  Recent advances in Socially Aware Networks (SANs) have allowed its use in
many domains, out of which social Internet of vehicles (SIOV) is of prime
importance. SANs can provide a promising routing and forwarding paradigm for
SIOV by using interest-based communication. Though able to improve the
forwarding performance, existing interest-based schemes fail to consider the
important issue of protecting users' interest information. In this paper, we
propose a PRivacy-preserving Interest-based Forwarding scheme (PRIF) for SIOV,
which not only protects the interest information, but also improves the
forwarding performance. We propose a privacy-preserving authentication protocol
to recognize communities among mobile nodes. During data routing and
forwarding, a node can know others' interests only if they are affiliated with
the same community. Moreover, to improve forwarding performance, a new metric
{\em community energy} is introduced to indicate vehicular social proximity.
Community energy is generated when two nodes encounter one another and
information is shared among them. PRIF considers this energy metric to select
forwarders towards the destination node or the destination community. Security
analysis indicates PRIF can protect nodes' interest information. In addition,
extensive simulations have been conducted to demonstrate that PRIF outperforms
the existing algorithms including the BEEINFO, Epidemic, and PRoPHET.
