BLA: Byzantine-Tolerant Lazy Auditing Framework for Decentralized Storage Data Integrity

Byzantine Fault Tolerant (BFT) protocols provide powerful guarantees in the presence of arbitrary machine failures, yet they do not scale. The process of creating new, scalable BFT protocols requires expert analysis and is often error-prone. Recent work suggests that localized, rule-driven rewrites can be mechanically applied to scale existing (non-BFT) protocols, including Paxos. We modify these rewrites--- decoupling and partitioning---so they can be safely applied to BFT protocols, and apply these rewrites to the critical path of PBFT, improving its throughput by 5×. We prove the correctness of the modified rewrites on any BFT protocol by formally modeling the arbitrary logic of a Byzantine node. We define the Borgesian simulator, a theoretical node that simulates a Byzantine node through randomness, and show that in any BFT protocol, the messages that a Borgesian simulator can generate before and after optimization is the same. Our initial results point the way towards an automatic optimizer for BFT protocols.

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.

Byzantine Fault Tolerant (BFT) protocols serve as a fundamental yet intricate component of distributed data management systems in untrustworthy environments. BFT protocols exhibit different design principles and performance characteristics under varying workloads and fault scenarios. The proliferation of BFT protocols and their growing complexity have made it increasingly challenging to analyze the performance and possible application scenarios of each protocol. This demonstration showcases BFTGym , an interactive platform that allows audience members to (1) evaluate, compare, and gather insights into the performance of various BFT protocols under a wide range of conditions, and (2) prototype new BFT protocols rapidly.

A major design to improve scalability and performance of blockchain is sharding, which maintains a distributed ledger by running classical Byzantine Fault Tolerance (BFT) protocols through several relatively small committees. However, there are several drawbacks with the existing sharding protocols. First, the sharding mechanism which ensures that each committee is strongly bias-resistant either weakens the decentralization or reduces the performance of the protocol. Second, BFT protocols are either unresponsive or take quadratic communication complexities under a byzantine leader. Third, they cannot defend against transaction censorship attacks. Finally, nodes do not have enough motivation to follow the protocol and selfish nodes can obtain more rewards through collusive behaviors. A recent study proposes HotStuff – a BFT protocol that achieves linear view-change and optimistic responsiveness. In this paper, we present HotDAG, a hybrid consensus protocol based on HotStuff via sharding in the permissionless model. By employing the parallel Nakamoto consensus protocol, we present a decentralized and bias-resistant sharding mechanism. HotDAG has a linear communication complexity on transaction confirmation by introducing a scalable BFT protocol and an inter-committee consensus mechanism based on blockDAG. By achieving an unpredictable leader rotation, HotDAG prevents the censorship attacks. At the same time, HotDAG provides an incentive mechanism that is compatible with the scalable BFT protocol to encourage nodes to actively participate in the protocol. Finally, we formally prove the security and analyze the performance of HotDAG.

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.

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.

The utilization of "cloud storage services (CSS)", empowering people to store their data in cloud and avoid from maintenance cost and local data storage. Various data integrity auditing (DIA) frameworks are carried out to ensure the quality of data stored in cloud. Mostly, if not all, of current plans, a client requires to utilize his private key (PK) to generate information authenticators for knowing the DIA. Subsequently, the client needs to have hardware token to store his PK and retain a secret phrase to actuate this PK. In this hardware token is misplaced or password is forgotten, the greater part of existing DIA plans would be not able to work. To overcome this challenge, this research work suggests another DIA without "private key storage (PKS)"plan. This research work utilizes biometric information as client's fuzzy private key (FPK) to evade utilizing hardware token. In the meantime, the plan might in any case viably complete the DIA. This research work uses a direct sketch with coding and mistake correction procedures to affirm client identity. Also, this research work plan another mark conspire that helps block less. Verifiability, yet in addition is viable with linear sketch Keywords– Data integrity auditing (DIA), Cloud Computing, Block less Verifiability, fuzzy biometric data, secure cloud storage (SCS), key exposure resilience (KER), Third Party Auditor (TPA), cloud audit server (CAS), cloud storage server (CSS), Provable Data Possession (PDP)

Byzantine Fault Tolerance (BFT) protocols can be divided into synchronous BFT protocols, partially synchronous BFT protocols, and asynchronous BFT protocols according to communication delay. Asynchronous BFT protocols are widely used because they can tolerate uncertain communication delays in the real world. However, asynchronous BFT protocols need to perform many rounds of broadcasts to reach agreement on a transaction subset, which consumes a lot of communication, computing, and storage resources. In this paper, we present Volia, an asynchronous BFT protocol which resolves above problem.We design new broadcast protocol to reduce the number of broadcast rounds needed for agreement. It reduces the communication overhead. Voting broadcast is used to maintain the order of transaction subsets rather than threshold signature to reduce computation cost. Above mechanisms speeds up the agreement phase, reduces the accumulated transaction subsets waiting for agreement and thus saves storage resources. We conduct experiment on Volia and the results show that Volia exhibits about 2~65× throughput, 2~25% latency, and 30% storage cost compared to other asynchronous BFT protocols.

It is critical to achieve the following objectives in partially synchronous Byzantine Fault Tolerance (BFT) protocols: (1) two-phase commit regime, (2) standard optimistic responsiveness, and (3) linear communication complexity. These three properties significantly affect the efficiency of BFT protocols. A number of attempts, such as HotStuff and Tendermint, have been made to solve this problem, but they typically manage to achieve only a subset of these properties. In this work, we propose a two-phase BFT protocol called TockCuckoo that fully achieves the aforementioned three properties. A primary challenge in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">two-phase</i> BFT protocols is HiddenLock: when a leader lacks visibility into the latest locked block states of honest replicas, it cannot safely proceed, potentially stalling the protocol. To address this issue, we introduce the proactive voting paradigm, which explicitly distinguishes between rejection and non-receipt states. After global stable time, an honest leader can always collect sufficient votes through proactive voting, enabling quick responses. TockCuckoo operates in continuous rounds of proactive voting, ensuring responsiveness. The proactive voting process requires only linear communication overhead, which directly results in TockCuckoo achieving linear communication complexity overall. Furthermore, we introduce TockCuckoo+, an extension of TockCuckoo. By introducing a cross-pipelined design, TockCuckoo+ enables more frequent block proposals without sacrificing the key characteristics of TockCuckoo, leading to improved throughput. Our experiments in wide-area networks demonstrate that, TockCuckoo reduces commit latency by 20% to 40% compared to HotStuff across different network sizes, and TockCuckoo+ achieves a throughput increase of 1.1× to 1.5× over HotStuff.

LWSBFT: Leaderless weakly synchronous BFT protocol

Consortium blockchain is the preferred implementation form of blockchain for cooperation between enterprises. As an indispensable underlying technology of consortium blockchain, the Byzantine fault tolerant protocol guarantees that the replicas in network reach agreement even when there are arbitrary faults of a fraction of the replicas. Byzantine fault tolerant protocols that currently exist for consortium blockchain fail to meet the requirements of practical applications, such as satisfying low algorithm complexity, robustness and dynamic scalability at the same time. In this paper, a new Fast, Dynamic and Robust Byzantine Fault Tolerance (FDRBFT) protocol is proposed to address this problem. It applies random threshold signature consensus scheme, unique cryptographic algorithm and proactive recovery scheme to achieve fast agreement, dynamic scalability and robust system. FDRBFT protocol is implemented on Hyperledger Fabric and its performance is compared with existing widely accepted protocols. Experimental results show that FDRBFT achieves competitive throughput, dynamic scalability and better robustness.

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.

Many state-machine Byzantine Fault Tolerant (BFT) protocols have been introduced so far. Each protocol addressed a different subset of conditions and use-cases. However, if the underlying conditions of a service span different subsets, choosing a single protocol will likely not be a best fit. This yields robustness and performance issues which may be even worse in services that exhibit fluctuating conditions and workloads. In this paper, we reconcile existing state-machine BFT protocols in a single adaptive BFT system, called ADAPT, aiming at covering a larger set of conditions and use-cases, probably the union of individual subsets of these protocols. At anytime, a launched protocol in ADAPT can be aborted and replaced by another protocol according to a potential change (an event) in the underlying system conditions. The launched protocol is chosen according to an 'evaluation process' that takes into consideration both: protocol characteristics and its performance. This is achieved by applying some mathematical formulas that match the profiles of protocols to given user (e.g., service owner) preferences. ADAPT can assess the profiles of protocols (e.g., throughput) at run-time using Machine Learning prediction mechanisms to get accurate evaluations. We compare ADAPT with well known BFT protocols showing that it outperforms others as system conditions change and under dynamic workloads. © 2015 IEEE.

Purpose Problems such as data security and trustworthy interactivity bring new challenges to the development and application of service ecosystems. As a decentralized ledger, blockchain has characteristics such as non-tamperability, unforgeability, traceability, global consistency, so that the integration between blockchain and service ecosystems can ensure data integrity and service availability. The purpose of this paper is to investigate problems of efficient consensus algorithm in service ecosystems alliance chain scenarios. Design/methodology/approach This method consists of two core modules: bubble sort and reputation mechanism. The bubble sort algorithm can reduce the number of consensus nodes, thereby reducing communication overhead and improving throughput. The reputation mechanism can improve the correctness of consensus nodes, thereby solving the problem of random selection of the primary in the PBFT algorithm and improving its security and efficiency. Findings Comparative experiments and analysis have been conducted between the practical Byzantine fault-tolerant algorithm combined with bubble sort and reputation mechanism (BR-PBFT) scheme proposed in this paper and existing similar PBFT algorithms in terms of communication complexity, transaction confirmation delay and throughput. The experimental results demonstrate that BR-PBFT maintains 1/3 fault tolerance of PBFT, effectively reduces communication overhead, lowers transaction confirmation delay and improves throughput. Originality/value The practical Byzantine fault tolerance (PBFT) algorithm used in the alliance chain still has the problems of high communication complexity and low throughput. Aiming at application scenarios of alliance chains in service ecosystems, an improved is proposed. It provides valuable insights into future research and practical applications in service ecosystems.

In cloud storage, the most common concerns for users are data integrity, confidentiality and availability. Recently, many data integrity auditing schemes have been proposed, some of which achieved privacy-preserving public auditing, some of which realised data sharing and group dynamic, and some of which supported data dynamic. However, as far as we know, there does not exist a practical auditing scheme which can simultaneously realise all the functions mentioned above; In addition, all the existing schemes adopt the method of computing message authentication code (MAC) by users to achieve the following data integrity auditing, nevertheless, it is a arduous task to compute MACs for these cloud users with constrained computing and storage capabilities. In this paper, we propose a novel privacy-preserving public auditing scheme for shared data in the cloud, which can also support data dynamic operation and group dynamic. First, we bring proxy signature into the existing auditing scheme. The cloud user can delegate the computation of MACs to a cloud computing server, so that the user's burden would be greatly reduced; second, by introducing a Lagrange interpolating polynomial, our scheme realises the identity privacy-preserving in the precondition of almost no addition of any new computation and less storage space, moreover it makes group dynamic simple; third, we make an index-switch table and combine it with the Merkle hash tree to realise the practical and secure dynamic operations of shared data by group users; fourth, in our scheme, the cloud storage server will add its private key in producing the proof information to protect the data privacy and resist the active attack. Theoretical analysis demonstrates our scheme is provably secure.