  This paper presents further insights into a recently developed round-trip
communication scheme called ``Secret-message Transmission by Echoing Encrypted
Probes (STEEP)''. A legitimate wireless channel between a multi-antenna user
(Alice) and a single-antenna user (Bob) in the presence of a multi-antenna
eavesdropper (Eve) is focused on. STEEP does not require full-duplex, channel
reciprocity or Eve's channel state information, but is able to yield a positive
secrecy rate in bits per channel use between Alice and Bob in every channel
coherence period as long as Eve's receive channel is not noiseless. This
secrecy rate does not diminish as coherence time increases. Various statistical
behaviors of STEEP's secrecy capacity due to random channel fading are also
illustrated.
