| 摘要 |
PROBLEM TO BE SOLVED: To provide an encryption method which allows modification of a secret key B with a control software D of secret information protection system implemented outside of the secret information protection system. SOLUTION: In the encryption method which has a cipher decoding circuit 1b for encoding or decoding secret information A that is a key or a contents required to be protected into or from an encrypted secret information Enc (A, B) with a secret key B for encoding or decoding the secret information A, a secret key C is input into a shift register 2a and a rotation is applied to the secret key C to generate a secret key B. The rotation bit count of the shift register 2a can be modified with a selection signal configured by the control software D. COPYRIGHT: (C)2007,JPO&INPIT
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