Cipher with improved dynamic indicators of the condition of a random substitution

摘要

Description of a new 256-bit SPN cipher, called a managed substitution cipher (MSC), is present. This is an SPN cipher with a two-layer substitution transformation in the first cycle and one-layer substitution transformations in the remaining cycles. Management of substitution transformations is carried out by including them in a chain so that the value of the output of the previous SL transformation is fed to the input of the current enlarged 32-bit substitution transformation (SL transformation) along with the current value of the input data block through the adder modulo 2. It is show that such a construction of the ciphered function of the cipher allows us to reduce the minimum number of cycles of its arrival to the state of random substitution. This in turn reduces the number of encryption cycles (to increase the speed) and create the conditions under which S-blocks of random type can be used in the cipher without sacrificing security.