  We consider multiple access games in which primary users are interested in
maximizing their confidential data rate at the minimum possible transmission
power and secondary users employ eavesdropping as a leverage to maximize their
data rate to a common destination at minimum transmission energy. For the
non-cooperative static game, Nash equilibria in pure and mixed strategies are
derived and shown to be Pareto inefficient in general, when channel gains are
common knowledge. For the two-player Stackelberg game where the primary user is
the leader, it is shown that the secondary user is forced to play as the
follower where the Stackelberg equilibrium dominates the Nash equilibrium, even
if the eavesdropper channel is better than the primary channel. Here, the
utility achieved by the Stackelberg game Pareto-dominates the achieved Nash
utility. Moreover, we study the unknown eavesdropper channel case numerically
where the primary user has only statistical knowledge about the channel gain.
We compare the results to the first scenario and show that it is not always
beneficial for the cognitive user to hide the actual eavesdropper channel gain.
Finally, we extend the equilibrium analysis to a multiple SU game where the
primary system selects a subset of the secondary users to transmit such that
the performance of the primary users is maximized.
