Biblio

Vehicular ad hoc networks (VANETs) ensure improvement in road safety and traffic management by allowing the vehicles and infrastructure that are connected to them to exchange safety messages. Due to the open wireless communication channels, security and privacy issues are a major concern in VANETs. A typical attack consists of a malicious third party intercepting, modifying and retransmitting messages. Heterogeneous vehicular communication in VANETs occurs when vehicles (only) or vehicles and other infrastructure communicate using different cryptographic techniques. To address the security and privacy issues in heterogeneous vehicular communication, some heterogeneous signcryption schemes have been proposed. These schemes simultaneously satisfy the confidentiality, authentication, integrity and non-repudiation security requirements. They however fail to properly address the efficiency with respect to the computational cost involved in unsigncrypting ciphertexts, which is often affected by the speeds at which vehicles travel in VANETs. In this paper, we propose an efficient conditional privacy-preserving hybrid signcryption (CPP-HSC) scheme that uses bilinear pairing to satisfy the security requirements of heterogeneous vehicular communication in a single logical step. Our scheme ensures the transmission of a message from a vehicle with a background of an identity-based cryptosystem (IBC) to a receiver with a background of a public-key infrastructure (PKI). Furthermore, it supports a batch unsigncryption method, which allows the receiver to speed up the process by processing multiple messages simultaneously. The security of our CPP-HSC scheme ensures the indistinguishability against adaptive chosen ciphertext attack (IND-CCA2) under the intractability assumption of q-bilinear Diffie-Hellman inversion (q-BDHI) problem and the existential unforgeability against adaptive chosen message attack (EUF-CMA) under the intractability assumption of q-strong Diffie-Hellman (q-SDH) problem in the random oracle model (ROM). The performance analysis indicates that our scheme has an improvement over the existing related schemes with respect to the computational cost without an increase in the communication cost.

A deniable authentication (DA) protocol plays a vital role to provide security and privacy of the mobile nodes in a mobile ad hoc network (MANET). In recent years, a number of similar works have been proposed, but most of them experience heavy computational and communication overhead. Further, most of these protocols are not secure against different attacks. To address these concerns, we devised an identity-based deniable authentication (IBDA) protocol with adequate security and efficiency. The proposed IBDA protocol is mainly designed for MANETs, where the mobile devices are resource-limited. The proposed IBDA protocol used the elliptic curve cryptography (ECC) and identity-based cryptosystem (IBC). The security of our IBDA protocol depends on the elliptic curve discrete logarithm (ECDL) problem and bilinear Diffie-Hellman (BDH) problem.

Searchable encryption technology can guarantee the confidentiality of cloud data and the searchability of ciphertext data, which has a very broad application prospect in cloud storage environments. However, most existing searchable encryption schemes have problems, such as excessive computational overhead and low security. In order to solve these problems, a lightweight searchable encryption scheme based on certificateless cryptosystem is proposed. The user's final private key consists of partial private key and secret value, which effectively solves the certificate management problem of the traditional cryptosystem and the key escrow problem of identity-based cryptosystem. At the same time, the introduction of third-party manager has significantly reduced the burden in the cloud server and achieved lightweight multi-user ciphertext retrieval. In addition, the data owner stores the file index in the third-party manager, while the file ciphertext is stored in the cloud server. This ensures that the file index is not known by the cloud server. The analysis results show that the scheme satisfies trapdoor indistinguishability and can resist keyword guessing attacks. Compared with similar certificateless encryption schemes, it has higher computational performance in key generation, keyword encryption, trapdoor generation and keyword search.