  In this paper, we consider the transmission of confidential information over
a $\kappa$-$\mu$ fading channel in the presence of an eavesdropper, who also
observes $\kappa$-$\mu$ fading. In particular, we obtain novel analytical
solutions for the probability of strictly positive secrecy capacity (SPSC) and
the lower bound of secure outage probability (SOP$^L$) for channel coefficients
that are positive, real, independent and non-identically distributed
($i.n.i.d.$). We also provide a closed-form expression for the probability of
SPSC when the $\mu$ parameter is assumed to only take positive integer values.
We then apply the derived results to assess the secrecy performance of the
system in terms of the average signal-to-noise ratio (SNR) as a function of the
$\kappa$ and $\mu$ fading parameters. We observed that for fixed values of the
eavesdropper's average SNR, increases in the average SNR of the main channel
produce a higher probability of SPSC and a lower secure outage probability
(SOP). It was also found that when the main channel experiences a higher
average SNR than the eavesdropper's channel, the probability of SPSC improved
while the SOP was found to decrease with increasing values of $\kappa$ and
$\mu$ for the legitimate channel. The versatility of the $\kappa$-$\mu$ fading
model, means that the results presented in this paper can be used to determine
the probability of SPSC and SOP$^L$ for a large number of other fading
scenarios such as Rayleigh, Rice (Nakagami-$n$), Nakagami-$m$, One-Sided
Gaussian and mixtures of these common fading models. Additionally, due to the
duality of the analysis of secrecy capacity and co-channel interference, the
results presented here will also have immediate applicability in the analysis
of outage probability in wireless systems affected by co-channel interference
and background noise.
