【Abstract】In our study, we have evaluated the impact of tweets, social indicators, uncertainty, and attention indices on the selected variables calculated from a pool of 51 decentralised finance entities. In so doing, we have identified some evidence that returns are impacted by tweets, but not by social indicators that appear to be more relevant for volatility. We have further confirmed that the S&P500 Index negatively influences cryptocurrency returns, which means that these two asset classes are substitutes. Uncertainty and attention indices are relevant in determining returns and the alternative measurement of volatility. However, they remain insignificant for illiquidity and our initial volatility choice.
【Abstract】The advent of group-oriented communication applications has triggered research on secure group communication (SGC) in vehicular ad hoc networks (VANETs). Given this, some researchers worked in this area and proposed various schemes. However, these systems lacking the dynamic nature, and struggling with larger processing loads, enormous storage, increased communications, security, and privacy concerns. Further, with the increase in the size of VANET, it is challenging to manage processing loads and storage requirements of group controller (GC)-centric group key agreement (GKA). To address these drawbacks in existing VANET communications, we propose a blockchain IOTA sharding-based smart contract-centric GKA for SGC in large VANETs. In this scheme, we partition the main network into ${r}$ sharded subnetworks using blockchain sharding technique, with $G_{1}, G_{2}, G_{3},\ldots, G_{r}$ as smart contract (SC) instances generated by GC, G, which functions as Sub-GC (Sub-GC) to their respective shards. Under the Elliptic curve decision Diffie-Hellman (ECDDH) and group-Elliptic curve Diffie-Hellman (GECCDH) assumptions, the proposed protocol is proven to be secure. The suggested protocol outperforms the other protocols for secure communication in large VANETs, according to the performance analysis.
【Keywords】Vehicular ad hoc networks; Blockchains; Security; Protocols; Internet of Things; Privacy; Public key; Blockchain; group key agreement (GKA); group controller (GC); IOTA; privacy preserving; sharding; smart contract (SC)
【Abstract】Federated learning, as an emerging distributed machine learning technology, can use cross-device data to train a usable and secure shared model under the premise of protecting data privacy. However, the existing federated learning usually uploads the intermediate parameters to the central server to achieve model aggregation, which will cause significant privacy leakage. Recently, blockchain technology has become a research hotspot due to its advantages of decentralized and non-tampering features, providing new ideas for the realization of security certification for federated learning. However, blockchain-enabled federated learning also faces the following two challenges: (1) the identity authentication relies on the central server being fully trusted and the computation cost is heavy; (2) center-less authentication faces the challenges of efficiency and privacy leakage. To solve the above challenges, we propose a lightweight authentication mechanism for blockchainenabled federated learning system, named LAFED. The innovations of LAFED are three-fold: (1) a lightweight authentication framework for blockchain-enabled federated learning; (2) a flexible consensus algorithm with zero-knowledge proof to verify the identity of each participant; (3) an adaptive model aggregation algorithm based on the model quality and node contribution to improve the performance. Extensive experimental results demonstrate that the proposed LAFED can achieve lightweight authentication while ensuring a high model accuracy.(c) 2023 Elsevier B.V. All rights reserved.
【Abstract】In the current global marketplace supply chains can span a huge number of countries, cross many borders and require interoperation of a multitude of organizations. This vastness of supply chains impacts business competitiveness since it adds complexity and can difficult securing traceability, chain of custody and transparency. We propose that assuring chain of custody and traceability via Blockchain (BC) allows organizations to demonstrate product provenance, integrity and compliance. This work proposes that to effect true traceability the more complete approach is to connect both the Supply Chain Actors (SCAs) and products identifications using digital certificates. A Blockchain is used to manage the traceability of products and validation of the identities. Importing, verifying and storing the certificates uses an off-chain data storage solution for products certificates, IDs and data (i.e., WalliD) . To create, validate the certificates and setup the chain of trust a Public Key Infrastructure (PKI) was designed as part of the proposal. Our study follows a Design Science research approach aimed to analyse the requirements and propose a solution to a more complete traceability in supply chains. The results were architectural artifacts, including an Ethereum Smart Contract and a PKI based certificate authentication system. The implementation of these deliverables allow for a supply chain system that can provide decentralized and trustful assurance of the provenance, chain of custody and traceability functionalities for all the Organizations and also for the final consumers.To exemplify the problem and demonstrate the applicability of the solution, its potential and benefits we applied it to a real food supply chain use case that already uses provenance certificates and stored them in the blockchain using the before mentioned SmartContract to assure and demonstrate the chain of custody and traceability of the food produce.
【Abstract】With the continuous development of the new crown epidemic and the outbreak of the Russian-Ukrainian war, the world is facing a serious food crisis, especially the agri-food (agricultural and food) crisis. The research of blockchain smart contracts in the agri-food industry has attracted great attention. To judge its trend, this research adopts the methods of bibliometric analysis and content analysis to conduct a comprehensive review and content analysis of the blockchain smart contract research in this industry. A general framework for blockchain smart contract research applied to the agri-food industry is proposed. Firstly, 78 relevant literatures were screened from 6 databases including the web of science and the Derwent Innovations Index for this review. Bibliometrics analyzes previous research from five dimensions, including publication year, document type and publication journal, country, author, and keywords. Secondly, the content analysis identified 4 issues, such as agri-food data storage, agri-food information management and control, agri-food data traceability, and agri-food data rights confirmation. Thirdly, the general framework provides a general research method for blockchain smart contracts. Finally, the advantages, challenges and development trends of blockchain smart contract research in the agrifood industry are discussed. This paper makes a qualitative and quantitative analysis of blockchain smart contracts in the agri-food industry, and clarifies the research status, challenges and development trends. We provide a common framework that contributes to the body of knowledge that will facilitate greater strategic adoption and use of blockchain smart contracts in the agri-food industry.
【Abstract】The utilization of cloud and edge computing has become one of the most prevailing resource supply mechanisms. Thousands of enterprise users and Internet of Things (IoT) devices have performed operations through services sold by computing resource providers. So far, the auction match is the main strategy for allocating resources, in which there exists a trusted third party playing a role as a broker to deal with resource allocation requests for both providers and consumers. The main concerns in resource allocation architecture are how and how long to solve the Winner Determination Problem (WDP), which is used to lay out the match outcome. It is not easy for a single broker with limited computing power to generate an optimal solution in a short period since its corresponding time complexity is regarded as the NP-hard problem. Meanwhile, it is hard for people to trust the third party thoroughly. That is, there are three potential issues, including centralization, data security, and untrustworthiness in traditional matching architecture. In particular, the real-time matching cannot be achieved to fulfill users who have urgent needs of computing resources. To solve above issues, we have designed a trustworthy and real-time decentralized computing resource allocation platform based on blockchain and smart contract. In order to optimize the allocation results, we improve the Non-dominated Sorting Genetic Algorithm II (NSGA-II) for miners to reach the consensus mechanism. Experimental results and comparison analysis have demonstrated that potential defects could be addressed in the new method, and the real-time resource allocation can be preserved firmly despite the balance vibration of market supply and demand.
