Abstract:
A digital broadcast receiving and playing apparatus for receiving digital program data of pay broadcast, generating an apparatus individual key and a program key different in every program or every program division of a divided program in the receiving and playing apparatus, recording after scrambling the program data and program key by the apparatus individual key, controlling the number of times of display of program data received or played from memory device, thereby capable of prohibiting reproduction or display of program data more than the permitted number of times.

Description:
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. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     FIG. 1 is a block diagram of a digital broadcast receiving and reproducing apparatus in embodiment 1 of the invention. 
     FIG. 2 is a flowchart showing a permission judging procedure of output of digital data to a digital memory device  113  in embodiment 1 of the invention. 
     FIG. 3 is a flowchart showing generation of program key and multiplexing process of generated key and digital data in embodiment 1 of the invention. 
     FIG. 4 is a structural diagram of digital data in embodiment 1 of the invention. 
     FIG. 5 is a flowchart showing a permission judging procedure of output of digital data reproduced from the digital data memory device  113  into a video and audio output device  112  in embodiment 1 of the invention. 
     FIG. 6 is a flowchart showing an updating procedure of the number of times of limited use and program key when reproducing data from the digital memory device  113  in embodiment 1 of the invention. 
     FIG. 7 is a block diagram of a digital broadcast receiving and reproducing apparatus in embodiment 2 of the invention. 
     FIG. 8 is a block diagram of a digital broadcast receiving and reproducing apparatus in prior art. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Exemplary Embodiment 1 
     A first embodiment of a digital broadcast receiving and reproducing apparatus of the invention is described below while referring to FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG.  6 . 
     In FIG. 1, a digital broadcast receiver  101  receives digital broadcast, and picks up copy protection information, further demultiplexes plural programs transmitted in multiplexed form to pick up a program signal designated by the user, descrambles, if necessary, digital data by using a descramble key in the copy protection information, and takes out digital audio and digital video data. 
     A decoder  106  decodes digital audio data and/or digital video data when receiving or reproducing, converts into analog video signal and/or analog audio signal, and sends out to a data output judging unit  108 . 
     An apparatus individual key generator  102  generates and stores a scramble key for scrambling when sending the received digital data to the digital data memory device  113 , and a descramble key for descrambling the signal issued from the memory device  113 . The scramble key and descramble key are apparatus individual keys assigned in every apparatus. A program key generator  103  generates a different program key for every program by using the time information contained in the received digital data, and stores this key and the number of times of limited use in the copy protection information received in the receiver  101  in pair. Time information may be also obtained from a clock incorporated in the apparatus. 
     A scrambler  104  multiplexes digital audio data and digital video data sent from the receiver  101  and program key sent from the program key generator  103 , further scrambles this multiplexed digital data by the scramble key issued from the apparatus individual key generator  102 , and transfers it to a data output judging unit  108 . An output data selector  111  selects only one of the three as the type of output data, that is, only the decoded data, only digital data, or both of them. 
     When the selector  111  selects only the decoded data, the data output judging unit  108  transfers the decoded data to a decoded data output unit  107 . 
     Or when the selector  111  selects only the digital data, the data output judging unit  108  transfers the digital data to a record judging unit  109 . 
     Further, when the selector  111  selects both the decoded data and digital data, the data output judging unit  108  transfers the decoded data to the decoded data output unit  107  and the digital data to the record judging unit  109 . 
     The record judging unit  109  judges permission of recording by comparing the number of times of limited use in the copy protection information received in the receiver  101  and the number of types of data selected and issued by the data output judging unit  108 . If recording is possible as a result of judging, the scrambled digital data is transferred to a digital data input and output unit  110 . The decoded data output unit  107  protects analog data with generation management information, which is analog copy protection, for example, a copy protection of Macrovision Co., and sends analog audio signal and/or analog video signal to a video-audio output device  112 . The digital data input and output unit  110  sends the scrambled digital data sent from the record judging unit  109  to a memory device  113 . Further, this input and output unit  110  also transfers the scrambled digital data regenerated from the memory device  113  to the descrambler  105 . 
     The descrambler  105  descrambles the scrambled digital data sent from the input and output unit  110  by the descramble key from the apparatus individual key generator  102 , and takes out the program key and digital audio and digital video data. 
     Further, the descrambler  105  compares the program key taken out from the descrambled digital data, and the program key stored in the program key generator  103 , confirms the coincidence of the two keys, judges permission of reproduction depending on the result of comparison and the number of times of limited use, and, if permitted to reproduce, transfers the descrambled digital data to the decoder  106 . The decoder  106  decodes the digital data reproduced from the digital data memory device  113 , and converts into analog video signal and/or analog audio signal, and sends the data to the decoded data output unit  107 . 
     The procedure of issuing the digital data received in the receiver  101  to the memory device  113 , and judging permission of memory is explained below while referring to FIG.  2 . 
     The receiver  101  receives a digital broadcast program, and issues the received digital data (step  201 ), the scrambler  104  checks if the received program is a pay broadcast or not (step  202 ), and if the checking result is free broadcast, the digital data can be recorded in the memory device  113  (step  203 ), or in the case of a pay broadcast, the scrambler  104  checks if the number of times of use of the digital data is limited or not (step  204 ). 
     The limitation of the number of times of use is judged by the number of times of limited use mentioned in the copy protection information in the digital data. As a result of checking, if the number of times of use is not limited, the program key generator  103  generates plural zero bit rows, for example, 0000 as the program key (step  205 ), and the apparatus individual key generator  102  generates the individual scramble key for the apparatus (step  206 ). As a result of checking at step  204 , if the number of times of use is limited, the program key generator  103  generates a different program key for every program. The program keys must be set individually so as not to be duplicated, and, for example, an eleven-digit figure showing the time may be used, that is, year-month-month-day-day-hour-hour-minute-minute-second-second (step  207 ). 
     The program key generator  103  stores the program key and the number of times of limited use in pair (step  208 ), and the apparatus individual key generator  102  generates a complement of apparatus individual key as scramble key (step  209 ). 
     The scrambler  104  multiplexes digital data of pay broadcast or free broadcast and program key (step  210 ), and scrambles the multiplexed digital data by using each scramble key (step  211 ). 
     Consequently, the data output judging unit  108  judges if the type of the output data designated by the user through the selector  111  is decoded data only or not (step  212 ), and in the case of decoded data only, the received digital data is decoded and issued to the display device, and there is no output to the recording device (step  213 ), and otherwise the data output judging unit  108  judges again whether digital data only or not (step  214 ), and in the case of digital data only, the scrambler  104  sets  0  as the number of times of present use which is the number of times of use of data during the present processing (step  216 ), and in the case of not digital data only, that is, both digital data and decoded data are judged, the scrambler  104  sets  1  as the number of times of present use (step  215 ). 
     Next, the scrambler  104  judges whether the program key is 0000 or not (step  217 ), and if not 0000, such digital data is prohibited from being issued to the memory device  113  (step  218 ), and if the program key is 0000, the scrambler  104  judges if the number times of present use is smaller than or equal to the number of times of limited use (step  219 ). 
     If not smaller as a result of judging, such digital data is prohibited from being issued to the memory device  113  (step  220 ), and if smaller, the program key generator  103  subtracts the number of times of present use from the number of times of limited use, and updates the result as a new number of times of limited use (step  221 ), and such digital data is issued to the memory device  113  (step  222 ). 
     In the event of limitation in the number of times of use, generation of program key and program end key, and scrambling and multiplexing process of the generated keys are described in detail below while referring to FIG.  3 . 
     As for the program key, meanwhile, either one same key is 
     defined throughout one program, or different program keys are defined for each program division which are generated by dividing one program into plural divisions in every specified time (for example, every 5 minutes). 
     The receiver  101  receives a digital broadcast program, and issues the received digital data (step  301 ). 
     The scrambler  104  checks if the digital data being received and processed at the present is beginning transport data of program or program division, or not (step  302 ), and in the case of beginning transport data, the program key generator  103  generates the program key different in every program which is, for example, a twelve-digit figure added zero to the end of the time code consisting of year-month-month-day-day-hour-hour-minute-minute-second-second, and generates (step  303 ), and the scrambler  104  multiplexes this program key and the digital data being processed (step  304 ). 
     As a result of checking, if not beginning transport data, the scrambler  104  checks if the digital data being processed is final transport data of program or program division, or not (step  305 ), and if final, the program key generator  103  generates a different program end key in every program or every program division. The program end key should be set so as not to duplicate, and to be stored in pair with the program key, and, for example, a twelve-digit figure may be used by adding  1  to the end of the time code consisting of year-month-month-day-day-hour-hour-minute-minute-second-second (step  306 ). 
     Further, the scrambler  104  multiplexes the program end key and digital data being processed (step  307 ). 
     The scrambler  104  scrambles by exclusive OR operation of digital data multiplexed with program key or program end key, or non-multiplexed digital data, with the scramble key (step  308 ). 
     The data structure of received digital data is specifically described below while referring to FIG.  4 . 
     The digital data taken out by the receiver  101  is a group of transport data  401 . The transport data  401  consists of a header  402  for storing information of data, and a payload  403  for storing audio and video data. 
     The header  402  includes a scramble bit  404  of two bits for storing information of scramble, and private data  405  of variable byte length capable of storing original data. 
     In the scramble bit  404 , specifically, 00, 01 or 10 is stored in order to distinguish non-pay broadcast program, that is, non-scrambled program, and pay broadcast program, that is, scrambled program not limited in the number of times of use and scrambled program limited in the number of times of use. 
     In the private data  405 , program key or program end key is stored. The method of storing is as follows. The program key generator  103  creates transport data showing program end key or program key, the scrambler  104  stores the transport data of the program end key in the final private data  405  of program or program division, and stores the transport data of program key in the beginning private data  405  of program or program division. 
     In the front and rear blanks of the scramble bit  404  and private data  405  in FIG. 4, flags and data are stored, but since they are not related to the invention, their description is omitted. 
     Scrambling is applied to the subsequent data excluding the scramble bit  404  of the transport data  401 . 
     Next, the procedure of judging permission of output of the digital data reproduced from the memory device  113  into the video and audio output device  112  is described while referring to FIG.  5 . 
     First, by the control of the input and output unit  110 , digital data is reproduced from the memory device  113  (step  501 ). 
     The descrambler  105  extracts the scramble bit  404  from the reproduced digital data (step  502 ), and checks whether the digital data is free broadcast or not, that is, whether the scramble bit  404  is 00 or not (step  503 ). 
     If the result of checking is free broadcast, that is, 00, the digital data can be issued to the video and audio output device  112  (step  504 ). 
     On the other hand, if the result of checking is pay broadcast, that is, other than 00, the descrambler  105  checks again whether the number of times of use of the digital data is limited or not, that is, whether the scramble bit  404  is 01 or not (step  505 ). 
     If the result of checking is not limited, that is, 01, the descrambler  105  generates an apparatus individual key as the descramble key (step  506 ), and if limited, the descrambler  105  generates a complement of the apparatus individual key as the descramble key (step  507 ). 
     Consequently, using the generated descramble key, the descrambler  105  descrambles the reproduced digital data (step  508 ), and further demultiplexes the descrambled digital data, and extracts a program key (step  509 ). 
     The descrambler  105  checks the extracted program key, and checks if the digital data is limited in the number of times of use or not, that is, whether the program key is 0000 or not (step  510 ). 
     As a result of checking, if the number of times of use is not limited, such digital data can be issued (step  513 ), and if limited, the descrambler  105  compares the regenerated program key and the program key of the program stored in the program key generator  103 , and checks whether two are matched or not (step  511 ). 
     If not matching, output of the digital data is prohibited (step  512 ), and if matching, output is permitted (step  513 ). 
     Referring now to FIG. 6, the updating process of the number of times of limited use and the program key is described below, that is, when reproducing the digital data limited in the number of times of use, the number of times of limited use stored in the program key generator  103  is decreased, and the program key is erased as required. 
     First, by the control of the input and output unit  110 , digital data is reproduced from the memory device  113  (step  601 ). 
     The descrambler  105  descrambles the reproduced digital data by using the descramble key (step  602 ). 
     The descrambler  105  checks whether program end key is provided or not in the transport data of the descrambled digital data (step  603 ). As a result of checking, when there is no program end key in the transport data, if the transport data is used, it is not necessary to update the number of times of limited use and the program key (step  604 ), and when program end key is present, 1 is subtracted from the number of times of limited use stored in the program key generator  103 , and the value is stored newly in the program key generator  103  as the updated number of times of limited use (step  605 ). 
     The descrambler  105  checks whether the updated number of times of limited use is larger than zero or not (step  606 ), and if the number of times of limited use is not larger than zero, the program key generator  103  deletes the program key and program end key of the pertinent program or the pertinent program division (step  607 ), and if the number of times of limited use is larger than zero, the program key and program end key is not deleted (step  608 ). 
     Exemplary Embodiment 2 
     A second embodiment of digital broadcast receiving apparatus of the invention is described below while referring to FIG.  7 . In the following explanation, only the different points from the first embodiment are mainly described, and explanation of common parts are omitted. 
     In FIG. 7, the digital broadcast receiver  101  picks up digital audio and digital video data by same means as in the first embodiment. 
     The digital audio and digital video data of a program picked up by the receiver  101  are sent into the decoder  106  and scrambler  104 . 
     The decoder  106  decodes the digital audio and/or digital video data when receiving or reproducing, converts into analog video and/or analog audio, and sends data to the data output judging unit  108  and decoded data output unit  107 . 
     An apparatus individual key generator  701  generates a scramble key used when sending digital data to the memory device  113  and a descramble key used when reproducing, on the basis of the ID code stored in a detachable smart card (ID card)  703 . 
     The scramble key and descramble key are generated by operating, for example, the ID code by exclusive OR of 10101010 in every byte, and are individually assigned in every apparatus. 
     A program key generator  702  generates a different program key for every program by using the time information mentioned in the received digital data, and the program key and the number of times of limited use of copy protection information received in the receiver  101  are stored in the smart card  703 . 
     The scrambler  104  multiplexes the digital audio data and digital video data sent from the receiver  101  and the program key sent from the program key generator  702 , and scrambles the multiplexed digital data by the scramble key from the apparatus individual key generator  701  and sends out the scrambled digital data to the data output judging unit  108 . 
     The descrambler  105  descrambles the scrambled digital data sent from the digital data input and output unit  110  by the descramble key from the apparatus individual key generator  701 , and picks up the program key and digital audio data and/or digital video data. 
     Furthermore, the descrambler  105  compares the program key picked up from the descrambled digital data, and the program key stored in the program key generator  702 , and confirms the two keys are matched, and judges permission of reproduction by using the result of comparison and the number of times of limited use, and if reproduction is permitted, the descrambled digital data is transferred to the decoder  106 . 
     The decoder  106 , the decoded data output unit  107 , data output judging unit  108 , record judging unit  109 , digital data input and output unit  110 , and output data selector  111  are exactly same as in the first embodiment, and their description is omitted. 
     Moreover, the permission judging procedure of output of the digital data received in the digital broadcast receiver  101  into the memory device  113 , the generation of program key and multiplexing process of generated keys and digital data, the scrambling process of multiplexed digital data, the data structure of multiplexed digital data, the permission judging procedure of output of reproduced digital data from the digital data memory device  113 , and the updating procedure of the number of times of limited use and program key when reproducing are exactly same as in the first embodiment, and their description is omitted. 
     In the description of the first embodiment, the program key is set by including the time information, but not limited to this, program keys may be any others as far as they are different and not duplicate keys in every program, and, for example, sequential values increasing in every record may be used. 
     In a program limited in the number of times of use, the complement of the apparatus individual key is used as the scramble key and descramble key, but any other code may be used as far as different from the apparatus individual key, such as complement of 2, and moreover, in a program limited in the number of times of use, if the apparatus individual key same as the key as in the program not limited in the number of times of use is used as the scramble key and descramble key, the protection of copyright is effective although resistance to hacking is lower than in the embodiment. 
     The program division is shown as an interval of every 5 minutes, but the interval is not limited to 5 minutes, and other time intervals or non-uniform time intervals may be also set. 
     As the program end key and program key, 1 and 0 are added to the time information, but other codes may be also added as far as the program end key and program key can be distinguished as a pair. 
     In the scrambling process, the digital data is operated by the scramble key and exclusive OR, but scrambling process may be also executed by other logic operation or data exchange. 
     To distinguish a program not scrambled, a program scrambled but not limited in the number of times of use, and a program scrambled and limited in the number of times of use, 00, 01, and 10 are respectively set in the scramble bit  404 , but the scramble bit  404  may have other bit pattern as far as the combination of bit patterns can be distinguished. 
     If a same scramble key is used in a program not limited in the number of times of use and a program limited in the number of times of use, a same bit pattern may be used in the scramble bit  404  in a program not limited in the number of times of use and a program limited in the number of times of use. 
     In the foregoing example, the scrambling position is right after the scramble bit  404  of the transport data  401 , but the scrambling position is not limited to right after the scramble bit  404  as far as it is after the private data  405 . However, if only the payload  403  is scrambled, the resistance to hacking is lower than in the embodiment, but the protection of copyright is effective. 
     The structure of data to be sent to the memory device  113  is explained in an example of transport data  401 , but the data structure may be also a packet and/or pack of one or plural transport data  401 . 
     The transport data composed of program key and program end key is mentioned in the private data  405 , but without composing transport data, the program key and program end key may be directly written into the private data  405  of the digital data being processed, or one program key or program end key may be divided into, for example, several bits, and distributed in the private data  405  of plural pieces of transport data. 
     In the explanation of embodiment 2, the apparatus individual key is obtained by ID code in the smart card  703  and exclusive OR operation with the data of 10101010 in every byte, but this apparatus individual key may be obtained by other logic operation for determining one apparatus individual key from one ID code, or by using completely different data. 
     Thus, according to the invention, the scrambled video and audio data can be reproduced only in the received apparatus or can be reproduced by the specified times only in the received apparatus in the case of ordinary pay broadcast, and can be reproduced once only in the received apparatus in the case of pay-per-view, and in anyway the copyright can be protected. 
     Moreover, the copy protection control code which is the key of pay broadcast system is not issued outside of the receiving and reproducing apparatus, and therefore the resistance to hacking is high, and it is expected to realize a digital broadcast receiving and reproducing apparatus applicable not only to the digital VCR, but also to magnetic disk device, write once type magneto-optical disk device, and rewritable magneto-optical disk device.