| 摘要 |
<P>PROBLEM TO BE SOLVED: To update an authentication key in a short time and to keep security even without intention of a user of an information recording medium during a normal operation. <P>SOLUTION: The information recording medium includes information files 28 and key files 29 positioned at respective memory addresses 21, file identifiers 22 for identifying the files, and information 23 of the files for storing a kind of the file and data contents or the like. The information file 28 is provided with a key setting number storage part 24 for storing the number of key files to be the authentication key, a key information storage part 25 for storing information corresponding to the key files in the order of use as the authentication key, and a key valid state storage part 26 for storing whether or not it is valid as the authentication key. When key data of the authentication key leaks or the like, the key valid state storage part 26 of the authentication key with the trouble is changed from being valid to invalid, the key valid state storage part 26 of the key file 29 to be the authentication key next in the setting of the key information storage prat 25 is changed from being invalid to valid, and thus the authentication key is updated. <P>COPYRIGHT: (C)2013,JPO&INPIT |
