Privacy signalling games with binary alphabets

In this paper, we consider a privacy signaling game problem for binary alphabets where a transmitter has a pair of messages one of which is a casual message that needs to be conveyed whereas the other message contains sensitive data and needs to be protected. The receiver wishes to estimate both messages with the aim of acquiring as much information as possible. For this setup, we study the interactions between the transmitter and the receiver with non-aligned information theoretic objectives (modeled by mutual information and hamming distance) due to the privacy concerns of the transmitter. We derive conditions under which Nash and/or Stackelberg equilibria exist and identify the optimal responses of the encoder and decoders strategies for each type of game. One particularly surprising result is that when both type of equilibria exist, they admit the same encoding and decoding strategies. We corroborate our analysis with simulation studies.