  Wireless communication is susceptible to eavesdropping attacks because of its
broadcast nature. This paper illustrates how interference can be used to
counter eavesdropping and assist secrecy. In particular, a wire-tap channel
with a helping interferer (WT-HI) is considered. Here, a transmitter sends a
confidential message to its intended receiver in the presence of a passive
eavesdropper and with the help of an independent interferer. The interferer,
which does not know the confidential message, helps in ensuring the secrecy of
the message by sending an independent signal. An achievable secrecy rate and
several computable outer bounds on the secrecy capacity of the WT-HI are given
for both discrete memoryless and Gaussian channels.
