【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), . . . , 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】While the Metaverse is becoming a popular trend and drawing much attention from academia, society, and businesses, processing cores used in its infrastructures need to be improved, particularly in terms of signal processing and pattern recognition. Accordingly, the speech emotion recognition (SER) method plays a crucial role in creating the Metaverse platforms more usable and enjoyable for its users. However, existing SER methods continue to be plagued by two significant problems in the online environment. The shortage of adequate engagement and customization between avatars and users is recognized as the first issue and the second problem is related to the complexity of SER problems in the Metaverse as we face people and their digital twins or avatars. This is why developing efficient machine learning (ML) techniques specified for hypercomplex signal processing is essential to enhance the impressiveness and tangibility of the Metaverse platforms. As a solution, echo state networks (ESNs), which are an ML powerful tool for SER, can be an appropriate technique to enhance the Metaverse's foundations in this area. Nevertheless, ESNs have some technical issues restricting them from a precise and reliable analysis, especially in the aspect of high-dimensional data. The most significant limitation of these networks is the high memory consumption caused by their reservoir structure in face of high -dimensional signals. To solve all problems associated with ESNs and their application in the Metaverse, we have come up with a novel structure for ESNs empowered by octonion algebra called NO2GESNet. Octonion numbers have eight dimensions, compactly display high-dimensional data, and improve the network precision and performance in comparison to conventional ESNs. The proposed network also solves the weaknesses of the ESNs in the presentation of the higher-order statistics to the output layer by equipping it with a multidimensional bilinear filter. Three comprehensive scenarios to use the proposed network in the Metaverse have been designed and analyzed, not only do they show the accuracy and performance of the proposed approach, but also the ways how SER can be employed in the Metaverse platforms.(c) 2023 Elsevier Ltd. All rights reserved.
【Abstract】The development of blockchain technology has brought prosperity to the cryptocurrency market and has made the blockchain platform a hotbed of crimes. As one of the most rampant crimes, phishing scam has caused a huge economic loss to blockchain platforms and users. In order to address the threat to the financial security of blockchain, this paper proposes a model based on hybrid deep neural network to detect phishing scam accounts, namely LBPS (LSTM-FCN and BP neural network-based Phishing Scam accounts detection model), and verifies its effectiveness on Ethereum. The LBPS model provides a novel approach to analyse transaction records by adopting the BP neural network to obtain the implicit relationship between features extracted from transaction records and the LSTM-FCN neural network to capture the temporal feature from all transaction records of a target account. The experimental results demonstrate that the features selected in this paper could identify phishing scam accounts effectively. Moreover, the LBPS model performs better than the existing methods and baseline models with an F1-score of 97.86%.
【Abstract】The interconnection between bitcoin and gold markets has attracted a lot of interest among investors, policy makers, practitioners and market participants. The objective of this paper is to examine the role of infectious diseases-based uncertainty on the connection between bitcoin and gold markets using a battery of spillovers and causality tests. The following findings are discernible from our analyses. First, the spillover tests, there exists a low level of connection between the two markets, and implying that there were diversification options. Second, the spillover results also reveal that the gold market is a net transmitter of volatility, while bitcoin market is a net receiver of the shocks. Third, BDS test shows strong evidence of nonlinearity is a very crucial factor to be put into consideration when examining the role of health-based uncertainty affecting the interactions between bitcoin and gold markets. Fourth, there is evidence of a linear relationship between bitcoin-gold connectedness and infectious diseases uncertainty mostly for the full sample period. Fifth, the non-parametric causality-in-quantile test confirms that the connectedness between uncertainty due to infectious diseases and the markets is stronger mostly around the lower quantiles. These results have important policy implications for policymakers and market participants.
【Abstract】Exploring the safe-haven characteristics of bitcoin from novel perspectives is crucial to diversify the investment and reap the benefits. This investigation employs bootstrap full-and sub-sample techniques to probe time-varying interrelation between global supply chain pressure (GSCP) and bitcoin price (BP), and further answer if "digital gold" could resist the strains of global supply chain. The empirical outcomes suggest that GSCP positively and negatively affects BP. The positive influence points out that high GSCP might boost the international bitcoin market, driving BP to rise, which indicates that "digital gold" could resist the pressures of global supply chain. But the negative effect of GSCP on BP could not support the above view, mainly affected by the weak purchasing power and more valuable assets, which is not consistent with the assumption of the inter-temporal capital asset pricing model (ICAPM). In turn, GSCP is adversely affected by BP, highlighting that the international bitcoin market may be viewed as a stress reliever for the global supply chain. Against a backdrop of the deteriorative Russia-Ukraine war and the intensifying global supply chain crisis, the above conclusions could bring significative lessons to the public, enterprises and related economies.
【Abstract】Digitalization has made it easier for centric systems to transition from single-factor to two-factor authentication. However, several access control practices struggle to authenticate users correctly due to their weak and outdated authorization systems. Moreover, the majority of cloud-centric models suffer from security and single-point-of-failure issues. Consequently, several systems have migrated their access control services to the blockchain. A good illustration is using two-factor authentication techniques to increase transaction security in Bitcoin systems. However, with this holistic trend of 2FAs, multi-factor authentication has yet to see this trend. In this regard, the study proposes an access control technique that combines multiple factors of knowledge, inherent, and possession to authenticate users to the blockchain. The multiple factors derive a time-based access code for users to generate private keys. The efficiency of the proposed method is tested with a Py-Eth-pairing library to determine the computation cost and transmission overhead. Furthermore, we use the EIP (Ethereum Improvement Proposals) library to assess the gas cost and determine the throughput. Our findings show the suggested approach to achieving the lowest operational cost, making it scalable on the blockchain while demonstrating its practicability through the model framework.
【Abstract】The blockchain technology has been gaining an increasing popularity for the last years, and smart contracts are being used for a growing number of applications in several scenarios. The execution of smart contracts on public blockchains can be invoked by any user with a transaction, although in many scenarios there would be the need for restricting the right of executing smart contracts only to a restricted set of users. To help deal with this issue, this article proposes a system based on a popular access control framework called RT, Role-based Trust Management, to regulate smart contracts execution rights. The proposed system, called Layer 2 DecentrAlized Role-based Trust management ( L2DART), implements the RT framework on a public blockchain, and it is designed as a layer-2 technology that involves both on-chain and off-chain functionalities to reduce the blockchain costs while keeping blockchain auditability, i.e., immutability and transparency. The on-chain costs of L2DART have been evaluated on Ethereum and comparedwith a previous solution implementing on-chain all the functionalities. The results show that the on-chain costs of L2DART are relatively low, making the system deployable in real-world scenarios.
【Abstract】With the advent of IoT technology, the dynamic nature of IoT devices has introduced new obstacles to access control. It is essential to consider the security requirements of the actual physical environment, rendering the traditional access control approach centered on the information space. In the IoT ecosystem, there are several issues such as the dynamics of devices frequently entering and leaving, the lack of computing and storage capacity, and distributed deployment. To address these challenges, this paper proposes the Domain Attribute Based Access Control(DABAC) that incorporates domain elements to implement the physical location limitation of dynamic devices. Moreover, an intelligent gateway is utilized to divide the physical area and act as a proxy to achieve regional device management, automatic networking of devices in the domain, and the dynamic expansion of the sensor network resulting from device entry or exit. Then, given the distributed deployment of devices, smart contracts are employed to deploy access control mechanisms and construct a trusted environment to mitigate threats such as single points of failure. Finally, the DABAC is implemented on the Ethereum platform, simulating a smart medical situation. The experimental results demonstrate that the proposed solution effectively addresses the problem of access control of device dynamics in an untrusted IoT environment while maintaining system security.
【Keywords】Access control; Internet of Things; Blockchains; Smart contracts; Security; Logic gates; Aerodynamics; blockchain; dynamics; the Internet of Things; spatio-temporal constraints
【Abstract】Smart contracts are tempting targets of attacks, as they often hold and manipulate significant financial assets, are immutable after deployment, and have publicly available source code, with assets estimated in the order of millions of dollars being lost in the past due to vulnerabilities. Formal verification is thus a necessity, but smart contracts challenge the existing highly efficient techniques routinely applied in the symbolic verification of software, due to specificities not present in general programming languages. A common feature of existingworks in this area is the attempt to reuse off-the-shelf verification tools designed for general programming languages. This reuse can lead to inefficiency and potentially unsound results, as domain translation is required. In this article, we describe a carefully crafted approach that directly models the central aspects of smart contracts natively, going from the contract to its logical representation without intermediary steps. We use the expressive and highly automatable logic of constrained Horn clauses for modeling and instantiate our approach to the Solidity language. A tool implementing our approach, called Solicitous, was developed and integrated into the SMTChecker module of the Solidity compiler solc. We evaluated our approach on an extensive benchmark set containing 22,446 real-world smart contracts deployed on the Ethereum blockchain over a 27-month period. The results show that our approach is able to establish safety of significantly more contracts than comparable, publicly available verification tools, with an order of magnitude increase in the percentage of formally verified contracts.
【Abstract】In the blockchain environment, smart contracts are computer programs that run on the blockchain platform. However, the development of smart contracts is a major challenge for developers, since blockchain platforms are still evolving. Owing to the inherited nature of blockchain, developing smart contracts without introducing vulnerabilities is not an easy task, as the deployed code is immutable and can be invoked by anyone with access to the network. Smart contracts have proved to be error-prone in practice due to the complexity of programming. Additionally, non-functional requirements, such as service cost, security, performance, authorization, and authentication, should be well implemented and defined in computer systems. In this paper, we aim to present a systematic literature review to outline in detail different approaches of smart contracts generation. Furthermore, we present a comparison of the existing approaches based on a classification according to automation paradigm and a set of defined criteria. Finally, we discuss the gaps in the literature, as well as identify a set of potential challenges which can significantly strengthen the existing work. The study shows that the examined works focused only on a limited number of specific features, such as authorization, asset control, and security. Additionally, formal verification of smart contracts and data privacy are poorly addressed.
【Abstract】One of the perennial fault-lines in monetary theory is that between commodity and credit theories of money. The emergence of alternative payment systems based on blockchain and distributed ledger technologies, of which Bitcoin is the most prominent example, has raised a host of important questions in relation to this debate. This article considers two. The first is ontological: Are Bitcoin and similar 'cryptocurrencies' best conceived of as money? The second is political: Do these money candidates represent an emancipatory development over state-backed fiat currency? The ontological question, we will argue, invites the political one. If it is the case, as Chartalists maintain, that (i) for some X to be money it must have certain properties which can only be imparted by political authority (broadly understood) and if (ii) political authority ought to be subject to public control, then attempts by private actors to usurp a social 'money function' cannot count as legitimate political developments. We will argue in support of this position. This discussion is limited to Bitcoin, though its implications generalize for relevantly similar cryptocurrencies. Our method involves considering, first, claims made by Bitcoin's defenders about its status as money, and what accounts for that status. While these claims are often thought to extend Mengerite or generally Austrian lines of economic argument, they resonate more with Marx's theory of monetary value. Moreover, a close assessment of that theory's defects yields specific normative conclusions that potentially undermine the notion that Bitcoin constitutes a valid means of resisting state monetary authority.
【Abstract】Tools such as blockchain and smart contracts represent an interesting opportunity for various sectors including the electro-energy one. This paper describes the study and implementation of a Proof of Concept for the creation of local energy markets using blockchain technologies and smart contracts in order to ensure decentralization, transparency, trustworthiness and accountability.
【摘要】要解决区块链账本公开带来的安全问题，关键在于对私密信息的隐藏。本文中提出使用多属性机构的属性基加密来实现区块链数据的隐私保护。相比单一属性机构，多属性机构在实现权力分散的同时避免了任何单点故障。首先方案修改了密钥组件生成算法，每个属性机构把用户身份作为参数来生成私钥组件，防止节点合谋访问无权访问的数据。然后修改了基于身份的签名技术来建立用户身份与钱包地址之间的连接，让区块链变得可监管的同时还能对非法用户进行可追溯。最后，基于DBDH(Determining the Bilinear Diffie-Hellman)假设，在随机预言模型中证明了该方案的安全性，同时实验结果表明，与基于椭圆曲线上的环签名的区块链隐私保护方案和支持关键字遗忘搜索的区块链隐私保护方案相比，在生成相同区块个数的情况下，本方案用时最少，更具可行性。
