METHOD FOR ITERATIVE BLOCK ENCRYPTION Russian patent published in 2002 - IPC

FIELD: electric communications and computer engineering; data encryption. SUBSTANCE: method involves generation of private key in the form of aggregate of sub-keys, division of data block into two sub- blocks, and execution of R≥ encryption rounds each involving conversion of first sub-block by execution of sequence of L₁, L₂,...,L_n operations, and conversion of second sub-block by execution sequence of H₁, H₂,..., H_n, operations, where n≥1, controlled operation being used as 1≤i≤n operation for at least one value of i, where H_i and controlled operation as 1≤j≤n, for at least one value of j, where L_j; used as H_i operation is controlled operation ; control vector is shaped prior to executing L_j operation depending on first sub- block and control vector is shaped prior to executing L₁ operation depending on second sub-block; in addition one of sub-keys is used during execution of at least one of L₂,..., L_n, H₁, H₂,..., H_n operations, sub-blocks being re- arranged upon execution of L_n and H_n operations during each encryption round; sub-blocks are additionally re-arranged and operations reverse to H_i ones, where j = n i + 1, are used at least as n operations of L_j, where i = 1, 2, ..., n. EFFECT: enhanced encryption stability. 4 cl, 4 dwg