Cryptography – Video cryptography – Copy protection or prevention
Reexamination Certificate
1999-02-25
2002-10-08
Smithers, Matthew (Department: 2132)
Cryptography
Video cryptography
Copy protection or prevention
C705S057000
Reexamination Certificate
active
06463152
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a digital broadcast receiving and reproducing apparatus having a function of protecting the copyright by preventing unauthorized viewing or copying of digital broadcast.
A digital broadcast receiving and reproducing apparatus according to a prior art is disclosed, for example, in Japanese Laid-open Patent No. H9-93561.
FIG. 8
is a block diagram of digital broadcast receiving and reproducing apparatus of prior art.
This receiving and reproducing apparatus comprises a smart card (ID card)
804
storing a copy protection control code for judging permission of reception of broadcast, a digital VCR
805
recording digital data, and a digital broadcast receiver
801
. The digital broadcast receiver
801
includes a descrambler
802
for canceling the scramble coded into program data, and a recording and digital output controller
803
for generating and issuing digital data and copy protection control code. The digital VCR
805
is
connected to the receiver
801
through data input and output ports
and provided with control signals for input and output data and erasing data recorded in tape.
In the digital broadcast receiving and reproducing apparatus according to such prior art, as the memory device of digital data, it is expected to be developed not only into the digital VCR, but also into magnetic disk device, write once type magneto-optical disk device, and rewritable magneto-optical disk device. Moreover, there is an increasing demand for digital broadcast receiving and reproducing means for pay broadcast and/or pay-per-view, capable of protecting the copyright of the broadcast program by allowing only the subscribers to reproduce in ordinary pay broadcast or allowing to reproduce only once in pay-per-view, and without recording the copy protection control code, which is the key of broadcasting system, in the recording medium so as to be high in hacking resistance.
SUMMARY OF THE INVENTION
To solve the problems, the digital broadcast receiving and reproducing apparatus of the invention is a digital broadcast receiving and reproducing apparatus for receiving digital broadcast, demodulating received digital data, and taking out analog signal and copy protection information from the digital data, which comprises an apparatus individual key generator for generating and storing an individual key for the receiving and reproducing apparatus, a program key generator for generating a program key for every received program and storing this program key and the number of times of limited use in the copy protection information, a scrambler for multiplexing the program key and the demodulated digital data and scrambling by the apparatus individual key, a record judging unit for judging permission of recording of the scrambled digital data, and a digital data memory device for recording digital data through the record judging unit.
This digital broadcast receiving and reproducing apparatus further comprises a descrambler for descrambling the scrambled digital data reproduced from the memory device by using the apparatus individual key, extracting the program key from the scrambled digital data, and comparing the extracted program key and the program key stored in the program key generator. The digital broadcast receiving and reproducing apparatus of the invention is characterized by determining permission of output of digital data from the number of times of limited use and the result of the comparison.
Thus scrambled video and audio data can be reproduced, in the case of ordinary pay broadcast, only in the apparatus used for receiving or can be reproduced by the specified number of times in the apparatus used for receiving only, or in the case of pay-per-view, it is permitted to reproduce once only in the received apparatus. In this way, the key of the broadcast system, that is, the copy protection control code is not sent out of the receiving and reproducing apparatus, it has a high resistance to hacking, and not limited to the digital VCR, the digital broadcast receiving and reproducing apparatus is applicable to other recording device such as magnetic disk device, write once type magneto-optical disk device, or rewritable magneto-optical disk device.
REFERENCES:
patent: 5991400 (1999-11-01), Kamperman
patent: 6282293 (2001-08-01), Itoh et al.
patent: 9-93561 (1997-04-01), None
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
Smithers Matthew
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