Vehicular Ad-hoc Network (VANET) is vital for supporting intelligent transport systems, such as traffic data sharing and cooperative processing in the modern city. However, data security and privacy are the critical factors restricting the development. To address these challenges, several certificateless conditional privacy-preserving authentication (CPPA) schemes with anonymity and traceability have been proposed. These schemes avoid complicated certificate management in the PKI framework and key escrow in the ID-based protocol. However, there still exist drawbacks such as computational complexity, high communication cost or security vulnerability. Recently, Ali et al. proposed an efficient certificateless CPPA (CLCPPA) scheme for VANETs, but we have found that this scheme fails to resist a signature forgery attack. To achieve a trade-off between security and efficiency, we first demonstrate the insecurity of Ali et al.’s protocol and then introduce a security-enhanced solution. To show the feasibility and utility of our proposal, we perform a security analysis in the security model. Moreover, we evaluate the performance via comparing it with other existing schemes. From the comparison results, we can find that our scheme is more efficient than prior state-of-art solutions, in terms of signing (improving 66.75%), the verification (improving 33.19%) and bandwidth requirement (reducing 14.75%). Therefore, our proposal is more suitable to be applied in VANETs.

The Internet of Medical Things (IoMT), which integrates medical sensors with the Internet of Things, is helpful for providing remote diagnosis and real-time decision making. Massive data collected by medical and healthcare monitoring sensors in the IoMT involves sensitive patient information. It brings some security challenges to validate the legitimacy of participating entities and protect patient data privacy. A certificateless signcryption (CLSC) scheme combines encryption and signature that can offer authenticity, confidentiality, and unforgeability, providing a viable solution to the data privacy issue of the IoMT. However, existing CLSC schemes fail to meet confidentiality or unforgeability, or require expensive computation overhead to perform pairing operations. This article first presents a new CLSC scheme for secure data transmission and better smart services in IoMT, which replaces the signature part with the Schnorr signature. We then give a thorough security proof under the random oracle model. Besides, we elaborately evaluate the performance and security of some existing solutions with our solution. Finally, the experiment results indicate that our solution can achieve a better balance between security and performance than some existing schemes. Therefore, in terms of feasibility, our scheme is more suitable for the IoMT scenario.

Internet of Things (IoT) enables terminal devices connecting with the Internet and provides various intelligent applications by analyzing devices data. As a typical IoT technique, edge computing provides a three-tier architecture to reduce communications and improve efficiency. Specifically, edge nodes are responsible for collecting and aggregating device data, and then send processed results to the cloud for subsequent analysis. However, the data aggregation function will compromise the privacy of device data. In this article, we proposed an efficient privacy-preserving multidimensional data aggregation scheme for IoT, called PMDA. The scheme uses the Chinese remainder theorem to design a homomorphic encryption method that encryptes a multiple-dimensional small integer vector into one ciphertext and keeps linear homomorphic properties per dimension. Combining with the signature mechanism and the batch verification method, the scheme guarantees nonrepudiation of device data and enhance verification efficiency at edge nodes. Through theoretical analysis, we demonstrate that the proposed scheme can achieve correctness, privacy, authentication, and integrity. After performance evaluation, we demonstrate that our scheme is superior to other schemes in terms of computation and communication costs. In particular, as the message dimension increases, our scheme computation costs almost a tenth of others at the 80-bits security level.

Recently, with the rapid improvement of e-health technology, a large amount of precious medical data has been accumulated in different entities, such as hospitals, clinics, and medical institutions, promoting the development of data sharing in e-health services. However, most of them lacks fine-grained functionalities: selective linkability and traceability, which are critical in an e-health environment. Furthermore, we observe that existing schemes mostly rely on centralized storage centers, which will lead to a single point of failure and privacy disclosure. In this paper, we first construct a group signature scheme suitable for a data sharing environment. It supports selectively linking two different message-signature pairs to the same signer. Further, it provides an algorithm to trace the signer. Then, based on the scheme, we leverage distributed technology (i.e., InterPlanetary file system and blockchain) and attribute-based encryption to propose a distributed data sharing scheme. We claim that our scheme meets anonymity, accountability, linkability, traceability, fine-grained and efficient access control, and distributed storage. Moreover, the proposed data sharing scheme yields a practical performance making it suitable for e-health applications.

As self-organizing, highly heterogeneous and multi-interactive networks, vehicular ad-hoc networks (VANETs) are rapidly improving the efficiency of modern traffic. This promising technology is significant for supporting current intelligent transportation by cooperative data sharing and processing. Considering requirements for secure interactions and the limitation of resources in VANETs, protecting data authenticity while enhancing computational efficiency has become the main challenge. A certificateless aggregate signature (CLAS) can not only ensure data security, but also reduce communication costs, which is suitable for a resource-constrained environment. However, most existing CLAS schemes either own serious security vulnerabilities or result in tremendous computational overhead. In this article, we propose an efficient, privacy-preserving, and pairing-free CLAS scheme with enhanced security. We prove that it is existentially unforgeable against adaptive chosen message attacks in the random oracle model. Performance evaluation illustrates that our proposed scheme is more appropriate to the VANETs scenario.

Wireless body area networks (WBANs) have become more commonplace, including in healthcare settings. For example, in a healthcare WBAN deployment, body sensor units (BSUs) are used to sense and collect health-related and medical-related information prior to sending relevant information to the server for analysis that can subsequently inform treatment plan. Given the sensitivity of both data-at-rest and data-in-transit, data authentication is fundamental to the success of such systems. However, BSUs are generally resource constrained and, hence, conventional cryptographic algorithms are not practical. Therefore, in this article, we propose an efficient certificateless online/offline signature scheme and design a lightweight data authentication protocol for WBANs. We then evaluate the security and performance of our proposed scheme, where the security analysis demonstrates that the proposed scheme satisfies existential unforgeability under the random oracle model. Findings from the performance evaluation also demonstrate that our scheme incurs very low computational cost during the signing operations. In comparison to several other competing approaches, our proposed scheme achieves a significant reduction in computational cost (up to 89%) for the offline signer and supports batch verification to reduce the verifier's execution time. In addition, we also show that the signature size of our proposed scheme is similar to those of the conventional signature schemes.