There is the analysis of existing approaches to evaluation of stability indices symmetric block cipher to differential attack and linear cryptanalysis in this work. The given work insisted upon the shortcomings and limitations of existing methods. The given work is set forth the essence of the new ideology (belief system) to assess stability of symmetric block cipher to differential attack and linear cryptanalysis, which rests on the possibility of a rapid method of cryptanalysis BSSH which basis is to develop and study the properties of reduced models of prototypes, and using established in fact the research, that modern ciphers asymptotically (with full set of cyclic transformations) repeating properties of random substitutions corresponding degree.
symmetric block ciphers, provable security, differential cryptanalysis, linear cryptanalysis, reduced model ciphers, laws conversions XOR distribution tables and table bias linear approximations
"O novoi metodyke otsenky stoikosty blochnыkh symmetrychnыkh shyfrov k atakam dyfferentsyalnoho y lyneinoho kryptoanalyza" ,
Information Processing Systems,