| 摘要 |
<p>If the generation of a master key that a reproducing apparatus has is older than that used when data is recorded and consequently the data cannot be reproduced, or if the generation of a master key that a recording apparatus has is older than that required when data is to be recorded on a record medium and consequently the data cannot be recorded, the user is prompted to update the master key, and the user acquires a required master key to perform reproducing or recording. the updated master key is delivered in the form handled only by a specific device through a transmission medium such as a record medium, a network, an IC card, or a telephone line by using, e.g., a tree-structured key delivery system.</p> |
