  In this work a four terminal Gaussian network composed of a source, a
destination, an eavesdropper and a jammer relay is studied. The jammer relay
does not hear the source transmission. It assists the eavesdropper and aims to
decrease the achievable secrecy rates. The source, on the other hand, aims to
increase the achievable secrecy rates. Assuming Gaussian strategies at the
source and the jammer relay, this problem is formulated as a two-player
zero-sum continuous game, where the payoff is the achieved secrecy rate. For
this game the Nash Equilibrium is generally achieved with mixed strategies. The
optimal cumulative distribution functions for the source and the jammer relay
that achieve the value of the game, which is the equilibrium secrecy rate, are
found.
