| 摘要 |
PROBLEM TO BE SOLVED: To prevent that programs cannot be viewed because of an acquisition failure of the latest work key (Kw) if power is turned off for a long time in a receiver or a transmitter is temporarily updated for security. SOLUTION: Even in a method that a receiver actively acquires an EMM, a transmitter inputs information on a work key (Kw) distributed by the EMM into an ECM, and update information on the work key (Kw) which is stored in the ECM is referred to be used when programs are viewed. Thereby, the receiver can acquire an update situation of the work key (Kw), and update operations can be performed if necessary. COPYRIGHT: (C)2009,JPO&INPIT
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