Figure 1.

A hidden Markov model for deciphering stegoscripts. It consists of two submodels, the 'secret message model' is for motifs and the 'covertext model' for background words. The blue boxes with dashed outlines each represent a word node, which is a combination of several position nodes. Node W_b is a single-base node and always belongs to the covertext model. States S, B, and M do not emit any letter.