The textbook discusses the general concepts of methods and means of information protection, the main types of threats to information security, describes classical, modern symmetric and asymmetric cryptosystems. The purpose of this manual is to develop students a variety of skills and abilities: extracting the necessary information, quick reading of information blocks, mastering the elements of monologue, dialogue and writing in the field of information technology. The proposed texts, a set of tasks and exercises are built on professionally-directed material and contribute to the formation of students' general cultural and professional competencies. The manual is intended for students studying in the direction of Computer Science and Computer Engineering 230100 and the specialty Automated systems of information processing and management of 230102 full-time forms of education, for work in classroom and extracurricular classes . Training manual created within the framework of the international project TEMPUS