| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent illegal acquisition, alteration, and leakage for a cipher key for decoding contents and its delivery control information at contents delivery servers, in contents providing servers or content distribution servers used in a system managing contents delivery, when encrypted contents are distributed. SOLUTION: At a contents providing server, a cipher key decoding contents is encrypted and the encrypted cipher key and its distribution control information are provided to a contents delivery server. If the provided encrypted data (the encrypted cipher key and its distribution control information) are not illegal, the provided encrypted data are stored at the contents delivery server. Upon a distribution request from a client, the encrypted data is decoded and the encrypted cipher key and its distribution control information are acquired. If it is within a grant period set by the delivery control information, the cipher key is again encrypted to be delivered to the client.</p> |
