The training manual is intended for students studying in the direction of training of IDPs 09. 03. 03 "Applied Informatics in Management" . The structure and content of the textbook reflect the tasks of information security and the problems of using methods and means of protecting computer information, as well as facilitating the independent work of students. Various problems and examples are considered, grouped in accordance with the main directions of development of methods and algorithms of information security of automated data processing systems. The presented tasks and examples cover both classical methods of information protection and modern methods of ensuring confidentiality and data integrity, focused on the application of computer technology.