Abstract:

At present, there are few effective models to evaluate the security of steganography. In this paper, first, a model to describe the statistical distribution of the discrete cosine transform （DCT） coefficients of an image is es- tablished, and a model based on the information-theory definition of steganography security is presented to measure the security of steganography in the DCT domain. The securities of several steganographic techniques in both spatial and DCT domains are then compared. Moreover, some experiments are performed to measure the effects of the methods of model solving, the size of hiding message, the block size in DCT, the embedding position and the dou- ble compression on the security evaluation. The results show that the proposed model is an effective model, which provides valuable references for the design of steganography and steganalytic algorithms.

Key words: steganography, evaluation model, discrete cosine transform, Gaussian distribution, maximum likelihood estimation, discrimination information