| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the efficiency from being deteriorated by controlling encryption in the unit of sectors with a data format fusing data of different systems. SOLUTION: Bits 32 (a1), 33 (a2) at the head of one sector are used for encryption control. The two bits and the remaining 30 bits are used for an IV (Initial Vector). Data of the bit 64 and theuafter are encrypted. In the MPEG2 system, control codes (a1, a2) are placed next to the head 32 bits (pack start code) and the SCR (System Clock Reference) is arranged after that. The IV comprises the SCR in 30 bits and the size of user data is 2016 bytes. In a conventional data format, the head 32-bits are used for reserved data or a system header, the 2-bit control codes a1, a2 are placed after them, and a random number is set to the remaining 30 bits. The control codes and the random numbers are the IV. The size of user data is 2016 bytes.</p> |
