摘要:Recently, streamlined Byzantine Fault Tolerant (BFT) consensus protocols, such as HotStuff, have been proposed as a means to circumvent the inefficient view-changes of traditional BFT protocols, such as PBFT. Several works have detailed trusted components, and BFT protocols that leverage them to tolerate a minority of faulty nodes and use a reduced number of communication rounds. Inspired by these works we identify two basic trusted services, respectively called the Checker and Accumulator services, which can be leveraged by streamlined protocols. Based on these services, we design Damysus, a streamlined protocol that improves upon HotStuff’s resilience and uses less communication rounds. In addition, we show how the Checker and Accumulator services can be adapted to develop Chained-Damysus, a chained version of Damysus where operations are pipelined for efficiency. We prove the correctness of Damysus and Chained-Damysus, and evaluate their performance showcasing their superiority compared to previous protocols.

摘要:We calculated the matching values of technology supply and demand texts based on texts semantic similarity with Word2Vec and Cosine similarity algorithms, and then proposed a new index named Supply-Demand Matching Efficiency (SDME) to measure the matching efficiency of online technology trading platforms (OTTPs). Through the empirical research on the three types of OTTPs, the findings are as follows: First, the SDME of Zhejiang Market (Government-Owned, Government-Operated, GOGO), Technology E Market (Government-Owned, ContractorOperated, GOCO), and Keyi Market (Market-Owned, Market-Operated, MOMO) are 64.69%, 54.38% and 28.99% respectively, indicating that the government plays an important role in attracting effective technology suppliers and demanders to participate in online trade and standardizing information expression, thereby improving the SDME. Second, by comparing the SDME and the newly announced signing rate of each OTTP, we found that the OTTP with high SDME also has high signing rate, and the changing trend of the two is consistent. Third, we used the TextRank and Latent Dirichlet Allocation (LDA) to study the topic distribution of technology supply and demand, and calculated the topic differences of each OTTP, which are 70%, 75%, 84% respectively. The Technology E Market and Zhejiang Market have low topic differences and high SDME, while Keyi Market has high topic differences and low SDME, which indicated that the topic differences have a negative effect on SDME. Intuitively, measuring the semantic matching efficiency of supply and demand texts on OTTPs can help the suppliers and demanders to retrieve information accurately, and assist the OTTPs to carry out trade promotion and evaluate trade performance.

摘要:Cloud storage is an effective way for data owners to outsource their data by remotely storing them in the cloud and enjoy on-demand high quality services. In traditional cloud storage systems, cloud data integrity verification relies on centralized entities and data is stored in a small number of storage servicers. However, these centralized entities and storage servicers may be untrustworthy, and malicious servicers may even refuse to perform a user’s query or update request. Though a few blockchain-based themes have been proposed to address some of these problems, they do not achieve decentralization, accountability, flexibility and practicability simultaneously. In this paper, we present Themis, an accountable P2P cloud storage scheme with smart contracts on Ethereum. Our scheme has the following advantages: First, cloud data integrity verification is decentralized and implemented by miners on blockchain without any trusted third party. Second, by carefully setting up the reward and punishment mechanism within a smart storage contract, all rational nodes will participate in the storage service following an accountable rule. Third, based on reliable information published on the blockchain, users are free to choose appropriate storage servicers who want to share idle storage, making storage service decentralized and flexible. Fourth, compared with the existing related systems, by adopting a payment at maturity method, the malicious behavior of breaking the contract after the servicer obtains some revenue is prevented, and the availability of user data within the specified period is enhanced. Fourthermore, we implement a prototype of Themis on Rinkeby, an Ethereum test network. Extensive experimental results demonstrate that our scheme is able to support a PB-level data storage in a single P2P storage service at a low cost and is feasible for practical deployment. And the entire decentralized arbitration process takes only 40 to 110 seconds.

摘要:The Moving Picture Experts Group (MPEG) is an International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) working group that develops media coding standards. These standards include a set of ontologies for the codification of intellectual property rights (IPR) information related to media. The Media Value Chain Ontology (MVCO) facilitates rights tracking for fair, timely, and transparent payment of royalties by capturing user roles and their permissible actions on a particular IP entity. The Audio Value Chain Ontology (AVCO) extends MVCO functionality related to the description of IP entities in the audio domain, e.g., multitrack audio and time segments. The Media Contract Ontology (MCO) facilitates the conversion of narrative contracts to digital ones. Furthermore, the axioms in these ontologies can drive the execution of rights-related workflows in controlled environments, e.g., blockchains, where transparency and interoperability is favored toward fair trade of music and media. Thus, the aim of this article is to create awareness of the MPEG IPR ontologies developed in the last few years and the work currently taking place addressing the challenge identified toward the execution of such ontologies as smart contracts on blockchain environments. © 2020 IEEE. (17 refs)

摘要:Cloud storage plays an important role in today’s cloud ecosystem. Increasingly clients tend to outsource their data to the cloud. In spite of its copious advantages, integrity has always been a significant issue. The audit method is commonly used to ensure integrity in cloud scenarios.

摘要:在传统的中心化数据交易系统中，电力数据类的敏感数据存在因可复制而易被滥用等问题. 为 此，设计了基于区块链技术的电力数据资产化及交易系统. 利用区块链技术的密码算法、多中心对等架构、分 布式多方共识协议，使参与记录数据交易信息的多方实体仅需通过对区块链技术的信赖建立多方信任关系. 该系统以超级账本项目的 Ｆａｂｒｉｃ 联盟链为框架，借助区块链的技术特性实现了电力数据交易业务的安全、透 明、可追溯、不可篡改，并加入了监管机制. 该系统实现了应用层 Ｗｅｂ 服务的开发，便于使用. 对该系统在一台 设备上模拟多节点部署进行测试ꎬ结果表明，该系统在前后端级联后运行正常，满足设计需求ꎬ维护成本低ꎬ安 全性提升. 相较于传统数据交易系统ꎬ基于区块链的电力数据资产化及交易系统展现了综合的功能和安全优势.

摘要:在创新驱动发展的知识经济时代，全面建设透明度高、稳定性好、交易速度快、安全可靠 的知识产权交易平台，是提高知识产权配置效率、促进知识产权价值实现的焦点问题。本文依托区 块链的分布式存储、非对称加密、智能合约等技术，设计知识产权交易架构，深入剖析身份认证机 制、共识机制和链上监管等不同功能模块在知识产权信息化交易中的实现路径，并从加强知识产权 交易顶层设计、优化知识产权交易结构、培养区块链技术复合人才以及完善知识产权交易监管模式 等方面提出区块链技术驱动知识产权交易发展的对策建议。

摘要:We introduce Blockene, a blockchain that reduces resource usage at member nodes by orders of magnitude, requiring only a smartphone to participate in block validation and consensus. Despite being lightweight, Blockene provides a high throughput of transactions and scales to a large number of participants. Blockene consumes negligible battery and data in smartphones, enabling millions of users to participate in the blockchain without incentives, to secure transactions with their collective honesty. Blockene achieves these properties with a novel split-trust design based on delegating storage and gossip to untrusted nodes. We show, with a prototype implementation, that Blockene provides throughput of 1045 transactions/sec, and runs with very low resource usage on smartphones, pointing to a new paradigm for building secure, decentralized applications.

摘要:Blockchain is a distributed ledger or data structure. Combined with many other technologies, it uses the internet of things, cloud computing, artificial intelligence, big data, and machine learning. Several industries, especially governments, have employed blockchain technology to overcome a variety of security challenges. Blockchain focuses on double-spending and distributed consensus. However, blockchain networks are inefficient and scalable. Communication overhead occurs due to many replications. This paper proposes an adaptive practical Byzantine fault tolerance algorithm in permission blockchains. This method divides the node into trust nodes and faulty nodes. The nodes with faulty reputations are excluded from voting. Also, the identified trust node has a high reputation in the consensus process. A majority of voting values select the master node. This adaptive PBFT algorithm is excellent for long-term periodicity and increased scalability, and lower overall communication costs. Finally, the performance of adaptive PBFT is compared to other algorithms.

摘要:In 2008, Blockchain was introduced to the world as the underlying technology of the Bitcoin system. After more than a decade of development, various Blockchain systems have been proposed by both academia and industry. This paper focuses on the consensus algorithm, which is one of the core technologies of Blockchain. In this paper, we propose a unified consensus algorithm process model that is suitable for Blockchains based on both the chain and directed acyclic graph (DAG) structure. Subsequently, we analyze various mainstream Blockchain consensus algorithms and classify them according to their design in different phases of the process model. Additionally, we present an evaluation framework of Blockchain consensus algorithms and then discuss the security design principles that enable resistance from different attacks. Finally, we provide some suggestions for selecting consensus algorithms in different Blockchain application scenarios.

摘要:Although the emergence of the programmable smart contract makes blockchain systems easily embrace a wider range of industrial areas, how to execute smart contracts efficiently becomes a big challenge nowadays. Due to the existence of Byzantine nodes, the mechanism of executing smart contracts is quite different from that in database systems, so that existing successful concurrency control protocols in database systems cannot be employed directly. Moreover, even though smart contract execution follows a two-phase style, i.e, the miner node executes a batch of smart contracts in the first phase and the validators replay them in the second phase, existing parallel solutions only focus on the optimization in the first phase, but not including the second phase. In this paper, we propose a novel efficient concurrency control scheme which is the first one to do optimization in both phases. Specifically, (i) in the first phase, we give a variant of OCC(Optimistic Concurrency Control) protocol based on batching feature to improve the concurrent execution efficiency for the miner and produce a schedule log with high parallelism for validators. Also, a graph partition algorithm is devised to divide the original schedule log into small pieces and further reduce the communication cost; and (ii) in the second phase, we give a deterministic OCC protocol to replay all smart contracts efficiently on multi-core validators where all cores can replay smart contracts independently. Theoretical analysis and extensive experimental results illustrate that the proposed scheme outperforms state-of-art solutions significantly.

摘要:Blockchain is very important in finance field and electronic business field, so many researchers are attracted to study the technologies of blockchain. Since the transactions in blockchain takes much time, and they make the blockchain poor efficiency, business processes across organizations require the transactions as soon as possible. Concurrency is attracted much attention and is very important in blockchain field. In this paper, a novel decentralized blockchain network model with high concurrency is proposed. First, the idea of the proposed model is stated. Second, the high concurrency blockchain network model is proposed. Third, the corresponding algorithms are designed according to the proposed model. Furthermore, the experiment is conduced and the results show that proposed model works well.

摘要:We propose separating the task of reliable transaction dissemination from transaction ordering, to enable high performance Byzantine fault-tolerant quorum-based consensus. We design and evaluate a mempool protocol, Narwhal, specializing in high-throughput reliable dissemination and storage of causal histories of transactions. Narwhal tolerates an asynchronous network and maintains high performance despite failures. Narwhal is designed to easily scale-out using multiple workers at each validator, and we demonstrate that there is no foreseeable limit to the throughput we can achieve. Composing Narwhal with a partially synchronous consensus protocol (Narwhal-HotStuff) yields significantly better throughput even in the presence of faults or intermittent loss of liveness due to asynchrony. However, loss of liveness can result in higher latency. To achieve overall good performance when faults occur we design Tusk, a zero-message overhead asynchronous consensus protocol, to work with Narwhal. We demonstrate its high performance under a variety of configurations and faults. As a summary of results, on a W AN, Narwhal-Hotstuff achieves over 130,000 tx/sec at less than 2-sec latency compared with 1,800 tx/sec at 1-sec latency for Hotstuff. Additional workers increase throughput linearly to 600,000 tx/sec without any latency increase. Tusk achieves 160,000 tx/sec with about 3 seconds latency. Under faults, both protocols maintain high throughput, but Narwhal HotStuff suffers from increased latency.

摘要:We present DAG-Rider, the first asynchronous Byzantine Atomic Broadcast protocol that achieves optimal resilience, optimal amortized communication complexity, and optimal time complexity. DAG-Rider is post-quantum safe and ensures that all values proposed by correct processes eventually get delivered. We construct DAG-Rider in two layers: In the first layer, processes reliably broadcast their proposals and build a structured Directed Acyclic Graph (DAG) of the communication among them. In the second layer, processes locally observe their DAGs and totally order all proposals with no extra communication.

摘要:We provide a new protocol for Validated Asynchronous Byzantine Agreement in the authenticated setting. Validated (multi-valued) Asynchronous Byzantine Agreement is a key building block in constructing Atomic Broadcast and fault-tolerant state machine replication in the asynchronous setting. Our protocol has optimal resilience of f < n/3 Byzantine failures and asymptotically optimal expected O(1) running time to reach agreement. Honest parties in our protocol send only an expected O(n^2) messages where each message contains a value and a constant number of signatures. Hence our total expected communication is O(n^2) words. The best previous result of Cachin et al. from 2001 solves Validated Byzantine Agreement with optimal resilience and O(1) expected time but with O(n^3) expected word communication. Our work addresses an open question of Cachin et al. from 2001 and improves the expected word communication from O(n^3) to asymptotically optimal O(n^2).