| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a secret information leak from an information distribution device. SOLUTION: Each information terminal device 10 has a tamper resistant function from before. The information distribution device 20 once acquiring new secret information Sn from an information management server 1 transfers it to a specified information terminal device 10. For the secret information Sn, the specified information terminal device 10 generates a generated encryption key Ks, generates encrypted secret information Ks(Sn) with it, and sends it back to the information distribution device 20, which stores it. The information distribution device 20 distributes the encrypted secret information Ks(sn) each time an arbitrary information terminal device 10 makes a request. Each information terminal device 10 is able to generate the encryption key Ks, and decrypts the encrypted secret information Ks(Sn) using the encryption key Ks to obtain the secret information Sn. COPYRIGHT: (C)2009,JPO&INPIT
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