Layered decoding and secrecy over degraded broadcast channels

A K-receiver degraded broadcast channel with layered decoding and secrecy constraints is investigated, in which receivers are ordered by their channel quality. Each receiver is required to decode one more message compared to the receiver with one level worse channel quality, and this message should be kept secure from all receivers with worse channel quality. For both the discrete memoryless channel and the Gaussian channel, the secrecy capacity region is characterized. The achievability scheme is based on stochastic encoding and superposition coding schemes. Novel generalization of the analysis of leakage rates and of the proof of the converse is developed for the K-receiver scenario.