  This paper investigates the role of the eavesdropper's statistics in the
implementation of a practical secret-key generation system. We carefully
conduct the information-theoretic analysis of a secret-key generation system
from wireless channel gains measured with software-defined radios. In
particular, we show that it is inaccurate to assume that the eavesdropper gets
no information because of decorrelation with distance. We also provide a bound
for the achievable secret-key rate in the finite key-length regime that takes
into account the presence of correlated eavesdropper's observations. We
evaluate this bound with our experimental gain measurements to show that
operating with a finite number of samples incurs a loss in secret-key rate on
the order of 20%.
