  In this letter, we propose to exploit an intelligent reflecting surface (IRS)
to secure multiuser two-way communications. Specifically, two end users
simultaneously transmit their signals, where the signal of one user is
exploited as information jamming to disrupt the reception of the other user's
signal at an eavesdropper. A simple user scheduling scheme is developed to
improve the secrecy rate. Analytical results in terms of a lower bound on the
average secrecy rate and its scaling laws are derived to evaluate the secrecy
performance and obtain valuable design insights. Simulation results are
provided to confirm the accuracy of the theoretical analysis and validate the
secrecy improvement of the proposed scheme over other baseline schemes.
