Information Rates Subjected to State Masking

We consider the problem of rate–R channel coding with causal/non–causal side information at the transmitter, under an additional requirement of minimizing the amount of information that can be learned from the channel output about the state sequence, which is defined in terms of the equivocation E (i.e., the mutual information between the state sequence and the channel output sequence). A single–letter characterization is provided for the achievable region of pairs {(R, E)}. Explicit results for the Gaussian case (Costa’s dirty–paper channel) are derived in full detail.