| 摘要 |
<p>PCT No. PCT/GB91/00343 Sec. 371 Date Sep. 4, 1992 Sec. 102(e) Date Sep. 4, 1992 PCT Filed Mar. 5, 1991 PCT Pub. No. WO91/14341 PCT Pub. Date Sep. 19, 1991.A video encryption/decryption system in which lines of video information are stored in digitised form in a block of RAM memory, and are typically shuffled in groups of 32 lines by pivot reading information corresponding to 32 lines from the memory in a first predetermined order, which may for example be sequential order, and writing new input line information into the corresponding locations, and then reading from, and writing to, the memory in a second different order which may be random or pseudo-random, and subsequently repeating these two read/write operations alternately. This enables the line shuffling process to be achieved with a reduced memory requirement, compared with known methods.</p> |
