| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent contents, which have already been written, from becoming unavailable when any malfunction such as ejecting a memory card from a device occurs during updating of key management information on the memory card. <P>SOLUTION: This invention relates to a host (100) to which an SD card (50) is connected. The SD card (50) stores thereon encrypted contents, a plurality of title keys (Kt) to be used for encrypting the contents, key management information (MKB), and a first application key (62) and a second application key (64) to be used for encrypting the plurality of title keys for each of applications of the contents. The host (100) includes: an updating unit (103) for updating the key management information; and a processing unit (110) for alternately updating the first and second application keys when updating the key management information. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
