Resumen
Since the roadside infrastructure and vehicles come from different manufacturers, vehicular ad hoc networks (VANETs) now are extremely heterogeneous. It is difficult to communicate securely for heterogeneous facilities in VANETs because secure communication needs to concurrently realize confidentiality, authentication, integrity, and non-repudiation. To meet the above security attributes in one logical step, four bi-directional signcryption schemes are proposed for specific heterogeneous vehicle to infrastructure (V2I) communication in this paper. The first scheme supports batch verification, which allows multiple vehicles registered in a public key infrastructure (PKI) system to transmit messages to a receiver in an identity-based cryptosystem (IBC), both which are the mainstream public key cryptosystems. The second scheme supports a sender in a PKI to securely broadcast a message to multiple vehicles in an IBC. The communication direction of the latter two schemes is opposite to the former two schemes (i.e., from IBC to PKI). All these schemes can be proved to satisfy confidentiality and unforgeability based on the assumptions of decisional and computational Diffie-Hellman problems in the random oracle model. Furthermore, numerical analyses and simulation results demonstrate the computation costs, communication costs, storage, and the aggregate ciphertext length of our schemes are better than the existing ones.