Wire-tap channel II.

Consider the following situation. K data bits are to be encoded into N > K bits and transmitted over a noiseless channel. An intruder can observe a subset of his choice of size mu N. The encoder is to be designed to maximize the intruder's uncertainty about the data given his N intercepted channel bits, subject to the condition that the intended receiver can recover the K data bits perfectly from the N channel bits. The optimal tradeoffs between the parameters K, N, micron and the intruder's uncertainty H (H is the "conditional entropy" of the data given the micron intercepted channel bits) were found.