Convolutional encoding for Wyner´s wiretap channel (Corresp.)

The wiretap channel introduced by Wyner is studied for the special case when the main channel is a noiseless binary channel and the wiretap channel is a binary symmetric channel. With a rate-one convolutional encoder, the steady-state uncertainty of the wiretapper is shown to depend only on the constraint length of the code, not on the specific taps, and is complete on k successive bits provided . During the initial transient period, the rate of growth of uncertainty does depend on the tap connections of the shift register.