Method and apparatus for recording and reproducing information on and from recording medium

摘要

A scrambling key information piece is periodically changed among a plurality of different key information pieces including first and second key information pieces. An input signal is scrambled into a scrambling-resultant signal in response to the periodically changed scrambling key information piece. The scrambling-resultant signal, the first key information piece, and the second key information piece are recorded on the recording medium. The first key information piece which is used in the scrambling of a portion of the input signal recorded during a first recording interval is recorded on the recording medium during a second recording interval being longer than the first recording interval and containing the first recording interval.