  This paper investigates the performance of physical layer security (PLS) in a
vehicle-to-vehicle (V2V) communication system, where a transmitter vehicle
exploits a dual reconfigurable intelligent surface (RIS) to send confidential
information to legitimate receiver vehicles under the non-orthogonal multiple
access (NOMA) scheme in the presence of an eavesdropper vehicle. In particular,
it is assumed that an RIS is near the transmitter vehicle and another RIS is
close to the receiver vehicles to provide a wider smart radio environment.
Besides, we suppose that the channels between two RISs suffer from the
Fisher-Snedecor F fading model. Under this scenario, we first provide the
marginal distributions of equivalent channels at the legitimate receiver
vehicles by exploiting the central limit theorem (CLT). Then, in order to
evaluate the PLS performance of the considered secure communication system, we
derive analytical expressions of the average secrecy capacity (ASC), secrecy
outage probability (SOP), and secrecy energy efficiency (SEE) by using the
Gauss-Laguerre quadrature and the Gaussian quadrature techniques. Moreover, to
gain more insights into the secrecy performance, the asymptotic expression of
the ASC is obtained. The numerical results indicate that incorporating the dual
RIS in the secure V2V communication under the NOMA scheme can significantly
provide ultra-reliable transmission and guarantee more secure communication for
intelligent transportation systems (ITS).
