The present paper deals with algebraic models and methods sufficient to solve effectively problems of investigation of two basic classes of control systems, namely, finite automata and boolean functions. Suggested models for finite automata are based on finite groups and result in establishing basic algebraic characteristics, developing a general scheme for estimating exponential lower bounds and in the design of nonstationary secret locks of arbitrary high complexity. It is also shown that the problem of the identification of boolean vector-functions may be effectively solved via the methods of the Theory of Vector Spaces over GF (2).