  The design of the forthcoming fifth generation (5G) system shall meet the
severe requirement of managing an always increasing amount of traffic generated
by both humans and machines, while guaranteeing data security. Among the
enabling technologies that will turn 5G into a reality, Device-to-Device (D2D)
and Multicasting will certainly play a key role because of their capability to
largely improve network resources utilization and to address emerging use cases
requiring the delivery of the same content to a large number of devices. D2D
communications can help to improve traditional point-to-multipoint
transmissions by reducing the multicast coverage area and exploiting properly
selected relay nodes as data forwarders towards users with worse channel
conditions. However, security issues are even more challenging for D2D
connections, as data exchange happens directly between nodes in proximity. To
enhance performance and security of delivered traffic in 5G-oriented networks,
in this paper we design SeT-D2D (Secure and Trust D2D), according to which
trustworthiness inferred from both direct interactions and social-awareness
parameters is exploited to properly select relay nodes. Main contributions of
our research consist in the introduction of a model for the assessment of
network nodes' trustworthiness and the implementation of security mechanisms to
protect the data transmitted in D2D communications and the privacy of the
involved users. The conducted simulation campaign testifies to the ability of
the proposed solution to effectively select relay nodes, which leads to an
improved network performance.

Networking and Internet Architecture