Oleshko O. Methods of fast cryptanalysis of symmetric block ciphers based on analysis of security strength of reduced prototypes.

Work is devoted to improvement of estimation methods of symmetric block ciphers security to the attacks of differential and linear cryptanalysis. Here we develop the method of analysis based estimation of small prototypes model properties. We estimate block ciphers security by investigating characteristics and properties of small model prototypes, thus we check up accordance between theoretical and empirical values of block ciphers security. We suggest using the number of transformation rounds to achieve asymptotic values of distribution laws. Accordingly we can measure the security level of block symmetric ciphers by calculating maximums of full differentials and linear corps.