The results of the author’s collective research on the theory of associative steganography are systematized in order to bring them to a wide range of developers and users of stegosystems. The concept of associative steganography is associated with the associative protection of a finite set of object types and their coordinates, the decimal code symbols of which are represented by masked binary matrices of the same size. Consideration is carried out from positions of constructive modeling of systems. The accepted postulates on the principles of concealment, the logical interpretation of the criterion of Shannon’s perfect secrecy, the choice of the sizes of matrices and the randomizing gamma are explained. The masking algorithm is described. Estimates of the effectiveness of associative protection are given: the proof of the basic theorem, the estimation of speed, stiffness and noise immunity.