JP2009246990A - Conditional access system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conditional access system in which contents broadcast from a broadcast center can be relayed in simple configuration without being descrambled at a relay station and further, the relay station can originally perform viewing control on a terminal device. <P>SOLUTION: When a broadcast signal from a broadcast center is relayed through a CATV station, viewing possibility information required for viewing is added to a part of signals, such as e.g., transmission control information. Further, if the viewing possibility information is not received for a specific time, a part of or all streams from a transmission line are disabled from being viewed. Thus, the CATV station can perform original viewing control, in simple configuration, regardless of performing modulation, conversion and retransmission without descrambling contents transmitted from the broadcast center. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a conditional access system that transmits content such as scrambled video, audio, or data sent from a center device of a digital broadcasting system to a terminal device via a relay device such as a CATV station, and more particularly, modulation conversion. It is possible to control viewing of the terminal device with a relay device of the system.

Conventionally, in the fields of digital broadcasting and digital CATV broadcasting, in order to effectively use communication resources, programs provided by a plurality of broadcasters are multiplexed and transmitted through one channel. This is called TMCC (Transmission Multiplexing Configuration Control) in BS digital broadcasting (multiple TS transmission format), for example, and is transmitted by being superimposed on a packet synchronization signal, and is received from a single frequency band based on the TMCC signal on the receiving side. TS can be taken out.

In the conventional retransmission method, two methods, a modulation conversion method and a remultiplexing method, are known as methods for retransmitting a scrambled stream sent from a broadcasting center or the like to a CATV terminal device. In the modulation conversion method, the stream is retransmitted only by changing a part of the program arrangement information without performing descrambling and re-scramble of the content in the CATV station. In this system, all conditional access management is performed at the broadcast center. On the other hand, in the remultiplexing scheme, the CATV station descrambles the received stream, adds its own limited reception information, and simultaneously re-scrambles the content and sends it to the CATV terminal device.

FIG. 14 shows a main part of a system configuration of a conventional modulation conversion system. Broadcast center 1401 and CATV station 1409 are connected by a satellite line using satellite 1408, and CATV station 1409 and terminal device 1415 are connected by a CATV line.

The broadcast center 1401 sends a content server 1402 for sending content such as video and audio, an identifier (PID) for identifying the content and a scramble key (Ks) to the scrambler 1405, and encrypts common information (ECM). ) Or individual information (EMM) to the multiplexing unit 1403, a limited reception control unit 1504, a multiplexing unit 1403 that multiplexes the ECM, EMM, and contents into one stream, and a PID specified in the stream A scrambler 1405 that scrambles the content with Ks and a transmission unit 1406 that modulates the stream and transmits the stream to the satellite line via the transmission antenna 1407 are provided.

The CATV station 1409 receives a stream from the satellite line via the receiving antenna 1410 and performs demodulation processing, and a PSI that converts part of the program sequence information (PSI) from satellite transmission to cable transmission. A conversion unit 1412; a QAM modulator 1413 that modulates a signal to a QAM system defined by CATV; and a frequency conversion unit 1414 that converts the modulated stream into a CATV transmission frequency and transmits the CATV transmission frequency to the CATV network. .

In the broadcast center 1401 of this system, the content server 1402 transmits content including video and audio to the multiplexing unit 1403.

The conditional access control unit 1404 encrypts an ECM having a determination area for determining permission to view content and Ks obtained by scrambled content with a work key (Kw) and transmits the encrypted ECM to the multiplexing unit 1403. The EMM having the contract information area for giving permission to view content to the 1415 and the Kw obtained by encrypting the ECM is encrypted with the master key (Kmi) unique to each terminal device 1415 and transmitted to the multiplexing unit 1406. Further, the limited reception control unit 1404 transmits a PID and Ks for identifying content to be scrambled to the scrambler 1405.

The multiplexing unit 1403 multiplexes the received content, the ECM, and the EMM as one stream and transmits it to the scrambler 1405. The scrambler 1405 has the PID specified by the conditional access control unit 1404 in the received stream. Is scrambled and transmitted to the transmission unit 1406. The transmission unit 1406 performs transmission processing such as modulation according to the satellite channel, and transmits the stream to the satellite channel via the transmission antenna 1507.

On the other hand, in CATV station 1409, reception unit 1411 receives a stream from the satellite line via reception antenna 1410, performs reception processing such as demodulation, and transmits the received stream to PSI conversion unit 1412. The PSI conversion unit 1412 is a part of PSI, and converts a network management table (NIT) for transmitting information associating transmission path information such as a modulation frequency and content from satellite transmission to cable transmission. The QAM modulator 1413 transmits the data to the QAM system defined by CATV, and transmits the modulated signal to the frequency converter 1414. The frequency converter 1414 converts the stream into a CATV transmission frequency and converts it into a CATV network. To send.

When the terminal device 1415 receives the stream from the CATV network, decrypts the EMM addressed to itself, retains the contract information and Kw, and views the scrambled content, first, the ECM associated with the content is displayed. It is received and decrypted with Kw, and the judgment area in the ECM is compared with the contract information to check whether viewing is permitted. If it is determined that “viewing permission exists”, the content can be descrambled using Ks in the ECM and can be viewed.

As described above, in the modulation conversion method, the CATV station 1509 simply converts the stream into a modulation method suitable for the CATV network, and does not need to decode the ECM or EMM, and does not participate in the contents of the stream. Can be relayed to. In this system, the center device can be realized at a small scale and at low cost, but the viewing management based on the limited reception of each terminal device 1415 is all performed by the broadcast center 1401.

FIG. 15 is a diagram illustrating a main part of the CATV station as a remultiplexing type relay apparatus that adds unique limited reception information in the CATV station.

The configuration of the broadcast center 1501 and the CATV terminal 1517, and the point that the broadcast center 1501 and the CATV station 1509 are connected by a satellite line using a satellite 1508, and the CATV station 1509 and the terminal device 1517 are connected by a CATV network are modulated. This is the same as the conversion method.

The CATV station 1509 receives the stream from the satellite line via the reception antenna 1510, and performs reception processing such as demodulation including scramble decoding, reception units 1510 and 1511-1 to 1511-3, and PID and Ks as scrambler 1514. A limited reception control unit 1513 that transmits ECM and EMM to the multiplexing unit 1512, and a multiplexing unit that multiplexes the output from each reception unit, program arrangement information (such as NIT) for CATV transmission, and ECM and EMM. 1512, a scrambler 1514 that scrambles the content having the specified PID in the stream with Ks, a QAM modulator 1515 that modulates the signal into a QAM system defined by CATV, and a CATV transmission of the modulated stream. And a frequency conversion unit 1516 that converts the frequency and sends it to the ATV network. .

The broadcast center 1501 of this system performs exactly the same operation as the modulation conversion method. In the CATV station 1509, the receiving units 1510 and 1511-1 to 1511-3 receive the stream from the satellite line via the receiving antenna 1510, perform reception processing such as demodulation including scramble decoding, and transfer the content in the transport stream format. Transmit to the multiplexing unit 1512. The multiplexing unit 1512 multiplexes a plurality of transport streams into one transmission path, and simultaneously multiplexes the program arrangement information (such as NIT) for CATV transmission and the ECM and EMM sent from the limited reception control unit 1513, Send to scrambler 1514.

The scrambler 1614 scrambles the content having the PID similarly sent from the conditional access control unit 1513 with Ks sent from the conditional access control unit 1513, and transmits the scrambled content to the QAM modulator 1515. 1515 modulates to the QAM system defined by CATV and transmits it to the frequency converter 1516. The frequency converter 1516 converts the stream into a CATV transmission frequency and sends it to the CATV network.

As described above, in the remultiplexing method, the limited reception unique to the CATV station can be added. Moreover, there exists a thing as shown in patent document 1 as a prior art.

JP 2000-244888 A

However, since the conventional modulation conversion method uses the limited reception method at the broadcasting center as it is in the CATV terminal, the terminal is connected without permission to the CATV line, and the content retransmitted from the CATV station is viewed without permission. Fraud may occur.

For example, if a signal demodulating means corresponding to CATV is provided in the front-end unit of a direct receiving terminal that can directly receive a broadcast from a broadcasting center through a satellite line, the user can view the retransmitted content sent through the CATV line. Is possible. Even if such a receiving terminal is connected to the CATV line without obtaining the permission of the CATV operator, the CATV station cannot grasp it. Therefore, the CATV station cannot collect the viewing fee for the user of this terminal.

In order to avoid such a situation, it is required that the CATV operator can manage the CATV terminal and perform unique viewing control.

On the other hand, in the conventional remultiplexing method, after demodulating the stream sent from the broadcast center into the transport stream format, information related to limited reception is added in the same way as the broadcast center, so descrambling and re-scramble etc. Installation of a limited reception system having a stream processing facility and a means similar to that of a broadcasting center is required, which causes an increase in the scale and cost of a CATV station. The present invention solves such conventional problems, and provides a conditional access system capable of limiting the viewing of retransmitted content only to terminal devices permitted by a CATV station while adopting a modulation conversion method. It is an object.

Therefore, in the present invention, one or more center devices and one or more relay devices are connected by a first transmission line, and the relay device and one or more terminal devices are connected by a second transmission line, A first stream including scrambled content, encrypted EMM, and encrypted ECM is transmitted from the center device to the relay device via the first transmission path, and the relay device transmits the scrambled content and the encrypted data. In a conditional access system of a digital broadcasting system that includes an encrypted EMM and an encrypted ECM as they are in a second stream and transmits them to a terminal device via a second transmission path, the relay device uses the transmission control information to view In addition to transmitting the permission information to the terminal device, the front end unit in the terminal device extracts viewing permission information from the transmission control information and includes a stream including a permitted program. Is a limited reception system that enables control to selectively send a program to a content decoding processing unit that cancels limited reception given by a broadcaster, and when the viewing permission information is not received for a specific time. Comprises means for disabling viewing or viewing of part or all of the second stream from the second transmission path.

With this conditional access system, a relay device adopting a modulation conversion system performs limited reception of a terminal device that has jurisdiction using the conditional access means of the center device, and at the same time uses a transmission control information generated by a CATV station. Can be restricted.

As is apparent from the above description, the conditional access system of the present invention is unique to the CATV station in a simple manner without changing the limited reception information and contents on the satellite side when relaying satellite broadcasting in the CATV station. Therefore, even in the modulation conversion method, there is an effect that the viewing control of the terminal device can be performed independently by the CATV station.

1 is an overall configuration diagram of a conditional access system according to a first embodiment of the present invention. The internal block diagram of the broadcast center in the 1st Embodiment of this invention The internal block diagram of the relay station in the 1st Embodiment of this invention The internal block diagram of the terminal device in the 1st Embodiment of this invention The figure explaining the viewing availability information in the first embodiment of the present invention The figure explaining the viewing availability information in the first embodiment of the present invention The figure explaining the viewing availability information in the first embodiment of the present invention The internal block diagram of the terminal device in the 1st Embodiment of this invention The internal block diagram of the terminal device in the 1st Embodiment of this invention The internal block diagram of the terminal device in the 1st Embodiment of this invention Internal configuration diagram of relay station according to the second embodiment of the present invention The internal block diagram of the terminal device in the 2nd Embodiment of this invention Internal configuration diagram of relay station according to the third embodiment of the present invention The figure explaining the conventional modulation conversion system The figure explaining the conventional re-multiplexing system

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments, and can be implemented in various modes without departing from the scope of the invention.

(First embodiment)
In the first embodiment, a digital broadcasting system that is an example of a conditional access system and broadcasts a satellite broadcast via a CATV station will be described.

FIG. 1 is a block diagram showing the overall configuration of this system. The broadcasting center 101 and the CATV station 105, and the broadcasting center 101 and the direct receiving terminal 104 are connected by a satellite line 102 using an artificial satellite 103, and contents such as video and audio are transmitted from the broadcasting center 101 through this line. The The CATV station 105 and the CATV terminal 107 are connected via the CATV line 106, and the retransmitted content is transmitted from the CATV station 105 to the CATV terminal 107. The broadcast center 101 transmits broadcast radio waves to the satellite line 102, and the direct receiving terminal 104 receives radio waves directly from the satellite line 102. The CATV station 105 relays broadcast radio waves received from the satellite line 102 to the CATV line 106, and the CATV terminal 107 receives this from the CATV line 106.

FIG. 2 is an example of a block diagram showing the main part of the internal configuration of the broadcast center 101. The broadcast center 101 reconfigures the TS created by each broadcaster, generates a single transmission stream by combining multiple information (TMCC) with superposition on a single transmission frequency band, and is suitable for satellite channels. After conversion to the transmission method, transmission to the relay station is performed by the transmission antenna.

Streams including video and audio generated by broadcasters 201 to 203 in the broadcast center 101 are input to the TMCC processing unit 204 as respective transport streams (TS). The TMCC processing unit 204 multiplexes TSs of a plurality of broadcasters 201 to 203 into one transmission band, and at the terminal side, outputs a TMCC signal that is information for extracting a stream for each broadcaster from the plurality of TSs. Append. A plurality of TS and TMCC signals in one transmission band generated by the TMCC processing unit 204 are modulated by the modulation unit 205 in a method suitable for the satellite transmission path, and then transmitted to the satellite line 105 via the transmission antenna 206. Sent.

FIG. 3 is an example of a block diagram illustrating a main part of the internal configuration of the relay station 102. The relay station 102 selects and reconfigures a TS to be retransmitted from a transmission stream composed of a plurality of TSs transmitted from the broadcast center 101 through the satellite line 105.

The relay station 102 receives a stream including a plurality of TS and TMCC signals generated at the broadcasting center 101 via the reception antenna 301, selects a frequency band at the tuner 302, and inputs the stream to the demodulation unit 303. The demodulator 303 demodulates a plurality of baseband level TSs including TMCC from the output of the tuner 302 and inputs them to the transmission control signal processor 304. The transmission control signal processing unit 304 selects, reconstructs a plurality of TSs, generates a CATV transmission control signal based on the TMCC signal given by the broadcasting center 101, and generates the control unit 305. In addition, the CATV station uniquely inputs the viewing permission / inhibition information and inputs it to the modulation unit 306. Thereafter, the stream generated in the transmission control signal processing unit 304 is modulated by the modulation unit 305 into a method suitable for the transmission method in CATV, and transmitted to the CATV line 106.

FIG. 4 is an example of a block diagram illustrating a main part of the internal configuration of the terminal device 103. The terminal control device 103 receives a stream selection based on the viewing availability information added by the CATV station 102, and receives a plurality of demodulated TSs from the front end unit 401, and decodes the corresponding content. It consists of a content decryption processing unit 405.

In terminal apparatus 103, a stream transmitted from relay station 102 via CATV line 106 is selected by tuner 402, demodulated to a baseband level signal by demodulator 403, and transmitted to transmission control information analyzer 404. input. The transmission control information analysis unit 404 extracts the transmission control information, further extracts viewing permission / inhibition information in the transmission control information, and inputs only TS including a program that can be selected by the terminal device to the content decoding processing unit 405. The content decryption processing unit 405 has the same function as that of a general satellite broadcast receiving apparatus, and performs limited reception processing and video decoding processing on the selected TS as necessary. Note that the selection operation by the user is mainly performed on the content decryption processing unit 405, and information necessary for the operation of the front end unit 401 is communicated.

The operation of the conditional access system having the above configuration will be described in more detail. The TMCC processing unit 204 of the broadcast center 101 superimposes the streams input from each provider and outputs them in the MPEG2 transport stream format. At this time, when a plurality of TSs are mixed, information receivable by the terminal device is transmitted as a TMCC signal in accordance with the stream.

The relay station 102 receives and reconfigures TSs transmitted by CATV from a plurality of demodulated TSs. At this time, referring to the TMCC signal added by the broadcasting center 101, the selected single TS is extracted, and transmission control information is generated and added when retransmitted by CATV based on the TMCC signal. To do.

For example, the transmission control information includes the front end unique ID 501 for specifying the front end shown in FIG. 5 and the content viewing permission / inhibition information 502 for making a selection / transmission determination to the content decoding unit 405 for each program or front end unique ID. The

Further, viewing permission / inhibition information will be described. An example of viewing availability information is shown in FIG. In FIG. 6, the original network ID and the TS-ID are used as information for program identification, and viewing permission / non-permission (1 · 0) is set in each case, and is managed by the control unit 305 in the relay station 102. The

As described above, the relay station 102 inserts transmission permission / inhibition information for performing terminal viewing control uniquely into the transmission control information and transmits it.

In the terminal device 103, frequency information, a program number, and the like related to the program selected by the content decoding processing unit 405 are input to the front end unit 401. In the front end unit 401, based on the program selection information specified by the content decoding processing unit 405, the tuner 402 and the demodulation unit 403 decode the desired TS and the baseband signal of the transmission control information, and the transmission control signal analyzing unit Input to 404. The transmission control signal analysis unit 404 extracts / analyzes the viewability information in the transmission control information, and sends the viewable TS to the decoding processing unit 405.

With the operation as described above, it is possible to add viewing control unique to the CATV station (relay station) without changing the content of the stream content created in the broadcast center 102.

Note that the front-end unique ID 501 and the viewing permission / inhibition information 502 are not limited to this, and may include control parameters for viewing control. It is also conceivable to perform the same viewing permission control on all terminals without including the front end unique ID 501 as viewing permission information. Furthermore, there is a case where viewing permission control in units of groups is performed as one operation form of the front end unique ID or as a new ID.

Furthermore, viewing permission / inhibition control may be performed by using a transport stream, original network ID, and a combination thereof as viewing permission / inhibition information.

Further, the terminal device 103 is provided with the output control unit 805 shown in FIG. 8, and the content decryption processing unit 808 is provided with communication means corresponding thereto, so that the front end unit 801 and the content decryption processing unit 805 are independent. It is also possible to operate as a device. At that time, as a communication means in the output control unit 805, for example, a general-purpose serial interface such as IEEE1394 or a BS-IF frequency band may be used.

Furthermore, as shown in FIG. 9, it is possible to provide a viewing control module in the front end unit 901 of the terminal device 103 and store the viewing availability information of the terminal device 103 in advance. It is also possible to change the format of information. At this time, the viewing control module 905 can be a removable medium such as an IC card. In addition, a case where viewing permission control is performed on a plurality of terminal devices using one viewing control module 905 may be considered.

Further, as shown in FIG. 7, there is a function of including frequency information as viewing permission / inhibition information and transmitting program selection information by the content decoding processing unit 1005 in the terminal device 103 shown in FIG. 10 to the tuner of the front end unit 1001. It is also conceivable to select at the RF frequency level.

Furthermore, as shown in FIG. 11, encryption units 1109 and 1110 are provided as means for performing an encryption process unique to the relay station on the output of the transmission signal processing unit 1104 in the relay station 102, and a transmission stream excluding transmission control information, Alternatively, a part or all of the viewing permission / inhibition information is encrypted and transmitted to the terminal device 103 together with the encryption key information for decryption, whereby the output of the transmission control signal analysis unit 1204 in the terminal device 103 shown in FIG. Alternatively, the content may be transmitted to the content decrypting unit 1205 after being decrypted using the encryption key information.

Further, the control unit 305 in the relay station 102 has means for accumulating viewing permission / inhibition information, and can be repeatedly superimposed on the transmission control information.

Further, the front-end unit 401 in the terminal device 103 has a timer means, and when the viewing availability information is not received for a certain period, all or a part of the TS output to the content decryption processing unit 405 can be omitted. .

Furthermore, the front-end unit 401 in the terminal device 103 has storage means, and the received viewing availability information can be stored and used when selecting a program.

Further, the relay station 102 can transmit the viewing availability information using a frequency band different from the content, for example, OoB. Also, a physically different line such as a telephone line or the Internet may be used.

Further, the front end unit has a function of holding the front end unique information and the content decryption unit unique information, and when these are different, TS output to all or a part of the content decryption processing unit 405 can be omitted.

(Second Embodiment)
The second embodiment relates to a digital broadcasting system that relays and broadcasts satellite broadcasting by a CATV station, which is an example of a conditional access system. In particular, transmission control information in the CATV station is not used by a TMCC signal from a broadcasting center. The case of transmitting with will be described.

FIG. 13 is an example of a block diagram showing the main part of the relay station 102 in the present embodiment. The control unit 1305 manages a plurality of MPEG-format TSs input from the information source 1306 not including the TMCC. A configuration for newly generating transmission control information based on the information obtained is shown. Note that a series of processing related to the reception antenna 1301 to the modulation unit 1307 is the same as that of the relay station 102 in the first embodiment.

The operation of the conditional access system having the above configuration will be described below. An information source 1306 in FIG. 13 indicates content in the MPEG transport stream format in which the independent broadcast program uniquely generated by the CATV provider or the current CS broadcast is decoded and then encoded in the MPEG system. In addition, the transmission control signal processing unit 1307 multiplexes content input from the information source 1306 and adds new transmission control information. Thereafter, a transmission stream composed of a plurality of TSs is converted into a format suitable for the CATV line 106 by the modulation units 1309 and 1310, and mixed by the mixing unit 1308 together with the satellite broadcast stream including the TMCC signal shown in the first embodiment. , To the CATV line 106. Note that the configuration and function of receiving apparatus 103 are the same as in the first embodiment.

Note that transmission control information generated by a CATV station in Embodiments 1 and 2 can be general TSMF information as CATV control information.

Furthermore, although the case of a satellite broadcasting station as a broadcasting center has been described, it is also conceivable that the broadcasting center is, for example, a terrestrial broadcasting station other than the satellite broadcasting station and is connected to a relay station that does not go through the satellite.

Furthermore, in Embodiments 1 and 2, the case where a wired line connection is made from a relay station to a receiving apparatus has been described. However, a wireless line connection is made from a relay station or a relay slave station to a terminal apparatus. Is also possible.

In the first and second embodiments, it is also conceivable that the transmission control information transmitted from the relay station is composed of TSMF (Transport Streams Multiplexing Frame: transmission control signal system in CATV) or TSMF extended specifications.

The conditional access system of the present invention enables the CATV station's unique viewing control by a simple method without changing the conditional access information and contents on the satellite side when relaying satellite broadcasts at the CATV station. Therefore, even in the modulation conversion method, viewing control of the terminal device can be performed independently by the CATV station, which is useful.

101, 1401, 1501 Broadcast center 102, 1409, 1509 Relay station 103, 1415, 1517 Terminal device 104, 1408, 1508 Satellite 105 Satellite line 106 CATV line 201, 202, 203 Broadcaster 204 TMCC processing unit 205, 306, 307, 1106, 1107, 1306, 1307, 1309, 1310 Modulators 206, 1407, 1507 Transmitting antennas 301, 1101, 1301, 1410, 1510 Receiving antennas 302, 402, 802, 902, 1002, 1102, 1202, 1302 tuner 303 , 403, 803, 903, 1003, 1003, 1203, 1303 demodulator 304, 1104, 1304, 1307 Transmission control signal processor 305, 1105, 1305 Controller 308, 110 8, 1308 Mixing unit 401, 801, 901, 1001, 1201 Front end unit 404, 804, 904, 1004, 1204 Transmission control signal analysis unit 405, 806, 907, 1005, 1205 Content decoding processing unit 501 Front end unique ID
502 Viewing availability information 805, 906 Output control unit 905 Viewing control module 1109, 1110 Encryption unit 1206 Decoding unit 1402, 1502 Content server 1403, 1503, 1512 Multiplexing unit 1404, 1504, 1513 Limited reception control unit 1405, 1505, 1514 Scrambler 1406, 1506 Transmitter 1411, 1511 Receiver 1412, PSI converter 1413, 1515 QAM modulator 1414, 1516 Frequency converter

Claims (7)

A conditional access system in a digital broadcasting system in which a center device and one or more relay devices are connected by a first transmission line, and the relay device and one or more terminal devices are connected by a second transmission line. And
The center device includes at least one transport stream including content scrambled as needed including any of video, audio, and data, and decoding information for descrambling the content, and the relay device or the Sending to the first transmission path as a first stream together with the first transmission control information for selecting a plurality of transport streams in the terminal device,
The relay device generates the first stream received from the first transmission path to the terminal device based on the first transmission control information when relaying and sending the first stream to the second transmission path. Sending the second transmission control information to the second transmission path to the second transmission path as a second stream together with the viewing availability information for the terminal device,
The terminal device includes a front end unit for determining whether or not the transport stream can be viewed based on the viewing availability information, and a decoding processing unit for decoding the content input from the front end unit. If the availability information has not been received for a specific time, it has means for making it impossible to view part or all of the information of the second stream from the second transmission path,
The front end unit extracts the viewing availability information from the second stream received from the second transmission path, performs viewing control based on the viewing availability information, and determines at least one transformer that is determined to be viewable. Select a port stream and send it to the decoding processor,
The conditional access system according to claim 1, wherein the decryption unit performs descrambling control on the content based on the decryption information.   The terminal device has front end specific information for specifying the front end unit, and the relay device has means for generating the viewing permission / inhibition information including the front end specific information, The conditional access system according to claim 1, wherein the front end unit performs viewing control of the content based on the front end unique information in the viewing permission / inhibition information.   The terminal device has terminal group information that allows specification of a group of terminal devices, and the relay device has means for generating the viewing permission / inhibition information including the terminal group information, in the terminal device 3. The conditional access system according to claim 1, wherein the front-end unit performs viewing control of the content based on the terminal group information in the viewing availability information.   The conditional access system according to any one of claims 1 to 3, further comprising means for accumulating the viewing availability information in a front end unit of the terminal device.   The relay device transmits the viewing availability information using a specific frequency band different from the transmission frequency of the second stream, and the terminal device transmits the viewing availability information transmitted in the specific frequency band. 5. The conditional access system according to claim 1, wherein viewing control is performed according to claim 1.   2. The relay apparatus according to claim 1, further comprising means for generating and transmitting new second transmission control information in the relay apparatus without using the first transmission control information from the center apparatus. The conditional access system according to any one of 1 to 5.   The conditional access system according to any one of claims 1 to 6, wherein TSMF information is used as the second transmission control information in the relay device.

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