As the sharp growth of cloud storage, a rising quantity of public auditing techniques are employed to check outsourced data integrity. However, existing public auditing schemes have issues with storage efficiency, security, and practicality. During traditional auditing process, the cloud is required to store all data blocks and corresponding tags, resulting in poor storage space utilization. Besides, public auditing schemes that leverage the public key infrastructure encounter certificate management challenges, and identity-based schemes inherently suffer from key escrow vulnerabilities. Furthermore, the demand of data dynamic operations cannot be well implemented in existing schemes. Therefore, this paper proposes a storage-efficient certificateless public auditing (SECPA) scheme with data dynamics, which allows any authorized third-party auditor to perform integrity checking such that outsourced data will not be tampered with. Meanwhile, an improved locally verifiable technology is designed to extremely optimize the cloud storage resources. Additionally, our scheme avoids the certificate management and key escrow problems while supporting the user to conduct data insertion, deletion, and modification. The security analysis demonstrates that SECPA fulfills unforgeability, auditing soundness, data privacy protection and detectability. The experiment results indicate that our scheme exhibits appropriate performance.

In recent years, with the increasing prevalence of online group chat applications, malicious information has been more easily disseminated on the internet. Asymmetric group message franking (AGMF) allows users to report received malicious messages to moderators, achieving content moderation in large-scale online end-to-end messaging systems. However, the state-of-the-art construction is built upon traditional public key cryptosystems, resulting in the complex certificate management problem. This paper systematically explores identity-based AGMF (IB-AGMF) to resolve this issue. Specifically, we first introduce a novel primitive called hash proof system-based anonymous identity-based key encapsulation mechanism supporting sigma protocol (HPS-AIB-KEMΣ) and present a practical construction based on DBDH assumption. After formalizing the concept and security notions of IB-AGMF, we propose the generic construction of IB-AGMF based on HPS-AIB-KEMΣand non-interactive zero knowledge proof system. Finally, we conduct comprehensive performance evaluations and comparisons to demonstrate the feasibility of IB-AGMF in group communication scenarios.

Vehicular Social Networks (VSNs), as an innovative mobile communication system, significantly enhance the driving experience and improve urban traffic management efficiency. To address the privacy issues that arise from the use of public channels in VSNs, fine-grained access control should be ensured. Nevertheless, existing schemes still face some practical challenges in the aspects of data source identification, key escrow, and dynamic vehicle management. Therefore, this paper proposes a registration-based bilateral fine-grained access control scheme (RBF-AC) in VSNs. Specifically, RBF-AC allows service providers to select target vehicles and offer tailored services, while allowing vehicles to identify the most suitable service providers based on their needs, and all of which are realized in a fine-grained level. Meanwhile, service providers and vehicles are capable of locally generating their own private and public keys without relying on any fully trusted authority. RBF-AC also keeps high flexibility and enables the vehicles to join, leave and update their attributes in a dynamic manner. Additionally, outsourced verification and decryption are provided to minimize the computation cost for vehicles. We present formal security proofs to validate the security of RFB-AC. The performance evaluation illustrates the practical applicability of RBF-AC in VSNs.

As an emerging class of internet of vehicles, vehicular social networks (VSNs) provide passengers, drivers, and vehicles with extensive data sharing services to improve traffic congestion and road safety. However, the insecure transmissions of shared data may disclose sensitive information, such as private data, location, and driving route. Although attribute-based encryption (ABE) is a promising technology to enable secure data sharing, the existing ABE solutions applied to VSNs encounter three-fold deficiencies: (1) the shared data stored in vehicular cloud server would be leaked in the event of key compromise; (2) relying on one or more fully trusted entities to generate keys for vehicles through secure channels; (3) private information leakage and misbehavior of data user vehicles are neglected. Motivated by these challenges, this paper proposes a puncturable registered ABE scheme called PR-ABE for VSNs with enhanced security and practicality. To be specific, our PR-ABE achieves flexible access control and precise data deletion. The former ensures that only registered vehicles with authorized attributes can obtain the shared data. The latter prevents data disclosure when key compromise happens. Meanwhile, PR-ABE enables vehicles to generate keys independently and eliminates the need for any fully trusted authority. In addition, hidden policy and traceability are fulfilled in PR-ABE to protect private information and deal with malicious vehicles, respectively. Finally, the rigorous security proof and performance evaluation demonstrate that PR-ABE is a practical and efficient solution.

With the continuous development of digitization evolutions, vehicular digital twin networks (VDTNs) facilitate traffic data and optimization results to be exchanged between the vehicle and digital twin as well as shared among a group of digital twins. However, the data exchange and group sharing processes take place in real-time over public communication channels, which suffer from various security and privacy threats. Key agreement technologies are promising to enable secure data communications for entities, but the existing key agreement schemes generally fail to fulfill the requirements of synchronization, privacy, and entity management for VDTNs. Therefore, we propose a blockchain-assisted privacy-preserving and synchronized key agreement scheme for VDTNs. In the proposed scheme, the anonymous vehicle and digital twin can negotiate a secret session key in the case of synchronization to achieve secure data exchange. Meanwhile, digital twins are capable of utilizing synchronized state information to dynamically establish a common group encryption key but hold individual decryption keys, which guarantee the security of group sharing. Additionally, the proposed scheme is able to protect identity privacy and manage vehicles and digital twins with the assistance of blockchain and smart contract. The security analysis demonstrates that the proposed scheme provides security and privacy assurances for VDTNs. The performance evaluation indicates that it has excellent expressions in terms of efficiency, practicality, and smart contract consumption.

The diverse properties of wireless networks are fulfilled with the assistance of digital twin (DT), which utilizes a virtual model of the physical object (PO) to provide predictions and control decisions. However, the open wireless channels and key leakage of compromised entities (including DT and PO) pose significant security issues, highlighting the need for secure data transmission schemes. Meanwhile, it is impractical to directly apply the existing works and cryptographic primitives to DT-empowered wireless networks (DTWNs) due to the absence of a solution to capture the security requirements comprehensively. Moreover, the essential characteristics for protecting historical data cannot be met. Therefore, this paper proposes a security-enhanced data transmission scheme with fine-grained and flexible revocation by customizing a novel cryptographic primitive named forward-secure puncturable signed encryption (FS-PSE). Our scheme enables confidential data dissemination/acquisition between the physical and virtual space while ensuring authentication of the real-time information and feedback results. In addition, three revocation modes are defined. Based on these modes, the entities can flexibly revoke any decryption-&-signature, decryption, and signature capability in a fine-grained approach, thereby providing security protections for the historically transmitted data even though the entity is compromised. Moreover, our scheme is instantiated with a concrete FS-PSE construction and extended to support outsourced computing to improve efficiency. Finally, the formal security proof and performance evaluation demonstrate the security and practicality of our scheme.

In transportation 5.0, digital twin (DT) is considered a promising paradigm to integrate physical entities into cyber physical systems by collecting massive data. However, the open collection process and key exposure issues bring critical security challenges. Furthermore, applying the existing authentication schemes to data collection in transportation DT (TDT) systems encounters three deficiencies: 1) forward security for collected data can only be achieved at a coarse-grained level; 2) one or more additional trusted authorities are introduced, causing the robustness of TDT systems to be downgraded; 3) dynamic attribute updating and revocability of physical entities are rarely considered. Therefore, we propose a dual fine-grained authentication scheme (DFAS) in this paper. Our DFAS can not only ensure data integrity and authenticity but also enable fine-grained access control, namely, only registered physical entities with authorized attributes can generate valid signatures. Meanwhile, DFAS provides the key puncturing for physical entities to guarantee fine-grained forward security without relying on any trusted authority. In addition, a non-interactive attribute updating and revocation of malicious entities are realized in DFAS. Finally, the security analysis indicates that DFAS can deal with various security challenges for data collection in TDT systems. The performance evaluation demonstrates that DFAS is efficient and practical.

In vehicular digital twin networks (VDTNs), digital twin (DT) can assist the vehicle in data handling and report traffic data to the management server, thereby providing enhanced and scalable services for intelligent transport systems. However, the reported data may suffer from forgery and eavesdropping attacks due to the transmission on the open channel. In addition, a critical threat in VDTNs is the physical vehicle capture attack, namely, an adversary is capable of compromising the vehicle to obtain the current secret key, which can break the reliability of historical reported data and make the services provided by DT unavailable. Puncturable signature (PS) is a promising solution to eliminate these concerns, despite that the existing PS constructions have non-negligible false-positive errors and impose a significant cost on practical deployments. In this paper, we design a novel PS and apply it to privacy-aware data reporting protocol (PA-DRP) for VDTNs. Specifically, the designed PS adopts a derivationbased way to achieve puncturing functionality, which is free from false-positive errors while extremely reducing the storage overhead of the secret keys. Meanwhile, we employ the designed PS to construct PA-DRP that enjoys authentication and forward security. Additionally, PA-DRP not only allows DT to remove privacy-sensitive information from the signed data but also provides fuzzy identity for protecting the real identity of the vehicle. Furthermore, the security analysis and performance evaluation demonstrate that the designed PS and PA-DRP not only can withstand various security and privacy assaults for VDTNs but also are efficient and practical.

The Snowden incident illustrates that an adversary may launch an algorithm substitution attack (ASA) by tampering with the algorithms of protocol participants to obtain users' secret information. A measure against ASA is to equip the protocol participants with cryptographic reverse firewalls (CRF). Public key encryption with keyword search (PEKS) as a cryptographic primitive allows users to search encrypted file in cloud servers while ensuring the security of the original file. The existing CRF constructions for PEKS does not consider the trust level of CRFs, leaving honest-but-curious CRF to deal with trapdoors that should be sent in the secure channels, which brings new security risks. This paper firstly introduces the notion of malleable designated tester public key encryption with keyword search (M-DPEKS). Based on M-DPEKS, we propose the generic construction of public key encryption with keyword search with cryptographic reverse firewalls to overcome the privacy leakage issue in cloud storage. Security proof indicates the generic construction is secure against ASA. Lastly, we instantiate the generic construction with a concrete M-DPEKS scheme and analyze the computation cost and communication overhead to evaluate the efficiency.

Most recently, Zhang et al presented a verifiable data aggregation scheme for smart grids in IEEE Transactions on Dependable and Secure Computing (doi: 10.1109/TDSC.2021.3124546). The authors claim that the privacy of the user's electricity data is preserved, and the control center can check whether the aggregator honestly computes the aggregated ciphertext. However, we indicate that Zhang et al's scheme fails to provide the properties of data privacy and aggregate correctness guarantee. Specifically, by offering concrete attacks, we illustrate that the adversary who has the ability to obtain the decryption key of control center can decrypt any user's ciphertext to get the detailed electricity data, and a misbehaved aggregator will not be detected when it does have some malicious behavior.

Vehicular ad hoc networks (VANETs), an increasingly significant technology in intelligent transportation systems, achieve information sharing, intelligent traffic flow control, and road condition prediction through data sharing between vehicles and other devices, enhancing traffic efficiency and driving safety. Nevertheless, there are still challenges to data sharing with respect to efficiency, flexibility, and security. In this paper, we build a flexible selective data sharing with fine-grained erasure (FSDS-FE) scheme in VANETs by introducing the novel cryptographic primitive called puncturable identity-based fine-grained proxy re-encryption and employing identity-based signature. In FSDS-FE, with the support for ciphertext transformation, the vehicles are able to flexibly share the outsourced traffic data with others. Different sharing content can be customized for various entities through fine-grained re-encryption to protect sensitive information. Furthermore, the outsourced traffic data could be erased in a fine-grained way by the vehicles. In order to optimize the efficiency and practicality of FSDS-FE, we construct an improved FSDS-FE scheme by designing a novel puncturable identity-based fine-grained broadcast proxy re-encryption with verifiable outsourced decryption scheme. Rigorous security analysis demonstrates that FSDS-FE can achieve the desired security requirements. The comprehensive performance evaluation shows that our schemes are efficient and practical enough in VANETs.

Vehicular digital twin networks (VDTNs) offer great opportunities for driver safety enhancements. By leveraging digital twin (DT) technology, VDTNs can collect and analyze traffic data to optimize driving routes, and allow the out-of-field vehicles to share traffic data via their DTs. However, the real-time data sharing process over a public channel raises concerns about security and privacy. Existing data sharing schemes cannot be directly adopted for VDTNs because they rarely consider dual (data and identity) privacy, synchronization, and flexibility, while also imposing a significant cost on resource-limited entities. To address these challenges, we propose a secure and flexible data sharing scheme with dual privacy protection for VDTNs. In the proposed scheme, a signature of knowledge protocol is developed for protecting the vehicle’s real identity and ensuring authentication, smart contract algorithms are designed to assist in realizing accountability, and a verification control mechanism is devised for allowing the vehicle to flexibly share the traffic data. Additionally, DT with consistent states is capable of removing sensitive information from the shared data, which guarantees synchronization and data privacy. The security analysis demonstrates that the proposed scheme is resilient against potential security threats in VDTNs. Furthermore, the performance evaluation indicates that the proposed scheme not only outperforms the state-of-the-art schemes but also achieves feasible blockchain consumption and data authentication delay.

Vehicular social networks (VSNs), as the convergence of social networks and vehicular ad hoc networks, have brought many useful services to vehicle communication by collecting and sharing data between vehicles. In order to efficiently share data and satisfy the growing requirement of privacy protection, data owners typically encrypt and outsource the data to the cloud. Nevertheless, encryption undoubtedly reduces the availability of shared data, e.g., keyword search. Although a number of schemes supporting keyword search of shared data have been put forward, they still have issues with respect to security, functionality, and efficiency. In this paper, a server-assisted data sharing (SADS) system with support for conjunctive keyword search is presented. Specifically, to resist online keyword guessing attack, we devise an advanced keyword derivation mechanism to derive the keyword set, in which the conception of verifiable parallel oblivious unpredictable function is proposed to check whether the assisted server honestly responds to the derived keyword request. Moreover, the computation and communication costs of keyword trapdoor in SADS are constant. Concurrently, SADS achieves the anonymous data sharing and traceability of malicious vehicle data owner. The security of SADS is formally proved and analyzed. Performance evaluation also shows that our system is efficient and practical.

As the rapid proliferation of Internet of Things (IoT) and edge computing, large amounts of data are needed to be stored and transmitted in the online storage system. Data deduplication can be adopted to improve communication efficiency and minimize storage space. However, in edge computing, data deduplication brings security and functionality requirements that are still unsatisfied. Most existing schemes are vulnerable to brute-force attacks and single-point attacks. Moreover, they impose a heavy burden on resource-constrained edge nodes and do not support cross-domain deduplication. Blockchain is a promising technology because the programmable smart contract can be utilized to perform cross-domain deduplication and guarantee the traceability of data. In this article, an efficient dynamic cross-domain deduplication scheme in blockchain-enabled edge computing is proposed to solve the above problems. Specifically, the smart contract is employed to assist cross-domain deduplication, which also can reduce the storage pressure of edge nodes. Meanwhile, a hash proof system-based oblivious pseudorandom function is created to reduce the time cost of key generation and achieve the security requirements of resistance to brute-force attacks and single-point attacks. The technology of accumulators is adopted to achieve Proofs of Ownership (PoO), which can prevent duplicate-faking attacks. The security analysis demonstrates that the proposed scheme has a higher security level. The performance evaluation shows that the proposed scheme significantly reduces computation cost and communication overhead, compared with other existing schemes. The smart contract is implemented in the Ethereum test network (i.e., Rinkeby), which shows acceptable gas cost even the functions are called frequently.

As the traditional grid produces a large amount of greenhouse gas and cannot adapt to such new demands as dynamic electricity prices, data analysis, and early warning, smart grid with high efficiency and reliability is increasingly valued. It plays a key role in achieving carbon neutrality. Nonetheless, smart grid requires the collection of real-time power data, and personal privacy may be leaked through the frequent electricity measurement reports. With the requirements of data analysis and prediction while preserving users’ personal privacy, data aggregation schemes have emerged. However, existing schemes cannot resolve all the troubles well. Some schemes do not consider the failures for smart meters, and most of the schemes have expensive computation cost. In view of this, an efficient privacy-preserving data aggregation scheme with fault tolerance in smart grid is put forward in this paper. To be specific, the proposed scheme is lightweight due to the application of the symmetric homomorphic encryption technology and the elliptic curve cryptography. Even if some smart meters are destroyed, the proposed scheme can still successfully obtain aggregated data. Moreover, the proposed data aggregation scheme is proved to be secure, and all security requirements can be satisfied. Performance evaluation illustrates the relatively low computation cost and communication overhead of the proposed scheme compared to other related schemes.

Mobile-edge computing (MEC) plays a significant role in enabling diverse service applications by implementing efficient data sharing. However, the unique characteristics of MEC also bring data privacy and security problem, which impedes the development of MEC. Blockchain is viewed as a promising technology to guarantee the security and traceability of data sharing. Nonetheless, how to integrate blockchain into MEC system is quite challenging because of dynamic characteristics of channel conditions and network loads. To this end, we propose a secure data sharing scheme in the blockchain-enabled MEC system using an asynchronous learning approach in this article. First, a blockchain-enabled secure data sharing framework in the MEC system is presented. Then, we present an adaptive privacy-preserving mechanism according to available system resources and privacy demands of users. Next, an optimization problem of secure data sharing is formulated in the blockchain-enabled MEC system with the aim to maximize the system performance with respect to the decreased energy consumption of MEC system and the increased throughput of blockchain system. Especially, an asynchronous learning approach is employed to solve the formulated problem. The numerical results demonstrate the superiority of our proposed secure data sharing scheme when compared with some popular benchmark algorithms in terms of average throughput, average energy consumption, and reward.

In this letter, we first propose a construction of aperiodic binary Z-complementary sequence sets (ZCSSs) with length 3·2memploying Boolean functions. Next we present a construction of binary ZCSSs with large set sizes by using orthogonal sequences. At last, we provide a large class of optimal binary ZCSSs of length 2m·L with large zero correlation zone width, where L is the length of Z-complementary pairs. The lengths of the ZCSSs are more flexible than the known methods. In this letter, these systematic constructions can generate more ZCSSs of the new sequence lengths and set sizes, which have not been reported before.

Proxy signature is extension of the standard signature, in which the original signer can delegate his or her signing capability to proxy signer in such a way that the latter can sign messages on behalf of the former. Certificateless cryptography eliminates the need of certificates in the traditional public key cryptography and solves the inherent key escrow problem in the identity based cryptography. In this paper, we extend security model of proxy signature to certificateless setting and formalize the security model of certificateless proxy signature. We propose a certificateless proxy signature scheme with concrete implementation which is probably secure in the standard model. Furthermore, the proposed scheme is proven to be existentially unforgeable under the hardness of the computational Diffie-Hellman problem.

Abstract Proxy signcryption is a novel cryptographic primitive that combines the functionality of a proxy signature with that of a signcryption. However, the security of all the known proxy signcryption schemes were proven in the random oracle, which has received a lot of criticism that the proofs in the random oracle model are not sound with respect to the standard model. Hence, it is an interesting research problem on how to construct a provably secure proxy signcryption scheme in the standard model. In this paper, motivated by Waters' signature scheme, we propose a new construction of proxy signcryption scheme based on bilinear pairing without using random oracles. Then, we use the techniques from provable security to show that the proposed scheme is indistinguishability under adaptive chosen ciphertext attacks secure under the decisional bilinear Diffie–Hellman assumption and existentially unforgeable under the computational Diffie–Hellman assumptions. Compared with the existing schemes with formal security proof, we show that no pairing computation is required in our proxy signcrypt phase with pre‐computations. To the best of our knowledge, our proposed scheme is the first provably secure proxy signcryption scheme in the standard model. Copyright © 2014 John Wiley & Sons, Ltd.

In this paper, we give the secure model of certificate-based signature (CBS) and propose an efficient CBS scheme. The proposed scheme is shown to be existentially unforgeable against adaptive chosen message and identity attacks under the discrete logarithm assumption in the random oracle model. Compared with the schemes in RSA 2004 and in EuroPKI 2007, no pairing computation and the special MapToPoint hash function is needed in all phase, and hence,our scheme is more efficient.