Serial encryption using the functions of real variable

Context. Using the functions of a real variable in cryptosystems as keys allow increasing their cryptographic strength since it is more difficult to select such keys. Therefore, development systems relevant. Objective. Cryptosystems with symmetric are proposed for encrypting and decrypting sequence characters represented one-dimensional numerical array ASCII codes. These that satisfies certain restrictions. They can be both continuous discrete. Method. Two cryptosystem options proposed. In first embodiment, transmitting receiving sides two functions, transmitted symbol, area function definition, step changing argument. Discrete messages encrypted by calculating first-order integral disproportion using function. The corresponding value second added obtained cipher each symbol scrambling complicate analysis intercepted message. On side, subtracted decryption performed inverse transformation formula disproportion. version, sequential encryption when one key stage again function, key. Accordingly, stages, performed. Results. Examples text presented. It shown same character encoded differently depending on its position given examples presented difficulty parameters choosing cryptosystem. Conclusions. Variants proposed, which serve To “crack” system, necessary not only form but also find values high accuracy. system has strength.