| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an encryption key distribution system for distributing timing when a client requests again an encryption key to an encryption key distribution server. Ž<P>SOLUTION: The encryption key distribution server connected with a plurality of clients through a network for distributing an encryption key for decrypting content data to the clients, includes: an encryption key generating means for generating a plurality of encryption keys to which periods of validity different from one another in a time sequential order are set; a first encryption key database for storing an encryption key list on which a plurality of encryption keys are registered; an encryption key selecting means for selecting from among the plurality of encryption keys registered on the encryption key list a plurality of encryption keys, to be distributed for each client, from the encryption key of the period of validity including the present to the encryption key of the different period of validity; and an encryption key distribution means for distributing to the clients the plurality of encryption keys from the encryption key of the period of validity including the present to the encryption key of the different period of validity. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
