JPH01246979A - Chargeable program distributing system and cryptographic key distributing structure - Google Patents

Abstract

PURPOSE:To improve the diversity and grade of the service of a cable facility by canceling the scramble of re-scrambled satellite wave program signals by means of individual keys. CONSTITUTION:At a head-end re-transmitter 3, in order to retransmit satellite broadcast, etc., to a cable transmission line, etc., scramble of video/sound signals is once canceled and the scrambling system is converted into the scrambling system suitable for the cable facility and, at the same time, related information multiplexed upon satellite waves is extracted and retransmitted by multiplexing the information upon TV signals transmitted through the cable. Moreover, a receiver 5 has a peculiar individual key 19 in its chargeable decoder 17 and the scramble of the re-scrambled satellite broadcasting program signals is canceled by using the key 19. Therefore, a charging system suitable for cable transmission system can be realized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a pay program distribution system and encryption key that make it possible to provide programs by broadcasting satellites or communication satellites using conventional pay broadcast systems such as CATV. Regarding the distribution structure of

[Prior Art] CATV and the like using cables and the like have been implemented as pay broadcast distribution services. In such paid broadcasting systems, scrambling technology is used to disrupt signals transmitted by broadcasting stations to prevent unauthorized viewing.
A technology is used to restore scrambled video/audio signals to their original state on the receiving side. The method of this scrambling technique is
There are various methods such as inverting the video signal under certain conditions, suppressing or removing the synchronization signal, and replacing or shifting the digitized video signal in units of segments. (pseudo
random noise, PN sequence signal or PN
The degree of secrecy is further increased by randomizing the information (signal). In other words, encryption is being attempted. Therefore, P
The subscriber side, which receives the program signal scrambled and transmitted by the N signal, prepares a PN signal generator similar to the broadcasting station side that generates the PN signal, and receives the initial value sent from the broadcasting station side. is removed, a PN signal is obtained by a PN signal generator based on this initial value, and the scramble is canceled to extract the original video/audio signal. This initial value is called a "key" for unscrambling, and is sent by some means from the broadcast station's management center to the subscriber's decoder. Regarding the handling of keys, if a common key is sent to each subscriber, there will be a problem with its confidentiality, so multiple types of keys are prepared to achieve hierarchical encryption. In other words, the keys include a unique individual key that is built into the subscriber's decoder and is different for each subscriber, a work key encrypted with this individual key, and a scramble/descrambler that is further encrypted with this work key. There is a scramble key used as the initial value for performing the above. The encrypted work key is sent to the subscriber's decoder as "individual information" together with the subscriber's contract information. In addition, the scramble key is used together with information indicating the attributes of the program.
It is transmitted as "program information" at the same time as the program is broadcast.

Another form of paid broadcasting service is a program distribution service by satellite broadcasting, which is scheduled to be implemented in Japan in recent years. The above-mentioned scrambling technology and encryption technology are also applied to this satellite broadcasting.

[Problem to be solved by the invention] From the perspective of popularizing satellite broadcasting, program distribution by satellite broadcasting pay service using broadcasting satellites and communication satellites requires subscription to the network through existing pay broadcasting networks such as CATV. It would be desirable to be able to distribute programs to all parties. In other words, it is desirable to be able to transmit satellite broadcast programs and manage paid services through the satellite broadcasting system and CATV system, and also to ensure the uniqueness of CATV program transmission and paid service management.

However, the transmission method of the satellite link in program distribution by satellite broadcasting is a transmission method suitable for satellites, and therefore, the transmission method for satellite waves and the transmission method for cable transmission waves are generally different. For example, in the case of satellite broadcasting, the baseband band of the television signal is a wideband digital subcarrier (bandwidth: 1 MH2) for the video signal.
Since it is frequency division multiplexed, a wide band of approximately 6.5 MHz is required. Satellite broadcast waves (RF low signals are weak radio waves using 12 GHz band radio waves with the required SN
In order to ensure the ratio, a transmission channel with a wide band width of 27 MH2 is formed, and transmission is performed using FM modulation. On the other hand, in the case of broadcasting such as 0ATV using terrestrial cable facilities, 6.
VSB/AM forming a transmission channel with MHz bandwidth
It is generally transmitted by modulation.

Therefore, in order to pass the satellite broadcasting system and the CATV system as described above, it is necessary to receive the satellite broadcast waves at the head end of the cable facility of the CATV system and retransmit them to the cable. Some measures will be required to reconcile the differences in transmission methods.

There is also a difference between the paid system or signal security of satellite broadcasting systems and the paid system or signal security of cable broadcasting systems.

Program distribution systems using broadcasting satellites and communication satellites use scrambling methods using advanced signal processing technology, whereas cable broadcasting systems use a limited transmission path of cables, and for various reasons a relatively simple scramble method is used. A CATV proprietary scrambling method is used. Therefore, in order to allow the satellite broadcasting system and the 0ATV system to pass, it is necessary to ensure the security of each and to harmonize the management systems of each pay system.

The purpose of the present invention is to ensure security while retransmitting satellite broadcasts, etc. to a cable transmission path, etc., in order to enable a pay-TV service by satellite broadcasting etc. and a pay-TV service by cable broadcasting to be passed through. In addition to allowing each cable broadcasting subscriber to have equal access to paid services such as satellite broadcasting before retransmission in addition to cable broadcasting's own fee system,
Furthermore, it is an object of the present invention to provide a pay program distribution system and an encryption key distribution structure that enable a unique scrambling method for cable broadcasting.

[Means for Solving the Problems and Their Effects] A pay program distribution system according to the present invention comprises: a headend retransmission device including a receiving means and a transmitting means; a receiving device including a subscriber receiving terminal and its pay decoder; In a pay program distribution system consisting of a transmission line such as a cable interposed between a headend retransmission device and a receiving device, the headend retransmission device includes a satellite broadcast receiving means and a satellite broadcast program signal that is transmitted to the head. a paid decoder that includes an individual key unique to the head-end retransmission device for test scrabbling with the end retransmission device, and allows individual information including the individual key unique to the paid decoder of the receiving device to pass through in an encrypted state; a scrambling/multiplexing means for re-scrambles the descrambled satellite broadcast program signal with a PN signal generated in a pay decoder for a head-end retransmission device and multiplexing it with the individual information in the encrypted state; is configured to have a unique individual key in its pay decoder and to include means for descrambling the rescrambled satellite broadcast program signal with this individual key.

According to the above configuration, the head-end retransmission device having the function of a satellite wave receiving station once descrambles the video/audio signal, converts it to a scrambling method suitable for the cable facility, and multiplexes it into the satellite wave. The relevant information is extracted, multiplexed during, for example, the vertical retrace interval of a cable-transmitted television signal, and retransmitted. Furthermore, since the individual information regarding the cable subscriber receiving device is transmitted in an encrypted state at the headend retransmission device, confidentiality is maintained and security is ensured.

Further, the encryption key distribution structure according to the present invention has an individual key Km+ unique to each of the headend retransmission device and the subscriber reception device.
. Kw, and further encrypts this work key KW with the two individual W! ) (mi, Km
j, and the encrypted information is multiplexed and transmitted.

[Example 1 Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of a head-end retransmission device and its surroundings in a program distribution system that passes through satellite broadcasting and CATV, and FIG. 2 shows an encryption key distribution structure.

In Figure 1, 1 is a receiving antenna that receives paid broadcasting waves 2 from satellite broadcasting, 3 is a head-end retransmission device of a CATV system, 4 is a CATV cable, and 5 is a CAT
V is a receiver of one subscriber name. In the head-end retransmission device 3, there is a satellite reception vs6 equipped with the reception antenna 1.
, a headend pay decoder 7, a related information multiplexer 8, a CATV scrambler @9, a remodulation converter 1N signal generator 13, and a video/audio descrambler 14. In addition, in the head end retransmission device 3, CATV
A related information generation device 15 for scrambling is provided for implementing a unique paid service, and this device 15 supplies related information to the related information multiplexing device 8 and a PN signal to the CATV scrambling device 9. do. On the other hand, it is composed of a pay decoder 17 including a CATV separate key Km19 and a PN signal generator 20. The video/audio signal obtained by the CATV converter 16 is given to a display device 21, where the video is shown.

In the above configuration, pay broadcast radio waves 2 from satellite broadcasting are received by the reception antenna 1 of the headend retransmission device 3, and demodulated into a baseband signal by the satellite receiver 6. The scrambled video signal a1 in the baseband signal and the audio signal are supplied to the video/audio descrambler 14, and the related information packet data C is supplied to the packet extraction circuit 11. Relevant information, including the key for unscrambling, is generally transmitted in the form of packets.

The packet extraction circuit 11 extracts packets of related information. Types of related information include information indicating program attributes and scramble It (KS), and work key (Kw).
It is roughly divided into "program (common) information" which is encrypted with "program (common) information" and "individual information" which is encrypted with an individual key (Km) which includes information regarding the subscription name contract and a common work key (KW). Ru.

These related information are decrypted by the W@ device 12, various pieces of information are collated, and when it is determined that the conditions match, a scramble key KS is obtained. This scramble key (Ks) is the initial value of the PN signal, the scramble key (Ks) is given to the PN signal generator 13, and the PN sequence signal corresponding to the scramble key (KS) is output from the PN signal generator 13. Output. This PN signal generator 13 is constructed using a non-linear shift register. The PN signal is supplied to the video/audio descrambler 14.

The scrambled video and audio signals supplied to the video/audio descrambler 14 are scrambled by adding the PN signal, so the same PN signal output from the PN signal generator 13 has a timing difference. When added together to the scrambled video and audio signals, the original unscrambled video and audio signals are obtained by the video/audio descrambler 14. The descrambled video signal a' is supplied via the related information multiplexing device 8, and the audio signal b' is directly supplied to the CATv scrambling device 9. In the related information multiplexing device 8, the related information packets provided from the packet extraction circuit 11 are multiplexed in encrypted form during the vertical bright line period of the video signal.

The scrambling device 9 for CATV uses a scrambling method unique to CA'TV, and performs scrambling using a PN sequence signal given from a PN signal generator 13. It is assumed that this scrambling method uses an RF scrambling method or synchronization suppression scrambling.

Alternatively, a method may be used in which the PN sequence is converted into a scramble algorithm control code that changes randomly. C.A.T.
The signal rescrambled by the V scrambling device 9 is converted into an RF signal for cable transmission by a remodulation converter 10, and then sent to the cable 4.

The CATV converter 16 of the CATV subscriber reception station 5 receives the signal transmitted through the cable 4. The relevant information in the received signal is sent to the decoder 18 of the decoder 17, and based on the individual key 19 and the action of the decoder 18, a PNN signal generator 20 outputs a PN sequence signal. This PN signal is CA
The signal is supplied to a descrambler in the TV converter 16 and transmitted through the cable 4, and the signal is descrambled to restore the video and audio signals, which are then played back on the display device 21.

The head-end retransmission device 3 can be manufactured using existing devices, and can perform signal conversion and signal transmission with less signal processing, so it can be realized easily and at low cost. Also, in the CATV subscriber receiver 5, 0A
The pay broadcast distribution system according to the present invention can be realized by incorporating a conventional inexpensive descrambler into the TV converter 16 and adding only the security circuit portion of the satellite broadcast receiving decoder as a pay decoder.

FIG. 2 shows the conversion and
Encryption key distribution that enables management of paid systems that bypass satellite broadcasting and CATV while ensuring security in retransmission! An i-layer structure is shown.

In FIG. 2, the same elements shown in FIG. 1 are designated by the same reference numerals. In FIG. 2, at the leftmost satellite program broadcasting station, a scrambler 3o scrambles the program signal with a PN signal output from a PN signal generator 31 based on a scramble key KS.

The scrambler 30 outputs a scrambled program signal. Next, scramble! Ks is the work i! in the encoder 32. The scramble key encrypted by the KW and encrypted by the encoder 32 is the common information Eks.
is output as Further, the work key KW is encrypted by the encoder 33 with the individual key Kmi for satellite broadcasting, and the individual information Ek
It is output as wi, and is also encrypted by the encoder 34 with the cable facility individual key Kmj and output as individual information Ekwj. The scrambled program signal, common information 1:ks, and individual information Ekwi and Ekwj are multiplexed and transmitted via a broadcasting satellite. In the head-end retransmission device 3, a decoder 12b included in the decoder 12 converts the multiplexed broadcast waves 2 into individual information Ekwi.
The common information Eks is decrypted by the decryptor 12a which outputs the individual key Kmi, and the scrambled information Eks is extracted. Next, the PN signal generator 13 uses this scramble key KS as an initial value.
generates a PN sequence signal from and supplies it to the video/audio descrambler 14 and CATV scrambling device 9,
This produces the effect described above.

On the other hand, the individual information E including the individual key Kmj for the cable facility
kwj is not processed by the head-end retransmission device 3, but is multiplexed with the scrambled program signal and the branched individual information EkS in its encrypted state, and sent to the cable 4, where it is sent to the CATV subscriber's receiving station. 5 will be given. In the receiving device 5, the decoder 18b included in the decoder 18 decrypts the individual information Ekwj with the individual key Kmj, and the work II
Take out Kw. Next, a decoder 18a also included in the decoder 18 decrypts the common information Eks with the work key KW and extracts the scramble key KS.

The PN signal generator 20 is operated using this scramble key KS as an initial value, and the descrambler 16a in the CATV converter 16 descrambles the program signal.

The pay broadcast distribution system according to the present invention employs a hierarchical structure for keys as described above. Such a key hierarchical structure has the following features.

■ Scrambling I that generates a PN sequence with a short update cycle and has an update cycle shorter than the time required for one cycle of the PN sequence.
You can use IKs. Since the KS update cycle can be shortened, it is difficult to illegally guess the PN sequence, and high security can be achieved.

■ Work ilK with long update cycle for encryption key during KS transmission
By using w, it is only necessary to deliver the next work key KW during this long update cycle, so the number of Kw that can be delivered,
In other words, the number of subscribers can be increased.

■ By having a different individual key (mask key) for each decoder, it is possible to provide addressing ability for each decoder and to individualize the encrypted non-transmitted signals that are in circulation, making it possible to maintain higher security. .

In the above embodiment, since the paid system management of CATV cable facility subscribers is performed separately, the individual key group Km
j is provided.

In order to implement CATV's unique pay broadcasting service,
It is necessary for the satellite broadcasting operator and the CATV operator to share the individual key file of the subscriber's decoder. Also, the first
It is necessary to independently send the scrambled program signal and related information to the cable 4 using a cable-specific scrambling method and a device 15 for generating and sending related information, which are shown by broken lines in the figure.

The following modified embodiments of the present invention are possible.

The order of the related information multiplexing device 8 and CATV scrambling device 9 shown in FIG. 1 can be changed. Furthermore, the present invention can be applied not only to CAT2 as a terrestrial pay broadcasting system, but also to pay broadcasting systems that utilize terrestrial broadcasting.

[Effects of the Invention] As is clear from the above description, according to the present invention, in a pay program distribution network using broadcasting satellites and communication satellites, a scramble system and a pay system that bypass satellite broadcasting systems, CATV broadcasting systems, etc. can be used. In addition to maintaining security, it is also possible to implement a unique paid system suitable for cable transmission. In addition, it is possible to cope with the increase in the accessible range and number of subscribers of satellite-based paid services, and it is also possible to diversify and improve the sophistication of services at cable facilities.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a pay program distribution system according to the present invention, and FIG. 2 is an explanatory diagram showing an encryption key distribution structure according to the present invention. [Explanation of symbols] 1...Receiving antenna 3...Head end retransmission device 4...
Cable 5...CATV subscriber receiver 7...Paid decoder for headend 8...
...Related information multiplexing device 9... CATV scrambling device 17...
...Paid decoder

Claims (2)

[Claims] (1) A paid system consisting of a headend retransmission device including a receiving means and a transmission means, a receiving device including a subscriber receiving terminal and its pay decoder, and a transmission line connecting the headend retransmission device and the receiving device. In the program distribution system, the headend retransmission device includes a satellite wave receiving means and an individual key unique to the headend retransmission device for descrambling the satellite wave program signal with the headend retransmission device, and A pay decoder that passes individual information including an individual key unique to the pay decoder of the receiving device in an encrypted state, and a descrambled satellite wave program signal generated in the pay decoder for a headend retransmission device. Scrambling and multiplexing means re-scrambles the PN signal and multiplexes it with the individual information in the encrypted state, the receiving device has the individual key unique in its paid decoder, and the receiving device uses the individual key to A pay program distribution system characterized by comprising means for unscrambling a rescrambled satellite wave program signal. (2) In a paid transmission distribution system that integrates a satellite transmission paid system and a cable transmission paid system and provides a satellite transmission paid service to cable broadcasting subscribers, the cable transmission paid system uses a unique individual key Kmi
and a plurality of subscriber receiving devices each having a pay decoder including a unique individual key Kmj, wherein the satellite-transmitted program signal is scrambled with a scramble key Ks. The scramble key Ks is encrypted and the scramble key Ks
is encrypted with the work key Kw, the work key Kw is separately encrypted with the two individual keys Kmi and Kmj, and the encrypted information is multiplexed and transmitted, and the head end An encryption key distribution structure characterized in that the satellite transmission program signal is decrypted using a corresponding individual key in each paid decoder of the retransmission device and the subscriber reception device to extract the satellite transmission program signal.