  Secret-key generation exploiting the channel reciprocity between two
legitimate parties is an interesting alternative solution to cryptographic
primitives for key distribution in wireless systems as it does not rely on an
access infrastructure and provides information-theoretic security. The large
majority of works in the literature generally assumes that the eavesdropper
gets no side information about the key from her observations provided that (i)
it is spaced more than a wavelength away from a legitimate party and (ii) the
channel is rich enough in scattering. In this paper, we show that this
condition is not always verified in practice and we analyze the secret-key
capacity under realistic propagation conditions.
