The Secrecy Capacity for a 3-Receiver Broadcast Channel with Degraded Message Sets

In this paper, we study the secrecy capacity region for the 3-receiver broadcast channel (BC) with degraded message sets, where a confidential message is kept secret from one of the receivers. This model is more general than the previously studied degraded broadcast channel (BC) with confidential messages, as the wiretap receiver is supposed to receive the common message. Our main results are the inner and outer bounds, which we derive using Wyner’s code partitioning in tandem with double-binning. For the case in which the receiver with the confidential message is less noisy than the wiretapper, the inner and outer bounds coincide and give the secrecy capacity region of this channel.