In recent years, it has become popular to upload patients’ medical data to a third-party cloud server (TCS) for storage through medical Internet of things. It can reduce the local maintenance burden of the medical data and importantly improve accuracy in the medical treatment. As remote TCS cannot be fully trusted, medical data should be encrypted before uploading, to protect patients’ privacy. However, encryption makes search capabilities difficult for patients and doctors. To address this issue, Huang et al. recently put forward the notion of Public-key Authenticated Encryption with Keyword Search (PAEKS) against inside keyword guessing attacks. However, the existing PAEKS schemes rely on time-consuming computation of parings. Moreover, some PAEKS schemes still have security issues in a multiuser setting. In this paper, we propose a new and efficient PAEKS scheme, which uses the idea of Diffie-Hellman key agreement to generate a shared secret key between each sender and receiver. The shared key will be used to encrypt keywords by the sender and to generate search trapdoors by the receiver. We prove that our scheme is semantically secure against inside keyword guessing attacks in a multiuser setting, under the oracle Diffie-Hellman assumption. Experimental results demonstrate that our PAEKS scheme is more efficient than that of previous ones, especially in terms of keyword searching time.

Vehicular ad hoc networks (VANETs) are essential technologies to ensure safe road traffic management and enhance driving convenience. Nowadays, diversified authentication schemes have been developed in VANETs for the purpose of safer communication between nodes. For instance, biometric technology which employs biometric information as users’ authentic identity is widely adopted in message authentication due to its visible benefits. Nonetheless, there is a significant problem in current biometric identity-based authentication schemes that noise is inevitable in each collection of biometric information, making these schemes lack critical error tolerance. Additionally, anonymous biometric identity is difficult to be realized, which fails to meet the basic standard of VANETs. For solving the above key issues, we propose the first efficient fuzzy certificateless signature-based (FCLS) authentication scheme using anonymous biometric identities for VANETs. In virtue of its superior error tolerance, it enables authentication between two identities represented by two attribute sets within a certain Hamming distance. Besides, the newly developed authentication scheme realizes effective conditional privacy so that drivers’ real biometric identities can be ensured. Through the formal security proof, this FCLS scheme is existentially unforgeable against adaptive chosen message attack (EU-CMA) in the random oracle model (ROM), which reaches the higher security. Compared with current advanced schemes, the new authentication scheme is more efficient in computation and communication according to performance analysis.