Blockchain Papers

Afeefa Noorain, Khaleel Ahmad, Laura Ricci

No abstract is available for this record.

Xiaohong Chen, Grigore Roşu

No abstract is available for this record.

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.

Yaakov Sokolik, Mohammad Nassar, Ori Rottenstreich

In blockchain networks, transaction latency is crucial for determining the quality of service (QoS). The latency of a transaction is measured as the time between its issuance and its inclusion in a block in the chain. A block proposer often prioritizes transactions with higher fees or transactions from accounts it is associated with, to minimize their latencies. To maintain fairness among transactions, a block proposer is expected to select the included transactions randomly. The random selection might cause some transactions to experience high latency following the variance in the time a transaction waits until it is selected. We suggest an alternative, age-aware approach towards fairness so that transaction priority is increased upon observing a large waiting time. We explain that a challenge with this approach is that the age of a transaction is not absolute due to transaction propagation. Moreover, a node might present its transactions as older to obtain priority. We describe a new technique to enforce a fair block selection while prioritizing transactions that observed high latency. The technique is based on various declaration schemes in which a node declares its pending transactions, providing the ability to validate transaction age. By evaluating the solutions on Ethereum data and synthetic data of various scenarios, we demonstrate the advantages of the approach under realistic conditions and understand its potential impact to maintain fairness and reduce tail latency.

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.

Mayank Raikwar, Nikita Polyanskii, Sebastian Müller

This paper is a Systematization of Knowledge (SoK) that focuses on Directed Acyclic Graph (DAG)-based consensus protocols in Distributed Ledger Technologies (DLTs). Our study evaluates their impact on performance and their tradeoffs concerning consistency, availability, and partition tolerance, as postulated by the CAP theorem. We delineate the key functionalities and tradeoffs of DAGbased consensus protocols, highlighting iterative improvements and deviations from foundational models. Additionally, we identify research gaps and suggest directions for future work to refine DAG-based consensus mechanisms.

Sana Naz, Scott Uk-Jin Lee

In a blockchain network, a rule set called consensus mechanism is used to create and finalize a block. In a proof-of-stake (PoS), consensus-based blockchain network, nodes become validators, minters, or stakeholders’ nodes to complete the consensus mechanism. In these networks, when a node becomes a validator node, its details need to be saved because the details of the validators are used in the network for many important decisions, such as selecting block proposers for the consensus process. In this paper, we present Sea Shield, which uses a validator chain to save a node’s information when it becomes a validator or leaves its responsibility as a validator in the PoS-based blockchain network. The validator chain is a blockchain that can run with the main chain of a PoS-based blockchain. The internal features of the validator chain are similar to those of the blockchain. We designed and simulated a consensus mechanism to create and finalize the block for the validator chain with no forks. We present a process by which a node may join or unjoin as a validator in a PoS-based blockchain network to improve the overall security of the main chain-consensus process.

Iván Abellán Álvarez, Vincent Gramlich, Johannes Sedlmeir

With the increasing adoption of decentralized information systems based on a variety of permissionless blockchain networks, the choice of consensus mechanism is at the core of many controversial discussions. Ethereum's recent transition from proof-of-work (PoW) to proof-of-stake (PoS)-based consensus has further fueled the debate on which mechanism is more favorable. While the aspects of energy consumption and degree of (de-)centralization are often emphasized in the public discourse, seminal research has also shed light on the formal security aspects of both approaches individually. However, related work has not yet comprehensively structured the knowledge about the security properties of PoW and PoS. Rather, it has focused on in-depth analyses of specific protocols or high-level comparative reviews covering a broad range of consensus mechanisms. To fill this gap and unravel the commonalities and discrepancies between the formal security properties of PoW- and PoS-based consensus, we conduct a systematic literature review over 26 research articles. Our findings indicate that PoW-based consensus with the longest chain rule provides the strongest formal security guarantees. Nonetheless, PoS can achieve similar guarantees when addressing its more pronounced tradeoff between safety and liveness through hybrid approaches.

Karen Terjanian, Aram Jivanyan, Dmitry Sidorov

We are introducing a novel consensus protocol for blockchain, called Proof of Stake and Activity (PoSA) which can augment the traditional Proof of Stake methods by integrating a unique Proof of Activity system. PoSA offers a compelling economic model that promotes decentralization by rewarding validators based on their staked capital and also the business value they contribute to the chain. This protocol has been implemented already into a fully-fledged blockchain platform called Bahamut (www.bahamut.io) which is designed specifically for iGaming and other markets, is actively operating in Emirati and boasts hundreds of thousands of active users.

Gyula Ádám Nemes, Bence Tureczki, Katalin Szenes, György Eigner

This paper introduces a blockchain-based solution for secure and efficient management of personal and EEG data for research subjects. Our approach separates but interlinks the data to ensure privacy and integrity, with role-based access controls implemented via a Solidity smart contract on the Ethereum blockchain. We integrate the principles of operational excellence to enhance traditional information security methodologies, focusing on a more comprehensive understanding and functionality of data management. Our method offers a secure, efficient, and user-friendly data management system, drawing stakeholders closer to essential professional practices and upholding the values of privacy and integrity.

Sam Blackshear, Andrey Chursin, George Danezis, Anastasios Kichidis · 12 authors

Sui Lutris is the first smart-contract platform to sustainably achieve sub-second finality. It achieves this significant decrease by employing consensusless agreement not only for simple payments but for a large variety of transactions. Unlike prior work, Sui Lutris neither compromises expressiveness nor throughput and can run perpetually without restarts. Sui Lutris achieves this by safely integrating consensuless agreement with a high-throughput consensus protocol that is invoked out of the critical finality path but ensures that when a transaction is at risk of inconsistent concurrent accesses, its settlement is delayed until the total ordering is resolved. Building such a hybrid architecture is especially delicate during reconfiguration events, where the system needs to preserve the safety of the consensusless path without compromising the long-term liveness of potentially misconfigured clients. We thus develop a novel reconfiguration protocol, the first to provably show the safe and efficient reconfiguration of a consensusless blockchain. Sui Lutris is currently running in production and underpins the Sui smart-contract platform. Combined with the use of Objects instead of accounts it enables the safe execution of smart contracts that expose objects as a first-class resource. In our experiments Sui Lutris achieves latency lower than 0.5 seconds for throughput up to 5,000 certificates per second (150k ops/s with transaction blocks), compared to the state-of-the-art real-world consensus latencies of 3 seconds. Furthermore, it gracefully handles validators crash-recovery and does not suffer visible performance degradation during reconfiguration.

Yue Li, Han Liu, Jianbo Gao, Jiashuo Zhang · 6 authors

The processing of block lifecycles is essential to the efficiency of a blockchain, which consists of four steps: creation, execution, consensus, and validation. The permissionless blockchain systems typically had very limited transaction throughput because of the performance bottleneck of consensus protocols. With recent advances in consensus protocols, the execution and validation of transactions have become the new performance bottleneck. We propose a novel framework, called FastBlock, to speed up the execution and validation steps by introducing fine-grained concurrency. Our early design of FastBlock supported three key modules: (1) a symbolic execution-based analyzer that automatically identifies minimal atomic sections in each transaction; (2) a concurrent execution step that executes possibly conflicting transactions in parallel using hardware transactional memory; (3) a concurrent validation step that introduces a happen-before relation to deterministically re-execute transactions. The improved FastBlock presented in this article supports the nonce mechanism to schedule concurrent transactions from the same account. Moreover, we empirically study the impact of concurrency on Ethereum except for performance and shed light on potential optimizations of FastBlock. Finally, we implemented FastBlock and then evaluated the performance of FastBlock. Our result shows that the FastBlock outperforms state-of-art solutions significantly in performance: the execution step and validation step speed up to 3.0x and 2.3x on average over the original serial model, respectively, with eight concurrent threads. In addition, we evaluated the impact of the nonce mechanism, and the result shows that the performance loss caused by this mechanism is acceptable in practice.

Takaki Asanuma, Takeshi Miyamae, Yuji Yamaoka

Traditional blockchains cannot achieve the same transaction throughput as Web2, so their use cases are limited. Therefore, state sharding has been proposed to improve transaction throughput by dividing the blockchain network and managing states and transactions in parallel. However, Nightshade in the NEAR Protocol, a type of state sharding, provides a rollback protocol to cancel the generation of blocks containing inconsistent transaction results because processing cross-shard transactions (CSTXs) in a 2-phase commit may cause state inconsistency. We present a new attack that interferes with the generation of new blocks by repeatedly executing CSTXs that certainly causes state inconsistency, causing continuous rollback. We also propose a block-generation protocol called Synchro to incorporate all the state changes of each CSTX into the same block by coordinating the block prior to approving transactions in each shard. Synchro eliminates the occurrence of the state inconsistency caused by the CSTXs and the necessity of the rollback protocol. We use zero-knowledge proof to make Synchro scalable in the global validation phase. Although the actual overhead of the zero-knowledge proof has not yet been evaluated, we show that Synchro could achieve the same transaction throughput as Nightshade theoretically, depending on the future innovations in zero-knowledge proof techniques.

Joachim Neu, Ertem Nusret Tas, David Tse

Motivated by proof-of-stake (PoS) blockchains such as Ethereum, two key desiderata have recently been studied for Byzantine-fault tolerant (BFT) state-machine replication (SMR) consensus protocols: Finality means that the protocol retains consistency, as long as less than a certain fraction of validators are malicious, even in partially-synchronous environments that allow for temporary violations of assumed network delay bounds. Accountable safety means that in any case of inconsistency, a certain fraction of validators can be identified to have provably violated the protocol. Earlier works have developed impossibility results and protocol constructions for these properties separately. We show that accountable safety implies finality, thereby unifying earlier results.

Subhasis Kundu

Multi-brain Federated Learning (MBFL) introduces an innovative approach to decentralized artificial intelligence, enabling joint model training across various fields while maintaining data privacy. This study clarifies the MBFL concept and explores its potential uses in industries such as healthcare, finance, and defense. It covers the core principles of MBFL such as data decentralization, model aggregation, and privacy-preserving techniques. The benefits of MBFL, including improved model performance and reduction of data silos, are examined along with possible challenges and limitations. A framework for implementing MBFL in different scenarios was provided, and its impact on the future direction of AI development was discussed. The paper concludes by highlighting the transformative potential of MBFL in advancing collaborative AI, while ensuring data security and privacy. Keywords — Multi-brain Federated Learning, Decentralized AI, Privacy-preserving, Collaborative models, Data security, Cross- domain learning, Model aggregation, Federated Learning, Healthcare, Finance, Defense.

Samuel Kernan Freire, Mina Foosherian, Chaofan Wang, Evangelos Niforatos

As agile manufacturing expands and workforce mobility increases, the importance of efficient knowledge transfer among factory workers grows. Cognitive Assistants (CAs) with Large Language Models (LLMs), like GPT-3.5, can bridge knowledge gaps and improve worker performance in manufacturing settings. This study investigates the opportunities, risks, and user acceptance of LLM-powered CAs in two factory contexts: textile and detergent production. Several opportunities and risks are identified through a literature review, proof-of-concept implementation, and focus group sessions. Factory representatives raise concerns regarding data security, privacy, and the reliability of LLMs in high-stake environments. By following design guidelines regarding persistent memory, real-time data integration, security, privacy, and ethical concerns, LLM-powered CAs can become valuable assets in manufacturing settings and other industries.

Junpei Ni, Jiang Xiao, Shijie Zhang, Bo Li · 6 authors

In most blockchain-based application scenarios, a complete application logic consists of multiple continuous transactions, in which the initiation of one transaction depends on the confirmation result of the previous one. This mandates that continuous transactions must be processed in the correct order. Unfortunately, existing chain-based blockchains fail to effectively support continuous transaction processing due to considerable latency in confirming continuous transactions. Recent studies shifted from chain-based blockchains toDirected Acyclic Graph(DAG) based blockchains, which reduced transaction confirmation latencies. However, DAG-based blockchains store transactions in an out-of-order manner that leads to unordered transaction processing. To address this challenge, we propose FLUID, a new DAG-based blockchain that supports continuous transaction processing while delivering high performance. The fundamental idea of FLUID is to design a transaction dependency tracking structure to ensure that continuous transactions can be processed in the correct order. FLUID utilizes a conflict resolution mechanism to provide instant confirmation and to support concurrent transaction processing with lower latencies. In addition, FLUID builds a checkpoint-based verification mechanism to achieve deterministic consensus on transaction processing results in the DAG. Extensive experiments demonstrate that our proposed FLUID can improve the throughput over state-of-the-art OHIE by 66% with two orders of magnitude lower latencies.

Lihua Zhang, Boping Li, Haodong Fang, Ganzhe Zhang · 5 authors

In the IoT (Internet of Things) environment, the existing access control schemes for device resources have some problems, such as poor scalability, high latency, security, and dynamics. Combining the advantages of the permissioned blockchain and edge computing, an access control scheme for the Internet of Things based on the permissioned blockchain and edge computing is proposed. By authenticating the user’s identity at the edge, the user’s identity is reliable and the response time is improved. In the ABAC (Attribute Based Access Control) model, the blockchain is regarded as a trusted entity, and the access control policy is written into a smart contract and deployed on the blockchain for calling. Most of the existing consensus algorithms have the problems of low throughput and scalability. A Kraft (Kademlia–Raft) consensus algorithm is introduced to solve the above issues. Security analysis and experimental results show that the scheme can achieve fine-grained, dynamic access control, has high throughput and low latency, and ensures security and reliability.

Ramesh Adhikari, Costas Busch

Sharding is used to address the performance and scalability issues of the blockchain protocols, which divides the overall transaction processing costs among multiple clusters of nodes. Shards require less storage capacity and communication and computation cost per node than the existing whole blockchain networks, and they operate in parallel to maximize performance. However, existing sharding solutions use locks for transaction isolation which lowers the system throughput and may introduce deadlocks. In this paper, we propose a lockless transaction method for ensuring transaction isolation without using locks, which improves the concurrency and throughput of the transactions. In our method, transactions are split into subtransactions to enable parallel processing in multiple shards. We use versions for the transaction accounts to implement consistency among the shards. We provide formal proof for liveness and correctness. We also evaluate experimentally our proposed protocol and compare the execution time and throughput with lock-based approaches. The experiments show that the transaction execution time is considerably shorter than the lock-based time and near to the ideal (no-lock) execution time.

Sarah Azouvi, Marko Vukolić

Blockchain systems based on a reusable resource, such as proof-of-stake (PoS), provide weaker security guarantees than those based on proof-of-work. Specifically, they are vulnerable to long-range attacks, where an adversary can corrupt prior participants in order to rewrite the full history of the chain. To prevent this attack on a PoS chain, we propose a protocol that checkpoints the state of the PoS chain to a proof-of-work blockchain such as Bitcoin. Our checkpointing protocol hence does not rely on any central authority. Our work uses Schnorr signatures and leverages Bitcoin recent Taproot upgrade, allowing us to create a checkpointing transaction of constant size. We argue for the security of our protocol and present an open-source implementation that was tested on the Bitcoin testnet.

Yongge Wang

The problem of Byzantine Fault Tolerance (BFT) has received a lot of attention in the last 30 years. Due to the popularity of Proof of Stake (PoS) blockchains in recent years, several BFT protocols have been deployed in the large scale of Internet environment. We analyze several popular BFT protocols such as Capser FFG/CBC-FBC for Ethereum 2.0 and GRANDPA for Polkadot. Our analysis shows that the security models for these BFT protocols are slightly different from the models commonly accepted in the academic literature. For example, we show that, if the adversary has a full control of the message delivery order in the underlying network, then none of the BFT protocols for Ethereum blockchain 2.0 and Polkadot blockchain could achieve liveness even in a synchronized network. Though it is not clear whether a practical adversary could actually control and re-order the underlying message delivery system (at Internet scale) to mount these attacks, it raises an interesting question on security model gaps between academic BFT protocols and deployed BFT protocols in the Internet scale. With these analysis, this article proposes a Casper CBC-FBC style binary BFT protocol and shows its security in the traditional academic security model with complete asynchronous networks. For partial synchronous networks, we propose a multi-value BFT protocol BDLS based on the seminal DLS protocol and show that it is one of the most efficient practical BFT protocols at large scale networks in the traditional academic BFT security model. The implementation of BDLS is available at https://github.com/yonggewang/bdls . Finally, we propose a multi-value BFT protocol XP for complete asynchronous networks and show its security in the traditional academic BFT security model.

Dev P. Singh, K.W. Sowerby, Andrew C. M. Austin

Trust lies at the center of the paradigm shift required to realize the ultra-dense networks needed by future radio communication systems. We propose a distributed, three-layer, trust-based hardware sharing scheme between operators that overcomes the limitations of a single-operator-owned monolithic network. Our system scales to tens of thousands of operators without requiring explicit contracts between them, or between operators and user equipment. User equipment in turn is free to requisition the services of any available hardware. This is achieved by abstracting the communication process as a transaction, and casting it within a distributed ledger technology framework paired with an efficient, fault-tolerant, distributed consensus protocol. A trust model associates a behavioral measure with each hardware device that signals its reliability, as well as its payoff. The proposed system offers multiple advantages for users, operators, and regulators.

Abdelrahman Sheham Abdellah, Sherif M. Saif, Hesham Eldeeb, Emad Abd-Elrahman · 5 authors

In this study, we propose an Information-Centric Network (ICN) approach for the Internet as an alternative to the present host-centric architecture. The proposed approach solves present Internet challenges, where most Internet users nowadays are involved in seeking knowledge by searching through large amounts of data, independent of the data's physical locations and these users usually have requests that need prompt responses. Hence, Internet requirements have got a new shape and the whole Internet paradigm should be shifting where different network considerations are needed. In this context, ICNs can play a vital role where the host-centered architecture is replaced by a content-centered one since the content itself is the aim and not the location. However, the ICN paradigm as a substitute for traditional Internet faces some challenges in terms of security and performance. ICN needs to be protected against some threats such as Denial-of-Service attacks (DoS), hacker attacks, loss of data, data replication, and cache pollution. To accomplish this, we propose this Secured Blockchain-Based ICN (SBBICN) implementation that exploits the secure aspects of Blockchain technology such as data integrity and non-tampering to secure the ICN against the aforementioned threats. In this proposed system, we describe and develop a voting system based on a blockchain consensus algorithm to avoid a single point of failure during the verification process and we apply the system using an Ethereum smart contract to verify the effectiveness of the proposed system. The experimental results and the security analysis demonstrate the effectiveness of the SBBICN proposal when compared to other schemes in the literature.

Chris Pollett, Thomas H. Austin, Katerina Potika, Justin Rietz · 5 authors

No abstract is available for this record.