STEEP -- An Alternative To Quantum Key Distribution

Secret-message transmission by echoing encrypted probes (STEEP) is discussed as an alternative to quantum key distribution (QKD). The former only needs classic or non-quantum channels while the latter needs both quantum and classic channels for secret-key generation. STEEP is shown to yield a secrecy rate sufficient for one-time pads encryption in many practical situations including in-air channels or undersea optical cables. Other advantages of STEEP over QKD include cost, complexity, compatibility, and robustness against constant eavesdropping.