Steganalysis of JSteg Algorithm Using Hypothesis Testing Theory
Eurasip Journal on Information Security
This paper investigates the statistical detection of JSteg steganography. The approach is based on a statistical model of Discrete Cosine Transformation (DCT) coecients challenging the usual assumption that among a subband all the coecients are independent and identically distributed (i. i. d. ). The hidden information detection problem is cast in the framework of hypothesis testing theory. In an ideal context where all model parameters are perfectly known, the Likelihood Ratio Test (LRT) is presented and its performances are theoretically established. The statistical performance of LRT serves as an upper bound for the detection power. For a practical use where the distribution parameters are unknown, by exploring a DCT channel selection, a detector based on estimation of those parameters is designed. The loss of power of the proposed detector, compared with the optimal LRT is small, shows the relevance of the proposed approach.