DRBFT: Delegated randomization Byzantine fault tolerance consensus protocol for blockchains

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.

As smart cities become more decentralized, the need for reliable and secure cyber-physical systems (CPS) that guarantee safe interactions and secure data storage without loss of privacy is continuously increasing. Blockchain is a rapidly emerging technology in this domain. It demonstrated effectiveness thanks to the cryptographic mechanisms it utilizes and to its immutability. Private blockchains are the most suited to applications that require privacy and confidentiality when data is very sensitive. In this case, the most commonly used consensus protocol is Practical Byzantine Fault Tolerance (PBFT). However, PBFT requires the participation of all nodes in the consensus process, which increases bandwidth consumption and consensus delay significantly. In this paper, we propose an adaptive PBFT protocol called APBFT that optimizes the number of nodes participating in the consensus based on their response time and credibility. Therefore, we reduce the amount of communication and the response delays. We maintain the asynchrony of the algorithm so that it remains resilient to DoS attacks. The simulation results show that our algorithm outperforms the original PBFT in terms of delays and message traffic.

Cyberspace Mimic Defense (CMD) has fundamentally changed the situation of traditional network security defense through Dynamic Heterogeneous Redundancy (DHR) architecture. Presently, research on DHR architecture is based on the trustworthiness of the arbiters and schedulers. However, in practical applications, the core logic is generally deployed on a single server, which is vulnerable to single points of attack and failure, thus damaging the entire system’s security. This paper proposed a decentralized DHR architecture, which transfers the arbitration and scheduling logic to all executors. Based on the Practical Byzantine Fault Tolerance (PBFT) protocol, this paper designed the consensus protocol used in the decentralized DHR architecture to ensure the consistency of the status of each executor. Theoretical analysis and experiments show that the architecture is more secure than the traditional DHR architecture and can tolerate Byzantine faults.

This all-encompassing strategy for improving the pharmaceutical supply chain management process places a strong emphasis on responsibility, transparency, and traceability. Role-based access control, secure hashing algorithms, and blockchain (Hyperledger Fabric) technologies work together to reduce the risk of counterfeit medications and guarantee accurate drug monitoring. In a drug traceability system made possible by blockchain technology, every participant in a supply chain is assigned a unique identity and has access to a shared, decentralized database that follows the transit of pharmaceuticals along the supply chain. To ensure data security and integrity, MedGuard uses the SHA-256 hashing technique for data validation and the PBFT (Practical Byzantine Fault Tolerance) consensus algorithm for network node consensus. To maintain the integrity and security of the data, each participant is only permitted to add new records to the database; they are not permitted to edit or remove alreadyexisting records. All things considered, a blockchain-based drug traceability system might greatly improve the quality and safety of pharmaceutical products and help protect patients and the public from the risks associated with fake or tainted drugs. The complete solution is currently accessible as the “MedGuard” online application.”

A permissioned blockchain (BC) is a secure distributed ledger maintained by a number of trusted validation nodes. However, a validator may become compromised and send inconsistent messages to different nodes. To counter the problem, consensus protocols like Practical Byzantine Fault Tolerance (PBFT) can be used. The paper presents a permissioned BC system and discusses various design issues including control messages, block size and window size of block creation time. Furthermore, it is necessary to identify those compromised nodes discovered during the consensus protocol. This paper then proposes a reputation system to track the trustworthiness of nodes as it is necessary to distinguish failed nodes from compromised nodes. A compromised node may send inconsistent messages to others or accuse other nodes compromised, and it should be removed as soon as it is identified and confirmed.

Because of its excellent properties of fault tolerance, efficiency and availability, the practical Byzantine fault tolerance (PBFT) algorithm has become the mainstream consensus algorithm in blockchain. However, current PBFT algorithms have problems such as inadequate security of primary node selection, high communication overhead and network delay in the process of consensus. To address these problems, we design a novel efficient Byzantine fault tolerance algorithm based on credit grouping, called CG-PBFT. First, we propose a new credit evaluation model to obtain nodes’ credit values and introduce an optimized three-way quick sorting algorithm to divide nodes into the master-node group, the consensus-node group and the observation-node group, which have different privileges. The nodes in the observation-node group are restricted from participating in consensus, which reduces the communication overhead and improves consensus efficiency. Second, we propose an optimized selection method for the primary node based on a voting mechanism whereby the consensus-node group and observation-node group vote to produce the primary node, which reduces the probability of malicious nodes acting as the primary node and improves the security of primary node selection. Finally, the identity conversion mechanism between node groups is designed, and the actual behavior of nodes within different groups is given credit rewards or punishment, so as to keep an incentive for nodes to participate in appropriate system behavior and improve the working enthusiasm of nodes. The experimental simulation results show that compared with existing PBFT algorithms, the CG-PBFT algorithm improves the average throughput by 51.3% and reduces the average delay by 64.5%; it greatly improves the operating efficiency of the system and can be more suitable for application in the consortium blockchain scenarios.

Counterfeit products, especially in the pharmaceutical sector, have plagued the international community for decades. To combat this problem, many anti-counterfeiting approaches have been proposed. They use either Radio Frequency Identification (RFID) or Near Field Communication (NFC) physical tags affixed to the products. Current anti-counterfeiting approaches detect two counterfeiting attacks: (1) modifications to a product's tag details, such as changing the expiration date; and (2) cloning of a genuine product's details to reuse on counterfeit products. In addition, these anti-counterfeiting approaches track-and-trace the physical locations of products as the products flow through supply chains. Existing approaches suffer from two main drawbacks. They cannot detect tag reapplication attacks, wherein a counterfeiter removes a legitimate tag from a genuine product and reapplies it to a counterfeit or expired product. Second, most existing approaches typically rely on a central server to authenticate products. This is not scalable and creates tremendous processing burden on the server, since significant volumes of products flood through the supply chain's nodes. In addition, centralized supply chains require substantial data storage to store authentication records for all products. Moreover, as with centralized systems, traditional supply chains inherently have the problem of a single-point of failure. The thesis of this dissertation is that a robust, scalable, counterfeiting-resistant supply chain that addresses the above drawbacks and can be simultaneously achieved by (i) using a combination of NFC tags on products and a distributed ledger such as blockchain for reapplication-proof, decentralized, and transparent product authentication (ii) a novel game-theoretical consensus protocol for enforcing true decentralization, and enhancing the protocol's security and performance. In this dissertation, we first propose a new Tag Reapplication Detection (TRD) system to detect reapplication attacks using low-cost NFC tags and public key cryptography. To detect reapplication attacks, TRD tracks the number of times a tag has been read in the supply chain using a 'central' authentication server. Second, leveraging the blockchain technology, we propose the Block-Supply Chain, a transformation of TRD into a decentralized supply chain. In this chain, each node maintains a blockchain (distributed public ledger) per product. This blockchain comprises chained blocks, where each is an authentication event. The Block-Supply Chain can detect tag reapplication attacks and can replace the centralized supply chain design, thus overcoming the centralization issues. One of the fundamental characteristics of blockchain technology is the consensus protocol. Consensus protocols ensure that all nodes in the blockchain network agree on the validity of a

Achieving good performance in terms of throughput and scalability, with high quality of security has always been a challenging problem in all sorts of scheduling. Permissioned blockchain allows multiple contracts of non-trusting peer organization to be deployed for working in consortium. It is the responsibility of the scheduler often called as an ordering service to form block of transactions to get committed through consensus. Practical Byzantine Fault Tolerance (PBFT) is one of the most popular consensus algorithm used in current implementations of blockchain. Most consensus algorithms including PBFT follow FIFO scheduling strategy to create the block of transactions. With block chain being supported for multi-contract environment, scheduling should consider difference in service requirements specifically security requirement for heterogeneous contracts. The current work proposes SAGA-PBFT (Security-Aware Genetic Algorithm based Practical Byzantine fault Tolerance) scheduler, which uses multi objective genetic algorithm for balancing the security requirement and security overhead at the time of block creations. The algorithm assigns the security level to each transaction as per its security requirement but in an unpredictable manner making security attack difficult. It further uses security aware PBFT for consensus. Experimental simulation proves that SAGA-PBFT when compared with PBFT, achieves better commit time and scalability with best possible security.

Blockchain-based audit systems use “Practical Byzantine Fault Tolerance” (PBFT) consensus protocol which suffers from a high message complexity and low scalability. Alternatives to PBFT have not been tested in blockchain-based audit systems since no blockchain testbed supports the execution and benchmarking of different consensus protocols in a unified testing environment. In this paper, we address this gap by developing a blockchain testbed capable of executing and testing five consensus protocols in a blockchain network; namely PBFT, Proof-of-Work (PoW), Proof-of-Stake (PoS), Proof-of-Elapsed Time (PoET), and Clique. We carry out performance evaluation of those consensus algorithms using data from a real-world audit system. Our results show that the Clique protocol is best suited for blockchain-based audit systems, based on scalability features.

The crisis of trust in the supply chain platform is a serious issue. Blockchain provides the technology to solve the multi-party trust problem. So the integration of supply chain and blockchain makes it possible to build a trust economic system. Consensus mechanism is an important content in the blockchain. But traditional consensus protocols cannot effectively meet the requirements of supply chain management. Based on the practical Byzantine fault tolerance protocol in alliance blockchain, this paper introduces the credit evaluation mechanism and designs an efficient consensus protocol. We construct a multi-class SVM, and evaluate the credits of supply chain enterprises from four aspects of financial risk, operating and profitability capabilities, supply chain cooperation level and information sharing degree. Then, the enterprises with high credits are chosen to participate in the consensus process. Due to the reduction of communication costs, the method has better performance in the case of a large number of participating nodes. It is suitable for the networks with supply chain and blockchain. In addition, it has the characteristics of openness, sharing and tamper resistance, and thus it avoids unfair and fraudulent transactions in the supply chain platform.

An improved practical Byzantine fault tolerance (Practical Byzantine Fault Tolerant consensus algorithm based on reputation, RPBFT) algorithm based on grouping and reputation value voting is proposed for the problems of high communication complexity, poor scalability, and random selection of master nodes of the practical Byzantine fault tolerance (PBFT) consensus algorithm of the consortium chain. First, the consistency process is optimized to take the response speed of nodes to each group leader as the basis of grouping, and the intragroup consensus is performed. The group leader then takes the result of intragroup consensus and participates in extra-group consensus to reduce the frequency and time of internode communication. Second, the reputation model and voting mechanism are proposed, and the group leader is generated by node reputation value voting, which enhances the initiative and reliability of trusted nodes and reduces the abnormal nodes as group leader. Finally, a simulation and performance testing system based on this improved scheme is built to prove the effectiveness as well as the usability of the scheme through simulation experiments. The experimental results show that when the number of network nodes is 36, the throughput of the RPBFT algorithm is six times that of PBFT. Therefore, the consensus delay is reduced by 91.7%, and the communication overhead is reduced by 37.8%.

Blockchain is a decentralized distributed ledger database. Consensus protocol is the core protocol of blockchain to solve Byzantine agreement problem. To let all blockchain nodes reach an agreement, the most commonly used Byzantine consensus protocol are Practical Byzantine Fault Tolerance (PBFT) protocols. PBFT requires that the number of malicious nodes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$t$</tex> is less than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$n/3$</tex> ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$n$</tex> is the total number of nodes), while quantum ones can raise the upper bound from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$n/3$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$n/2$</tex> . However, there is a problem with quantum Byzantine consensus protocols, that is, the lack of malicious-degree evaluation. When the primary and reporting nodes are malicious, the number of agreements rounds and communication overhead will be significantly increased. Thus, a prevention mechanism for quantum consensus protocols is proposed in this paper, which includes two measures to prevent (or constrain) the malicious behaviors: (1) The trust-value calculation method to judge the honesty of nodes, which adjust the value according to nodes' behaviors using our trust-value evaluation formula; (2) The dual signature method to verify the legitimacy of reporting messages, which requires two nodes to agree and sign a message. The security analysis shows that our prevention mechanism can effectively prevent malicious nodes from being the primary node and substantially reduce the false messages from dishonest nodes.

We discuss blockchain technology and its expected impact on smart cities in this paper. A significant development in technology, blockchain is made up of a number of core standards and technologies. We especially look at the question of how blockchain technology could contribute to urban growth. We developed our conceptual framework and research ideas after carefully reviewing the literature. The process of smarting cities has determined Fourteen application areas for blockchain technology: (1) Smart electronic voting; (2) Smart healthcare; (3) Smart home; (4) Smart property management; (5) Smart transportation; (6) Smart Logistics and Supply Chains; (7) Smart Education; (8) Smart Factory, (9) Smart Mobility, (10) Smart grid, (11) Intelligent Traffic Systems, (12) Smart agriculture, (13) Energy Consumption Tracking and (14) Carbon Footprint Tracking. We look at recent developments in several fields, highlight the importance of blockchain technology and make recommendations for future research directions

Practical Byzantine Fault Tolerance (PBFT) has been widely used in consortium blockchain systems; however, it suffers from performance degradation and susceptibility to Byzantine faults in complex environments. To overcome these limitations, this paper proposes RE-BPFT, an enhanced consensus algorithm that integrates a nuanced node credibility model considering direct interactions, indirect reputations, and historical behavior. Additionally, we adopt an optimized ID3 decision-tree method for node classification, dynamically identifying high-performing, trustworthy, ordinary, and malicious nodes based on real-time data. To address issues related to centralization risk in leader selection, we introduce a weighted random primary node election mechanism. We implemented a prototype of the RE-BPFT algorithm in Python and conducted extensive evaluations across diverse network scales and transaction scenarios. Experimental results indicate that RE-BPFT markedly reduces consensus latency and communication costs while achieving higher throughput and better scalability than classical PBFT, RBFT, and PPoR algorithms. Thus, RE-BPFT demonstrates significant advantages for large-scale and high-demand consortium blockchain use cases, particularly in areas like digital traceability and forensic data management. The insights gained from this study offer valuable improvements for ensuring node reliability, consensus performance, and overall system resilience.

In some liberal democracies, governments allow people to legally own guns to protect their lives and property. However, gun crime has been increasing in recent years. Taking the United States, for example, a report pointed out that Americans are 10 times more likely to be shot than citizens of other countries. Murder using guns in the United States is 25 times more than that in the other 22 high-income countries. Most of these guns came from other cities. These illegally circulating guns are directly linked to deadly street violence. This means that effective firearm management can reduce deadly violence. In the past few years, Radio Frequency IDentification (RFID) technology was often used to track the supply chain. However, in the traditional supply chain, only the participants of the supply chain can query information. Furthermore, only the participants can verify the correctness of the data. This result causes information to be not transparent. On the other hand, blockchain technology, with a unique combination of features such as distributed notes, decentralized structure, consensus algorithm, storage mechanism, asymmetric encryption, and smart contract, ensures network visibility, transparency, and security. Therefore, we combine blockchain and RFID technology to propose a traceable firearm management system based on blockchain and Internet of Things (IoT) technology. The proposed method achieves several goals. First of all, the characteristic data through the blockchain can be publicly verified and the information will not be modified. The traceability of the data and the application of RFID can effectively manage the production chain. In addition, we used Burrows–Abadi–Needham logic (BAN logic) logic to prove mutual authentication, and the nonrepudiation and integrity method can also be achieved in our proposed scheme.