Enhanced usage of keys obtained by physical, unconditionally secure distributions

Unconditionally secure physical key distribution is very slow whenever it is undoubtedly secure. Thus it is practically impossible to use a one-time-pad based cipher to guarantee perfect security be-cause using the key bits more than once gives out statistical information, such as via the known-plain-text-attack or by utilizing known components of the protocol and language statistics. Here we outline a protocol that seems to reduce this problem and allows a near-to-one-time-pad based communication with unconditionally secure physical key of finite length. The unconditionally secure physical key is not used for communication; it is use for a secure communication to generate and share a new software-based key without known-plain-text component, such as keys shared via the Diffie-Hellmann-Merkle protocol. This combined physical/software key distribution based communication looks favorable compared to the physical key based communication when the speed of the physical key distribution is much slower than that of the software-based key distribution. The security proof of this scheme is yet an open problem.