Provably Secure Universal Steganographic Systems

We propose a simple universal (that is, distribution–free) steganographic system in which covertexts with and without hidden texts are statistically indistinguishable. Moreover, the proposed steganographic system has two important properties. First, the rate of transmission of hidden information approaches the Shannon entropy of the covertext source as the size of blocks used for hidden text encoding tends to infinity. Second, if the size of the alphabet of the covertext source and its minentropy tend to infinity then the the number of bits of hidden text per letter of covertext tends to log(n!)/n where n is the (fixed) size of blocks used for hidden text encoding. The proposed stegosystem uses randomization.