Related Schemes Research Articles

Hyper-Relations: A Model for Denormalization of Transactional Relational Databases

A formal model of denormalized relational schemas based on outer joins of base relations is presented. The composition of joins is modeled with a hyper-tree, called hyper-schema, with vertexes representing equi-joins, and edges representing joined base relations. The base relations are not the relations defined in the conceptual schema, but their “atoms.” The semantics of hyper-relations is defined in terms of join disjunctions. Three different denormalized outer join forms are also defined, in terms of constraints imposed to hyper-schemas that gradually make the maintenance of hyper-relations simpler and more efficient. The presented model can be used as a formal underpinning for 1) a special, but important case of materialized views, 2) an implementation of the physical, yet relational schema of a highly denormalized database, or 3) different optimization techniques based on denormalization.

Secure channel free public key authenticated encryption with multi-keyword search on healthcare systems

A significant amount of electronic health records (EHRs) have been kept in the cloud due to the quick development of healthcare information systems. However, storing EHRs in the cloud may raise security and data privacy issues. Because of the privacy of a patient’s medical data, storing it on a cloud server requires encryption. Public-key encryption with keyword search (PEKS) solves the problem of retrieval on ciphertext, thus avoiding the problem of plaintext information leakage. However, most PEKS schemes are susceptible to inside keyword guessing attacks (KGA). Besides, transmitting the trapdoor to the cloud server requires a secure channel, which is impractical in healthcare information systems. Roughly speaking, PEKS does not protect the privacy of trapdoor and it is expensive to establish secure channels. In this paper, we propose a secure-channel free public key authenticated encryption with multi-keyword search (SCF-PAEMKS) scheme. The proposed SCF-PAEMKS scheme supports conjunctive keyword search, meanwhile satisfying multi-ciphertext indistinguishability (MCI) and multi-trapdoor privacy (MTP) simultaneously. The efficiency analysis and experimental results show that our SCF-PAEMKS scheme enjoys a better performance compared with related schemes.

Intersection-Based Unicast Routing Using Ant Colony Optimization in Software-Defined Vehicular Networks

A vehicular ad hoc network (VANET) is a mobile ad hoc network composed of communication between vehicles, between vehicles and roadside units, and between vehicles and pedestrians, in order to achieve traffic safety and entertainment services. The design of the routing protocol is very important for the realization of the service function of VANET. Local optimum and network congestion problems are restraints of traditional geographic routing protocols for VANET. In this paper, a software-defined network (SDN) based unicast routing scheme in an urban traffic environment is proposed, which uses Dijkstra’s algorithm to find a global optimal anchor path. The RSU neighbor discovery protocol is proposed, through which each RSU can discover its neighbor RSUs, and then each RSU periodically sends ant packets to its neighbor RSUs, evaluates the communication connection quality of each street segment according to the statistical data of the ant packets received, and sends the evaluation value to the SDN server in time. The SDN server has the connection quality evaluation values of all street segments in the global scope, from which an optimal anchor path can be calculated. The simulation results show that the proposed scheme has better packet delivery ratio than other related schemes.

Toward Designing a Secure Authentication Protocol for IoT Environments

Authentication protocol is a critical part of any application to manage the access control in many applications. A former research recently proposed a lightweight authentication scheme to transmit data in an IoT subsystem securely. Although the designers presented the first security analysis of the proposed protocol, that protocol has not been independently analyzed by third-party researchers, to the best of our knowledge. On the other hand, it is generally agreed that no cryptosystem should be used in a practical application unless its security has been verified through security analysis by third parties extensively, which is addressed in this paper. Although it is an efficient protocol by design compared to other related schemes, our security analysis identifies the non-ideal properties of this protocol. More specifically, we show that this protocol does not provide perfect forward secrecy. In addition, we show that it is vulnerable to an insider attacker, and an active insider adversary can successfully recover the shared keys between the protocol’s entities. In addition, such an adversary can impersonate the remote server to the user and vice versa. Next, the adversary can trace the target user using the extracted information. Finally, we redesign the protocol such that the enhanced protocol can withstand all the aforementioned attacks. The overhead of the proposed protocol compared to its predecessor is only 15.5% in terms of computational cost.

Harnessing large-scale agro-based investments in the Sagcot area for inclusive agricultural transformation in Tanzania

The colonial and post-colonial large-scale agriculture has brought the far-ranging implications on the local population in Tanzania. These include dispossession of land, dislocation of migrant labourers who are also subjected to poor work conditions and induced imbalances in terms of gender and ethnic relations. The government and other actors in Tanzania have strived to reduce the effects by fostering inclusive large-scale agriculture that benefit the small-scale farmers. This includes the move to initiate a 20-year public-private partnership on large-scale agribusiness namely Southern Agricultural Growth Corridor of Tanzania (SACGOT) in 2010. Serious concerns were raised against SAGCOT especially on the extent to which it entails uprooting and taking away lands from poor rural dwellers and turning them into poorly paid casual labourers thus increasing poverty and food insecurity. Consequently, the coordinating unit of SAGCOT vowed to improve food security to hundreds of thousands of poor farmers. The primary research was designed to examine the inclusivity aspects of the six selected large-scale investment schemes under the SAGCOT partnership. The Responsible Agriculture Investment (RAI) Framework was employed to assess sustainable labour practices, community engagements and fairness in out-grower arrangements. While the investment schemes demonstrated a fairly positive outlook pertaining to social sustainability under the RAI framework, a notable variation was observed across the six schemes in relation to specific RAI indicators. For instance, a company that demonstrated the outstanding performance in corporate social responsibility also performed poorly in the domain of wages and employee relations. A set of sustainability benchmarks developed jointly by the SAGCOT Center and civil society organizations and implemented on voluntary basis by a few member investors need to be harmonized and monitored across all investment schemes. This is especially important for the small-scale sub-contracted firms which lacked the requisite skills and capacity to engage in a more sustainable manner. Key words: Inclusion, agriculture, Tanzania, growth corridor, investments, sustainability, out-grower schemes, decent work

Encryption Scheme of Verifiable Search Based on Blockchain in Cloud Environment

While transferring data to cloud servers frees users from having to manage it, it eventually raises new problems, such as data privacy. The concept of searchable encryption has drawn more and more focus in research as a means of resolving the tension between data accessibility and data privacy. Due to the lack of integrity and correctness authentication in most searchable encryption techniques, malicious cloud servers may deliver false search results to users. Based on public key encryption with searching (PEKS), the study suggests a privacy-preserving method for verifiable fuzzy keyword searches based on the Ethernet blockchain in a cloud context to overcome the aforementioned security concerns. The search user can check the accuracy and integrity of the query document using the unalterability characteristics of the Ethernet blockchain system in this scheme to prevent the cloud server from giving incorrect query results. Furthermore, a fair transaction between the cloud server and the data user is achieved and can be tracked back to the malicious user using hash functions and Ethereum smart contracts, even if the user or the cloud is malicious. Finally, the security analysis shows that, under the random oracle model, our technique fulfils the adaptive selection keyword’s semantic security. The performance assessment demonstrates that the proposed scheme outperforms other related schemes in terms of computational efficiency.

Provably Secure Dynamic Anonymous Authentication Protocol for Wireless Sensor Networks in Internet of Things

Wireless sensor networks are a promising application of the Internet of Things in the sustainable development of smart cities, and have been afforded significant attention since first being proposed. Authentication protocols aim to protect the security and confidentiality of legitimate users when accessing and transmitting data. However, existing protocols may suffer from one or more security flaws. Recently, Butt et al. proposed an energy-efficient three-factor authentication protocol for wireless sensor networks. However, their protocol is vulnerable to several attacks, and lacks certain security properties. In this paper, the causes of these design flaws are analyzed. Furthermore, we propose a novel three-factor authentication protocol (password, smart card, and biometric information) for wireless sensor networks in Internet of Things contexts. A dynamic anonymous strategy is designed to prevent privacy disclosure and to resist sensor node capture attacks, tracking attacks, and desynchronization attacks. The Find–Guess model and random oracle model are combined to prove the security of the proposed protocol. A comparative analysis with related schemes shows that the proposed protocol has higher security and is able to maintain a low computational overhead.

CD-BCM:Cross-Domain Batch Certificates Management Based On Blockchain

AbstractWith the development of information networks, the entities from different network domains interact with each other more and more frequently. Therefore, identity management and authentication are essential in cross-domain setting. The traditional Public Key Infrastructure (PKI) architecture has some problems, including single point of failure, inefficient certificate revocation status management and also lack of privacy protection, which cannot meet the demand of cross-domain identity authentication. Blockchain is suitable for multi-participant collaboration in multi-trust domain scenarios. In this paper, a cross-domain certificate management scheme CD-BCM based on the consortium blockchain is proposed. For the issue of Certificate Authority’s single point of failure, we design a multi-signature algorithm. In addition, we propose a unified structure for batch certificates verification and conversion, which improve the efficiency of erroneous certificate identification. Finally, by comparing with current related schemes, our scheme achieves good functionality and scalability in the scenario of cross-domain certificate management.

Extremely Lightweight Constant-Round Membership-Authenticated Group Key Establishment for Resource-Constrained Smart Environments toward 5G

AbstractWith rapid development of next-generation mobile networks and communications (5G networks), group-oriented applications in resource-constrained smart environments (RSEs), such as smart homes and smart classrooms, have attracted great attentions. Due to the insecure communications between resource-constrained devices, secure group communications in RSE toward 5G face many challenges. In RSE toward 5G, lightweight communications and low computational overheads are crucial. Besides, the private tokens used to generate the group key are expected to be reused multiple times. However, the conventional frameworks for secure group communications cannot meet these requirements. A practical construction of extremely lightweight constant-round membership authenticated group key establishment framework is proposed in this paper for RSE toward 5G, which not only implements identity authentication among the members and group key establishment but also ensures extremely lightweight computation and communication costs by each group member. In our proposed scheme, the increase in the number of group members will not lead to a linear or logarithmic increase in the communication and calculation costs at the member side. Our framework also resists external and internal attacks and meets all the desirable security features. In this framework, the privacy of tokens can be well protected, so that they can be reused for multiple times. Therefore, our scheme significantly reduces the costs of communication and calculation, and it is more efficient compared with the related schemes in the literature. This proposal is fairly suitable for lightweight membership authentication and group key establishment in RSE toward 5G.

Distributed and Federated Authentication Schemes Based on Updatable Smart Contracts

Federated authentication, such as Google ID, enables users to conveniently access multiple websites using a single login credential. Despite this convenience, securing federated authentication services requires addressing a single point of failure, which can result from using a centralized authentication server. In addition, because the same login credentials are used, anonymity and protection against user impersonation attacks must be ensured. Recently, researchers introduced distributed authentication schemes based on blockchains and smart contracts (SCs) for systems that require high availability and reliability. Data on a blockchain are immutable, and deployed SCs cannot be changed or tampered with. Nonetheless, updates may be necessary to fix programming bugs or modify business logic. Recently, methods for updating SCs to address these issues have been investigated. Therefore, this study proposes a distributed and federated authentication scheme that uses SCs to overcome a single point of failure. Additionally, an updatable SC is designed to fix programming bugs, add to the function of an SC, or modify business logic. ProVerif, which is a widely known cryptographic protocol verification tool, confirms that the proposed scheme can provide protection against various security threats, such as single point of failure, user impersonation attacks, and user anonymity, which is vital in federated authentication services. In addition, the proposed scheme exhibits a performance improvement of 71% compared with other related schemes.

Fuzzy finite-time consensus control for uncertain nonlinear multi-agent systems with input delay

A fuzzy finite-time consensus control method for a class of uncertain nonlinear multi-agent systems (MASs) with input delay is developed. The Pade approximation approach and Laplace transform technology are employed to eliminate the effect of input delay. Then, the fuzzy logic systems are applied to deal with the uncertain nonlinear terms. Furthermore, a relative threshold event-triggered control scheme is established to alleviate the communication burden of the control network. Meanwhile, to ensure MASs can synchronize in finite time, an adaptive consensus control method is developed. With the proposed method, even if the MASs suffer from input delay, all followers in the MASs reach finite-time synchronization and track the virtual leader. Finally, the validity of the proposed method is illustrated by the theoretical analysis and simulation examples.

The development and application of convertible Bonds -- A case study of Shanghai Pudong Development Bank's Convertible Bonds

In recent years, with the continuous strengthening of refinancing demand, banks have more diversified ways of refinancing, such as perpetual bonds, secondary capital bonds, and convertible bonds. It is found that convertible bonds meet the capital replenishment needs of commercial banks, and the financing cost is compared with that of other financing instruments. The method adopted in this paper is the case analysis, and the "Pudong Development Convertible Bond" publicly issued by Shanghai Pudong Development Bank (SPDB) in 2019 is taken as the case study object. Based on the background that commercial banks are scrambling to issue related schemes of convertible bonds, this paper expounds on the financing effect and significance of the issuance of convertible bonds by SPDB based on the historical process and current situation of convertible bonds and the basic situation and financing process of SPDB. Comprehensive analysis shows that before the issuance of convertible bonds, the asset-liability ratio of SPD Bank is relatively high. After the issuance of convertible bonds, the asset-liability ratio and capital adequacy ratio of banks have been improved, but the return rate and net profit level have been negatively affected. The paper hopes to provide a reference value for issuers such as commercial banks and listed companies as well as regulators of convertible bonds on the improvement of the market system of convertible bonds.

One piece of the puzzle: Treatment of fostered and adopted children with RAD and DSED

Reactive attachment disorder (RAD) and disinhibited social engagement disorder (DSED) are two interrelated diagnoses emerging from pathogenic and insufficient care during the first few years of life. They have been reported in children who were fostered or adopted after experiencing severe early deprivation through institutionalisation, as well as youth with foster care and maltreatment histories. Substantial comorbid and overlapping difficulties often coexist with both disorders, which complicates their identification. Despite a consensus that RAD and DSED are distinctive diagnoses that capture relational behaviours not elsewhere described, many questions remain about their development and treatment. Research probing underlying mechanisms for both disorders is scarce, and only a few studies exist that chronicle potential interventions. Extant treatments tend to focus on parent management training rather than attachment-based interventions and often do not incorporate assessment of the child’s relational schemata and comorbid difficulties into interventions. This article expands on earlier interventions by detailing the current state of knowledge about RAD and DSED and their common comorbidities in children with foster care and adoption histories and by suggesting how to weave that knowledge into comprehensive assessment and treatment. Two case vignettes are presented.

Privacy-Preserving Fast Three-Factor Authentication and Key Agreement for IoT-Based E-Health Systems

Electronic healthcare (e-health) systems have received renewed interest, particularly in the current COVID-19 pandemic (e.g., lockdowns and changes in hospital policies due to the pandemic). However, ensuring security of both data-at-rest and data-in-transit remains challenging to achieve, particularly since data is collected and sent from less insecure devices (e.g., patients’ wearable or home devices). While there have been a number of authentication schemes, such as those based on three-factor authentication, to provide authentication and privacy protection, a number of limitations associated with these schemes remain (e.g., (in)security or computationally expensive). In this study, we present a privacy-preserving three-factor authenticated key agreement scheme that is sufficiently lightweight for resource-constrained e-health systems. The proposed scheme enables both mutual authentication and session key negotiation in addition to privacy protection, with minimal computational cost. The security of the proposed scheme is demonstrated in the Real-or-Random model. Experiments using Raspberry Pi show that the proposed scheme achieves reduced computational cost (of up to 89.9% in comparison to three other related schemes).

ASPA-MOSN: An Efficient User Authentication Scheme for Phishing Attack Detection in Mobile Online Social Networks

Over the last few years, with the massive growth of smartphone technology and mobile Internet, the use of various online social networks (OSNs) have increased rapidly. This ever-growing use of social networks leverages cyber-attackers to exploit various phishing schemes, spoofed accounts, and other threats to steal users’ credentials. Phishing is an online crime that employs both technical subterfuge and social engineering to steal consumers’ personal identity, financial account credentials, and other sensitive information. In general, a phishing attack is carried out by the exercise of sending fraudulent communications (like a fake email with harmful uniform resource locators), that pretends to come from a reputable source. The problem of designing user authentication protocol for mitigating phishing attacks in OSNs is a challenging research problem. In this article, we propose a secure and lightweight cryptography-based authentication scheme, called authentication scheme for phishing attack (ASPA)-mobile online social network (mOSN), that provides resistance to phishing and other related attacks in OSNs. The security of the proposed scheme is explained using both informal security analysis and formal security analysis through the widely recognized real-or-random model and ProVerif simulation tool. Finally, we compare the security, functionality, computation, and communication costs of the proposed ASPA-mOSN with related schemes. The comparison results show that ASPA-mOSN outperforms other existing competing schemes.

FSDA: Flexible Subset Data Aggregation for Smart Grid

Data aggregation is a practical method to protect individual privacy while using data utility, which aggregates the real-time electricity consumption data in an area into a single value in smart grids. Based on traditional data aggregation, multisubset data aggregation can obtain data distribution characteristics rather than just the sum of data. However, almost all existing multisubset aggregation schemes do not pay attention to adjusting the size of subsets according to the data distribution, which limits the data utility. In this article, a flexible subset data aggregation (FSDA) scheme based on Paillier homomorphic encryption for smart grids is proposed. The proposed FSDA scheme can dynamically adjust the size of each subset and aggregate the electricity consumption data into the corresponding subsets while protecting individual privacy. It is proved that FSDA scheme can obtain the distribution of consumption data and resist various internal attacks aiming to expose the individual or aggregated data. Experimental results show that FSDA scheme has lower overhead compared with related schemes, which is practical for resource-constrained smart meter devices.

Privacy-Preserving Authentication Scheme With Revocability for Multi-WSN in Industrial IoT

Wireless sensor network (WSN), as one of the core technology in the Industrial Internet of Things (IIoT) system, plays a critical role in collecting data for the monitoring areas. Security and privacy are essential to ensure the trustworthy completeness of data access and transmission for the WSN-based IIoT system. Recently, a series of excellent privacy-preserving authentication schemes for the WSN-based IIoT system have been proposed. There is, however, strong demand for further improvements in multiple registrations, user revocation, and forward secrecy. Targeted by these security issues, we propose an efficient privacy-preserving authentication scheme with revocability for multi-WSNs in the IIoT environment. In the proposed scheme, the user can access multiple different WSNs with the same identity and password through a single registration. Our scheme is provable secure under the random oracle model, and security analysis via practical circumstances shows that it is able to provide a variety of security requirements, such as user revocation, forward secrecy, etc. In addition, the comparison with related schemes indicates that the proposed one has fewer sensor nodes-based computations and overall communication overheads. It is, therefore, more suitable for the resource-constrained IIoT environment than existing approaches.

Achieving any desirable dispersion curves using non-local phononic crystals

Phononic crystals and vibro-elastic metamaterials are characterized by their dispersion relations—how frequency changes with wave number/vector. While there are many existing methods to solve the forward problem of obtaining the dispersion relation from any arbitrarily given design. The inverse problem of obtaining a design for any arbitrarily given dispersion bands has only had very limited success so far. Here, we report a new design scheme for arbitrary dispersion relations by incorporating non-local interactions between unit cells. Considering discrete models of one-dimensional mass-spring chains, we investigate the effects of both local (i.e., springs between the nearest neighbors) and non-local (i.e., springs between the next nearest neighbors and other longer-range springs) interactions. First, we derive the general governing equations of non-local phononic chains. Next, we examine all design constraints for a linear, periodic, passive, statically stable, non-gyroscopic, and free-standing system. Finally, we perform analytical calculations and numerical simulations to solve the inverse problem. The results illuminate a new path toward novel wave manipulation functionalities, such as ordinary and higher-order critical points with zero-group-velocity (ZGV) modes, as well as multi-wavelength and multi-speed propagations of the same mode at the same frequency.

An Assessment of the Oceanic Physical and Biogeochemical Components of CMIP5 and CMIP6 Models for the Ross Sea Region

AbstractThe physical and biogeochemical performance of 16 CMIP5 and 16 CMIP6 Earth System models (ESM) are examined relative to present day (1976–2005) observational data sets for a Ross Sea Region (RSR) containing the Ross Gyre (RG) and the Ross Sea Continental Shelf. A relative ranking scheme using error metrics and published ESM properties (including climate sensitivity parameters and anomalous deep ocean convection statistics) enables identification of a “best” ensemble of models for the RSR. Over the RSR the CMIP6 models are generally found to have improved physical representations compared to the CMIP5 set (based on our metrics for sea ice concentration, sea surface temperature, salinity, and height, and mixed layer depth), but the CMIP5 and CMIP6 biogeochemical representations remain similar. Examination of mean properties for the period 2081 to 2100 for RCP8.5 and SSP585 for CMIP5 and CMIP6, respectively, shows significant surface temperature increases, with significant decreases in sea surface salinity, sea ice concentration, and mixed layer depth across the RSR. Biogeochemically, there are generally small increases in surface values for chlorophyll, integrated primary production, and zooplankton carbon concentrations. The projections also have robust reductions in surface nitrate, phosphate, and silicate across the RSR. For that part of the RG circulation to the east of 180°E—which we refer to as the “inner RG”—significant barotropic transport increases are found by the end of century.

A Wireless-Power-Transfer-Based Three-Phase PMSM Drive System With Matrix Converter

Wireless power transfer system has played an important role in rail transit, industrial production, and daily life. This article proposes a wireless power transfer permanent-magnet synchronous motor (WPT-PMSM) drive system based on the matrix converter (MC). The direct conversion of low-frequency ac and high-frequency ac is realized without dc link by using MC. The dual <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> compensation network is designed for better performance. In addition, a new control method has been proposed for the proposed WPT-PMSM drive to operate stably. In particular, the bidirectional power flow is achieved with the proposed WTP-PMSM drive and related control scheme. Through the mathematical modeling, the coordinated control of power converters on both sides of the coupling coil is achieved and the reactive power of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> compensation network is eliminated. The experiments on a 1 kW and 85 kHz laboratory prototype of the WPT-PMSM drive are presented to verify the feasibility and effectiveness of the proposed system.