  This work deals with the secrecy performance analysis of a dual-hop RF-FSO DF
relaying network composed of a source, a relay, a destination, and an
eavesdropper. We assume the eavesdropper is located close to the destination
and overhears the relay's transmitted optical signal. The RF and FSO links
undergo ($\alpha$-$\kappa$-$\mu$)-shadowed fading and unified M\'alaga
turbulence with pointing error. The secrecy performance of the mixed system is
studied by deriving closed-form analytical expressions of secure outage
probability (SOP), strictly positive secrecy capacity (SPSC), and intercept
probability (IP). Besides, we also derive the asymptotic SOP, SPSC, and IP upon
utilizing the unfolding of Meijer's G function where the electrical SNR of the
FSO link tends to infinity. Finally, the Monte-Carlo simulation is performed to
corroborate the analytical expressions. Our results illustrate that fading,
shadowing, detection techniques (i.e., heterodyne detection (HD) and intensity
modulation and direct detection (IM/DD)), atmospheric turbulence, and pointing
error significantly affect the secrecy performance. In addition, better
performance is obtained exploiting the HD technique at the destination relative
to IM/DD technique.
