  This paper studies the K-user Gaussian interference channel with secrecy
constraints. Two distinct network models, namely the interference channel with
confidential messages and the one with an external eavesdropper, are analyzed.
Using interference alignment along with secrecy pre-coding at each transmitter,
it is shown that each user in the network can achieve non-zero secure Degrees
of Freedoms (DoFs) in both scenarios. In particular, the proposed coding scheme
achieves (K-2)/(2K-2) secure DoFs for each user in the interference channel
with confidential messages model, and (K-2)/2K secure DoFs in the case of an
external eavesdropper. The fundamental difference between the two scenarios
stems from the lack of channel state information (CSI) about the external
eavesdropper. Remarkably, the results establish the positive impact of
interference on the secrecy capacity of wireless networks.
