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DRBFT: Delegated Randomization Byzantine Fault Tolerance Consensus Protocol for Blockchains
Abstract
Blockchain, as a potentially revolutionary technology, has been used in cryptocurrency to record transactions chronologically among multiple parties. Due to the fast development of the blockchain and its de-centralization, blockchain technology has been applied in broader scenarios, such as smart factories, supply chains, and smart cities. Consensus protocol plays a vital role in the blockchain, which addresses the issue of reaching consensus on transaction results among involved participants. Nevertheless, with the complexity of the network environment and growing amount of network users, the advance of blockchain is gradually restricted by the efficiency, security and reliability of consensus protocols. In this paper, we propose a delegated randomization Byzantine fault tolerance consensus protocol named DRBFT based on Practical Byzantine Fault Tolerance(PBFT) to enhance the efficiency and reliability of the consensus procedure. Specifically, a random selection algorithm called RS is developed to cooperate with the voting mechanism, which can effectively reduce the number of nodes participating in the consensus process. Our proposed scheme is characterized by the unpredictability, randomicity and impartiality, which accelerate the system to reach consensus on the premise of ensuring the system activity. Furthermore, the feasibility of our proposed scheme is also proved by both theoretical analysis and experimental evaluations.
... In this section, we investigate protocols using these techniques to see how committees are formed, how they work, and what aspects should be considered for scalability. 1) Committee: In a committee, only a subset of nodes participates in the consensus algorithm, as depicted in Fig. 9c, while non-committee members observe the results of the consensus [13], [46], [77]. As only a substantially smaller subset of the total nodes participate in the consensus algorithm, the communication efforts needed inside of the committee are reduced. ...
... Different algorithms use different randomness to select committee nodes. For example, Algorand utilizes VRFs [13] (c. f., §IV-C5), DRBFT picks committee nodes based on previous blocks [77], and RapidChain uses verifiable secret sharing to generate randomness within committees [44]. Some algorithms modify the committee formation based on metrics such as stake [13], [63] or quality characteristics [62] such as bandwidth or latency to prioritize nodes by some weight. ...
... Commonly the results of the committee are verified. This verification is both to check that progress is made, e. g., that blocks are proposed, but also of the blocks themselves [35], [77]. For example, in Proteus, a committee is replaced with new members if the committee does not generate valid blocks [35]. ...
With the advancement of blockchain systems, many recent research works have proposed distributed ledger technology~(DLT) that employs Byzantine fault-tolerant~(BFT) consensus protocols to decide which block to append next to the ledger. Notably, BFT consensus can offer high performance, energy efficiency, and provable correctness properties, and it is thus considered a promising building block for creating highly resilient and performant blockchain infrastructures. Yet, a major ongoing challenge is to make BFT consensus applicable to large-scale environments. A large body of recent work addresses this challenge by developing novel ideas to improve the scalability of BFT consensus, thus opening the path for a new generation of BFT protocols tailored to the needs of blockchain. In this survey, we create a systematization of knowledge about the novel scalability-enhancing techniques that state-of-the-art BFT consensus protocols use. For our comparison, we closely analyze the efforts, assumptions, and trade-offs these protocols make.
... At present, the improvement of PBFT mainly focuses on improving its performance and efficiency. The existing related schemes can roughly divide into two categories: optimizing the structure of the consensus procedure [24][25][26][27] and reducing the number of nodes participating in consensus while increasing the randomness of the participating nodes [28][29][30]. ...
... It can not guarantee the performance of this scheme in asynchronous networks with network delay. Zhan et al. proposed DRBFT, which divides nodes into the normal nodes and the candidates [30]. The normal nodes select the councilors through DPoS. ...
... That is to say, the scheme proposed in this paper can well hide the generated primary sequence. [30]. ...
Blockchain technology has aroused great interest from society and academia since the inception of Bitcoin. Its de-centralization and non-tampering can apply in broader scenarios, such as the Internet of Things, smart cities, and cloud computing. Among various core components, the consensus protocol is the core of maintaining blockchain networks’ performance, stability, and security. However, with the increase of network nodes and the improvement of network complexity, these properties are difficult to meet simultaneously. In this paper, we propose an advancement of the practical Byzantine consensus algorithm (LRBFT). The algorithm uses Lagrange interpolation that all backups can participate in to generate random seeds, uses the seeds to optimize the election process of the primary set, improves consensus efficiency through delegated nodes, and prevents the primary from doing evil through the supervisory mechanism. The generation of random seeds has the characteristics of full participation, unpredictability, and verifiability. The election process of the primary set has randomness, uniform distribution, and supervision. Furthermore, we proved the feasibility of our proposed algorithm through theoretical analysis and experimental evaluations. Experimental analysis shows that when there are 70 nodes in the practical Byzantine fault tolerance (PBFT) consensus protocol. If LRBFT selects only 7 nodes as delegated nodes, the time it takes for LRBFT to reach 100 consensuses is only 0.83% of that of PBFT.
... Проведений дослідниками [10][11][12][13][14][15][16] аналіз висвітлює, що у блокчейн мережах з обмеженою кількістю учасників, як це є у корпоративних системах, немає сенсу використовувати непродуктивні та повністю розподілені типи консенсусів, на кшталт Proof of Work і Proof of Stake. Це дає завжди збільшення вартості проведення та зберігання транзакцій: одна справа зберігати транзакцію на десятках корпоративних вузлах, а зовсім інша -на сотнях тисяч у всьому світі, як укриптовалютних системах. ...
... Як показано на рис. 2, у моделі системи DBFT є три сторони, включаючи кандидатів, радників і звичайні вузли [14]. Кандидати обираються з усіх вузлів у системі блокчейн на початку процесу консенсусу. ...
The concept of the new generation of the Internet is based on decentralization and today is widely implemented in cryptocurrency tokens and information systems based on blockchain technology. The purpose of the article is to investigate the impact of algorithms for confirming the authenticity of information on the effectiveness of the functioning of corporate information systems using blockchain technology through the analysis of existing concepts of consensus. The scheme of the corporate information system of document circulation proposed by the authors of the article in previous works using blockchain technology is based on ensuring the decentralization of the system and the integrity of data regarding the preservation and revision of the institution's documents. To automate the consensus process using a smart contract, the system uses a dynamic consensus. Концепція нового покоління Інтернету заснована на децентралізації і сьогодні широко реалізована в токенах криптовалюти та інформаційних системах на основі технології блокчейн. Метою статті є дослідження впливу алгоритмів підтвердження достовірності інформації на ефективність функціонування корпоративних інформаційних систем з використанням технології блокчейн через аналіз існуючих концепцій консенсусу. Запропонована авторами статті в попередніх роботах схема корпоративної інформаційної системи документообігу з використанням технології блокчейн базується на забезпеченні децентралізації системи та цілісності даних щодо збереження та перегляду документів установи. Для автоматизації процесу консенсусу за допомогою смарт-контракту система використовує динамічний консенсус.
... [46] Medical devices that are connected to the internet can collect important patient data, improve workflows, provide useful information about symptoms and patterns in sickness, enable remote care, and give patients more choice over their lives and treatments. [93] Patients can be monitored in real-time with the help of IoT devices. There will be less need for frequent trips to the doctor's office as a result of their use. ...
... When you delegate jobs or responsibilities to other people at random, you are engaging in delegated randomization. To integrate blockchain into large-scale asynchronous network applications, Zhan et al. (2021) [94] propose Byzantine fault tolerance (DRBFT). The nodes that will run the PBFT protocol are selected at random using a rigorously unbiased approach. ...
Transparency, auditability, trustworthiness, privacy, and security are some of the issues plaguing existing
healthcare data management systems. Other concerns include data origin tracing, immutability, traceability, and
auditability. In addition, many of the healthcare data management systems in use today are centralized, which
increases the risk of a single point of failure and makes them susceptible to natural disasters. The emerging
decentralized technology known as blockchain has the potential to completely revamp, transform, and change the
way healthcare organizations handle patient data. This article offers a comprehensive overview of blockchain
architecture, platforms, and classifications to assist in the selection of the most suitable blockchain platform for
healthcare applications. This compilationpresents the latest discoveries from state-of-the-art research on healthcare
blockchain and current healthcare applications that are based on blockchain technology. Furthermore, to provide
insight into future research, we present the challenges and prospective areas of study. We utilized threat model
classifications to analyze the various security attacks on the blockchain protocol and conducted a comparative
analysis of detection and prevention techniques. In addition, this paper also covers techniques to enhance the
privacy and security of the blockchain network.
... In Delegated Byzantine Fault Tolerance (DBFT), voting determines a set of nodes that verify operations and insert a fresh block on the blockchain in a similar manner to PBFT instead of all nodes [105]. ...
... Network Proof-based consensus PoW [96], PoS [97], PoA [98], PoSp [99], PoB [100], PoAu [101], PoET [102] Vote-based consensus PBFT [103], DBFT [105], Raft [106] Hybrid consensus DPoS [107] Scripts TBAC [114] P2P communication Bitcoin protocol [111], Ethereum wire protocol [112], IPFS [113] Network attacks DoS attacks, routing attacks, domain name service attacks, eclipse attacks [142] Data Architectures Linear [3], Directed acyclic graph [4] Types Private [149], Public [150], Consortium [151] Cryptography Hashing [82], Public key cryptography [80], Zero-knowledge proofs [84], Post-quantum cryptography [87,88,90], Hybrid cryptography [86,89], fault-tolerant ciphers [91][92][93][94][95] Endpoint attacks 51% vulnerability, cryptojacking [143] Application Smart contracts Contractual automation [116], access control [117] Cryptocurrency Bitcoin [2], Ethereum [81] Supply chain Cold chain management [121] Networking TRUCON [123], IoTChain [124], UASTrustChain [125] Healthcare Drug counterfeiting [127], Medblock [128], MedShare [129] Insurance ClaimChain [130], Insurance fraud protection [131], Decentralized reinsurance [132] Voting PriScore [133], Auditable voting [134] Intellectual property IP protection [135], IP rights management [136] ...
Knowledge-Defined Networking (KDN) necessarily consists of a knowledge plane for the generation of knowledge, typically using machine learning techniques, and the dissemination of knowledge, in order to make knowledge-driven intelligent network decisions. In one way, KDN can be recognized as knowledge-driven Software-Defined Networking (SDN), having additional management and knowledge planes. On the other hand, KDN encapsulates all knowledge-/intelligence-/cognition-/machine learning-driven networks, emphasizing knowledge generation (KG) and dissemination for making intelligent network decisions, unlike SDN, which emphasizes logical decoupling of the control plane. Blockchain is a technology created for secure and trustworthy decentralized transaction storage and management using a sequence of immutable and linked transactions. The decision-making trustworthiness of a KDN system is reliant on the trustworthiness of the data, knowledge , and AI model sharing. To this point, a KDN may make use of the capabilities of the blockchain system for trustworthy data, knowledge, and machine learning model sharing, as blockchain transactions prevent repudiation and are immutable, pseudo-anonymous, optionally encrypted, reliable, access-controlled, and untampered, to protect the sensitivity, integrity, and legitimacy of sharing entities. Furthermore, blockchain has been integrated with knowledge-based networks for traffic optimization, resource sharing, network administration, access control, protecting privacy, traffic filtering, anomaly or intrusion detection, network virtualization, massive data analysis, edge and cloud computing, and data center networking. Despite the fact that many academics have employed the concept of blockchain in cognitive networks to achieve various objectives, we can also identify challenges such as high energy consumption, scalability issues, difficulty processing big data, etc. that act as barriers for integrating the two concepts together. Academicians have not yet reviewed blockchain-based network solutions in diverse application categories for diverse knowledge-defined networks in general, which consider knowledge generation and dissemination using various techniques such as machine learning, fuzzy logic, and meta-heuristics. Therefore, this article fills a void in the content of the literature by first reviewing the diverse existing blockchain-based applications in diverse knowledge-based networks, analyzing and comparing the existing works, describing the advantages and difficulties of using blockchain systems in KDN, and, finally, providing propositions based on identified challenges and then presenting prospects for the future.
... Extensible-PBFT [23] uses verifiable random function to elect consensus nodes for reducing communication overhead. A random selection was developed to cooperate with the voting mechanism in [24], which can be applied to reduce the number of nodes participating in the consensus process. This scheme is characterized by unpredictability and impartiality. ...
... Each node has uncertainty about the consensus role in advance, achieving the purpose of restraining the evil nodes. However, these methods as mentioned above [22][23][24][25][26] take time for calculation due to the addition of encryption algorithms. ...
Consensus protocol is challenging due to the poor node reliability, low efficiency and decentralization. A comprehensive reputation based Practical Byzantine Fault Tolerance consensus method (CRPBFT) has been proposed. Comprehensive reputation model has been developed to evaluate the credibility of each node from service behavior and consensus process at first. The nodes with higher reputation are selected to participate in the consensus process, which helps to reduce the probability of consensus failure caused by the existence of malicious nodes. A consensus communication structure is optimized by replacing the whole network broadcast structure in the commit phase with a star one. It can be applied to degrade the network communication overhead and improve consensus efficiency. A rotation mechanism for replacing the consensus nodes regularly has been proposed to increase the degree of decentralization and enhance the robustness and dynamic of the consensus network. Some experimental results demonstrate that the developed method has excellent performance by comparisons with some state-of-the-arts.
... Techniques of addressing security and reliability issues include Moving Target Defense (MTD) [9][10][11], Cyber Mimic Defense (CMD) [12,13], Byzantine Fault Tolerance [14][15][16], and Redundancy Fault Tolerance [17,18] technologies. The characteristics of these technologies are summarized in Table 1. ...
With more China railway business information systems migrating to the China Railway Cloud Center (CRCC), the attack surface is expanding and there are increasing security threats for the CRCC to deal with. Cyber Mimic Defense (CMD) technology, as an active defense strategy, can counter these threats by constructing a Dynamic Heterogeneous Redundancy (DHR) architecture. However, there are at least two challenges posed to the DHR deployment, namely, the limited number of available schedulable heterogeneous resources and memorization-based attacks. This paper aims to address these two challenges to improve the CRCC-DHR reliability and then facilitate the DHR deployment. By reliability, we mean that the CRCC-DHR with the limited number of available heterogeneous resources can effectively resist memorization-based attacks. We first propose three metrics for assessing the reliability of the CRCC-DHR architecture. Then, we propose an incomplete-information-based game model to capture the relationships between attackers and defenders. Finally, based on the proposed metrics and the captured relationship, we propose a redundant-heterogeneous-resources scheduling algorithm, called the Entropy Weight Scheduling Algorithm (REWS). We evaluate the capability of REWS with the three existing algorithms through simulations. The results show that REWS can achieve a better reliability than the other algorithms. In addition, REWS demonstrates a lower time complexity compared with the existing algorithms.
... time and communication overhead [25], which affects the efficiency of the consensus. PBFT is unable to recognize Byzantine nodes, and although the security of the system is not affected when the number of Byzantine nodes is not more than one-third of the total number of nodes [26], the smaller the number of Byzantine nodes is, the more efficient the consensus is. ...
Blockchain technology provides a reliable and efficient environment for digital asset transactions. Consensus algorithms are the cornerstone of its security and accuracy. However, there are still security problems and performance bottlenecks associated with blockchain consensus algorithms in the context of current digital asset transactions, an improved PBFT algorithm (GamePBFT) based on reputation and game was proposed on the basis of Practical Byzantine Fault Tolerance (PBFT).Better applied to digital asset trading, we establish a reputation model that enables the dynamic reward and punishment of nodes according to their consensus behavior in this paper. Furthermore, a game model is constructed, which allows for the minimum number of nodes to participate in the consensus and the highest efficiency of eliminating malicious nodes. This can resist some common attacks, reduce the complexity of the algorithm, and improve the security and consensus efficiency of the algorithm. Finally, the results of the simulated node digital transaction scenario demonstrate that the improved consensus algorithm exhibits a notable enhancement over the PBFT consensus algorithm in terms of consensus latency, communication overhead, throughput, and security.
... Neo is a Blockchain platform furnishing a decentralized infrastructure for smart contracts and dApps [70]. It operates using the Delegated Byzantine Fault Tolerance (dBFT) consensus mechanism [71], wherein designated nodes (bookkeepers) validate transactions. SHA-256 is used for cryptographic operations within the network; however, the consensus process itself focuses on achieving Byzantine fault tolerance (BFT) and swift block confirmation times, leading to unique algorithmic complexity properties. ...
Organizations worldwide are under pressure to reduce their use of non-renewable energy sources and carbon emissions due to their increasing negative impact on the ongoing climate crisis. Blockchain technology, popularized by its use in Bitcoin, has been adopted for various use cases but is criticized for its high energy consumption, depending on the consensus mechanism used. Consensus mechanisms are vital for securing blockchain networks by ensuring all nodes agree on the ledger's state, but they often trade-off between low energy consumption and high security. This paper analyzes the critical factors contributing to power consumption in blockchain networks, focusing on consensus mechanisms and hashing techniques. Through a comprehensive State-of-the-Art (SOTA) review and algorithmic analysis, we examine how various consensus algorithms impact energy usage and detail the computational and space complexities of different hashing algorithms. We also investigate the energy profiles and reduction strategies of major blockchain platforms. Our findings highlight the potential to enhance blockchain energy efficiency without compromising security or performance, providing a foundation for future research in sustainable blockchain technologies.
... In a blockchain system, each newly generated block is appended with the latest transactions. Once all nodes validate its legitimacy, it is linked to the preceding block, and only the transactions appended to the block are executed [19]. Blockchain, serving as a distributed ledger and database, possesses qualities of openness, transparency, decentralization, and immutability, addressing the issue of trust among nodes within decentralized systems and thus facilitating the transformation of information to value on the internet [20]. ...
Online social media (OSM) has revolutionized the manner in which communication unfolds, enabling users to spontaneously generate, disseminate, share, and aggregate multimedia data across the internet. Nevertheless, in this exchange of information, OSM platforms assume a dominant, central role, wielding excessive power. Blockchain online social media (BOSM) seeks to mitigate the drawbacks of traditional centralized OSM by leveraging the decentralized nature of blockchain technology, migrating the functionalities of social media into a decentralized realm, and positioning the users at the core of the OSM ecosystem. However, current BOSM models often rely on tokens for incentives and are hampered by the centralized, inefficient blockchain consensus mechanisms, alongside vulnerabilities such as collusion attacks. This paper introduces a novel blockchain system, NexoNet, tailored for decentralized social media, exploring the application of blockchain technology in the realm of online social media from both technical and economic perspectives. The NexoNet quantifies and evaluates user participation within the system, employing a multiple incentive mechanism to equitably distribute value created by users without the need for tokens. Furthermore, we propose the Proof-of-Active-Participation (PoAP) blockchain consensus mechanism, enabling all users to partake in the maintenance of the blockchain system, thus ensuring its security and efficiency. Theoretical analysis and simulations across various scenarios demonstrate that the NexoNet, with extensive user engagement, achieves equitable value distribution through its multiple incentive mechanism. It successfully safeguards against a spectrum of malicious attacks and attains high transaction processing efficiency. The simulation results show that NexoNet achieves an average transaction throughput of 2000 transactions per second (TPS) and a consensus delay of 2.385 s with 100 maintainers in the network. Furthermore, our tests demonstrated that even collusion with users comprising 75% of the total would only allow an additional 30 chances to propose a block. By deeply integrating user behavior with the underlying mechanisms of the blockchain system, the NexoNet fosters a user-centric blockchain social media ecosystem.
... However, this scheme only takes the node's trust as the weight of the recommendation degree, without taking into account the attack of cooperative malicious nodes and may cause the calculation result of the node's trust value to deviate from the correct value. Zhan et al. [24] utilized the hash function to construct a random selection algorithm and randomly selected some nodes as consensus nodes, which can effectively reduce the size of the consensus group, but cannot reduce the proportion of malicious nodes. To further optimize the consensus efficiency, Li et al. [25] proposed a consensus mechanism called SHBFT to reduce consensus latency by layering consensus nodes. ...
Blockchain has been widely used in finance, the Internet of Things (IoT), supply chains, and other scenarios as a revolutionary technology. Consensus protocol plays a vital role in blockchain, which helps all participants to maintain the storage state consistently. However, with the improvement of network environment complexity and system scale, blockchain development is limited by the performance, security, and scalability of the consensus protocol. To address this problem, this paper introduces the collaborative filtering mechanism commonly used in the recommendation system into the Practical Byzantine Fault Tolerance (PBFT) and proposes a Byzantine fault-tolerant (BFT) consensus protocol based on collaborative filtering recommendation (CRBFT). Specifically, an improved collaborative filtering recommendation method is designed to use the similarity between a node’s recommendation opinions and those of the recommender as a basis for determining whether to adopt the recommendation opinions. This can amplify the recommendation voice of good nodes, weaken the impact of cunning malicious nodes on the trust value calculation, and make the calculated results more accurate. In addition, the nodes are given voting power according to their trust value, and a weight random election algorithm is designed and implemented to reduce the risk of attack. The experimental results show that CRBFT can effectively eliminate various malicious nodes and improve the performance of blockchain systems in complex network environments, and the feasibility of CRBFT is also proven by theoretical analysis.
... The framework works on defined criteria and priorities by using multi decisionmaking system. A fault-tolerant consensus algorithm for Blockchain is proposed [35]. The protocol is based on Practical Byzantine Fault Tolerance (PBFT) to ensure the reliability and efficiency of the consensus protocols. ...
Blockchain is a distributed ledger in which transactions are grouped in blocks linked by hash pointers. Blockchain-based solutions provide trust and privacy because of the resistance to the inconsistency of data and advanced cryptographic features. In various fields, blockchain technology has been implemented to ensure transparency, verifiability, interoperability, governance, and management of information systems. Processing large volumes of data being generated through emerging technologies is a big issue. Many researchers have used Blockchain in various fields integrated with IoT, i.e., industry 4.0, biomedical, health, genomics, etc. Blockchain has the attributes of decentralization, solidness, security, and immutability with a possibility to secure the system design for transmission and storage of data. The purpose of the consensus protocols is to keep up the security and effectiveness of the blockchain network. Utilizing the correct protocol enhances the performance of the blockchain applications. This article presents essential principles and attributes of consensus algorithms to show the applications, challenges, and opportunities of blockchain technology. Moreover, future research directions are also presented to choose an appropriate consensus algorithm to enhance the performance of Blockchain based applications
... dBFT is a good choice for applications that need quick and reliable transaction processing since it delivers high transaction throughput, low latency, and effective. However, it is crucial to remember that dBFT necessitates confidence in the elected validators because of their enormous impact and level of control over the consensus procedure [19]. ...
... This algorithm outperforms the PBFT consensus algorithm in terms of throughput, latency, and scalability. Zhan et al. [30] introduced the Delegated Randomized Byzantine Fault Tolerant (DRBFT) consensus protocol based on PBFT, incorporating a random selection algorithm matching the voting mechanism. The goal is to reduce the number of nodes involved in the negotiation in an unpredictable, random, and fair manner. ...
The consensus mechanism serves as the fundamental technology behind blockchain, enabling the establishment of a decentralized and reliable network system that achieves consensus among nodes without relying on the trustworthiness of individual nodes. In the enterprise composite blockchain, the master chain adopts a licensed public chain. However, existing consensus mechanisms cannot be directly applied to the licensed public chain. To address this, this paper proposes a dual-layer consensus algorithm that combines DPoS and PBFT. Aiming at the problem that DPoS voting mechanism commonly elects the node holding more tokens, which can lead to issues of political indifference. On the other hand, PBFT suffers from concerns such as inflexible and singular master node election, high communication complexity during the consensus process, and substantial overhead associated with view changes. In light of these challenges, this paper introduces an improved DPoS and BFT-based double-layer consensus algorithm designed specifically for the enterprise composite blockchain. Initially, the algorithm votes to generate a set of consensus nodes by improved DPoS verification pool selection. Subsequently, the elected consensus nodes generate blocks and conduct on-chain operations using a BFT consensus algorithm that integrates VRF and TS. Through experimental verification, this paper proposed algorithm effectively enhances system security and node activity without sacrificing usability. Moreover, comparative analysis against existing algorithms demonstrates higher transaction throughput, lower transaction latency, and reduced CPU load associated with this paper proposed algorithm.
... Yu Zhan and his team have identified that the Practical Byzantine Fault Tolerance (PBFT) becomes less efficient as the number of nodes increases, due to its complexity. To address this issue, they introduced a new protocol named Delegated Randomization Byzantine Fault Tolerance (DRBFT), as described in their study [20]. This protocol aims to fairly select delegate nodes from all participants to implement the PBFT using a Random Selection (RS) algorithm. ...
Blockchain technology offers a decentralized and secure method for storing and authenticating data, rendering it well-suited for various applications such as digital currencies, supply chain management, and voting systems. However, the decentralized nature of blockchain also exposes it to vulnerabilities, particularly Byzantine faults, which arise when nodes in the network behave maliciously or encounter unexpected failures. Such incidents can result in inconsistencies within the blockchain and, in extreme scenarios, lead to a breakdown in consensus. Byzantine fault-tolerant consensus algorithms are crafted to tackle this challenge by ensuring that network nodes can agree on the blockchain's state even in the presence of faulty or malicious nodes. To bolster the system's resilience against these faults, it is imperative to detect them within the system. However, our examination of existing literature reveals a prevalent assumption: solutions typically operate under constraints regarding the number of faulty nodes. Such constraints confine the proposed solutions to ideal environments, limiting their practical applicability. In response, we propose a novel approach inspired by social paradigms, employing a trusted and fully monitored communication sub-process to detect Byzantine nodes. Upon detection, these nodes can be either disregarded in the consensus-building process, subjected to penalties, or undergo modifications as per the system's policy. Finally, we statistically demonstrate that our approach achieves a detection probability that exceeds 95\% for Byzantine nodes. In essence, our methodology ensures that if Byzantine nodes exhibit malicious behavior, healthy nodes can identify them with a confidence level of 95\%.
... Additionally, Li et al. [32] devised a hierarchical structure to enhance scalability and consensus efficiency. Zhan et al. [33] introduced the DRBFT consensus protocol, which is a Byzantine fault-tolerant protocol that utilizes a commissioned randomization approach. They also developed an RS random selection algorithm in conjunction with a voting mechanism. ...
Medical data are an intangible asset and an important resource for the entire society. The mining and application of medical data can generate enormous value. Currently, medical data management is mostly centralized and heavily relies on central servers, which are prone to malfunctions or malicious attacks, making it difficult to form a consensus among multiple parties and achieve secure sharing. Blockchain technology offers a solution to enhance medical data security. However, in medical data security sharing schemes based on blockchain, the widely adopted Practical Byzantine Fault-Tolerant (PBFT) algorithm encounters challenges, including intricate communication, limited scalability, and the inability to dynamically add or remove nodes. These issues make it challenging to address practical requirements effectively. In this paper, we implement an efficient and scalable consensus algorithm based on the PBFT consensus algorithm, referred to as Me-PBFT, which is more suitable for the field of medical data security. First, we design a reputation evaluation model to select more trusted nodes to participate in the system consensus, which is implemented based on a sigmoid function with adjustable difficulty. Second, we implement the division of node roles to construct a dual consensus layer structure. Finally, we design a node dynamic join and exit mechanism on the overall framework of the algorithm. Analysis shows that compared to PBFT and RAFT, ME-PBFT can reduce communication complexity, improve fault tolerance, and have good scalability. It can meet the need for consensus and secure sharing of medical data among multiple parties.
... A group of researcher have proposed an improved version of DBFT called delegated randomization byzantine fault tolerance (DRBFT). In their experiments, they have showed that basic DBFT performs well when dealing with large-scale applications while keeping efficiency and low resource wastage [39]. ...
Over the past few decades, the harmful effects of industrial activity and consumer society have resulted in global warming. Governments and international organizations are looking for ways to monitor activities of individuals and companies to assess their ecological impact. Unfortunately, such an approach would easily be seen as a mass surveillance tool. This is why we are proposing in this paper a novel privacy-aware global infrastructure for ecological footprint calculator based on the Internet of things and blockchain. Indeed, we take advantage of the data collection capacity of the Internet of things, the anonymization provided by public key identification and encryption, and the immutability of blockchain to implement this global system. A three-stage approach was used to validate our architecture: modeling in Petri nets to verify that the infrastructure fulfills all the required missions, implementing the three central authorities with python to record parameters such as durations, and finally modeling in queuing networks to demonstrate stability. The blockchain and Internet of things parts are used in a purely abstract manner relying on standard concepts; therefore, we have not implemented them. The experiments have produced very promising results. We have shown that for the simplest form of queue modeling, the involved servers have a utilization rate that is close to 50% and that the overall waiting time remains below one minute.
... Moreover, they change the number of transactions included in one block to be alterable due to the application scenario and performance of nodes. Zhan et al. [30]used a random selection algorithm called RS to improve the DBFT. RS chose the nodes participating in consensus from the nodes having won the voting process. ...
The consensus algorithm, as one of the cores of blockchain technology, plays a very critical role. As one of the mainstream consensus methods, PBFT has the advantages such as low energy consumption and large throughput. However, the traditional PBFT algorithm also has disadvantages, such as high network bandwidth occupation, for PBFT needs broadcasting information for all nodes in stage 3 and 4; limited expandability. With the increase of nodes, the bandwidth overhead of the blockchain network will increase significantly, which leads to a decrease in throughput, so that cause a crash of the blockchain network. We proposed an improved PBFT consensus based on a credit value bidirectionally waning, named BW-PBFT. The algorithm first elects some nodes to form a committee according to the ballot and the credit value, and then the committee nodes use the PBFT algorithm for consensus, and calculate the credit value of the nodes according to the performance in the consensus process. If nodes do not get punishment anymore, their credit value will approach 50 with the increase of the blockchain height. Theoretical analysis and experiments prove that the proposed algorithm can effectively improve the quality of the nodes involved in the consensus.
... Moreover, Riahi et al. [28] improved the quantity of the consensus nodes by add some evaluation index, and increased the speed of consesus in this way. Zhan et al. [29]used a random selection algorithm called RS to improve the DBFT. RS chose the nodes participating in consensus from the nodes having won the voting process. ...
The consensus algorithm, as one of the cores of blockchain technology, plays a very critical role. As one of the mainstream consensus methods, PBFT has the advantages such as low energy consumption and large throughput. However, the traditional PBFT algorithm also has disadvantages, such as high network bandwidth occupation, for PBFT needs broadcasting information for all nodes in stage 3 and 4; limited expandability. With the increase of nodes, the bandwidth overhead of the blockchain network will increase significantly, which leads to a decrease in throughput, so that cause a crash of the blockchain network. We proposed an improved PBFT consensus based on a credit value bidirectionally waning, named BW-PBFT. The algorithm first elects some nodes to form a committee according to the ballot and the credit value, and then the committee nodes use the PBFT algorithm for consensus, and calculate the credit value of the nodes according to the performance in the consensus process. If nodes do not get punishment anymore, their credit value will approach 50 with the increase of the blockchain height. Theoretical analysis and experiments prove that the proposed algorithm can effectively improve the quality of the nodes involved in the consensus.
... Through mutual cooperation between the two, the robustness of the network can be improved and a higher degree of decentralization can be maintained. DRBFT [42] proposed an algorithm called RS, which utilizes random selection to choose a certain number of replicas from all available replicas to participate in the consensus process. This approach reduces the number of replicas involved in the consensus process, improves consensus speed, and ensures both security and liveness. ...
The emergence of numerous consensus algorithms for distributed systems has resulted from the swift advancement of blockchain and its related technologies. Consensus algorithms play a key role in decentralized distributed systems, because all nodes in the system need to reach a consensus on requests or commands through consensus algorithms. In a distributed system where nodes work together to reach consensus, there may be Byzantine nodes present. The emergence of Byzantine nodes will affect the consensus of nodes in the distributed system. Therefore, tolerating Byzantine nodes in a distributed system and then reaching a consensus is an essential function of a consensus algorithm. So far, many Byzantine fault-tolerant (BFT) consensus algorithms have emerged, and there are correspondingly many methods to improve the performance of these algorithms. In order to allow researchers to have a clearer understanding of the existing methods, this paper systematically investigated and studied the research progress of the current Byzantine fault-tolerant consensus algorithm. The scope of the research ranged from the classic Byzantine consensus algorithm to some of the latest Byzantine consensus algorithms. The articles were classified according to the methods used to improve the Byzantine consensus algorithm. Through classification and centralized analysis and discussion, we achieved a clearer understanding of the development of Byzantine consensus algorithms and, at the same time, clarified the advantages and disadvantages of this type of method and the latest research progress using this method. At the end of this article, an in-depth discussion and analysis is also presented. By analyzing the impact of the use of these methods on the performance of the BFT consensus algorithm, it is proposed that future research can be improved.
... By separating components in a consensus into modules, we can design each part individually. As described in DRBFT [9], the delegation took place first, then by using quorum chosen during the delegation step, we use PBFT to reach consensus. ...
Distributed systems solve large scale complex problems and consensus is at its core, coordinating every single subsystem towards the same goal. Among consensuses, byzantine fault tolerating consensus is a particularly useful kind of consensus which we will extensively discuss. In this paper, we will review the general approaches to solve the consensus problem – deterministic consensus and probabilistic consensus, PBFT and HotStuff's frameworks and properties, impact that HotStuff has on consensus’ framework in the future, and how federated learning uses principle of distributed system to leverage privacy.
... Hence, this model is suitable for healthcare blockchain systems. Delegated randomization Byzantine fault tolerance (DRBFT) is proposed by Zhan et al. (2021) to suit blockchain for large scale asynchronous network applications. Random selection algorithm is used to fairly select participating nodes to execute PBFT. ...
... dBFT is a good choice for applications that need quick and reliable transaction processing since it delivers high transaction throughput, low latency, and effective. However, it is crucial to remember that dBFT necessitates confidence in the elected validators because of their enormous impact and level of control over the consensus procedure [19]. ...
... To solve the type of failure and conflicting problems, an important concept: Byzantine generals problem, is developed, e.g., see Lamport et al. [33], Lamport [32], Schlichting and Schneider [66], Reischuk [62] and Martin and Alvisi [44] for more details. Based on the Byzantine generals problem, Pease et al. [59] and Lamport et al. [33] proposed the Byzantine fault tolerant consensus mechanism (BFT), and further research includes Thai et al. [71], Li et al. [40], Zhan et al. [78] and so on. ...
In a practical Byzantine fault tolerance (PBFT) blockchain network, the voting nodes may always leave the network while some new nodes can also enter the network, thus the number of voting nodes is constantly changing. Such a new PBFT with dynamic nodes is called a dynamic PBFT. Clearly, the dynamic PBFT can more strongly support the decentralization and distributed structure of blockchain. However, analyzing dynamic PBFT blockchain systems will become more interesting and challenging. In this paper, we propose a large-scale Markov modeling technique to analyze the dynamic PBFT voting processes and its dynamic PBFT blockchain system. To this end, we set up a large-scale Markov process (and further a multi-dimensional Quasi-Birth-and-Death (QBD) process) and provide performance analysis for both the dynamic PBFT voting processes and the dynamic PBFT blockchain system. In particular, we obtain an effective computational method for the throughput of the complicated dynamic PBFT blockchain system. Finally, we use numerical examples to check the validity of our theoretical results and indicate how some key system parameters influence the performance measures of the dynamic PBFT voting processes and of the dynamic PBFT blockchain system. Therefore, by using the theory of multi-dimensional QBD processes and the RG-factorization technique, we hope that the methodology and results developed in this paper shed light on the study of dynamic PBFT blockchain systems such that a series of promising research can be developed potentially.
... Furthermore, centralized solutions have a single point of failure, decreased efficiency for larger networks, and notable delay [25], [26]. Blockchain is coined as a solution by security practitioners because it works on decentralized and geographically distributed technology with attributes such as immutability, transparency, and fault tolerance [27]. In summary, security and privacy in AmI-IoT networks can be ensured by implementing robust authentication and key exchange mechanisms using blockchain [28], [29]. ...
Ambient Intelligence (AmI) in Internet of Things (IoT) has empowered healthcare professionals to monitor, diagnose, and treat patients remotely. Besides, the AmI-IoT has improved patient engagement and gratification as doctors’ interactions have become more comfortable and efficient. However, the benefits of the AmI-IoT-based healthcare applications are not availed entirely due to the adversarial threats. IoT networks are prone to cyber attacks due to vulnerable wireless mediums and the absentia of lightweight and robust security protocols. This paper introduces computationally-inexpensive privacy-assuring authentication protocol for AmI-IoT healthcare applications. The use of blockchain & fog computing in the protocol guarantees unforgeability, non-repudiation, transparency, low latency, and efficient bandwidth utilization. The protocol uses physically unclonable functions (PUF), biometrics, and Ethereum powered smart contracts to prevent replay, impersonation, and cloning attacks. Results prove the resource efficiency of the protocol as the smart contract incurs very minimal gas and transaction fees. The Scyther results validate the robustness of the proposed protocol against cyber-attacks. The protocol applies lightweight cryptography primitives (Hash, PUF) instead of conventional public-key cryptography and scalar multiplications. Consequently, the proposed protocol is better than centralized infrastructure-based authentication approaches.
... The framework works on defined criteria and priorities by using multi decisionmaking system. A fault-tolerant consensus algorithm for Blockchain is proposed [35]. The protocol is based on Practical Byzantine Fault Tolerance (PBFT) to ensure the reliability and efficiency of the consensus protocols. ...
Blockchain is a distributed ledger in which transactions are grouped in blocks linked by hash pointers. Blockchain-based solutions provide trust and privacy because of the resistance to the inconsistency of data and advanced cryptographic features. In various fields, blockchain technology has been implemented to ensure transparency, verifiability, interoperability, governance, and management of information systems. Processing large volumes of data being generated through emerging technologies is a big issue. Many researchers have used Blockchain in various fields integrated with IoT, i.e., industry 4.0, biomedical, health, genomics, etc. Blockchain has the attributes of decentralization, solidness, security, and immutability with a possibility to secure the system design for transmission and storage of data. The purpose of the consensus protocols is to keep up the security and effectiveness of the blockchain network. Utilizing the correct protocol enhances the performance of the blockchain applications. This article presents essential principles and attributes of consensus algorithms to show the applications, challenges, and opportunities of blockchain technology. Moreover, future research directions are also presented to choose an appropriate consensus algorithm to enhance the performance of Blockchain based applications
... The PBFT consensus mechanism has shown great potential in enhancing the consensus reaching efficiency due to the existence of the primary node [32,33]. It is worth noting that the primary node plays a critical role in generating blocks in turn in the PBFT consensus mechanism. ...
This study proposes a primary node election method based on probabilistic linguistic term set (PLTS) for the practical Byzantine fault tolerance (PBFT) consensus mechanism to effectively enhance the efficiency of reaching consensus. Specifically, a novel concept of the probabilistic linguistic term set with a confidence interval (PLTS-CI) is presented to express the uncertain complex voting information of nodes during primary node election. Then, a novel score function based on the exponential semantic value and confidence approximation value for the PLTS-CI, called Score-ESCA, is used to solve the problems of comparing different nodes with various voting attitudes. This method helps select the node with the highest score by utilizing complex decision attitudes, making it an accurate primary node election solution. Furthermore, the feasibility of our proposed method is proved by both theoretical analysis and experimental evaluations.
... Delegated Practical Byzantine Fault Tolerance is similar to PBFT however, unlike PBFT each node participation for adding the block is not required here, this makes it more scalable. Here, few nodes are selected as delegates of other nodes and these nodes are responsible for achieving consensus [31]. ...
As the size of data is increasing exponentially, its security is a major concern. Emerging technology like blockchain is used to provide security to systems. Since the inception of blockchain, it has been adopted by researchers and industry both, however, it gained enormous attention after cryptocurrency. It can be defined as a means of storing information in such a way that modification and hacking the system is difficult or impossible. A blockchain is a decentralized ledger that is digital and public, consisting of records of transactions called blocks. A consensus technology assures that all nodes agree on a unique sequence for appending blocks. A comprehensive examination of these algorithms will aid in understanding how and why each blockchain operates in the manner that it does. In this study, we addressed extensively used consensus techniques in the blockchain and the importance of consensus protocol in blockchain technology. The underlying consensus algorithm is a critical component of every blockchain-based system which determine the performance and security of the system. Ensuring the correctness of consensus protocols is uttermost important to create trust in the blockchain-based systems and formal methods are the way to create that trust and develop correct and verified systems. Formal modeling is a method of writing a system mathematically and examining the correctness and verifying the developed system. This study analyzed the importance of consensus mechanisms and how formal methods are helping to develop a correct blockchain-based system. The current scenario of the application of formal methods in the consensus mechanism of blockchain for their verification is presented.
... In view of the existing problems of blockchain systems, this article proposes a blockchain cross-chain exchange model based on cluster centers. is model divides the nodes in the consortium blockchain system into three different types of nodes: consensus service nodes, cross-chain exchange nodes, and application nodes [10]. e consensus service nodes with efficient computing capability through a high-speed network are connected to form a blockchain P2P network serving a business field [11], which specifically provides consensus computing services for the application nodes in the blockchain network. e cross-chain switching node is connected to different blockchain networks at the same time, the block data of different blockchains are synchronized, the status database of different blockchain networks on this node is formed, and a blockchain switching network between switching nodes based on the P2P protocol is formed to provide cross-chain access services for application nodes of different blockchain networks. ...
Aiming to solve the problems of low fault tolerance, low throughput, and high delay in traditional methods, an improved method of the blockchain cross-chain consensus algorithm based on weighted PBFT is proposed. This article constructs a blockchain cross-chain exchange model based on cluster centers and divides the nodes in the blockchain system into consensus service nodes, cross-chain exchange nodes, and application nodes to improve the performance of consensus computing services. On this basis, according to the weighted PBFT consensus mechanism, the blockchain consensus environment is set up, and the distribution of nodes in the consensus domain and the blockchain signature scheme are obtained. Therefore, the blockchain cross-chain consensus optimization algorithm is designed to reduce throughput and delay and optimize the consensus effect. The experimental results show that the proposed method can effectively improve the shortcomings of traditional methods, with high throughput and low latency, and strong security. It shows that it is a low resource consumption and secure consensus method.
Blockchain technology has been introduced to tackle the data issues arising from centralization in carbon management. However, current blockchain systems remain inefficient for carbon management in construction projects, falling short in scalability, security, and high throughput. Moreover, blockchain mainly serves as a database, so it is not easy to shape stakeholders’ low-carbon behaviors actively and directly. Thus, this paper designs a novel incentive mechanism (i.e., consensus mechanism with incentive design) in blockchain, Proof of Carbon Reduction (PoCR), to enhance blockchain system performance and promote low carbon practices among stakeholders. To this end, carbon reduction credit (CR credit) is first proposed to evaluate stakeholders’ carbon performance via the reporting and crowd-wisdom subsystems. Second, the optimized Byzantine Fault Tolerance (BFT) with a novel block leader election algorithm and a fair reward allocation method is proposed for the transaction consensus process in the blockchain to reduce communication complexity while enhancing consistency using cryptographic techniques. Third, controlled experiments are conducted and research findings show that PoCR can achieve (1) effective low-carbon incentive, providing financial returns for low-carbon performance and enhancing income fairness, (2) excellent efficiency, reducing the quadratic message complexity of typical BFT-based protocols to 0(mn), and increasing the throughput over 10% (Delegated BFT) and 25% (Algorand) while reducing latency over 80% (Practical BFT) and 20% (Algorand), (3) enhanced security, outperforming existing protocols in anti-attack and anti-corruption capabilities. This paper contributes to both blockchain design and low-carbon incentive design, paving the way for decentralized low-carbon management in construction.
The practical Byzantine fault tolerance (PBFT) algorithm stands out as one of the most frequently employed consensus algorithms in consortium blockchains. However, due to the frequent global communication mechanism, the PBFT’s communication overhead increases exponentially with the number of nodes, resulting in poor scalability. Therefore, the PBFT is typically used only in small networks. To improve the PBFT’s efficiency in large-scale systems such as massive smart grids and the Internet of Things, we put forward a reputation-based PBFT algorithm with node grouping strategy (RGPBFT). Specifically, we firstly develop an improved consistency subprotocol based on node grouping strategy to improve the consensus efficiency and the scalability of the PBFT. Then, we propose a reputation-based strategy to enhance the reliability of the elected master node. The simulated test results show that the node grouping strategy could significantly improve the consensus efficiency of the PBFT, and the reputation-based strategy could reduce the impact of Byzantine nodes on the throughput and consensus latency. Overall, the test results demonstrate that the RGPBFT outperforms the PBFT in consensus latency, throughput, communication overhead, and fault tolerance. The RGPBFT exhibits high consensus efficiency in large-scale networks.
Widespread use of lead acid batteries (LABs) is resulting in the generation of million tons of battery waste, globally. LAB waste contains critical and hazardous materials, which have detrimental effects on the environment and human health. In recent times, recycling of the LABs has become efficient but the collection of batteries in developing countries is not efficient, which led to the non-professional treatment and recycling of these batteries in the informal sector. This paper proposes a blockchain-enabled architecture for LAB circularity, which ensures authentic, traceable and transparent system for collection and treatment of batteries. The stakeholders—battery manufacturers, distributors, retailers, users, and validators (governments, domain experts, third party experts, etc.)—are integrated in the circular loop through a blockchain network. A mobile application user interface is provided to all the stakeholders for the ease of adoption. The batteries manufactured and supplied in a geographical region as well as the recycled materials at the battery end-of-life are traced authentically. This architecture is expected to be useful for the battery manufacturers to improve their extended producer responsibility and support responsible consumption and production.
Authentication and Session Key Generation Protocols (SKGPs) play an essential role in securing the communication channels of connected Internet of Things (IoT) devices. Recently, through blockchain integration, scholars have tried to enhance the security and applicability of SKGPs. In brief, blockchain is a distributed ledger technology that can provide interesting features such as immutability, transparency, and accountability without any need for the active participation of trusted parties. This survey presents a comprehensive critical review of blockchain-assisted authentication and SKGPs, suggested for different IoT domains, including Internet of Vehicles (IoV), Internet of Drones (IoD), and Industrial IoT (IIoT). Our survey categorizes existing schemes based on several criteria, including IoT application domains, security aspects, and blockchain components. By presenting an unbiased critical review and taxonomy of protocols, we aim to clarify the key challenges. Our review will specifically indicate what properties authors gained or lost through the integration of blockchain. This survey is the only one that offers all prerequisites for interested readers in blockchain-integrated SKGPs, such as security features and attacks, attack models, verification tools, blockchain types, blockchain platforms, consensus mechanisms, and etc. Further, our survey elaborates existing research gaps in blockchain-assisted SKGPs. Doing so, we aim to guide future research in this field and provide researchers with the essential information they require.
Digital Identity is a prominent practice across every digital platform for maintaining confidentiality and privacy. The demand for Internet of Things (IoT) and its allied technologies such as Internet of Medical Things (IoMT), the Industrial Internet of Things (IIoT), and the Internet of Video Things (IoVT) is constantly on the rise in both wired and wireless domains. IoT communications emerge as a major challenge for digital identity-based security solutions in the areas of healthcare, transportation, and their allied applications. This paper addresses the different aspects of digital identity for security preservation and maintenance in IoT and blockchain based solutions. It focuses on Confidentiality, Integrity, and Availability (CIA) issues and corresponding digital identity solutions using the duo. The writers perused over 112 publications and shared their findings on cutting-edge technologies related to Digital Identity (DId) in the healthcare industry.
CPU Scheduling is the process of allocating CPU time to various processes of different kinds. There are many existing algorithms that schedule waiting processes, but each of those algorithms achieve good results in only one of the many useful features of a scheduler. Some important features of a scheduling algorithm are to reduce the waiting time, to give a fair share of CPU time to all the processes and to give preference to higher priority processes; Shortest Job First, Round Robin and Priority scheduling algorithms do them respectively. The proposed work combines all these desired properties into one algorithm, by making use of convolution neural network architecture. Using CNN architecture is advantageous because the data is controllable in the hidden layers. The data in the hidden layers could be both understood and manipulated; hence a more powerful neural network could be designed. In comparison to these common algorithms the proposed work achieves 66% better performance, when all the above mentioned desired properties are taken into consideration.KeywordsCPU schedulingOperating SystemNeural networksConvolutional neural networksMin-pooling
In the era of data explosion, data contains massive information, such as health data, time and place, hydrological waves, etc. In order to process and calculate these data, local Wang networking devices will send data to the cloud data center for outsourcing processing due to their limited storage and computing capabilities. However, our data contains a large amount of private data, so we need to protect the privacy of our outsourced data before outsourcing, so as to protect our personal privacy. At the same time, cloud data centers have strong advantages in data storage and computing capabilities, so cloud data centers are increasingly used.
Blockchain technology has gained increasing attention in the construction sector. The process of developing a blockchain-based application that fits user requirements largely depends on the selection of a suitable consensus protocol, which acts as the centerpiece of blockchain architecture. In distributed networks, consensus protocols not only help maintain data consistency among all stakeholders, but also allow users to work together and stay secure. However, limited efforts have been delivered to analyze and compare existing consensus protocols under various construction scenarios, leading to uncertainties when applying blockchain technology in the construction domain. Therefore, this paper performs a critical review extracting literatures from (1) blockchain-based applications in the construction industry, and (2) existing blockchain consensus protocols. Additionally, a mixed method that integrates qualitative and quantitative analysis is proposed to evaluate the suitability of mainstream consensus protocols for various construction-related applications. Based on the selection criteria and efficiency requirements of consensus protocols generated, a recommendation strategy is also presented for consensus protocol selection under different construction scenarios. This study contributes to the following: (1) it helps construction stakeholders to understand the consensus process in a specific construction application case, and (2) it provides lucid reference guidance in developing a robust blockchain-based system underlying an appropriate consensus protocol.
Today, Raft’s distributed cluster scale is growing rapidly and cluster throughput is declining. The Raft consensus algorithm needs to be continuously optimized to adapt to a complex and changeable application environment. To solve the above problems, we propose a federal reconstruction Committee Raft consensus algorithm FRCR. Based on the Federation reconstruction technology, the algorithm trains, updates and evaluates the model of the characteristic data set of the Raft node, runs the model to get the nodes with better performance, constructs the committee mechanism, and improves the quality and speed of the election. We also design a semi asynchronous buffer mechanism and a strategy to resist malicious node attacks to solve the inconsistency and security problems of federation aggregation. Finally, seven aspects of FRCR are tested and analyzed to verify the effectiveness of FRCR in the consensus cluster.
Recently, blockchain technology has been used in diverse systems and applications beyond cryptocurrencies. With features such as data immutability and a decentralized structure, blockchain technology is increasingly being adopted in various governance use cases where trust and security are essential concerns, particularly in smart campus areas. Education or learning is a field that offers several opportunities to integrate blockchain into its systems. However, there is a luck of studies into which blockchain platforms, based on consensus algorithms, are most suitable for adopting into a smart education environment. Further study is required to guide education informatics researchers in selecting and developing a suitable blockchain platform for experimenting with their applications. This paper will evaluate which consensus algorithm and blockchain platform are appropriate to apply to such an environment based on its quality requirements.KeywordsBlockchain technologySmart education systemsSmart campusConsensus algorithms
Blockchain is a new technology for processing complex and disordered information with respect to business and other industrial applications. This work is aimed at studying the consensus algorithm of blockchain to improve the performance of blockchain. Despite their advantages, the proof of stake (POS) algorithm and the practical Byzantine fault tolerance (PBFT) algorithm have high latency, low throughput, and poor scalability. In this paper, a blockchain hybrid consensus algorithm which combines advantages of the POS and PBFT algorithms is proposed, and the algorithm is divided into two stages: sortition and witness. The proposed algorithm reduces the number of consensus nodes to a constant value by verifiable pseudorandom sortition and performs transaction witness between nodes. The algorithm is improved and optimized from three dimensions: throughput, latency, and scalability. The experimental results show that the improved hybrid consensus algorithm is significantly superior to the previous single algorithms for its excellent scalability, high throughput, and low latency.
Blockchain has numerous benefits such as decentralisation, persistency, anonymity and auditability. There is a wide spectrum of blockchain applications ranging from cryptocurrency, financial services, risk management, internet of things (IoT) to public and social services. Although a number of studies focus on using the blockchain technology in various application aspects, there is no comprehensive survey on the blockchain technology in both technological and application perspectives. To fill this gap, we conduct a comprehensive survey on the blockchain technology. In particular, this paper gives the blockchain taxonomy, introduces typical blockchain consensus algorithms, reviews blockchain applications and discusses technical challenges as well as recent advances in tackling the challenges. Moreover, this paper also points out the future directions in the blockchain technology.
Algorand is a new cryptocurrency that confirms transactions with latency on the order of a minute while scaling to many users. Algorand ensures that users never have divergent views of confirmed transactions, even if some of the users are malicious and the network is temporarily partitioned. In contrast, existing cryptocurrencies allow for temporary forks and therefore require a long time, on the order of an hour, to confirm transactions with high confidence.
Algorand uses a new Byzantine Agreement (BA) protocol to reach consensus among users on the next set of transactions. To scale the consensus to many users, Algorand uses a novel mechanism based on Verifiable Random Functions that allows users to privately check whether they are selected to participate in the BA to agree on the next set of transactions, and to include a proof of their selection in their network messages. In Algorand's BA protocol, users do not keep any private state except for their private keys, which allows Algorand to replace participants immediately after they send a message. This mitigates targeted attacks on chosen participants after their identity is revealed.
We implement Algorand and evaluate its performance on 1,000 EC2 virtual machines, simulating up to 500,000 users. Experimental results show that Algorand confirms transactions in under a minute, achieves 125x Bitcoin's throughput, and incurs almost no penalty for scaling to more users.
A smart city uses information technology to integrate and manage physical, social, and business infrastructures in order to provide better services to its dwellers while ensuring efficient and optimal utilization of available resources. With the proliferation of technologies such as Internet of Things (IoT), cloud computing, and interconnected networks, smart cities can deliver innovative solutions and more direct interaction and collaboration between citizens and the local government. Despite a number of potential benefits, digital disruption poses many challenges related to information security and privacy. This paper proposes a security framework that integrates the blockchain technology with smart devices to provide a secure communication platform in a smart city.
A new mechanism is proposed for securing a blockchain applied to contracts management such as digital rights management. This mechanism includes a new consensus method using a credibility score and creates a hybrid blockchain by alternately using this new method and proof-of-stake. This makes it possible to prevent an attacker from monopolizing resources and to keep securing blockchains.
We prove that a pair of polynomially samplable distributions are statistically indistinguishable if and only if no polynomial size circuits relative to NP sets (P
nu
NP
-distinguishers) can tell them apart. As one application of this observation, we classify zero-knowledge notions that are used for interactive systems.
The high replication cost of Byzantine fault-tolerance (BFT) methods has been a major barrier to their widespread adoption in commercial distributed applications. We present ZZ, a new approach that reduces the replication cost of BFT services from 2f+1 to practically f+1. The key insight in ZZ is to use f+1 execution replicas in the normal case and to activate additional replicas only upon failures. In data centers where multiple applications share a physical server, ZZ reduces the aggregate number of execution replicas running in the data center, improving throughput and response times. ZZ relies on virtualization---a technology already employed in modern data centers---for fast replica activation upon failures, and enables newly activated replicas to immediately begin processing requests by fetching state on-demand. A prototype implementation of ZZ using the BASE library and Xen shows that, when compared to a system with 2f+1 replicas, our approach yields lower response times and up to 33% higher throughput in a prototype data center with four BFT web applications. We also show that ZZ can handle simultaneous failures and achieve sub-second recovery.
This paper argues for a new approach to building Byzan- tine fault tolerant replication systems. We observe that although recently developed BFT state machine replica- tion protocols are quite fast, they don't tolerate Byzantine faults very well: a single faulty client or server is capa- ble of rendering PBFT, Q/U, HQ, and Zyzzyva virtually unusable. In this paper, we (1) demonstrate that exist- ing protocols are dangerously fragile, (2) define a set of principles for constructing BFT services that remain use- ful even when Byzantine faults occur, and (3) apply these principles to construct a new protocol, Aardvark. Aard- vark can achieve peak performance within 40% of that of the best existing protocol in our tests and provide a sig- nificant fraction of that performance when up tof servers and any number of clients are faulty. We observe useful throughputs between 11706 and 38667 requests per sec- ond for a broad range of injected faults.
Our growing reliance on online services accessible on the Internet demands highly available systems that provide correct service without interruptions. Software bugs, operator mistakes, and malicious attacks are a major cause of service interruptions and they can cause arbitrary behavior, that is, Byzantine faults. This article describes a new replication algorithm, BFT, that can be used to build highly available systems that tolerate Byzantine faults. BFT can be used in practice to implement real services: it performs well, it is safe in asynchronous environments such as the Internet, it incorporates mechanisms to defend against Byzantine-faulty clients, and it recovers replicas proactively. The recovery mechanism allows the algorithm to tolerate any number of faults over the lifetime of the system provided fewer than 1/3 of the replicas become faulty within a small window of vulnerability. BFT has been implemented as a generic program library with a simple interface. We used the library to implement the first Byzantine-fault-tolerant NFS file system, BFS. The BFT library and BFS perform well because the library incorporates several important optimizations, the most important of which is the use of symmetric cryptography to authenticate messages. The performance results show that BFS performs 2% faster to 24% slower than production implementations of the NFS protocol that are not replicated. This supports our claim that the BFT library can be used to build practical systems that tolerate Byzantine faults.
2017 Copyright is held by the owner/author(s). Algorand is a new cryptocurrency that confirms transactions with latency on the order of a minute while scaling to many users. Algorand ensures that users never have divergent views of confirmed transactions, even if some of the users are malicious and the network is temporarily partitioned. In contrast, existing cryptocurrencies allow for temporary forks and therefore require a long time, on the order of an hour, to confirm transactions with high confidence. Algorand uses a new Byzantine Agreement (BA) protocol to reach consensus among users on the next set of transactions. To scale the consensus to many users, Algorand uses a novel mechanism based on Verifiable Random Functions that allows users to privately check whether they are selected to participate in the BA to agree on the next set of transactions, and to include a proof of their selection in their network messages. In Algorand’s BA protocol, users do not keep any private state except for their private keys, which allows Algorand to replace participants immediately after they send a message. This mitigates targeted attacks on chosen participants after their identity is revealed. We implement Algorand and evaluate its performance on 1,000 EC2 virtual machines, simulating up to 500,000 users. Experimental results show that Algorand confirms transactions in under a minute, achieves 125× Bitcoin’s throughput, and incurs almost no penalty for scaling to more users.
A peer-to-peer crypto-currency design derived from Satoshi Nakamoto's Bitcoin. Proof-of-stake replaces proof-of-work to provide most of the network security. Under this hybrid design proof-of-work mainly provides initial minting and is largely non-essential in the long run. Security level of the network is not dependent on energy consumption in the long term thus providing an energy-efficient and more cost-competitive peer-to-peer crypto-currency. Proof-of-stake is based on coin age and generated by each node via a hashing scheme bearing similarity to Bitcoin's but over limited search space. Block chain history and transaction settlement are further protected by a centrally broadcasted checkpoint mechanism.
A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power. As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. The network itself requires minimal structure. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.
A new probabilistic model of data encryption is introduced. For this model, under suitable complexity assumptions, it is proved that extracting any information about the cleartext from the cyphertext is hard on the average for an adversary with polynomially bounded computational resources. The proof holds for any message space with any probability distribution. The first implementation of this model is presented. The security of this implementation is proved under the interactability assumptin of deciding Quadratic Residuosity modulo composite numbers whose factorization is unknown.
Existing Byzantine-resilient replication protocols satisfy two standard correctness criteria, safety and liveness, in the presence of Byzantine faults. In practice, however, faulty processors can, in some protocols, significantly degrade performance by causing the system to make progress at an extremely slow rate. While ldquocorrectrdquo in the traditional sense, systems vulnerable to such performance degradation are of limited practical use in adversarial environments. This paper argues that techniques for mitigating such performance attacks are needed to bridge this ldquopracticality gaprdquo for intrusion-tolerant replication systems. We propose a new performance-oriented correctness criterion, and we show how failure to meet this criterion can lead to performance degradation. We present a new Byzantine replication protocol that achieves the criterion and evaluate its performance in fault-free configurations and when under attack.
This paper argues for a simple change to Byzantine fault tolerant (BFT) state machine replication libraries. Traditional BFT state machine replication techniques provide high availability and security but fail to provide high throughput. This limitation stems from the fundamental assumption of generalized state machine replication techniques that all replicas execute requests sequentially in the same total order to ensure consistency across replicas. We propose a high throughput Byzantine fault tolerant architecture that uses application-specific information to identify and concurrently execute independent requests. Our architecture thus provides a general way to exploit application parallelism in order to provide high throughput without compromising correctness. Although this approach is extremely simple, it yields dramatic practical benefits. When sufficient application concurrency and hardware resources exist, CBASE, our system prototype, provides orders of magnitude improvements in throughput over BASE, a traditional BFT architecture. CBASE-FS, a Byzantine fault tolerant file system that uses CBASE, achieves twice the throughput of BASE-FS for the IOZone micro-benchmarks even in a configuration with modest available hardware parallelism.
The blockchain: The future of business information systems
- Brandon
Ethereum: A secure decentralised generalised transaction ledger
- Wood
Delegated proof-of-stake (dpos), Bitshare whitepaper
- D Larimer
Separating agreement from execution for Byzantine fault tolerant services
- J Yin
- J.-P Martin
- A Venkataramani
- L Alvisi
- M Dahlin
Blackcoin’s proof-of-stake protocol v2
- P Vasin
A next-generation smart contract and decentralized application platform
- Buterin