  We investigate the secure connectivity of wireless sensor networks under the
pairwise key distribution scheme of Chan et al.. Unlike recent work which was
carried out under the assumption of full visibility, here we assume a
(simplified) communication model where unreliable wireless links are
represented as on/off channels. We present conditions on how to scale the model
parameters so that the network i) has no secure node which is isolated and ii)
is securely connected, both with high probability when the number of sensor
nodes becomes large. The results are given in the form of zero-one laws, and
exhibit significant differences with corresponding results in the full
visibility case. Through simulations these zero-one laws are shown to be valid
also under a more realistic communication model, i.e., the disk model.
