Game-theoretic analysis of a semi-fragile watermarking scheme based on SCS

Semi-fragile watermarking can be used to detect illegal and local manipulation of images, while being robust towards legal manipulations such as lossy compression. This paper describes a game-theoretic approach to design a blind semi-fragile watermarking system based on the scalar costa scheme. A natural choice for the game criterion is a false alarm probability, i.e. the probability to still detect the watermark, even if part of the data has been replaced. Optimal embedding strategy is then derived in presence of a legal processing (e.g. lossy compression, through some model). Finally, the results are applied to design an efficient DCT semi-fragile watermarking system which allows to detect local forgery signals in spite of JPEG compression.