| 摘要 |
PROBLEM TO BE SOLVED: To provide an encryption processing device and a method therefor which reduce the processing load on software by shortening the processing time for enciphering or deciphering data streams of character data or the like in an OFB mode or a CFB mode of a DES encryption system. SOLUTION: In an initial cycle, initial data in an IV register 22 is taken into an IV data holding part 31, and arithmetic operation in a block cipher arithmetic part 11 is executed, and L2 upper bits of an arithmetic result are added to held data in an encryption data holding part 32 and the IV data holding part 31. In following processing, held data in the IV data holding part 31 and the encryption data holding part 32 are successively updated by the arithmetic result of the block cipher arithmetic part 11 in the same manner. This processing is repeated the number of times which is equal to the number of unit data of L2 bits included in input data S, and finally enciphered or deciphered data is obtained in a second data extraction part 52 by exclusive OR between extracted data and input data S. COPYRIGHT: (C)2004,JPO
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