On the capacity game of public watermarking systems

Watermarking codes are analyzed as a game between two players: an information hider, and a decoder, on the one hand, and an attacker on the other hand. The information hider is allowed to cause some tolerable level of distortion to the original data within which the message is hidden, and the resulting distorted data can suffer some additional amount of distortion caused by an attacker who aims at erasing the message. Motivated by a worst-case approach, we assume that the attacker is informed of the hiding strategy taken by the information hider and the decoder, while they are uninformed of the attacking scheme. A single-letter expression for the capacity is found under the assumption that the covertext is drawn from a memoryless stationary source and its realization (side information) is available at the encoder only.