| 摘要 |
PROBLEM TO BE SOLVED: To enable a user to freely set a pass word, without making a conversion method and a calculating formula secret. SOLUTION: For example, a password PSW consisting of 8 digits of 8 bit per digit is inputted (S1), the PSW is, for example, divided into four parts a1||a2||a3||a4 (S21), an XOR for every bit of a1 , a2 , a3 , a4 is taken (S22), d=2P mod LR (LR is the bit length of a secret key R) is calculated by taking the XOR (S23), the secret key R is defined by generating random numbers, storage information R' is generated (S4) by calculating R'=R×OR PSW×2<d> , and the secret key R is stored. R=R'×OR PSW×2<d> is calculated to obtain the secret key R.
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