The textbook is devoted to the study of basic methods of information protection with digital watermarks, methods of digital steganography (that is, the transmission of hidden messages within digital containers), as well as methods of countering systems that implement such methods. The material is divided into 9 chapters, most of which, in addition to theoretical material, also contain practical and laboratory tasks, consisting in the software implementation and research of various systems for embedding information in digital images and video. One chapter provides a brief overview of the MATLAB environment used to perform tasks. The manual is intended for students on the main educational program of higher education in the direction of training 10. 03. 01 Information Security and Specialties 10. 05. 03 Information security of automated systems .