| 摘要 |
<p>PROBLEM TO BE SOLVED: To permit a viewer to view contents only once at time when the viewer desires to view, to record them in a medium, to copy and edit them in a different medium only once and to guarantee the security of data at that time. SOLUTION: A recording/reproducing device has a ciphering means 5 ciphering information where a plurality of unit blocks continue for respective unit blocks, a plurality of recording means 6 recording ciphered information, a decoding means decoding a plurality of unit blocks ciphered by the ciphering means 5 and a plurality of reproducing means reproducing decoded information. The seed of a password key for ciphering the unit block and the seed of the password key for decoding the ciphered unit block are information based on the password key when the unit block except for the prescribed unit block is ciphered.</p> |
