  This paper develops a new physical layer framework for secure two-way
wireless communication in the presence of a passive eavesdropper, i.e., Eve.
Our approach achieves perfect information theoretic secrecy via a novel
randomized scheduling and power allocation scheme. The key idea is to allow
Alice and Bob to send symbols at random time instants. While Alice will be able
to determine the symbols transmitted by Bob, Eve will suffer from ambiguity
regarding the source of any particular symbol. This desirable ambiguity is
enhanced, in our approach, by randomizing the transmit power level. Our
theoretical analysis, in a 2-D geometry, reveals the ability of the proposed
approach to achieve relatively high secure data rates under mild conditions on
the spatial location of Eve. These theoretical claims are then validated by
experimental results using IEEE 802.15.4-enabled sensor boards in different
configurations, motivated by the spatial characteristics of Wireless Body Area
Networks (WBAN).
