority. Compared to the traditional HotStuff algorithm, the improved algorithm demonstrates higher efficiency and faster response times in handling faulty copies and transaction ordering.
Mikel Cortes-Goicoechea, Tarun Mohandas-Daryanani, José L. Muñoz, Leonardo Bautista-Gomez
Abstract Modern public blockchains like Ethereum rely on p2p networks to run distributed and censorship-resistant applications. With its wide adoption, it operates as a highly critical public ledger. On its transition to become more scalable and sustainable, shifting to PoS without sacrificing the security and resilience of PoW, Ethereum offers a range of consensus client implementations to participate in the network. In this paper, we present a methodology to measure the performance of the consensus clients based on the latency to receive messages from the p2p network. The paper includes a study that identifies the incentives and limitations that the network experiences, presenting insights about the latency impact derived from running the different consensus implementations at different locations. Our study highlights the need for a holistic approach to node deployment, where hardware, software, and geographic factors have to be carefully considered. Properly dimensioned hardware is essential to mitigate latency-related performance issues and ensure the reliable operation of beacon nodes, especially in geographically distant locations.
Mohammed Alghazwi, Tariq Bontekoe, Leon Visscher, Fatih Türkmen
Abstract Non-interactive zero-knowledge (NIZK) proofs of knowledge have proven to be highly relevant for securely realizing a wide array of applications that rely on both privacy and correctness . They enable a prover to convince any party of the correctness of a public statement for a secret witness . However, most NIZKs do not natively support proving knowledge of a secret witness that is distributed over multiple provers. Previously, collaborative proofs [54] have been proposed to overcome this limitation. We investigate the notion of composability in this setting, following the Commit-and-Prove design of LegoSNARK [19]. Composability allows users to combine different, specialized NIZKs (e.g., one for arithmetic circuits, one for boolean circuits, and one for range proofs) with the aim of reducing the proof generation time. Moreover, it opens the door to efficient realizations of many applications in the collaborative setting such as mutually exclusive prover groups, combining collaborative and single-party proofs and efficiently implementing publicly auditable secure multiparty computing (PA-MPC). We present the first, general definition for collaborative commitand- prove NIZK (CP-NIZK) proofs of knowledge and construct MPC protocols to enable their realization. We implement our protocols for two commonly used NIZKs, Groth16 and Bulletproofs, and evaluate their practicality in a variety of computational settings. Our findings indicate that composability adds only minor overhead, especially for large circuits. We also evaluated our construction in two application settings, one of which shows 18– $$55\times $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>55</mml:mn> <mml:mo>×</mml:mo> </mml:mrow> </mml:math> runtime reduction when compared to prior works while requiring only a fraction ( $$0.2\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0.2</mml:mn> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> ) of the communication.
The Proof-of-Stake (PoS) consensus algorithm has been criticized, in the literature and in several cryptocurrencies communities, due to the so-called compounding effect: who is richer has more coins to stake, therefore higher probability of being selected as a block validator and obtaining the corresponding rewards, thus becoming even richer. In this paper, we present a PoS simulator written in the Julia language that allows one to test several variants of PoS-based consensus algorithms, tweaking their parameters, and observe how the distribution of cryptocurrency coins among the users evolves over time. Such a tool can be used to investigate which combinations of parameters values allow to obtain a “fair” and stable consensus algorithm, in which, over the long term, no one gets richer or poorer by the mere act of validating blocks. Based on this investigation, we also introduce a new PoS-based consensus mechanism that allows the system to keep the wealth distribution stable even after a large number of epochs.