A signal reproducing apparatus for prohibiting copying or unauthorized use. The
apparatus includes a copying management information decision circuit 19
for discriminating the state of the copying management information read out from
each header of a data sector and within the TOC, a protect signal generating circuit
20 for generating a protect signal based on the discrimination signal and
a mixing circuit 24 for mixing a protect signal in a vertical blanking period
of an analog video signal D/A converted from digital video data reproduced from
an optical disc D. The apparatus also includes a descrambling circuit 31
for descrambling the digital data based on the copying management information and
a scrambling circuit 32 for descrambling the digital data. The apparatus
enables prohibition of unauthorized analog copying and digital copying, inhibition
of serial generational copying and prohibition of unauthorized analog and digital
copying simultaneously.