  Secret key generation (SKG) between authenticated devices is a pivotal task
for secure communications. Diffie-Hellman (DH) is de-facto standard but not
post-quantum secure. In this paper, we shall invent and analyze a new security
primitive that is specifically designed for WPAN. For WPAN, wireless
channel-based SKG has been proposed but was not widely deployed due to its
critical dependence on the channel's entropy which is uncontrollable. We
formulate a different approach: We still exploit channel properties but mainly
hinge on the reciprocity of the wireless channel and not on the channel's
entropy. The radio advantage comes from the use of full duplex communication.
We show that in this situation both legitimate parties can agree on a common
secret key even without ever probing the channel at all. At the core is a new
bisparse blind deconvolution scheme for which we prove correctness and
information-theoretic, i.e. perfect, security. We show that, ultimately, a
secret key can be extracted and give a lower bound for the number of secret key
bits which is then verified by experiments.
