# nonlinear dynamics

## Cryptography from the Physicist's Point of View

The results of treating of crypto algorithms such as DES (USA) and GOST 28147-89 (Russia) with the help of nonlinear dynamics methods are presented. Point maps which are generated by the blocks of substitutions (S-blocks) are investigated. The phenomenon of return is demonstrated. The ergodicity of these maps are treated. An estimation of quality of S-block could be made by maps of first return. The results of statistical treating of S-biocks are presented.

## Department of Electronics,Oscillations and Waves of Saratov State University Celebrates Sixtieth Anniversary

A brief history of the Department of Electronics, Oscillations and Waves of Saratov State University are presented. This year, the Department of Electronics, Oscillations and Waves celebrates sixtieth anniversary. Department of Electronics Oscillations and Waves is one of the leading departments of Saratov State University training specialists for the electronics industry.

## Phase Dynamics Modeling Technique for Estimation of Delayed Couplings between Nonlinear Oscillators Accounting for Influence of Amplitudes

An established interval estimator of a time delay in coupling between oscillators, which is based on empirical modeling of phase dynamics and maximum likelihood formalism, is shown to give sometimes erroneous conclusions about the value of the time delay. It occurs when the dynamics of amplitudes affects phases, which is typical of nonlinear oscillatory systems under the influence of strong noises or in chaotic regimes. We suggest an empirical criterion to diagnose such situations and a modified estimator of time delay which allows one to avoid erroneous conclusions.