METHOD FOR NONLINEAR THREE-DIMENSIONAL MULTI-ROUND RDOZEN DATA CONVERSION Russian patent published in 2016 - IPC G06F7/58 G06F21/60 H04L9/06 

FIELD: information technology.

SUBSTANCE: invention relates to protection of computer information. Method for nonlinear three-dimensional multi-round conversion of data, in which second and third rounds conversion are similar to first: when performing conversions of second and third round, method includes dividing unit 1 of data S into four layers 4_x0, 4_x1, 4_x2, 4_x3(respectively L_x0, L_x1, L_x2, L_x3) along x axis; each layer L_xk, k = 0, 1, 2, 3, is presented in form of a square array of bytes 4×4, followed by two-dimensional stochastic conversion 5_xk T_Layer of each layer L_xk and combination of layers L_xk into converted unit S; between first and second rounds, as well as between second and third rounds, method includes converting 6 of permutation of bytes PermBytes; when converting 5_xk T_Layer L_xk, successively performing replacement 9 of bytes SubBytes, mixing 10 bytes of MixState state and adding 11 with a round sub-key AddRoundSubKey; operation of mixing 10 bytes of MixState state is carried out as follows: - layer L is broken into 16 bytes; - essence of mixing operation of state bytes - multiplication of row of state bytes with a square matrix 16×16, wherein all operations of multiplication and summation of elements of row and matrix are carried out in a GF(2⁸) field; mixed bytes are combined into converted layer L.

EFFECT: high cryptographic robustness and faster nonlinear conversion.

1 cl, 5 dwg