Patent ID: 7227948

Claim:
An encryption apparatus, comprising: a plurality of stage sections connected in series, each of said plurality of stage sections comprising a diffusing unit configured to diffuse 128-bit block data and four first randomizing units, said four first randomizing units configured to receive input 128-bit plaintext block data at a first stage or 128-bit block data processed by a preceding stage at a second and subsequent stages, said four first randomizing units further configured to randomize four sets of 32-bit data obtained by dividing the 128-bit block data, and said diffusing unit is configured to diffuse the 128-bit block data obtained by coupling the four sets of 32-bit data output from said four randomizing units using a Maximum Distance Separable matrix; four second randomizing units connected to a last stage of said plurality of stage sections and configured to randomize four sets of 32-bit data obtained by dividing the 128-bit block data; and a first key adder connected to said four second randomizing units and configured to add 128-bit key data to 128-bit block data obtained by coupling the four sets of 32-bit data output from said four second randomizing units; wherein each of said stage sections further comprises four second key adders configured to add 8-bit key data to four sets of 8-bit data obtained by dividing one of the four sets of 32-bit data, four randomizing units configured to randomize outputs of said four second key adders by using an input/output table of 8-bits, a diffusion unit configured to diffuse 32-bit data obtained by coupling four sets of 8-bit data output from said four randomizing units using said Maximum Distance Separable matrix, and four third key adders configured to add 8-bit key data to four sets of 8-bit data obtained by dividing one of the four sets of 32-bit data and which are connected to said diffusion unit.