Secret dither estimation in lattice-quantization data hiding: a set membership approach

In this paper, security of lattice-quantization data hiding is considered under a cryptanalytic point of view. Security in this family of methods is implemented by means of a pseudorandom dither signal which randomizes the codebook, preventing unauthorized embedding and/or decoding. However, the theoretical analysis shows that the observation of several watermarked signals can provide sufficient information for an attacker willing to estimate the dither signal, quantifying information leakages in different scenarios. The practical algorithms proposed in this paper show that such information leakage may be successfully exploited with manageable complexity, providing accurate estimates of the dither using a small number of observations. The aim of this work is to highlight the security weaknesses of lattice data hiding schemes whose security relies only on secret dithering.