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Cloud computing offers scalable implementation of applications by sharing internet-based storage and computing resources. However, its ubiquitous nature introduces the security and privacy risks to sensitive data. Existing encryption techniques often rely on access control mechanisms to allow selective sharing of encrypted data. However, they don’t efficiently support secure integration of space and time constraints in the authorization mechanism, rendering them unsuitable for dynamic cloud environments. In this paper, we propose a privacy-preserving spatio-temporal attribute-based access control technique for cloud-based applications. Our approach utilizes ciphertext policy attribute-based encryption (CP-ABE) with distributed key generation, geohashes for proximity detection, and fog server-based verification. The proposed cryptosystem generates decryption keys based only on the user’s static attributes eliminating the need to manage user revocation due to frequent contextual changes. Time and location constraints are enforced through spatio-temporal locks in the access policy. Geohash enables defining authorized geographic areas while preserving user location privacy. Additionally, our system supports multiple attribute authorities for key generation, enhancing security by limiting user identity leakages and preventing key escrow attacks. Most of the decryption-related computations are outsourced to fog servers, thus, making the decryption independent of the number of attributes in the policies. The analysis of security and performance demonstrates the effectiveness of our scheme in practical cloud-based applications, enabling precise control over real-time data access while satisfying user privacy. [ABSTRACT FROM AUTHOR]

Existing anonymous communication systems that resisted traffic analysis could hide the identities of the communicating parties from the attacker. However, the identities of the communicating parties couldn’t be hidden from each other, and thus these systems did not apply to the scenario of anonymous whistleblowing and replying, where it was necessary to protect the identity of the whistleblower. To address this issue, an efficient anonymous whistleblower response scheme was proposed. With the technology of distributed point functions and secret sharing, the message was stored in two separate mailbox databases of non-colluding servers, so that the identity of the data receiver was hidden from the attacker. With the technology of secret sharing and encryption, the email address of the whistleblower was hidden, so that the receiving organization could reply without learning the whistleblower’s identity. The security analysis showed that the proposed scheme enabled the anonymity of both data receivers and whistleblowers at the same time. The experimental results show that compared to the Express scheme, the proposed scheme reduces the computational complexity during a reply to O(1) from O(logN), resulting in a 60% reduction in computational overhead for the receiving organization and a 50% reduction for the server.

The identity authentication schemes in the traditional network environment are designed according to the characteristics of their own environments, which are difficult to meet the design requirements in the metaverse environment. In order to solve the problem of identity authentication in the metaverse environment, the characteristics, attributes, application scenarios and main attack threats faced by the metaverse are studied. The identity privacy and security risks related to users, avatars, platforms, wearable devices and communications in the metaverse are discussed. The work related to identity authentication in the metaverse environment is sorted out and categorized into user-avatar, user-platform and userwearable device authentication. Finally, the research directions of identity authentication mechanism in the metaverse environment are discussed. [ABSTRACT FROM AUTHOR]

Collaborative edge storage (CES) can provide high-quality data sharing for end users through the collaborative use of edge storage resources. However, due to the lack of trust between different edge storage servers, satisfying data authenticity, storage reliability, and identity privacy protection simultaneously become the main research challenge in the field of CES. While the emerging blockchain-based collaborative storage solutions (BBCES) can solve the problems of data authenticity and storage reliability, the transparency of blockchain makes privacy become the main issue. In this paper, we propose a CP-ABE-based identity management framework (CIM), which can effectively protect the identity information of edge entities in the BBCES. On CIM, we design a CP-ABE scheme to protect the identity privacy of edge entities by encrypting classified identity information. The encrypted identity information of a new joining entity will be recorded in the blockchain. When edge entities participate in CES, the identification number of their encrypted identity information will be recorded in the blockchain. Besides, via the tracing algorithm, the system entity can get the authorized identity information of these edge entities participating in a specific CES, which can realize identity traceability while protecting identity privacy. Further, theoretical analysis and extensive experiments have demonstrated the effectiveness and performance of this scheme in the identity privacy protection of CES. [ABSTRACT FROM AUTHOR]

With the rocketing progress of the fifth generation (5G) mobile communication technology, identity-based authenticated key agreement (ID-AKA) protocol performs an increasingly significant part in secure communication. The majority of current efficient and secure ID-AKA protocols need to transmit each participant’s identity and public key information in the clear. Moreover, the long-term secret keys of participants are fully handled by the key generate center, which may give rise to new security concerns. To protect the privacy of user’s identity and ensure the security of the private keys, we propose a strongly secure identity-based authenticated key agreement scheme with identity concealment for 5G environment. The proposed scheme provides the property of non-full key escrow and eliminates the need of pairing operations. Furthermore, we show a modified security model for our protocol, and demonstrate the security analysis based on the hardness assumptions of the gap Diffie-Hellman problem and authentication encryption security. Finally, with the help of experiments and performance analysis, the detailed comparative results show that our scheme makes improvements in both efficiency and security while compared with recently proposed ID-AKA schemes.

The rapid advancements in technology have given rise to groundbreaking solutions and practical applications in the field of the Industrial Internet of Things (IIoT). These advancements have had a profound impact on the structures of numerous industrial organizations. The IIoT, a seamless integration of the physical and digital realms with minimal human intervention, has ushered in radical changes in the economy and modern business practices. At the heart of the IIoT lies its ability to gather and analyze vast volumes of data, which is then harnessed by artificial intelligence systems to perform intelligent tasks such as optimizing networked units' performance, identifying and correcting errors, and implementing proactive maintenance measures. However, implementing IIoT systems is fraught with difficulties, notably in terms of security and privacy. IIoT implementations are susceptible to sophisticated security attacks at various levels of networking and communication architecture. The complex and often heterogeneous nature of these systems makes it difficult to ensure availability, confidentiality, and integrity, raising concerns about mistrust in network operations, privacy breaches, and potential loss of critical, personal, and sensitive information of the network's end-users. To address these issues, this study aims to investigate the privacy requirements of an IIoT ecosystem as outlined by industry standards. It provides a comprehensive overview of the IIoT, its advantages, disadvantages, challenges, and the imperative need for industrial privacy. The research methodology encompasses a thorough literature review to gather existing knowledge and insights on the subject. Additionally, it explores how the IIoT is transforming the manufacturing industry and enhancing industrial processes, incorporating case studies and real-world examples to illustrate its practical applications and impact. Also, the research endeavors to offer actionable recommendations on implementing privacy-enhancing measures and establishing a secure IIoT ecosystem. [ABSTRACT FROM AUTHOR]

With the development of the Internet of Things (IoT) and its applications, a large amount of data is generated regularly. If this information is used by malicious attackers, it will be a great disaster for the relevant users. In this regard, this article focuses on the user’s identity privacy issues involved in the IoT. By protecting the user’s identity privacy, the attacker cannot associate the obtained data with the user’s real identity, and so achieve the purpose of protecting the user. This article uses the features of blockchain that cannot be tampered with nor forged to strengthen the reliability of the system. The proposed scheme saves the transaction information of user information through the Hyperledger and uses the ring signature method to obscure the real identity. A key generator is used to generate system public parameters and ring membership information required for signature. Users can use this information to hide their identity in a ring group of n users so that other users can only guess the true identity of the user with a probability of 1/n. Additionally, the method of aggregated signature is used to shorten the time and space required for k signature verification to 1/k, which greatly improves the efficiency. Finally, this article also uses an accountability mechanism to punish some attackers who attempt to waste system resources by revealing the real identity of the attacker and refusing to serve him. In this paper, GO language is used to write chain code to realize the proposed algorithm, and a prototype system is built through HyperLeger Fabric blockchain network, and the prototype system is verified by experiment. The correctness and efficiency of the above scheme are also proved through theoretical analysis and experiments.

Multi-access edge computing (MEC) is one of the emerging key technologies in fifth generation (5G) mobile networks, providing reduced end-to-end latency for applications and reduced load in the transport network. This paper proposes mechanisms to enhance user privacy in MEC within 5G. We consider a basic MEC usage scenario, where the user accesses an application hosted in the MEC platform via the radio access network of the mobile network operator (MNO). First, we create a system model based on this scenario. Second, we define the adversary model and give the list of privacy requirements for this system model. We also analyze the impact on user privacy when some of the parties in our model share information that is not strictly needed for providing the service. Third, we introduce a privacy-aware access protocol for the system model and analyze this protocol against the privacy requirements.

Abstract As the important transmission approach of the perception data, the security and privacy of the perception layer nodes have been paid more and more attention. To evaluate the credibility of the perception nodes and protect autologous identity privacy, a remote attestation mechanism using group signature (GS-RAM) for the perception layer of centralized networking is proposed in this paper. First, a RAM, based on the computational Diffie–Hellman (CDH) problem and GS, is established for the data source of the perception nodes. Second, the specific construction of the proposed GS-RAM is given to identify the trusted state of data sources without exposing the privacy of the perception nodes. Then, a strict security certification was carried out to verify the correctness, unforgeability, anonymity, traceability, unrelatedness, non-framing, anti-joint aggression and forward security of the proposed GS-RAM. Finally, simulation experiments are carried out to verify that the proposed scheme has better security and dynamic adaptability.

With the development of the Internet of Things (IoT) and its applications, a large amount of data is generated regularly. If this information is used by malicious attackers, it will be a great disaster for the relevant users. In this regard, this article focuses on the user's identity privacy issues involved in the IoT. By protecting the user's identity privacy, the attacker cannot associate the obtained data with the user's real identity, and so achieve the purpose of protecting the user. This article uses the features of blockchain that cannot be tampered with nor forged to strengthen the reliability of the system. The proposed scheme saves the transaction information of user information through the Hyperledger and uses the ring signature method to obscure the real identity. A key generator is used to generate system public parameters and ring membership information required for signature. Users can use this information to hide their identity in a ring group of n users so that other users can only guess the true identity of the user with a probability of 1/n. Additionally, the method of aggregated signature is used to shorten the time and space required for k signature verification to 1/k, which greatly improves the efficiency. Finally, this article also uses an accountability mechanism to punish some attackers who attempt to waste system resources by revealing the real identity of the attacker and refusing to serve him. In this paper, GO language is used to write chain code to realize the proposed algorithm, and a prototype system is built through HyperLeger Fabric blockchain network, and the prototype system is verified by experiment. The correctness and efficiency of the above scheme are also proved through theoretical analysis and experiments. [ABSTRACT FROM AUTHOR]

In García-Rodríguez et al. 2024, two generic constructions for biometric-based non-transferable Attribute Based Credentials (biometric ABC) are presented, which offer different trade-offs between efficiency and trust assumptions. In this paper, we focus on the second scheme denoted as BioABC-ZK that tries to remove the strong (and unrealistic) trust assumption on the Reader R, and we show that BioABC-ZK has a security flaw for a colluding R and Verifier V. Besides, BioABC-ZK lacks GDPR-compliance, which requires secure processing of biometrics, for instance in form of Fuzzy Extractors, as opposed to (i) storing the reference biometric template a B i o in the user's mobile phone and (i i) processing of biometrics using an external untrusted R, whose foreign manufacturers are unlikely to adjust their products according to GDPR. The contributions of this paper are threefold. First, we review efficient biometric ABC schemes to identify the privacy-by-design criteria for them. In view of these principles, we propose a new architecture for biometric ABC of Sarier 2021 by adapting the recently introduced core/helper setting. Briefly, a user in our modified setting is composed of a constrained core device (a SIM card) inside a helper device (a smart phone with dual SIM and face recognition feature), which – as opposed to García-Rodríguez et al. 2024 – does not need to store a B i o. This way, the new design provides Identity Privacy without the need for an external R and/or a dedicated hardware per user such as a biometric smart card reader or a tamper proof smart card as in current hardware-bound credential systems. Besides, the new system maintains minimal hardware requirements on the SIM card – only responsible for storing ABC and helper data –, which results in easy adoption and usability without loosing efficiency, if deep face fuzzy vault and our modified ABC scheme are employed together. As a result, a total overhead of 500 ms to a showing of a comparable non-biometric ABC is obtained instead of the 2.1 s in García-Rodríguez et al. 2024 apart from the removal of computationally expensive pairings. Finally, as different from García-Rodríguez et al. 2024, auditing is achieved via Blockchain instead of proving in zero-knowledge the actual biometric matching by the user to reveal malicious behavior of R and V. • Review on biometric-based non-transferable Attribute Based Credential (biometric ABC) • Insecurity/inefficiency of BioABC-ZK for Know-Your-Customer (KYC) attributes • Privacy-by-design principles of biometric ABC considering KYC attributes • Adapting ABC of Sarier (2021) via core/helper setting for biometric ABC on Blockchain • Security – including Identity Privacy – and Cost Analysis of biometric ABC [ABSTRACT FROM AUTHOR]

Internet of Vehicles (IoV) is a variant of Vehicular Ad-Hoc Network (VANET), it is being developed as an important communication way between vehicles. However, when some traffic messages are collected in IoV, these messages are usually linked to specific identifiable information. Therefore, there exists the privacy-preserving problem of vehicular identities in IoV. On the other hand, if the private information of vehicles is fully protected in IoV, then the true vehicular identities cannot be determined because the transferred messages are not related with the specific information of vehicles. Then it will also lead to more security problems in IoV. Additionally, fog computing seamlessly integrates heterogeneous computing resources widely distributed in edge networks and then provides stronger computing services for users. Therefore, in this paper we propose a decentralized traceable privacy-preserving scheme for vehicular identity in fog computing-based IoV, where our scheme uses multiple fog servers to trace the specific identity and most likely trajectory of a vehicle by the collected data under certain conditions. In our scheme, the true identity of a vehicle is hidden to some related parameters generated by the certificate authority; further the secret sharing scheme is used to hide and trace the true identity of a vehicle. We construct a voting mechanism to generate the most reliable fog server, which is able to calculate the true identity and corresponding trajectory of a vehicle by reconstructing the polynomial based on the secret sharing scheme. Additionally, we analyze that our scheme can satisfy the security requirements, and formally prove that the data collection procedure is secure under the real-or-random model. Also, the experimental results show our scheme is efficient in IoV. [ABSTRACT FROM AUTHOR]

Intelligent systems are technologically advanced machines that can sense and respond to the surrounding environment. They have been widely used in medicine, military, transportation, automation, and other fields. However, when these systems deal with their environments, problems such as leakage of identities may occur. The adversary can damage the system communication and attack important nodes. To handle resource‐constrained wireless sensor network environments, we propose a secure and anonymous data aggregation scheme. First, based on the bilinear mapping operation and onion routing concepts, we propose a key negotiation and secure information transmission scheme, which conducts confidential transmission and anonymous forwarding of messages in data aggregation. Second, an aggregation routing scheme based on link direction and residual energy is proposed to pledge messages that can arrive the base station without passing through many nodes, which saves network resources to a certain extent. Third, on the basis of the first two contributions, we propose an identity‐privacy‐aware secure and anonymous data aggregation scheme that protects the identity's privacy. This scheme can conceal the real identity of important nodes and protect the anonymity of messages and link relationships. In addition, an anonymous identity update and synchronization scheme is also proposed to ensure the reliability and security of communication. Meanwhile, our performance evaluations and simulations show that the proposed framework is more effective than several standard schemes with respect to the ability against various attacks, security, and overhead. [ABSTRACT FROM AUTHOR]

In mobile network, ensuring privacy to the subscriber is an obligation of the mobile operator. It is the responsibility of the operator to ensure that the private information about the subscriber like his/her identity does not get compromised. While adopting technologies with regards to issues like this, operators mostly follow specifications standardized by the third Generation Partnership Project (3GPP). In a recent technical specification published by 3GPP for 5G mobile network, an Elliptic Curve Integrated Encryption Scheme (ECIES) is adopted for identity privacy. However, this scheme does not emphasize on protecting the identity of the home network with which the subscriber is registered. This may make the subscriber vulnerable to tracking by an adversary in a visited network through his/her home network identity. In this paper, we propose an enhanced scheme called scheme for home network identity privacy. Through a formal and an informal security analysis, the proposed scheme is found to be secured. Through a performance analysis, it is found that the scheme achieves its objective of securing the home network identity of the subscriber at the expense of 47% additional computation at the UE in comparison with the execution time that is incurred by ECIES. [ABSTRACT FROM AUTHOR]

Recently, with the rapid development of blockchain technology, the information interaction and value transfer problems between different blockchains have become the focus of research. The cross-chain technology is to solve the cross-chain operation problems of assets and data between different chains. However, the existing cross-chain technology has the problem of identity privacy leakage. Therefore, this article proposes a cross-chain privacy protection scheme for consortium blockchains based on group signature, certificate authority, and relay chain. The scheme is divided into three cross-chain service layers, called the management layer, the transaction layer, and the group layer. The management layer is responsible for the forwarding of cross-chain transactions, the transaction layer includes the blockchains that actually participate in cross-chain transactions, and the group layer is responsible for group signature related work. Through this scheme, the identity privacy of both parties to the transaction can be protected during the cross-chain transaction process. [ABSTRACT FROM AUTHOR]

Multi-access edge computing (MEC) is one of the emerging key technologies in fifth generation (5G) mobile networks, providing reduced end-to-end latency for applications and reduced load in the transport network. This paper proposes mechanisms to enhance user privacy in MEC within 5G. We consider a basic MEC usage scenario, where the user accesses an application hosted in the MEC platform via the radio access network of the mobile network operator (MNO). First, we create a system model based on this scenario. Second, we define the adversary model and give the list of privacy requirements for this system model. We also analyze the impact on user privacy when some of the parties in our model share information that is not strictly needed for providing the service. Third, we introduce a privacy-aware access protocol for the system model and analyze this protocol against the privacy requirements. [ABSTRACT FROM AUTHOR]

To verify that an organization-friendly blockchain system may suffer from forgery and collusion attacks, forgery and collusion attacks were theoretically carried out according to the phase sequence of an organization-friendly blockchain system. Then, the organization-friendly blockchain system was improved and based on the phase sequence forgery and collusion attacks were conducted. The results show that the attacker can obtain illegal transaction data from forgery and collusion attacks on the organization-friendly blockchain system. However, for the improved organization-friendly blockchain, the attacker's forgery and collusion attacks cannot be completed. Therefore, the organization-friendly blockchain system may be subject to forgery and collusion attacks, but the improved organization-friendly blockchain system can prevent such attacks. [ABSTRACT FROM AUTHOR]

As the important transmission approach of the perception data, the security and privacy of the perception layer nodes have been paid more and more attention. To evaluate the credibility of the perception nodes and protect autologous identity privacy, a remote attestation mechanism using group signature (GS-RAM) for the perception layer of centralized networking is proposed in this paper. First, a RAM, based on the computational Diffie–Hellman (CDH) problem and GS, is established for the data source of the perception nodes. Second, the specific construction of the proposed GS-RAM is given to identify the trusted state of data sources without exposing the privacy of the perception nodes. Then, a strict security certification was carried out to verify the correctness, unforgeability, anonymity, traceability, unrelatedness, non-framing, anti-joint aggression and forward security of the proposed GS-RAM. Finally, simulation experiments are carried out to verify that the proposed scheme has better security and dynamic adaptability. [ABSTRACT FROM AUTHOR]

As data sharing has become one of the most popular services offered by cloud storage, designing public auditing mechanisms for integrity of shared data becomes more important. Two problems which arise in shared data auditing include preserving users identity and collusion resistant revocation of users. When data stored at the cloud is shared among a group of users, different users may modify and sign different data blocks which leaks signer identities to the public verifier. Also, when a user is revoked from the group, signatures generated by this user should be re-signed by the cloud server using re-signature keys. In addition, collusion of cloud server and the revoked user should leak no information about the private key of other users. In this paper, by employing a new proxy re-signature scheme, we propose a public shared data auditing mechanism that provides identity privacy and collusion resistant user revocation, simultaneously. The proposed protocol requires only lightweight computations at the user side for signing data blocks in real-time online phase. Moreover, our protocol supports large dynamic group of users, batch auditing and dynamic data operations. Experimental results demonstrate excellent efficiency of our scheme in comparison to the state of the art. [ABSTRACT FROM AUTHOR]

In email system, the cryptography technology has been used to defend email secrets, so it is important to search specific encrypted emails on cloud sever without local decryption. The Public key encryption with keyword search (PEKS) might is a suitable way to perform the email ciphertext search. However, most existing PEKS schemes cannot protect the identity privacy of data sender. Deniably authenticated encryption (DAE) technique allows the data sender to deny his/her involvement after the communication. Moreover, the receiver can verify the authenticity of ciphertext in DAE, which assures the identity privacy of data sender. In this paper, so as to solve the above shortages in existing PEKS schemes, we introduce an original scheme called designated server certificateless deniably authenticated encryption with keyword search (dCLDAEKS), where leverages the techniques of DAE and designated server. In dCLDAEKS, data sender authenticates the messages and simultaneously encrypt them. Meanwhile, only designated server has ability to execute search ciphertext operation for receivers. So there is no adversary including the server can launch inside or outside offline KGA. Therefore dCLDAEKS scheme can better protect the identity privacy of data sender. In addition, compared the related schemes in the literature, dCLDAEKS scheme perform less efficient in some procedure, but it can against inside KGA and better protect the sender's identity privacy.

In 5G, identity privacy of a user is proposed to be protected by concealing the identifier of the user. In order to route the concealed identifier to the appropriate destination, certain information about the international mobile subscriber identity (IMSI) - country code and network code, need to be revealed. But, as was recently pointed out, the routing of requests for authentication information between visited and home network and also within the home network, needs more information about the IMSI to be revealed. It was also recently pointed out that there are restrictions on user identity privacy due to lawful interception in the serving network. In this new context, we reexamine published alternative solutions of identity privacy. We find the previously promising solutions e.g., solution based on public key of home network become less promising. We find the solution based on identity based encryption becomes more promising than it was before.

In the cloud applications of medical data based on blockchain, doctors and managers usually want to obtain image data shared by other healthcare institutions. To ensure the privacy and workability of the image data, it is necessary to encrypt plain image data, retrieve cypher data and verify the authenticity of the data. Public key authenticated searchable encryption (PAEKS) is an effective mechanism to realize the privacy and workability properties of data. However, the existing PAEKS schemes are unable to realize the identity privacy protection of the data owner, and the traditional blockchain system (such as the Bitcoin) cannot achieve these goals directly. To overcome the above drawback, we first present a deniably authenticated searchable encryption scheme for medical image data sharing (DASES) that is based on blockchain and deniably authenticated encryption technology. The DASES takes advantage of blockchain technology to ensure the non-tampered, unforgettable and traceability of the image data, and it also avoids the limitation of the blockchain's own storage and computing power. The DASES can not only withstand inside keyword guessing attack (IKGA) but also provide effective privacy protection and verify the authenticity of medical image data. Hence, it can better protect the privacy of data senders and provide stronger security. Next, we prove that the DASES satisfies the indistinguishability of the ciphertext and trapdoor. It is regrettable that the DASES is less efficient than related schemes in the literature, but its greatest strength is its ability to provide better identity privacy protection and stronger security. [ABSTRACT FROM AUTHOR]

In hybrid cloud data sharing, the amount of users and the attributes are large. As a result, the calculation amount of the client increases with the number of attributes, which affects the cloud data sharing efficiency among group users. And there is also a risk of leaking users' identity privacy and related attributes. To solve these problems, this paper proposed a secure and efficient g roup data sharing method in hybrid cloud environment. The m ethod combined the use of anonymous techno logy, attribute-hiding and com putational outsourcing technology to ensure the security of the user's identity privacy and attributes, and reduced the amount of calculations at the user end. Security and performance analysis, and the experimental results show the method has better safety and efficiency. [ABSTRACT FROM AUTHOR]

Vehicular social networks (VSNs) are moving from infancy to maturity. However, the characteristics of wireless channel availability and the high mobility of vehicles in the VSNs create new challenges for privacy preservation; the corresponding solutions require a combination of technologies. A common theme in this paper is the combination of crowdsensing (CS) and the VSNs. We first design a three-layer CS-based VSN architecture that includes a CS layer, mobile management layer, and core control layer. Then, we propose a two-stage privacy-preserving (TSPP) algorithm to protect identity and location privacy for the CS-based VSN. In TSPP algorithm, to protect identity privacy, we design a way of identity management. Simultaneously, by correlation analysis, we design a suppression strategy to satisfy ε-privacy with no information loss for location privacy protection. The simulation results show that our proposed TSPP algorithm better protects identity and location privacy than current algorithms. The results are based on four metrics: average processing time, identity privacy, location privacy, and information loss.

The unprecedented proliferation of mobile smart devices has propelled a promising computing paradigm, Mobile Crowd Sensing (MCS), where people share surrounding insight or personal data with others. As a fast, easy, and cost-effective way to address large-scale societal problems, MCS is widely applied into many fields, e.g., environment monitoring, map construction, public safety, etc. Despite the popularity, the risk of sensitive information disclosure in MCS poses a serious threat to the participants and limits its further development in privacy-sensitive fields. Thus, the research on privacy protection in MCS becomes important and urgent. This paper targets the privacy issues of MCS and conducts a comprehensive literature research on it by providing a thorough survey. We first introduce a typical system structure of MCS, summarize its characteristics, propose essential requirements on privacy on the basis of a threat model. Then, we survey existing solutions on privacy protection and evaluate their performances by employing the proposed requirements. In essence, we classify the privacy protection schemes into four categories with regard to identity privacy, data privacy, attribute privacy, and task privacy. Besides, we review the achievements on privacy-preserving incentives in MCS from four viewpoints of incentive measures: credit incentive, auction incentive, currency incentive, and reputation incentive. Finally, we point out some open issues and propose future research directions based on the findings from our survey. [ABSTRACT FROM AUTHOR]

With the breakthroughs in sensor technology and internet of things, Vehicular Ad Hoc Network (VANET) is developing into a new generation. The technical challenges of current VANET are decentralized architecture deployment and privacy protection. Since the blockchain owns the characteristics of being decentralized, distributed, collective maintenance and non-tampering, this paper designs a novel decentralized architecture using blockchain technology, which is called blockchain-based VANET. The blockchain-based VANET involves four major stages: blockchain set-up, registration of vehicles, SBMs upload, and blockchain record. It can effectively address the problems of centralization and mutual distrust between entities in current VANET. For protecting identity and location privacy, we propose UGG, IPP and LPP algorithms with the way of dynamic threshold encryption and k-anonymity unity in the stage of SBMs upload of blockchain-based VANET. To quantify the availability of k-anonymity unity, we propose two indicators: connectivity and average distance. Extensive simulations have been conducted to validate the effectiveness of blockchain-based VANET. We analyze the simulation results from four aspects: system time, average distance, connectivity, and privacy leakage. The simulation results show that our proposed architecture performs better in terms of processing time than current architectures. Furthermore, our proposed architecture shows its superior in the aspect of protecting identity and location privacy. [ABSTRACT FROM AUTHOR]

Data integrity is a critical security issue in cloud storage. The data integrity checking schemes by a third-party auditor (TPA) have attracted a lot of attention. Sharing data among multiple users (uploaders) is an attractive feature of cloud storage. Considering the scenario of multiple uploaders, privacy-preserving cloud auditing makes it possible for the TPA to publicly verify the data integrity while guarantees that it cannot learn the identity of the data uploader. In this paper, we propose a (t, n)-threshold privacy-preserving auditing scheme. Every user could generate a tag piece of a message from the tag generation algorithm individually. To respond a challenge from the TPA, the server needs at least t tag pieces from different users among all n users. Our scheme does not resort to ring signature or group signature techniques. The tag of a message consists of only one element, which is independent of the number of the users within the group. Therefore, the efficiency of tag generation and auditing of our scheme is compatible with an efficient construction (Wu et al., in: International conference on information security practice and experience ISPEC 2016, Springer, New York, 2016). We use the pairing-based cryptography library (PBC library-0.5.14) to implement the scheme and compare both the computation and transmission cost of our scheme with some existing schemes. [ABSTRACT FROM AUTHOR]

Vehicular ad-hoc networks (VANETs) have become increasingly significant in intelligent transportation systems, they play a great role in improving traffic safety and efficiency. In the deployment of intelligent VANETs, intelligent vehicles can efficiently exchange important or urgent traffic information and make driving decisions. Meanwhile, secure data communication and vehicle's identity privacy have been highlighted. To cope with these security issues, in this paper, we construct an efficient anonymous authentication scheme with secure communication in intelligent VANETs. Combing the ElGamal encryption technique with a modified Schnorr signature technique, the proposed scheme provides secure anonymous authentication process for encrypted message in the vehicle-to-infrastructure communication model, and achieves identity privacy, forward security, and reply attack resistance simultaneously. Moreover, except the trusted authority (TA), any outside entity cannot trace the real identity of an intelligent vehicle. The proposed scheme is designed on an identity-based system, which can remove the costs of establishing public key infrastructure (PKI) and certificates management. Compared with existing authentication schemes, the proposed scheme is much more practical in intelligent VANETs. [ABSTRACT FROM AUTHOR]

In cloud service over crowd-sensing data, the data owner (DO) publishes the sensing data through the cloud server, so that the user can obtain the information of interest on demand. But the cloud service providers (CSP) are often untrustworthy. The privacy and security concerns emerge over the authenticity of the query answer and the leakage of the DO identity. To solve these issues, many researchers study the query answer authentication scheme for cloud service system. The traditional technique is providing DO's signature for the published data. But the signature would always reveal DO's identity. To deal with this disadvantage, this paper proposes a cooperative query answer authentication scheme, based on the ring signature, the Merkle hash tree (MHT) and the non-repudiable service protocol. Through the cooperation among the entities in cloud service system, the proposed scheme could not only verify the query answer, but also protect the DO's identity. First, it picks up the internal nodes of MHT to sign, as well as the root node. Thus, the verification computation complexity could be significantly reduced from O(log2N) to O(log2N0.5) in the best case. Then, it improves an existing ring signature to sign the selected nodes. Furthermore, the proposed scheme employs the non-repudiation protocol during the transmission of query answer and verification object to protect trading behavior between the CSP and users. The security and performance analysis prove the security and feasibility of the proposed scheme. Extensive experimental results demonstrate its superiority of verification efficiency and communication overhead.

In order to protect the security of the data stored in the cloud by group users,a data integrity verification scheme was designed which can protect the privacy of the group users.The scheme can efficiently detect the shared data in the cloud and support the dynamic updating of the data,and use the characteristic of the ring signature to hide the iden-tity of the signer corresponding to the data block.That is,the third-party verifier can not spy on the users identity and other private information when validating.The aggregated approach is used to generate data labels,which reduces the storage cost of labels and supports the dynamic operation of group data,so that the users in the group can easily modify the cloud group data.