Quantum secure direct communication in Internet of Vehicles.

The Internet of Vehicles (IoVs) is one of the most popular techniques among the applications of Internet of Things. The existing IoVs are mainly protected by public key cryptographic systems, which provide identity authentication and information security. Nevertheless, using the proposed Shor's algorithm, the security of all classical cryptographic schemes will be exposed to future quantum computer technologies. Fortunately, based on the unconditional security property of quantum mechanics, direct communication protocols can resist quantum computer attacks and deliver secret messages directly without the requirement of pre-shared keys. For IoV networks, we present a continuous-variable quantum secure direct communication (CV-QSDC) protocol in which the orbital angular momentum (OAM) is used as the information carrier. For one thing, the field of continuous-variable quantum communication system is compatible with the standard telecommunication technology; for another, orbital angular momentum eigenstates for coding possess higher information capacity.