Industrial Internet of Things (IIoT) is considered as one of the most promising revolutionary technologies to prompt smart manufacturing and increase productivity. With manufacturing being more ...complicated and sophisticated, an entire manufacturing process usually involves several different administrative IoT domains (e.g., factories). Devices from different domains collaborate on the same task, which raises great security and privacy concerns about device-to-device communications. Existing authentication approaches may result in heavy key management overhead or rely on a trusted third party. Thus, security and privacy issues during communication remain unsolved but imperative. In this paper, we present an efficient blockchain-assisted secure device authentication mechanism <inline-formula> <tex-math notation="LaTeX">\textsf{BASA} </tex-math></inline-formula> for cross-domain IIoT. Specifically, consortium blockchain is introduced to construct trust among different domains. Identity-based signature (IBS) is exploited during the authentication process. To preserve the privacy of devices, we design an identity management mechanism, which can realize that devices being authenticated remain anonymous. Besides, session keys between two parties are negotiated, which can secure the subsequent communications. Extensive experiments have been conducted to show the effectiveness and efficiency of the proposed mechanism.
Machine learning (ML) techniques have been widely used in many smart city sectors, where a huge amount of data is gathered from various (IoT) devices. As a typical ML model, support vector machine ...(SVM) enables efficient data classification and thereby finds its applications in real-world scenarios, such as disease diagnosis and anomaly detection. Training an SVM classifier usually requires a collection of labeled IoT data from multiple entities, raising great concerns about data privacy. Most of the existing solutions rely on an implicit assumption that the training data can be reliably collected from multiple data providers, which is often not the case in reality. To bridge the gap between ideal assumptions and realistic constraints, in this paper, we propose secureSVM, which is a privacy-preserving SVM training scheme over blockchain-based encrypted IoT data. We utilize the blockchain techniques to build a secure and reliable data sharing platform among multiple data providers, where IoT data is encrypted and then recorded on a distributed ledger. We design secure building blocks, such as secure polynomial multiplication and secure comparison, by employing a homomorphic cryptosystem, Paillier, and construct a secure SVM training algorithm, which requires only two interactions in a single iteration, with no need for a trusted third-party. Rigorous security analysis prove that the proposed scheme ensures the confidentiality of the sensitive data for each data provider as well as the SVM model parameters for data analysts. Extensive experiments demonstrates the efficiency of the proposed scheme.
China has the most minimal proportion of intermediate service inputs among the input-output datasets encompassing 43 countries and regions within the WIOD database. This study employs a ...non-parametric estimation methodology to compute the appropriate input levels for two distinct categories of intermediate goods. Furthermore, it evaluates the decline in total factor productivity resulting from distortions in intermediate input. The research findings are as follows: 1) China's producer services exhibit an output elasticity approximately twice that of industrial intermediate goods. However, the input for producer services is only about half of that for the latter. This points to a notable deviation of China's input for producer services from the optimal level. 2) Upon achieving an optimal level of input allocation for intermediates, the entire industry could experience an 11.48% boost in total factor productivity. In particular, the manufacturing sector could witness an impressive surge of 33.91%. 3) A positive correlation is discerned between intermediate input distortions and the import of intermediate products.
A novel MnO2/g-C3N4 heterojunction composite was synthesized via a simple in-situ redox reaction between KMnO4 and MnSO4·H2O adsorbed on the surface of g-C3N4 for the first time. MnO2 featuring 2D ...δ-phase layered structure was intimately attached onto the surface of g-C3N4 layers via CO bonding. Notably, the synthesized MnO2/g-C3N4 photocatalyst showed substantially enhanced photocatalytic activity in the reduction of CO2 than pure g-C3N4 and MnO2. The highest CO production amount of 9.6 μmol g−1 has been obtained at an optimized loading amount of MnO2 under 1 h irradiation of a 300 W Xe lamp. The incorporation of narrow band gap MnO2 on the surface of g-C3N4 enhanced its light harvesting ability. And the solid hetero-interface between MnO2 and g-C3N4 together with their well matched band structure was favorable for the separation of photo-induced carriers, consequently enhanced its photocatalytic activity. This novel 2D-2D MnO2/g-C3N4 heterostructure is expected to have great potentials in CO2 photoreduction.
A novel MnO2/g-C3N4 heterojunction composite was synthesized via a simple in-situ redox reaction between KMnO4 and MnSO4·H2O adsorbed on the surface of g-C3N4 for the first time. The incorporation of narrow band gap MnO2 on the surface of g-C3N4 enhanced its light harvesting ability. Moreover, the perfect matching of the band structures and the solid bonding interfaces between g-C3N4 and MnO2 have been reasoned to favor the separation of photo-induced charge carriers, leading to enhanced photocatalytic activity. This novel 2D-2D MnO2/g-C3N4 heterostructure is expected to have great potentials in CO2 photoreduction. Display omitted
With a profusion of network applications, traffic classification plays a crucial role in network management and policy-based security control. The widely used encryption transmission protocols, such ...as the secure socket layer/transport layer security (SSL/TLS) protocols, lead to the failure of traditional payload-based classification methods. Existing methods for encrypted traffic classification cannot achieve high discrimination accuracy for applications with similar fingerprints. In this paper, we propose an attribute-aware encrypted traffic classification method based on the second-order Markov Chains. We start by exploring approaches that can further improve the performance of existing methods in terms of discrimination accuracy, and make promising observations that the application attribute bigram, which consists of the certificate packet length and the first application data size in SSL/TLS sessions, contributes to application discrimination. To increase the diversity of application fingerprints, we develop a new method by incorporating the attribute bigrams into the second-order homogeneous Markov chains. Extensive evaluation results show that the proposed method can improve the classification accuracy by 29% on the average compared with the state-of-the-art Markov-based method.
Existing distributed denial-of-service attack detection in software defined networks (SDNs) typically perform detection in a single domain. In reality, abnormal traffic usually affects multiple ...network domains. Thus, a cross-domain attack detection has been proposed to improve detection performance. However, when participating in detection, the domain of each SDN needs to provide a large amount of real traffic data, from which private information may be leaked. Existing multiparty privacy protection schemes often achieve privacy guarantees by sacrificing accuracy or increasing the time cost. Achieving both high accuracy and reasonable time consumption is a challenging task. In this paper, we propose Predis, which is a privacy-preserving cross-domain attack detection scheme for SDNs. Predis combines perturbation encryption and data encryption to protect privacy and employs a computationally simple and efficient algorithm k-Nearest Neighbors (kNN) as its detection algorithm. We also improve kNN to achieve better efficiency. Via theoretical analysis and extensive simulations, we demonstrate that Predis is capable of achieving efficient and accurate attack detection while securing sensitive information of each domain.
A light-mediated asymmetric dicarbofunctionalization of enamides with carboxylic-acid-derived redox-active esters (RAEs) and indoles has been established by using chiral lithium phosphate catalysis ...in the presence or absence of photoredox catalyst. This reaction features mild reaction conditions and broad substrate scopes, delivering a wide range of highly functionalized chiral amine derivatives. Mechanistic studies suggest that chiral lithium phosphate can serve as a pocket to accelerate the aggregation of enamide and RAE through hydrogen-bonding and coordination interaction, enabling the formation of a charge-transfer complex (CTC). Either enamide or CTC can be excited by direct irradiation or Ru(II)-mediated photosensitization to furnish chiral iminium intermediates for the asymmetric Friedel–Crafts reaction of indole.
The emerging metal single‐atom catalyst has aroused extensive attention in multiple fields, such as clean energy, environmental protection, and biomedicine. Unfortunately, though it has been shown to ...be highly active, the origins of the activity of the single‐atom sites remain unrevealed to date owing to the lack of deep insight on electronic level. Now, partially oxidized Ni single‐atom sites were constructed in polymeric carbon nitride (CN), which elevates the photocatalytic performance by over 30‐fold. The 3d orbital of the partially oxidized Ni single‐atom sites is filled with unpaired d‐electrons, which are ready to be excited under irradiation. Such an electron configuration results in elevated light response, conductivity, charge separation, and mobility of the photocatalyst concurrently, thus largely augmenting the photocatalytic performance.
The high catalytic activity of metal single atoms originates from their unique electronic configuration. By finely tuning the oxidation states of metal single atoms, their electronic configurations were modulated, resulting in more unpaired d‐orbital electrons and a markedly elevated photocatalytic activity.
Allylamines are important building blocks in the synthesis of bioactive compounds. The direct coupling of allylic C−H bonds and commonly available amines is a major synthetic challenge. An allylic ...C−H amination of 1,4‐dienes has been accomplished by palladium catalysis. With aromatic amines, branch‐selective allylic aminations are favored to generate thermodynamically unstable Z‐allylamines. In addition, more basic aliphatic cyclic amines can also engage in the reaction, but linear dienyl allylic amines are the major products.
A Pd‐catalyzed branch‐ and Z‐selective allylic C−H amination from 1,4‐dienes and aromatic amines has been established for the efficient synthesis of thermodynamically unstable Z‐allylamines. In addition, more basic aliphatic cyclic amines also smoothly engage in the allylic C−H amination reaction without any Lewis acid additive, preferentially giving linear‐selective allylamines as the major regioisomers.
As an integral part of V2G networks, EVs receive electricity from not only the grid but also other EVs and may frequently feed the power back to the grid. Payment records in V2G networks are useful ...for extracting user behaviors and facilitating decision-making for optimized power supply, scheduling, pricing, and consumption. Sharing payment and user information, however, raises serious privacy concerns in addition to the existing challenge of secure and reliable transaction processing. In this article, we propose a blockchain-based privacy preserving payment mechanism for V2G networks, which enables data sharing while securing sensitive user information. The mechanism introduces a registration and data maintenance process that is based on a blockchain technique, which ensures the anonymity of user payment data while enabling payment auditing by privileged users. Our design is implemented based on Hyperledger to carefully evaluate its feasibility and effectiveness.
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