| 摘要 |
PROBLEM TO BE SOLVED: To provide an information recording and reproducing device, which improves efficiency in processing on a key renewal block (KRB) receiving side by performing the distribution of a key by KRB distribution as a key distribution configuration in a tree structure. SOLUTION: A key (such as master key, media key or contents key) is transmitted by the key distribution configuration in the tree structure together with a KRB. After the recording and reproducing device calculates and acquires the key of a certain recording medium on the basis of the received KRB, the acquired key is enciphered while using a cryptographic key peculiar for that recording and reproducing device such as leaf key, for example, and stored on the recording medium or memory of the recording and reproducing device. Therefore, when next using that recording medium or contents, the recording and reproducing device can calculate the key only by once deciphering that cryptographic key and the computational complexity in KRB deciphering processing or the like required for accessing the recording medium or utilizing the contents from the recording and reproducing device can be decreased. |
