Abstract: We introduce a complex approach to evaluating cryptographic protection efficiency. Classically, the research has mostly focused on information system security as a whole, whereas cryptographic tools evaluation techniques have not received as much attention. The main thread of our work is the development of mathematical models of threats to analyze the security of cryptographic systems based on various types of attacks that the cryptographic system is exposed to. The approach allows to build an economic rationale for investments to cryptographic systems and to provide sound arguments for implementing an information security strategy.