| 摘要 |
PROBLEM TO BE SOLVED: To provide an encryption method using an encryption block chain where it is difficult to decode/presume an encrypted sentence by generating a different encrypted sentence each time even from the same plaintext. SOLUTION: A random number is added before a plaintext, and it is encrypted by an encryption block chain system so that encrypted sentence strings to be generated from the same plaintext A<SB>m</SB>are different. A bit operation is added to the encryption processing result of a block A<SB>i-1</SB>before it is used for the encryption processing of the next block A<SB>i</SB>, so that the relevancy between random number or an encrypted sentence B<SB>0</SB>of the random number and generated encrypted sentence series B<SB>1</SB>, B<SB>2</SB>to B<SB>n</SB>can be made difficult to understand. COPYRIGHT: (C)2007,JPO&INPIT
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