Key sharing based on the wire-tap channel type II concept with noisy main channel

Abstract

We give a solution to the following problem: how to upper bound an eavesdropper's information on the key shared by legal users when eavesdropper obtains at most s digits of her choice from each block of length n>s transmitted between legal users on noisy channel. In particular an eavesdropper obtains no information on the key. We consider a regular coding without public discussion on channel required for privacy amplification. This approach can be used also for design of the ramp schemes extended on noisy channels.