METHOD FOR ITERATIVE ENCODING OF DIGITAL DATA BLOCKS Russian patent published in 2003 - IPC

FIELD: electrical communications and computer engineering; cryptographic method for data encoding. SUBSTANCE: method includes generation of private key in the form of set of ports, division of data block into two subblocks, and execution of R≥2 encoding rounds, each incorporating conversion of first subblock by executing sequence of L₁, L₂, ..., L_n, operations, where n > 1, and conversion of second subblock by executing sequence of H₁, H₂, ..., H_m operations, where m > 1, at least one of L₁, L₂, ..., L_n, H₁, H₂, ..., H_m operations being controlled operation; prior to executing this operation control vector is generated; during execution of at least L₁, L₂, ..., L_n, H₁, H₂, ..., H_m operations use is made of one of ports, m being even number and n, odd number; in addition upon execution of L_n and H_m operations in all encoding rounds except for last one, subblocks are permutated; H_i operations are reverse to H_n-i+1, where 1≤i≤m/2, operations and L_i operations are reverse to L_n-j+1 operations, where 1≤j≤(n-1)/2,; L_(n-1)/2+1 operation is involution, modulo two bitwise addition operation of controlled permutation involution being used as L_(n-1)/2+1 operation and also as L₁, L₂, ..., L_n operation, where n≥3; in addition to L_(n-1)/2+1 operation use is made of controlled two-place operations executed for first subblock and for one of ports; controlled permutations are used as H₁, H₂, ..., H_m operations , where m≥2, and controlled permutation involution, as L_(n-1)/2+1; in addition prior to executing L₁, L₂, ..., L_n operation for first subblock control vector is generated as function of private key and current value of second subblock and prior to executing H₁, H₂, ..., H_m operation for second subblock control vector is generated as function of private key and current value of first subblock. EFFECT: facilitated encoding and decoding procedures using same electronic circuit. 5 cl, 2 dwg