| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a technology capable of appropriately decrypting encrypted stream data. <P>SOLUTION: Stream data whose unencrypted region includes pointer information for pointing out a key used for decrypting data in encrypted region are processed. In this processing, a change in the pointer information extracted (U3) at decryption of the stream data is detected (U4a), and a decryption key of the stream data is generated (U2) from key generating data (U1) by using coincidence (U4b) between the pointer information whose change is detected and information (U6) established separately as a trigger. The data of the encrypted region of the stream data are decrypted (U5) on the basis of the decryption key generated in this way. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
