The advances of cloud computing, fog computing and Internet of Things (IoT) make industries more prosperous than ever. However, in this sophisticated system security and privacy issues are major concerns. In this paper, we focus on the issue of assured data deletion. We firstly propose a framework to integrate the cloud, the fog and the things together to manage stored data from industries or individuals. We then focus on secure data deletion in this framework by proposing an assured data deletion scheme which fulfills verifiable data deletion as well as flexible access control over sensitive data. Only data owners and fog devices are involved when deleting cloud data and validating the deletion of these data, which makes the protocol practical. The proposed protocol takes advantage of attribute-based encryption, whose security can be proved under standard model. The theoretical analysis and the implementation results demonstrate the feasibility of our proposal.

In recent years, many researchers have applied aggregated signature techniques to resource-constrained vehicular Ad Hoc networks (VANET) authentication scenarios. We reviewed two recent VANET authentication schemes based on certificateless aggregated signatures (CLAS) while demonstrating that neither of them is resistant to public key replacement attacks under their security models. An eavesdropper can successfully forge a legitimate signature to perform malicious operation. To further address the above security flaws, we propose an improved CLAS scheme for VANET. Considering that some researchers have briefly or even incorrectly used forking lemmas in their security proofs to prove an insecure CLAS scheme, we further improve and refine the security model and security proof method for CLAS, which make the proof process transparent by using general forking lemma. Based on these improvements, our scheme can resist attacks from two types of adversaries in the CLAS security model. In the final performance analysis, the improved CLAS scheme outperforms the secure related scheme of recent years in terms of both computational and communication efficiency. Therefore, our proposal is more suitable for resource-constrained VANET environments.

Nowadays, as an essential technique for intelligent transportation, vehicular ad hoc networks (VANETs) has significantly improved people’s travel experience, providing richer, and smarter services for vehicles while ensuring driver safety. However, considering that VANETs are complex, some security challenges still remain, including but not restricted to privacy preserving of vehicles, authentication of messages, limited resources in computational power, and network bandwidth. To address these issues, many privacy-preserving identity authentication schemes for VANETs have been proposed recently. However, these schemes still suffer some limitations. First, their computational overheads are heavy due to the complex calculations. Second, some schemes are vulnerable to various security weaknesses, unable to resist normal attacks. Third, in some schemes, the same pseudonym keeps unchanged and it is linked to the corresponding private key of user. The consequence is that if the user wants to change its pseudonym, the corresponding private key must be changed. In order to further solve the above problems, we propose a novel privacy-preserving identity authentication protocol based on the certificateless aggregate signature scheme, allowing the user to generate a fuzzy identity to hide her real identity, and the private key can be kept unchanged even if the corresponding pseudonym is updated. Furthermore, to achieve efficiency in computation, bilinear mapping is avoided in our proposed scheme. We prove that our protocol satisfies unforgeability in the random oracle based on a classic complexity assumption. Finally, the security and efficiency analyses demonstrate that our construction enjoys more security features and better performance compared with the existing schemes.

In recent years, the development of Internet of Things technology has led to a surge in interest in the Vehicular Ad-Hoc network (VANET), which has greatly improved travel efficiency and facilitated vehicle data sharing. To ensure the privacy and security of both vehicles and personnel, researchers have proposed various measures for securing VANET systems. Recently, certificate-based aggregate signature (CBAS) schemes have been proposed to design an identity authentication protocol for the VANET to prevent tampering and corruption of private vehicle data. In this study, we conduct a security analysis of the previous CBAS scheme by presenting a security attack. Afterward, we propose a novel and concrete construction of the CBAS scheme that offers improved performance for VANET, which can enhance protection in the VANET scenario. We also demonstrate its security based on standard cryptographic assumptions. Comparative results from theoretical analysis and experimental evaluation illustrate the practicality of our proposed scheme. Similarly, the identity authentication protocol created based on the above CBAS scheme has the properties of dynamic anonymity, mutual identity authentication, unforgeability.

In the vehicular ad-hoc network (VANET), the communication between the vehicle and other nodes is performed in an open channel, which puts forward the requirements for its privacy security and message integrity. Most previous protocols either frequently verify identities before accepting traffic information or do not involve identity revocation mechanisms, and they may assume that third parties are fully trusted. To further solve the above problem, a certificateless-based anonymous and revocable authentication protocol for vehicle-to-vehicle communications is proposed in this paper. Our construction separates the identity authentication process from the traffic message verification, which not only avoids the disadvantage of frequent identity revocation list (IRL) checking but also reduces the overhead in communication and message authentication. These features can make “identity authentication once, broadcast efficiency" really happen. In addition, since our authentication process is based on certificateless signature, it can resist malicious key generation centers (KGC) and road-side units (RSU), which is very necessary for privacy-sensitive application scenarios. Finally, the performance analyses show that our proposal is superior to the existing schemes in terms of authentication speed and communication overhead.

With the rapid development of Internet of Things, the related data are growing explosively. However, IoT devices have limited storage and computing capabilities so that they cannot deal with massive data storage and computing locally. The integration of IoT and cloud is regarded as an effective solution to the above issue, i.e., IoT devices outsource collected data to cloud to enjoy powerful storage and computing resources. Because the data stored in cloud are out of the control of IoT users, some security risks need to be addressed in advance. In this paper, we propose a public data integrity verification scheme, called AIVCI, to check the data integrity for Cloud-IoT scenarios. Firstly, based on algebraic signature and homomorphic hash function, AIVCI can efficiently complete data auditing. Secondly, AIVCI adopts blind technology to prevent the privacy leakage of IoT data and further protect the privacy of IoT users. Thirdly, batch auditing is implemented to improve auditing efficiency and meet realistic demands for Cloud-IoT scenarios. And a new data structure named Improved Divide and Conquer Table (ID&CT) is designed to realize efficient data dynamics. Finally, the security and performance analysis demonstrates that AIVCI is more secure and efficient.