【Abstract】As a distributed ledger technology, the addition of new members in permissioned blockchain is usually composed of several steps among distributed nodes. The addition can not be considered successful until all of the steps are completed. In other words, these steps are an atomic operation. However, there is no solution for the atomic operation in existing permissioned blockchain, leading to an inconsistent state when the addition of new members is partially completed. To implement the atomic member addition in permissioned blockchain, we propose a method targeting at the atomic addition of new members based on distributed and autonomous rollback. After member addition starts, distributed nodes of existing members detect the new node and decide whether to rollback or not, instead of getting commands from the coordinator. After deciding to rollback, a new configuration block is added to achieve rollback of the uncompleted member addition. In order for the new configuration block to pass the policy validation of orderers, we set a rollback mode for orderers. The evaluation results show that our method can actually implement atomic member addition and has little impact on performance.
【Abstract】Payment channel network (PCN) is a layer-two scaling solution that enables fast off-chain transactions but does not involve on-chain transaction settlement. PCNs raise new privacy issues including balance secrecy, relationship anonymity and payment privacy. Moreover, protecting privacy causes low transaction success rates. To address this dilemma, we propose zk-PCN, a privacy-preserving payment channel network using zk-SNARKs. We prevent from exposing true balances by setting up public balances instead. Using public balances, zk-PCN can guarantee high transaction success rates and protect PCN privacy with zero-knowledge proofs. Additionally, zk-PCN is compatible with the existing routing algorithms of PCNs. To support such compatibility, we propose zk-IPCN to improve zk-PCN with a novel proof generation (RPG) algorithm. zk-IPCN reduces the overheads of storing channel information and lowers the frequency of generating zero-knowledge proofs. Finally, extensive simulations demonstrate the effectiveness and efficiency of zkPCN in various settings.
【Abstract】The 6th generation (6G) communication network in the future will be participated by multi-parties (e.g., cellular network, satellite network, vehicular network, etc.). Integrating blockchain into 6G can provide a credible decentralized environment between untrusted parties. Most existing works assume that the block propagation time is ignorable as it is insignificant compared with the block mining time in consensus. However, the block propagation time is no longer negligible in such a wireless and heterogeneous 6G network. To be specific, the deterministic communication in the wired network changes to the opportunistic communication resulting from the moving nodes (e.g., vehicles and satellites) that adopt wireless communication. In this work, we study block propagation in the 6G network. Specifically, we establish the analytical model with the discrete-time Markov chain from the microscopic view to portray the block propagation process in three specific cases. On this basis, we present a hybrid-communication-modes-based block propagation mechanism (HCM) to optimize the propagation time. Finally, the simulation results demonstrate the effectiveness of the proposed mechanism.
【Abstract】With the rise of the Internet of Things (IoT), many IoT end devices have entered the market, most of which have the disadvantage of having very constrained computing and storage resources of their own, so the lightweight MQTT protocol is widely used. However, lightweight also means a certain lack of security, so IoT sensors using the MQTT protocol inevitably become the target of many malicious attackers. Digital forensics, as a discipline that applies scientific investigation to digital crime and attacks, can be used to collect evidence of a crime and study how perpetrators attack to in turn help build more dynamic defenses against IoT attacks. However, most current IoT forensic solutions suffer from a lack of granularity and system integrity, so this paper designs a blockchain-based MQTT IoT sensor forensic system that implements a complete path from evidence collection to evidence protection, to evidence analysis and classification, and uses federated blockchains to maintain evidence integrity, and finally the system uses machine learning to qualitative, managing the level of harm to the sensor, forming feedback that can be used to build contingency measures against threats and facilitate the rational allocation of back-end monitoring resources.
【Abstract】In recent years, the concept of Digital Twins (DTs) has been implemented in different sectors to support product lifecycle. However, because of a huge number of participants in the development process, managing data flows in DTs becomes a challenge, especially when we concentrate on evaluating the product or entity quality from supply chain partners - in other words, the customer in a supply chain may have a different view of quality assurance (QA) than the supplier has, due to a typical large interpretation scope of quality in contracts and agreements, especially for Cyber Physical Systems. To overcome the problem, blockchains can be applied to build a secured environment for the QA information exchange. With the concept of smart contracts, suppliers and customers can align the required information about quality assurance to transparently work towards a bilateral quality agreement. While the general information like a number of passing tests can be shared, the details of tests are only shared among private agreements. In this paper, we present a blockchain based QA process management for DTs to increase the reliability of the network and maintain the private information of participants. Our experiments showed that our blockchain application has the capability to be deployed in multiple partners while guaranteeing network reliability and data privacy.
【Abstract】The conventional centralized data trading system confront the problem that the Trusted Third Party (TTP) may be dishonest, which harms the fairness and transparency of the system. Besides, we notice that most data trading systems lack distinguishing between the copyright and the use-right in trading. To address these issues, we propose a novel blockchainbased data trading system with copyright-preserving, called CDTP, mainly including two blockchains and an agreement. The copyright chain, one of the blockchains, is designed for registering and trading copyrights stored in the form of atomic transactions. It adopts an auction-based Byzantine agreement, namely ABFT. Another is use-right blockchain, which records use-right transactions and stores data, combined with IPFS-based storage. Moreover, we carry out experiments to simulate the performance of ABFT when it is under attacks.
【Abstract】As a new computing paradigm to solve large-scale group collaboration problems, crowdsourcing has attracted more and more attention. However, malicious users' participation in crowdsourcing tasks will affect the completion of crowdsourcing tasks or generate malicious evaluations that are inconsistent with the facts, which will reduce the user satisfaction of ordinary users and even lose their trust in the system. In addition, most of the existing crowdsourcing systems rely on the central server and are vulnerable to a single point of failure, affecting users' trust in the system. To solve the above problems, this paper proposes a trusted distributed crowdsourcing framework based on user preferences. Firstly, we propose a trust model of identifying malicious users (IMU) based on reputation value, which can quickly identify all kinds of malicious users. Secondly, the framework is based on an open, transparent, and tamper-proof consortium blockchain to ensure the security and reliability of transaction information, and has developed a complete service process for it. Finally, this paper also takes into account the different preferences of users, and gives priority to the tasks that best meet users' preferences to improve user satisfaction. The proposed framework is deployed on the IBM Hyperledger Fabric. The average transaction confirmation time is 1.4424 s and the average system throughput is 186tps. The experimental results show that the framework can quickly identify malicious users.
【Abstract】Mobile edge computing is considered as a promising solution to mobile blockchain system, where mobile nodes with limited computing capability may participate in the mining process by offloading the computing intensive mining tasks to nearby edge service providers (ESPs). However, malicious ESP will dishonestly perform miners' mining tasks, which harms miners' interests. We consider blockchain mining and computing offloading services jointly, and model the interaction between the ESP and miner nodes as a two-stage Stackelberg game. Then, we obtain the optimal edge computing demand and the corresponding price of each miner by solving the Nash equilibrium of the game iteratively with gradient descent method. Simulation results show that the more computing power ESP has, the more computing services it will provide for miners. When the revenues coefficient of ESP on vehicular services increases, ESP will provide more computing resources for vehicular services to obtain maximum benefits.
【Abstract】Mimblewimble is a privacy-oriented cryptocurrency technology that provides security and scalability properties that distinguish it from other protocols. Mimblewimble's cryptographic approach is based on Elliptic Curve Cryptography which allows verifying a transaction without revealing any information about the transactional amount or the parties involved. Mimblewimble combines Confidential transactions, CoinJoin, and cut-through to achieve a higher level of privacy, security, and scalability. In our previous work ([2], [26], [25]), we have presented and discussed these security properties and presented a model-driven verification approach in order to guarantee the correctness of the protocol implementations. In particular, we have proposed an idealized model that is essential to the described verification process. In that formal setting, we say that a transaction is valid if it is balanced, all output range proofs are valid and the kernel signature is valid for the excess. However, no formal and precise definition was given to the signature requirement. In this paper, we put forward an extension of our model to enable signatures. We specify a signature scheme that allows us to develop several properties and lemmas we have defined on our initial idealized model. The definition of a valid transaction is extended accordingly.
【Abstract】The Internet Computer Protocol is a new generation blockchain that aims to provide better security and scalability than the traditional blockchain solutions. In this paper, this innovative distributed computing architecture is introduced, modeled and then simulated by means of an agent-based simulation. The result is a digital twin of the current Internet Computer, to be exploited to drive future design and development optimizations, investigate its performance, and evaluate the resilience of this distributed system to some security attacks. Preliminary performance measurements on the digital twin and simulation scalability results are collected and discussed. The study also confirms that agent-based simulation is a prominent simulation strategy to develop digital twins of complex distributed systems.
【Abstract】On the one hand, data provenance provides the history of the origin of data and updates the modification cycle on one side, on the other hand, blockchain offers features that meet these immutability requirements of a version of data. These two technologies have applications and features that, in union, contribute to generate ideal technological structures to the management of data in several organizations. The objective of this study is to present an analysis of the relations between the main applications of data provenance as well as the blockchain features and point out applications in the Health Information Systems (HIS), in addition to a literature review on the theme. In regard to that, an analysis has been made as described in this study methodology, where the following questions were answered: i) What relations are there between data provenance and blockchain? ii) Can data provenance in union with blockchain contribute to applications in the HIS? Soon after, it was possible to prove through some of the studies present in the literature the combined use of data provenance and blockchain in HIS. Based on the relationships found between data provenance and blockchain, it was possible to conclude that these relationships contribute to data management in any organization, including HIS. It was also observed that different data provenance and blockchain methods, techniques, models, and methodologies are intertwined to generate the structures of data management in HIS, especially in Personal Health Record (PHR) and Electronic Health Record (EHR).
【Abstract】Blockchain is a public ledger, decentralized and distributed on the peer-to-peer network that uses a block structure to verify and store data, employing a reliable consensus mechanism. With the rapid development of this technology in recent years, several concerns and obstacles to its application in some scenarios began to emerge, among them privacy being one of the topics mentioned in several works. This work proposes an architecture to guarantee the privacy of health data, which are stored within a Blockchain network in a decentralized way, through the use of encryption techniques that will be compared such as RSA (Rivest-Shamir-Adleman) and the ECC (Elliptic Curve Cryptography).
【Abstract】Blockchain is an emerging technology that enables storing data and sharing it among many entities without the need for a central organization. Data is stored in an append-only ledger after the majority of participants agree on it. This mechanism is called the consensus, and many protocols are proposed in the literature (PoW, PoS, DPoS, RAFT, PBFT, etc.). In this paper, we focus on the Practical Byzantine Fault Tolerance (PBFT) protocol that has the advantages of being resilient to byzantine nodes, being faster than other protocols and energy saving in contrast to PoW. However, PBFT is not sufficiently scalable due to the important number of messages exchanged before consensus is reached which impacts the delays as well. In this paper, we propose FPBFT, a BFT protocol that is faster and more scalable than the traditional PBFT. We establish a scoring mechanism that eliminates slow and malicious nodes. In addition, PBFT steps are reduced following the SG-PBFT protocol and adapted to the blockchain use case. According to our experiments, our protocol performs better in terms of delays and communication traffic than PBFT and SG-PBFT.
【Abstract】In the last few years, technological development has multiplied. New technologies are affecting almost every industry. One of these which noticed the abrupt change in their ecosystem is the healthcare industry. As this industry has a direct impact on the human lives so adoption of new technology is not so easy. Proper testing and trials are performed before amalgamating any new technology with the healthcare system. Emerging technologies are being employed to deliver better health-related services to patients. Different communication and information collection technologies are used to maintain and access patients' health data to authorized users. But with the employment of technology, health data security and privacy-related issues are increasing. Maintaining trust among multiple entities of the healthcare system is a challenging task. One emerging technology, distributed ledger technology (DLT), is creating some hope for resolving the fears mentioned above of the healthcare ecosystem. Attributes like Security, privacy and authentication can be enhanced by integrating this technology with the healthcare ecosystem. This study examines the role of distributed ledger technology in the healthcare system while highlighting how some aspects of this disruptive technology can completely alter current business practices. To achieve this, the theoretical foundations of numerous research papers published in prestigious scientific journals and several reports from industries are included in this survey. This helps to streamline our analysis and fully capture the constantly expanding blockchain domain. This survey also identifies several research holes and prospective areas for further study using these findings as a starting point. Both academics and practitioners should find great value in these discoveries. This survey presents a comprehensive evaluation of current DLT-supported approaches in the healthcare system. and provides benefits and limitations of the recent work. This survey also emphasizes the essential security needs for a healthcare ecosystem and discusses the security flaws with existing methods.
【Abstract】IT Infrastructures have grown in both size and complexity. To help administrators to manage their infrastructure, several Infrastructure Management (IM) Tools have been created. However, none of them implements a secure and traceable log of changes that can bring accountability to the management of such infrastructures. On the other hand, recent research and development in blockchain technologies has allowed for the creation of Distributed Ledgers that can provide secure, immutable and traceable ledgers. These technologies have the potential to solve the problem by dynamically registering the changes the infrastructure management tools apply to IT infrastructures. For that purpose, a Proof-of-Concept tool was developed that incorporates a Permissioned Distributed Ledger, based on Hyperledger Fabric, as a middle layer to infrastructure management tools such as Ansible and Terraform, to prove the suitability of these technologies to provide a secure and immutable resource inventory and log of changes that enables for traceability and accountability of all modifications to the IT infrastructure, while also providing user identity management and control.
