Mobile Crowd Sensing (MCS) is a new sensing paradigm that uses portable intelligent mobile devices (smartphones, wearable devices, etc.) carried by users to capture dynamic changes of social and urban information. Thanks to the ubiquity of mobile devices, MCS is able to collect data efficiently and achieve some valuable practical applications. Research reviews on MCS mostly focus on a single direction such as task assignment or incentive mechanism. This paper comprehensively reviews the research work on task allocation, incentive mechanisms, quality control and privacy protection in recent years. First, the system architecture and workflow of MCS are described and representative applications of MCS are illustrated. Furthermore, taking MCS as the target object, this paper expounds and discusses key issues such as task allocation, incentive mechanisms, quality control, and privacy protection, and introduces the latest research results in these fields. Subsequently, we provide a systematic review of the datasets reported in the literature. Ultimately, we point out the limitations of existing studies and look forward to future research directions to provide valuable references for related researchers.

As a form of distributed machine learning, Federated learning allows users to complete training without sharing local data, thereby protecting user privacy to a certain extent. However, the gradients uploaded by users during the training process can still leak user privacy. Additionally, malicious or lazy cloud servers may tamper with or forge the aggregated results before returning them to users, causing significant losses to the entire training process. Existing solutions focus on security issues, but most privacy protection schemes based on complex cryptographic primitives require high computational power and communication bandwidth. Moreover, to verify the aggregated results, each user must compute proofs, which imposes an additional computational burden on users. Therefore, designing more efficient and lightweight solutions that ensure security while adapting to resource-constrained scenarios is necessary. An efficient group-based scheme for privacy preservation and verification outsourcing in federated learning, referred to as GPVO-FL, is introduced in this work. Specifically, we design a lightweight privacy protection mechanism based on group structure and masking techniques to protect user gradients. In addition, we design an outsourced verification mechanism that offloads the verification process to edge servers, thus reducing the computational burden on users. A detailed security and experimental analysis demonstrates the security and efficiency of our scheme.

Internet of Things (IoT) networks have penetrated our daily life and industries. However, IoT devices are typically small-sized with constrained storage. Distributed storage systems are emerging as promising solutions to tackle such challenges. InterPlanetary File System (IPFS) is a desired framework enabling IoT devices to upload its data to a distributed cloud while returning a hash-ID for downloading and file-sharing purposes. Nevertheless, IPFS lacks of robust security design and is vulnerable to security threats such as data tampering, and data leakage. In particular, whenever device A’s file hash-ID is shared to an arbitrary device B, device A will fully lose the control over file. In other words, device B could further share it to anyone without device A’s agreements. To conquer the challenge, we propose a comprehensive design for securing the distributed IoT storage systems, named StorSec. Specifically, we design a new heterogeneous framework using an improved attribute encryption algorithm to eliminate the single-point performance bottleneck problem, which not only realizes fine-grained access control and ensures the security of data during transmission, but also improves the performance of key generation. Secondly, we design an anomaly detection algorithm, which is based on hashchain technology and combines the user privacy metadata stored on the blockchain to complete the verification process, effectively protecting the file hash identifier, ensuring access control to the file, and thus providing protection for the security and integrity of data storage. Furthermore, we design an auditing algorithm that helps the system in tracking malicious entities. Ultimately, the security and efficiency of the proposed scheme are evaluated by both security analysis and experimental results.

In the era of big data and growing privacy concerns, Federated Learning (FL) has emerged as a promising solution for collaborative model training while preserving user data privacy. However, FL faces challenges such as inconsistent data quality and frequent client dropouts, which hinder its performance. To address these challenges, we propose FedHPM, a novel framework that leverages the predictive capabilities of Long Short-Term Memory (LSTM) networks. FedHPM incorporates an intelligent client selection mechanism that utilizes LSTM-based analysis of historical data to forecast clients’ potential data quality and dropout likelihood. This mechanism enables efficient selection of the top best-performing clients for participation in each round of global model training. By mitigating the impact of dropouts and optimizing the composition of participating clients, FedHPM significantly improves both the convergence speed and final performance of the global model. Through extensive empirical evaluations, we demonstrate the superior performance of FedHPM in enhancing FL stability, accelerating the convergence rate, and maintaining model accuracy. The results highlight the effectiveness of our framework in addressing the challenges associated with data quality and dropouts, thereby advancing the field of federated learning.

With the increasing integration of location-based services (LBSs) into various societal domains, location privacy preservation has emerged as a pivotal concern. In most continuous LBS privacy protection approaches, the user needs to send a query to an untrusted location service provider (LSP) to request the corresponding query results, and these results are discarded immediately after being used. This leads to similar queries in the future having to be sent to the LSP again, which increases the risk of privacy leakage when facing the LSP. To solve these issues, caching techniques are typically used to provide answers to users’ future queries. However, minimizing the interaction with the LSP is a challenge. Here, we propose a trajectory privacy-preserving scheme based on a transition matrix and caching (TMC) scheme for continuous LBS in the Industrial Internet of Things (IIoT). It employs multilevel caching to reduce the risk of exposing sensitive information to untrusted entities. We designed a transition matrix to predict the user’s next query location and simplify the computation complexity. We designed a cloaking set generation algorithm by considering transition entropy, location prediction, data freshness, and cache contribution degree to enhance user location privacy and improve the cache hit rate. The security analysis demonstrates how the TMC scheme resists attacks from both internal and external entities and ensures robustness in trajectory privacy. The experimental results show that the proposed TMC scheme can provide a higher level of privacy protection and lower system overhead compared to several previous schemes.

Biometric and password-based two-factor authentication has received attention from the community over the past decades because of its simplicity, portability, and robustness. In wireless body area networks (WBANs), dozens of authentication and key agreement schemes have been proposed. Despite well-studied security issues, preserving user privacy in these schemes is still challenging. In this work, we propose biometric-based authentication and key agreement (BAKA), a scheme based on a fuzzy extractor for WBAN, where a novel biometric and password-based authentication algorithm is proposed by using a fuzzy extractor to achieve anonymous identity authentication, a privacy-preserving key agreement algorithm for session key security, and finally, we deploy blockchain to record biometric information using its noncomparability and distributed storage to protect users’ privacy to a large extent. BAKA is secure as per formal security proof and informal security analysis, symmetric encryption is utilized to reduce computation overhead to improve the efficiency of BAKA, where security is not compromised. Extensive experiments to validate the performance of BAKA are performed, and the results demonstrate the security efficacy proposed.

With the vigorous development of the Internet of Things (IoT), mobile users need to access data from other domains in edge computing. To achieve secure data sharing, mobile users first need to be authenticated by servers from different domains and then negotiate session keys among them. However, traditional schemes cannot solve cross-domain identity authentication and key agreement problems well due to the limited computational resources of IoT devices. In this work, we propose a Blockchain-based Cross-domain Authentication scheme for Edge computing, namely BCAE. First, to achieve secure identity verification, we design a novel cross-domain mutual identity authentication algorithm based on digital certificates and digital signatures. Next, to improve efficiency, we utilize the blockchain to share information among different domains to reduce the computation overhead. To realize quick key agreement, we apply the elliptic curve cryptography technique to design a lightweight key agreement algorithm and obtain secure session keys. Extensive experiments conducted on an actual smart healthcare issue to validate the performance of BCAE and formal security analysis confirmed the potential of the proposed work.

Summary With the advancement of global positioning systems and communication technologies, location‐based services (LBS) have become widely used. However, user location privacy is vulnerable during service exchange, and location‐related queries may result in serious privacy disclosure issues. In this article, considering that attackers may make use of auxiliary information to track a mobile user, we propose a real‐time privacy‐preserving scheme based on the grouping of queries in continuous LBS. In this scheme, we first design the probability density functions to select virtual locations. Then, we group these virtual locations and the query location of the user into several queries. Simultaneously, we send these grouping queries to the LBS server. Following the steps outlined above, grouping queries can be used to conceal the true query. Moreover, the results of security analyses and performance evaluations show that the proposed scheme is effective and secure.

Abstract With the development of the drying rack system, users with limited time tend to use the fully functional drying rack system to realize various intelligent control functions. However, the existing control methods for drying rack system has some defects such as, low intelligence and system delay, which are unsuitable for most users. In this paper, an efficient intelligent control algorithm based on the back‐propagation (BP) neural network is proposed. In this system, STM32F103 is first utilized as the central controller and multiple sensors are used to collect environmental information. Then, the remote control, voice keywords, and buttons can be used to achieve intelligent control. Subsequently, a motor drive intelligence control algorithm based on the BP neural network (MCBP) is proposed to improve the accuracy of the intelligent control. Next, an Application (APP) that can display environmental data such as wind speed, temperature, and humidity is developed. The APP can realize various intelligent control functions such as lifting, panning, rotating, and harvesting. Finally, MCBP is compared with normal control and programmable logic controller control. The accuracy of the MCBP is higher than other two control methods. The final extensive experiments confirm the accuracy and efficiency of the proposed intelligent control algorithm.

Location-based services have become prevalent and the risk of location privacy leakage increases. Most existing schemes use third-party-based or third-party-free system architectures; the former suffers from a single point of failure (SPOF) and the latter experiences a heavy load on user terminal equipment and higher communication costs. Ensuring location privacy while lowering system overhead becomes a challenge. Many existing schemes fail to leverage the responses from an LBS server; such responses can be cached to answer subsequent queries. As a result, providing users with a relatively comprehensive level of location privacy protection is troublesome. In this article, we propose a caching-based dual${K}$-anonymous (CDKA) location privacy-preserving scheme in edge computing environments. Our scheme employs an edge server to intercedes between a user and LBS the server. We reduce the load on the user device by applying multilevel caching and to protect location privacy through dual anonymity. To ensure the location privacy in our construction, we set mobile clients and edge servers as anonymous. We use caching to lower the communication overhead and enforce the location privacy. The security analysis of our scheme supports its robustness against the edge server and the LBS server privacy offenses. We rely on the computation time, the communication cost, and the cache hit ratio to evaluate our work against existing constructions. The results are twofold: our work possesses a better response rate down to 15–32.6 ms and exhibits lower communication cost requirements down to 6.2–38.9 kB compared to existing works. Our scheme witnesses a higher cache hit ratio of up to 13.6% and 39.1% compared to the literature.

With recent advances in cloud computing, mobile devices are increasingly being used to record patient physiological parameters, and transfer them to a cloud-based hospital information system, for access control mediation over a variety of stakeholders. In such a cloud-based architecture, the patient must specify an access policy for a group of authorized parties towards its outsourced data. Multiauthority ciphertext-policy attribute-based encryption (CP-ABE) was provided as an innovative cloud-based access control cryptographic primitive to tackle the key escrow issue in a centralized architecture, and boost flexibility through cross-domain attributes management. Existing works, however, still have glaring drawbacks. First, they still rely on a trusted authority to generate and distribute user secret keys. Second, they do not simultaneously provide encryption, decryption, or revocation outsourcing, resulting in high processing and communication cost for both the data sender and the data receiver. Third, they do not support both user and attribute revocation, and the integrity of ciphertext downloaded from the cloud is not always verified at the user end. As a result, this paper exploits the dummy attribute technique and introduces a novel, efficient, and secure multiauthority ciphertext-policy ABE method for mediating access control over medical data, in the mobile cloud. The ciphertext access policy enforcement, partial ciphertext decryption, and both the user and attribute indirect revocation updates are safely outsourced to the cloud server in this study. Theoretical analysis demonstrates that our scheme is efficient and verifiable, and we prove that our construction is secure under the decisional bilinear Diffie-Hellman assumption.

Online social networks (OSNs) are nowadays an important field of applications thanks to the recent surge in online interaction. However, the illegal disclosure of user's private data can cause damaging consequences and even threaten the safety of users' life. The privacy issues of OSNs have become a matter of great concern for many people. In recent years, there are some research works to address this privacy issue, yet they do not always focus on providing the normal social network services for users, such as data sharing, data retrieval and data access services. Therefore, it is a challenge to ensure the security of sensitive data while providing efficient and privacy-preserving social network services for users. In this paper, we propose a novel blockchain-based privacy-preserving framework for online social networks, called BPP. Combined blockchain and public-key cryptography technique, the BPP framework can achieve secure data sharing, data retrieving, and data accessing with fairness and without worrying about potential damage to users' interest. Specifically, based on blockchain and public key encryption with keyword search technique, a secure, fair and efficient keyword search algorithm is proposed, with which the BBP framework realises privacy preservation of user's query and then obtain accurate query results with assurance and without needing for any further verification operation in online social network. Finally, we implement a prototype of our framework and deploy it to a locally simulated network. The extensive experiments and security analysis demonstrate the security, efficacy and efficiency of our proposed framework.

In wireless sensor networks, owing to the limited energy of the sensor node, it is very meaningful to propose a dynamic scheduling scheme with data management that reduces energy as soon as possible. However, traditional techniques treat data management as an isolated process on only selected individual nodes. In this article, we propose an aggressive data reduction architecture, which is based on error control within sensor segments and integrates three parallel dynamic control mechanisms. We demonstrate that this architecture not only achieves energy savings but also guarantees the data accuracy specified by the application. Furthermore, based on this architecture, we propose two implementations. The experimental results show that both implementations can raise the energy savings while keeping the error at an predefined and acceptable level. We observed that, compared with the basic implementation, the enhancement implementation achieves a relatively higher data accuracy. Moreover, the enhancement implementation is more suitable for the harsh environmental monitoring applications. Further, when both implementations achieve the same accuracy, the enhancement implementation saves more energy. Extensive experiments on realistic historical soil temperature data confirm the efficacy and efficiency of two implementations.

Video Surveillance has been widely used in business establishments. Since digital cameras everlastingly collect the video data, the volume of sampled data is extensively large, which is hard to be stored and managed locally. Outsourcing surveillance video data to the cloud can achieve cost saving and flexibility, but also will incur potential privacy leakage. In this paper, we utilize the Compressed Sensing (CS) technique for sampling and compressing, to achieve secure and efficient video surveillance in cloud computing. Firstly, we identify the known-plaintext attack in such environment. That is, given sufficient information about the original signal and corresponding CS measurements, the attacker is likely to calculate the measurement matrix. Then, we propose a Dynamic Compressive Sensing(DCS) scheme to resist such an attack. Specifically, we use a dynamic measurement matrix that is changeable over time to prevent the attackers from gaining sufficient information to calculate the measurement matrix. Furthermore, we allow the cloud to help users decode the non-reference frames without leaking any information, to take full advantage of the powerful computing. Experimental results show that the proposed scheme effectively protects the security of the surveillance video, and provides a good recovery quality for users to conduct further analysis.