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A survey on blockchain technology and its security

Blockchain(Research and Applications) 2022年第2期3卷 102-116页

作者： Huaqun Guo Xingjie Yu Institute for Infocomm Research A*STARSingapore Singapore

Blockchain is a technology that has desirable features of decentralization,autonomy,integrity,immutability,verification,fault-tolerance,anonymity,auditability,and *** this paper,we first carry out a deeper survey about blockchain technology,especially its history,consensus algorithms'quantitative comparisons,details of cryptography in terms of public key cryptography,Zero-Knowledge Proofs,and hash functions used in the blockchain,and the comprehensive list of blockchain ***,the security of blockchain itself is a focus in this *** particular,we assess the blockchain security from risk analysis to derive comprehensive blockchain security risk categories,analyze the real attacks and bugs against blockchain,and summarize the recently developed security measures on ***,the challenges and research trends are presented to achieve more scalable and securer blockchain systems for the massive deployments.

关键词： Blockchain consensus algorithm Smart contract Risk Blockchain security

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Decentralized Learning with Approximate Finite-Time consensus

arXiv

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arXiv 2025年

作者： Fainman, Aaron Vlaski, Stefan Department of Electrical and Electronic Engineering Imperial College London United Kingdom

The performance of algorithms for decentralized optimization is affected by both the optimization error and the consensus error, the latter of which arises from the variation between agents’ local models. Classically, algorithms employ averaging and gradient-tracking mechanisms with constant combination matrices to drive the collection of agents to consensus. Recent works have demonstrated that using sequences of combination matrices that achieve finite-time consensus (FTC) can result in improved communication efficiency or iteration complexity for decentralized optimization. Notably, these studies apply to highly structured networks, where exact finite-time consensus sequences are known exactly and in closed form. In this work we investigate the impact of utilizing approximate FTC matrices in decentralized learning algorithms, and quantify the impact of the approximation error on convergence rate and steady-state performance. Approximate FTC matrices can be inferred for general graphs and do not rely on a particular graph structure or prior knowledge, making the proposed scheme applicable to a broad range of decentralized learning settings. Copyright © 2025, The Authors. All rights reserved.

关键词： consensus algorithm

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Exponentially Distributed Nonlinear Proof-of-Work: Saving Energy while Preserving Decentralisation in Bitcoin Mining

Exponentially Distributed Nonlinear Proof-of-Work: Saving En...

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2023 IEEE International Conference on Electrical, Computer and Energy Technologies, ICECET 2023

作者： Bezuidenhout, Riaan Nel, Wynand University of the Free State Department of Computer Science and Informatics Bloemfontein South Africa

ISBN: (纸本)9798350327816

Bitcoin is one of the most prominent blockchain systems but is infamous for its massive energy consumption. The proof-of-work (PoW) consensus algorithm used for appending transactions to the Bitcoin ledger (also known as Bitcoin mining) incurs substantial energy expenditure due to the energy-intensive nature of PoW. The root of this inefficiency lies in the current implementation of the PoW algorithm. PoW establishes a linear relationship between a miner's computational power and their probability of successfully mining a block by assigning an identical cryptographic puzzle to all miners. This paper investigates the energy inefficiency inherent in PoW mining by exploring the potential benefits of introducing a nonlinear probability of success based on a miner's computational power. This nonlinear proof-of-work (nlPoW) algorithm reduces energy consumption without compromising the decentralised nature of Bitcoin. This study formulates four distinct nlPoW algorithms through a meticulous design science approach by deducing requisite algorithmic specifications and structures. Rigorous statistical simulations are employed to assess the performance of nlPoW against conventional PoW within the Bitcoin mining process. Preliminary outcomes obtained from simulating a sizable network of miners, each possessing equivalent computational power, demonstrate that nlPoW effectively curtails the hash computations required during Bitcoin mining. nlPoW achieves energy efficiency enhancements without compromising the decentralised consensus model or substituting energy consumption with alternate resources, a trade-off often observed in prior attempts to mitigate the energy challenge associated with PoW. © 2023 IEEE.

关键词： Bitcoin mining blockchain consensus algorithm nonlinear proof-of-work proof-of-work

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Stability of consensus Quantum Networks in General Dimension

Stability of Consensus Quantum Networks in General Dimension

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European Control Conference (ECC)

作者： Genki Akimoto Koji Tsumura Department of Information Physics & Computing University of Tokyo Japan

ISBN: (数字)9783907144107

ISBN: (纸本)9798331540920

In this study, we deal with quantum networked systems consisting of $N$ quantum subsystems having $D$ states. In previous studies, it was proved that a symmetric-state consensus (SSC) can be attained by an algorithm composed of local measurements and a local feedback control in cases of $D=2$ and 3. However, a proof for general $D$ remained an open problem. In this study, we rigorously prove that an SSC can be attained by the same algorithm in the case of general $D$ .

关键词： Quantum entanglement Europe consensus algorithm Stability analysis Generators Feedback control Quantum networks

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consensus in Multiagent Systems with lack of connection

arXiv

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arXiv 2024年

作者： Bentaibi, Mohamed Caravenna, Laura Gauthier, Jean-Paul A. Rossi, Francesco The Department of Mathematics ‘Tullio Levi-Civita’ Università degli Studi di Padova Via Trieste 63 Padova35121 Italy The University of Toulon France Università Iuav di Venezia Dipartimento di Culture del Progetto Ca’ Tron S. Croce 1957 Venezia30135 Italy

We consider multi-agent systems with cooperative interactions and study the convergence to consensus in the case of time-dependent lack of interaction. We prove a new condition ensuring consensus: we define a graph in which directed arrows correspond to connection functions that converge (in the weak sense) to some function with a positive integral on all intervals of the form [t, +∞). If the graph has a vertex reachable from all other indices, then the system converges to consensus. We show that this requirement generalizes some known sufficient conditions for convergence, such as the Persistent Excitation one. We also give a second new condition, transversal to the known ones: total connectedness of the undirected graph formed by the non-vanishing of limiting functions. © 2024, CC BY.

关键词： consensus algorithm

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Information-Weighted consensus Optimal Kalman Filter for Linear Systems with Fading Channels

Information-Weighted Consensus Optimal Kalman Filter for Lin...

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Chinese Control and Decision Conference, CCDC

作者： Xiaohan Liu Chunyan Han School of Electrical Engineering University of Jinan Jinan P.R.China

ISBN: (数字)9798350387780

ISBN: (纸本)9798350387797

This paper is concerned with the optimal Kalman consensus filter (KCF) for discrete-time systems with fading channels, where each channel is suffered from different transmission delays and packet losses. Firstly, the reorganisation observation technology is adopted to transform the observation sequence with time delay into a delay-free observation sequence. Secondly, an KCF is presented by the mean squared method, and the closed-form expressions for the Kalman gains and consensus gains are derived. The novelty of this paper is that a novel matrix-weighted consensus algorithm is applied to deal with the distributed state filter of the fading channel systems, which is with the optimality property and recursion form.

关键词： Fading channels Linear systems Discrete-time systems Delay effects Packet loss Transforms consensus algorithm

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Privacy Preserving Second-Order consensus by Adding Edge-Based Perturbations

Privacy Preserving Second-Order Consensus by Adding Edge-Bas...

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Chinese Automation Congress (CAC)

作者： Zhuo Ma Hongjun Chu Zuxia Cheng College of Automation & College of Artificial Intelligence Nanjing University of Posts and Telecommunications NanJing China Institute of Advanced Technology for Carbon Neutrality Nanjing University of Posts and Telecommunications NanJing China

ISBN: (数字)9798350368604

ISBN: (纸本)9798350368611

Many works on privacy-preserving consensus of multi-agents are limited to first-order dynamics, and developing privacy-preserving consensus algorithms based on second-order dynamical network systems has a stronger need for engineering practicality and presents a greater challenge. In this paper, we propose a privacy-preserving second-order consensus algorithm based on strongly connected directed graphs. The algorithm avoids direct interaction of real states among individuals by adding well-designed perturbation signals based on commu-nication edges. Theoretical results indicate that the proposed algorithm is able to achieve accurate second-order dynamic consensus. Moreover, through rigid theoretical analysis, we give necessary and sufficient conditions for an agent to maintain its position and velocity privacy in the face of an internal honest-but-curious agent. Simulation examples verify the effectiveness of the proposed algorithm.

关键词： Privacy Sufficient conditions Leadership Accuracy Heuristic algorithms Perturbation methods Directed graphs consensus algorithm Network systems Multi-agent systems

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Dynamic Difficulty Scaling for Proof-of-Work consensus Protocol

Dynamic Difficulty Scaling for Proof-of-Work Consensus Proto...

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International Conference on Knowledge and Smart Technology (KST)

作者： Areerat Tupwong Vasin Suttichaya Department of Computer Engineering Faculty of Engineering Mahidol University Nakorn Pathom Thailand

ISBN: (数字)9798331520403

ISBN: (纸本)9798331520410

Blockchain technology is widely utilized across various sectors, including economics and intellectual property, with consensus algorithms being fundamental to ensuring security and functionality. Proof-of-Work (PoW) is a fundamental consensus mechanism in Bitcoin, requiring significant computational resources, with GPUs outperforming CPUs in mining efficiency. A critical vulnerability in PoW is the ${5 1 \%}$ attack, where dominant mining nodes gain disproportionate control of the network. This study proposes the Dynamic Difficulty Scaling Factor for Proof-of-Work (DPoW), a novel approach designed to mitigate this issue. DPoW adjusts mining difficulty based on a node's previous unsuccessful attempts, allowing nodes with lower computational power to face reduced difficulty levels. This dynamic adjustment promotes fairness, enabling less powerful nodes to compete more effectively against stronger nodes. Experimental results demonstrate that DPoW effectively mitigates the risk of a 51% attack in PoW and ensures an equitable distribution of benefits among all mining nodes within the network.

关键词： Knowledge engineering Scalability Refining consensus algorithm Intellectual property Proof of Work Dynamic scheduling consensus protocol Security Testing

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Privacy-Preserving Resilient Vector consensus

arXiv

引用

arXiv 2024年

作者： Liu, Bing Zhao, Chengcheng Chai, Li Cheng, Peng Chen, Jiming The State Key Laboratory of Industrial Control Technology Zhejiang University Zhejiang Hangzhou310027 China The School of Automation Hangzhou Dianzi University Zhejiang Hangzhou310018 China

This paper studies privacy-preserving resilient vector consensus in multi-agent systems against faulty agents, where normal agents can achieve consensus within the convex hull of their initial states while protecting state vectors from being disclosed. Specifically, we consider a modification of an existing algorithm known as Approximate Distributed Robust Convergence Using Center-points (ADRC), i.e., Privacy-Preserving ADRC (PP-ADRC). Under PP-ADRC, each normal agent introduces multivariate Gaussian noise to its state during each iteration. We first provide sufficient conditions to ensure that all normal agents’ states can achieve mean square convergence under PP-ADRC. Then, we analyze convergence accuracy from two perspectives, i.e., the Mahalanobis distance of the final value from its expectation and the Hausdorff distance based alteration of the convex hull caused by noise when only partial dimensions are added with noise. Then, we employ concentrated geo-privacy to characterize privacy preservation and conduct a thorough comparison with differential privacy. Finally, numerical simulations demonstrate the theoretical results. Copyright © 2024, The Authors. All rights reserved.

关键词： consensus algorithm

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RRPoS: A Fair and Efficient Approach to Blockchain consensus using Round Robin

RRPoS: A Fair and Efficient Approach to Blockchain Consensus...

引用

Blockchain and Distributed Systems Security (ICBDS), IEEE International Conference on

作者： Adla Sanober Shamama Anwar Department of Computer Science and Engineering Birla Institute of Technology Mesra Ranchi India

ISBN: (数字)9798350354348

ISBN: (纸本)9798350354355

Due to advanced technological development, the application of blockchain is not just for financial services. It has inherent potential uses in various industries, including healthcare, supply chain, industrial goods, E-commerce, and others. Any group or individuals agree in a blockchain network to make transactions on the basis of a consensus mechanism. The critical role of the consensus mechanism is that it improves the efficiency and security of the blockchain system. Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS), Proof of Authority (PoA), Practical Byzantine Fault Tolerance (PBFT) and some other recent proof of concepts such as Proof of Burn (PoB), Proof of Learning, Proof of Luck (PoLu), etc. are the various existing consensus algorithms. However, there are problems with these algorithms including centralization risk, security, efficiency, and waste of resources. Proof of Work (PoW) consumes high computational power to solve the cryptographic puzzle and makes the system more costly. Proof of Stake (PoS) encourages high-stakes node selected as a validator to propose and validate the new block in the blockchain, which promotes inequality and monopolies. The paper introduces Round Robin Proof of Stake (RRPoS) based on the existing Proof of Stake (PoS) that involves block creation in a round-robin fashion to increase the chances of high- to low-stakes validators for the validation of the proposed block. The proposed consensus algorithm is able to ascertain the existence of malicious validator nodes and eliminate them to enhance system security. The performance analysis demonstrates that RRPoS is better and more efficient than PoW and PoS.

关键词： Industries Proof of stake Supply chains consensus algorithm Medical services Proof of Work consensus protocol Performance analysis Monopoly Round robin

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