  This paper investigates the fundamental performance limits of the two-user
interference channel in the presence of an external eavesdropper. In this
setting, we construct an inner bound, to the secrecy capacity region, based on
the idea of cooperative encoding in which the two users cooperatively design
their randomized codebooks and jointly optimize their channel prefixing
distributions. Our achievability scheme also utilizes message-splitting in
order to allow for partial decoding of the interference at the non-intended
receiver. Outer bounds are then derived and used to establish the optimality of
the proposed scheme in certain cases. In the Gaussian case, the previously
proposed cooperative jamming and noise-forwarding techniques are shown to be
special cases of our proposed approach. Overall, our results provide structural
insights on how the interference can be exploited to increase the secrecy
capacity of wireless networks.
