Component algebraic immunity of S-boxes used in some block ciphers

The basis of block ciphers are S-boxes which are vector Boolean functions. The resistance of ciphers to various methods of cryptanalysis is achieved through the use of functions with good cryptographic properties. In this paper, we establish the exact value of the component algebraic immunity of S-boxes which are used in the known block ciphers. It is obtained that such ciphers as DES, CAST-256, KASAMI, PRESENT do not have the maximum immunity and are potentially badly resist to algebraic cryptanalysis.