JPH07154770A - Pay television broadcast transmission/reception system and decoder for receiving pay television broadcast - Google Patents

Abstract

PURPOSE:To provide a pay television broadcast transmission/reception system and decoder capable of minimizing damage caused by illicit reception even when the state of illicit decoding the contents of a master key of one part is generated concerning the transmission/reception system for transmitting/ receiving the pay television broadcast such as satellite broadcast or CATV and its decoder. CONSTITUTION:A multiplex part 36 respectively multiplex a scramble key Ks, ciphered with a master key Kmx as a cyptographic key, to scrambled video and sound signals and transmits those signals. A decoder 10 for pay television broadcast reception reads the master key Kmx stored in an IC card 20 with a card reader 13 and decodes the scramble key Ks by inputting that master key to a decoding part 12 as a decode key. Since the master key Ks is changed periodically, it is necessary to newly purchase the IC card 20 periodically as well. The master key Kmx is used commonly for all the decoders.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pay broadcast transmitting / receiving system and a pay broadcast receiving decoder, and more particularly to a pay transmitting / receiving system for transmitting and receiving pay broadcasting such as satellite broadcasting and cable television (CATV) and receiving pay broadcasting. Regarding the decoder.

[0002] In pay broadcasting such as satellite broadcasting and CATV,
In order to prevent unauthorized reception, it is common practice to send a video signal and / or an audio signal (hereinafter referred to as “broadcast signal”) at a broadcasting center after performing a scramble process that electrically stirs the signal. In order to receive this broadcast signal and play it back properly, obtain the scramble key used to operate the scrambler at the broadcast center, and use this scramble key to set the descrambler in the decoder for pay broadcast reception. Just run it.

The scramble key is usually mixed with a data signal, then multiplexed with a broadcast signal and distributed to a decoder installed in each recipient's house. Therefore, if a person who does not have a regular contract with the pay broadcasting company obtains the scramble key by some means, even a person other than the contractor can easily illegally receive the pay broadcasting. For this reason,
Even if the scramble key is illegally decrypted, there is a need for a pay broadcast receiving decoder that minimizes illegal reception.

[0004]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of a conventional pay broadcast transmitting / receiving system disclosed in a document (Telecommunications Technology Council Council Advisory Report No. 44, No. 76, 1990). In the figure, 30 is a broadcasting center, and 40 is a conventional pay broadcast receiving decoder. The broadcasting center 30 includes a video scrambler 31, an audio scrambler 32, a PN generator 33,
It includes a multiplexing unit 36, a master key file 37 for each recipient, and encryption units 38 and 39. The pay broadcast receiving decoder 40 includes a signal separation unit 11, a PN generator 14, a video descrambler 15, an audio descrambler 16, a master key storage unit 41, decryption units 42 and 43, and a contract condition comparison circuit 4.
It consists of 4.

In the broadcasting center 30, the PN generator 3
The initial value of 3 is set by the scramble key Ks, and the PN sequence (pseudo random sequence) output from the PN generator 33 is used as the video scrambler 31 and the audio scrambler 3.
2 respectively, and scrambles the video signal and the audio signal to be broadcast separately. The above-mentioned scramble key Ks is encrypted by the encryption unit 39 together with common information such as broadcast station identification information and services so that it is not known to a third party.

Here, the work key Kw is input to the encryption unit 39 as an encryption key for transmitting the scramble key Ks.
Further, individual information such as contract content and decoder ID is input to the master key file 37 for each receiver, and a different master key Kmi is read for each receiver (each decoder). The master key Kmi is input to the encryption unit 38 as an encryption key and used for encryption of the work key Kw and the individual information in the encryption unit 38.

The output signals of the video scrambler 31, the audio scrambler 32, and the encryption units 38 and 39 are multiplexed by the multiplexing unit 3.
After being input to the channel 6 and multiplexed, it is transmitted to each receiver as a scrambled broadcast signal. The scramble key Ks is transmitted for synchronization of the transmission and reception PN generators 33 and 14.

The pay broadcast receiving decoder 40 receives the above scrambled broadcast signal, and separates the signals multiplexed by the multiplexing unit 36 by the signal separating unit 11.
As a result, the scrambled video signal is input to the video descrambler 15, the scrambled audio signal is input to the audio descrambler 16, the output encrypted signal of the encryption unit 38 is input to the decryption unit 42, and further encrypted. Part 3
The output encrypted signal of 9 is input to the decryption unit 43.

The decoder 40 has a storage unit 41 which stores a unique master key Kmi, and this master key Km
Using i, the decrypting unit 42 performs the decryption operation to decrypt the work key Km and the individual information in the received scrambled broadcast signal. The decrypted work key Kw is input to the decryption unit 43 as a decryption key, and decrypts the scramble key Ks and common information in the scramble broadcast signal received here.

The individual information extracted by the decryption unit 42 and the common information extracted by the decryption unit 43 are input to the contract condition comparison circuit 44, where it is automatically determined whether or not a predetermined contract condition is satisfied. To be done. When the contract conditions are satisfied, the contract condition comparison circuit 44 outputs an operation signal to the PN generator 14. The PN generator 14 generates the same PN sequence as the PN sequence output from the PN generator 33 in the broadcasting center 30 when the actuation signal is input and the correct scramble key Ks is input from the decryption unit 43. Video descrambler 15 and audio descrambler 1
Fill in 6 respectively.

In this way, the video descrambler 15
The video signal from which the scramble processing has been released is taken out from, and the audio signal from which the scramble processing has been released is taken out from the audio descrambler 16.

As a conventional pay-broadcast receiving decoder, there is also known one which compares the contract condition comparison in the contract condition comparison circuit 44 with the charging condition read from a card from the outside (for example, Japanese Patent Laid-Open No. 2-111185
Issue).

[0013]

In the conventional pay broadcast receiving decoder 40, the decryption master key Kmi (where i is the ID number assigned to each decoder) set for each decoder is stored in the IC chip. 4 in the decoder 40 in the form
It is assembled as shown in 1 and has a structure that cannot be easily removed.

However, in the conventional pay broadcast receiving decoder shown in FIG. 3 and the conventional pay broadcast decoder in which the charging condition is input by a card, the master key Kmi is used.
Is built in the decoder in the form of hardware, the work key Kw and the scramble key Ks will be decrypted once the contents of the master key Kmi are illegally decrypted, and a means for countering this will occur. There is no. Only by changing the corresponding master key Kmi in the master key file 37 on the broadcast center side, it is possible to counter it.
Since there is no way to know which master key was decrypted, it is virtually impossible to change only the relevant master key Kmi. Further, if the contents of the master key file 37 are completely changed, a receiver who purchases and owns the decoder properly cannot receive the data.

Also, on the side of the broadcasting center 30, all the master keys for the regular subscribers, excluding those for fee delinquents and contract terminating parties, among the different master key information, must be transmitted at each decoder. Therefore, as the number of subscribers increases, it is necessary to perform complicated and time-consuming work.

The present invention has been made in view of the above points,
By changing the contents of the master key at regular intervals, even if some master key contents are illegally decrypted, it is possible to minimize the damage caused by illegal reception. It is an object of the present invention to provide a decoder for video.

[0017]

In order to achieve the above object, the pay broadcast transmission / reception system of the present invention scrambles at least one of a video signal and an audio signal using a pseudo random sequence, and at the same time, initializes the pseudo random sequence. A scramble key that determines a value is encrypted by using a master key as an encryption key and is multiplexed with the video signal and the audio signal and transmitted as a scramble broadcast signal. Separate the audio signal and the encrypted scramble key,
A pay broadcast transmission / reception system which decrypts an encrypted scramble key to determine an initial value of a pseudo random sequence generator, and descrambles the video signal and the audio signal separated after the reception by using a pseudo random sequence. , A master key common to all the receiving decoders is used as the master key on the transmitting side, and the master key is changed at regular intervals, and a decoding key for decoding the encrypted scramble key on the receiving decoder. The master key used as is read and input from a recording medium inserted from the outside.

Further, in the pay broadcast receiving decoder of the present invention, a signal which receives the scrambled broadcast signal and separates a video signal and an audio signal, at least one of which is scrambled, and an encrypted scramble key. A separation unit, a first reading unit that reads the master key from a recording medium inserted from the outside, and an encrypted scramble key that is input from the signal separation unit using the master key from the first reading unit as a decryption key. A decryption unit for decryption,
Pseudo-random sequence generator whose initial value is set by a scramble key from the decryption unit, and a descrambler for descramble-processing the scrambled video signal and / or audio signal from the signal separation unit based on the pseudo-random sequence It is configured to have and.

Further, in the pay broadcast receiving decoder according to claim 3, second master reading means for reading the master key and the billing information from a recording medium inserted from the outside and outputting the master key as a decryption key to the decryption unit is provided. The billing information and the billing type information input from the signal separation unit are input, a signal indicating whether or not operation is permitted is output to the pseudo random sequence generator based on the billing information, and the predetermined type is based on the billing type information. 3. The first reading means of the pay broadcast receiving decoder according to claim 2, further comprising: a billing control unit for calculating a new remaining number in the case of the billing type and a recording unit for updating and recording the new remaining number on a recording medium. Instead of this, the configuration is provided.

[0020]

In the pay broadcast transmission / reception system of the present invention, the master key in the transmission scramble broadcast signal is changed at regular intervals. Therefore, the recording medium inserted into the decoder from the outside is the master in the transmission scramble broadcast signal. It is possible to change to a recording medium in which the same master key is recorded at fixed intervals corresponding to the key.

Further, in the pay-broadcast receiving decoder according to the second aspect, the master key read from the recording medium inserted from the outside by the first reading means does not correspond to the recipients, but all the recipients ( Since the same master key is common to all the decoders, the pay broadcast receiving decoder can be configured to be common to all receivers.
In addition, it is possible to receive a pay broadcast simply by inserting a recording medium from the outside.

Further, in the pay broadcast receiving decoder according to the third aspect, when the billing type is a predetermined type, the billing control unit calculates a new remaining number, and the recording unit updates and records the remaining number on the recording medium. Therefore, it is not necessary for the transmitting side to manage the residual number, and the pay broadcast can always be received based on the latest residual number recorded in the recording medium.

[0023]

EXAMPLES Next, examples of the present invention will be described. FIG. 1 shows a block diagram of a first embodiment of the present invention. In the figure, FIG.
The same reference numerals are given to the same components as. In FIG. 1, reference numeral 10 is a first embodiment of a pay broadcast receiving decoder of the present invention, which is a signal separation unit 11, a decoding unit 12, and a card reader 1.
3, a PN generator 14, a video descrambler 15, and an audio descrambler 16.

The card reader 13 is a device for reading information recorded on the IC card 20, and constitutes the first reading means. The IC card 20 is a recording medium on which a master key Kmx, which is a decryption key for decrypting the encrypted scramble key Ks in the scrambled broadcast signal to be received, is recorded. The PN generator 14 is a circuit that generates a PN sequence that is a pseudo-random sequence, and its initial value is set by the scramble key Ks.

A broadcasting center 30 constitutes a pay broadcasting transmitting / receiving system together with the pay broadcasting receiving decoder 10. The broadcast center 30 includes a video scrambler 31, an audio scrambler 32, a PN generator 33, and a master key file 3
4, an encryption unit 35 and a multiplexing unit 36. The PN generator 33 is a pseudo random sequence generator having the same configuration as the PN generator 14. Also, the master key file 3
4 stores a large number of master keys Km1 to Kmn, and one of the master keys Km is selected by an external selection command.
mx is selected. This master key Kmx is designed to be changed at fixed intervals (for example, every 6 months).

By the way, the contents of the contract for pay broadcasting are as follows:
We have prepared a flat fee that allows you to watch all programs on that channel by paying a fixed monthly fee for each channel, a program table and a fee list that combines several programs and fee setting methods. A tier that viewers select and subscribe to, a pay per program that sets a fee for each individual program and charges only for the viewed program,
A predetermined fee is set for each unit time, and there is pay-per-time, etc., which charges for the time of viewing. Of these, the present embodiment is a system effective for flat fee pay broadcasting.

Next, the operation of this embodiment will be described.
First, the video signal and the audio signal to be broadcast are input to the corresponding video scrambler 31 and audio scrambler 32, respectively, where the scramble processing is performed based on the PN sequence supplied from the PN generator 33. Various concrete methods of scrambling have been proposed (for example, a scanning line signal switching system, a scanning line transition system, or a combination of these systems for video signals, and a PN signal series addition system for audio signals). Since these are publicly known and are not the gist of the present invention, detailed description thereof will be omitted.

The initial value of the PN sequence used for the scrambler in the above video scrambler 31 and audio scrambler 32 is set by the scramble key Ks.
The scramble key Ks is input to the encryption unit 35, and is encrypted here using the master key Kmx read from the master key file 34 according to the selection command as an encryption key. The master key Kmx is commonly used by all receiving decoders, and is changed at regular intervals as described above.

The encrypted scramble key Kmx and the video signal and the audio signal scrambled by the video scrambler 31 and the audio scrambler 32, respectively, are multiplexed in the multiplexing unit 36. The multiplexed signal extracted from the multiplexing unit 36 is transmitted as a scrambled broadcast signal wirelessly or by wire.

The pay-broadcast receiving applicant (subscriber) purchases the pay-broadcast receiving decoder 10 and the IC card 20 from the pay-broadcasting broadcasting station (or a substitute thereof) in advance. I
Master key information (here, Kmx) is pre-recorded in the C card 20. When the IC card 20 is inserted into the pay broadcast receiving decoder 10, the card reader 13 reads the recorded information, and the master key Kmx is input to the decryption unit 12 as a decryption key.

On the other hand, the pay-reception decoder 10 receives the scrambled broadcast signal and separates the scrambled video signal and the scrambled audio signal from the received signal by the signal separation unit 11 to separate them from the video desk. The data is input to the rambler 15 and the voice descrambler 16, and the encrypted scramble key Ks is separated from the received signal and input to the decryption unit 12.

The decryption unit 12 uses the encrypted scramble key Ks as the master key Km from the card reader 13.
It decrypts x as a decryption key, and decrypts the scramble key Ks used in the broadcasting center 30. The decrypted scramble key Ks is input to the PN generator 14 to determine the initial value of its output PN sequence.

As a result, the PN sequence synchronized with the PN sequence output from the broadcast center 33 is extracted from the PN generator 14 and supplied to the video descrambler 15 and the audio descrambler 16 to perform descrambler processing. . As a result, the descrambler 15 and the audio descrambler 16 respectively extract normal video signals and audio signals that have been descrambled.

In this embodiment, the master key Kmx is changed to a master key having a different value (for example, Kmy) after a certain period of time.
Therefore, the IC in which the information of the master key Kmx is recorded
Even if the card 20 is used, the pay broadcast cannot be received. Therefore, the reception applicant can newly receive another IC card in which the information of the new master key Kmy is recorded and insert the IC card into the pay broadcast receiving decoder 10 to receive it again.

Therefore, when the scramble key Ks or the master key Kmx is illegally decrypted by some means, there has conventionally been no countermeasure, but according to this embodiment, at the longest, it is illegal only for the above-mentioned fixed period. Since it cannot be viewed, damage caused by unauthorized viewing can be minimized.

Further, in this embodiment, since the master key Kmx and the like are common to all the pay-broadcast receiving decoders 10, all the pay-broadcast receiving decoders 10 can have the same structure. It is possible to reduce the cost, and it is possible to eliminate the complexity of the conventional master key file creation work for the receiver in the broadcasting center. Further, in the present embodiment, since the IC card 20 needs to be prepaid in order to operate the pay-broadcast receiving decoder 10, the fee for the already-broadcast before the suspension of transmission for the long-term delinquent, which has occurred conventionally, is charged. Can be prevented.

Next, a second embodiment of the present invention will be described. FIG. 2 shows a block diagram of a second embodiment of the present invention. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 2, 10 ′ is a second embodiment of the pay broadcast receiving decoder of the present invention, in which a card reader / writer 18 and an accounting control section 19 are provided in place of the card reader 13 of the first embodiment. Is characterized by.

The card reader / writer 18 is a device having a function of reading recorded information from the IC card and a function of writing input information to the IC card, and constitutes the above-mentioned second reading means and recording means. . Further, the encryption unit 35 'in the broadcasting center 30 uses the scramble key Ks.
At the same time, the billing type information is also encrypted. The present embodiment is a pay broadcast transmitting / receiving system effective for pay-per-view (that is, pay-per program and pay-per-time).

Next, the operation of this embodiment will be described.
In the broadcasting center 30, in the encryption unit 35 ′, together with the scramble key Ks, charging type information indicating whether the broadcast program is flat fee or pay-per-view (that is, pay-per program and pay-per time) is sent from the master key file 34. It is encrypted with the master key Kmx as an encryption key.

The scramble key Ks and billing type information encrypted by the encryption unit 35 'are scrambled by the multiplexing unit 36 from the video scrambler 31 and the audio scrambler 32, respectively, and the extracted video signal and audio are extracted. It is multiplexed with the signal to form a scrambled broadcast signal, which is transmitted wirelessly or by wire.

The pay-broadcast receiving applicant (subscriber) purchases the pay-broadcast receiving decoder 10 'and the IC card 21 from the pay-broadcasting broadcasting station (or a substitute thereof) in advance.
In addition to master key information (here, Kmx), the IC card 21 is pre-recorded with billing information indicating the remaining number of recipients. The IC card 21 is inserted into the pay-broadcast receiving decoder 10 'so that the card reader / writer 18 reads the recorded information, and the master key Kmx is input to the decrypting unit 12 as the decrypting key, and the billing information is obtained. Is input to the charging control unit 19.

On the other hand, the pay-broadcast receiving decoder 10 'receives the scrambled broadcast signal transmitted from the broadcast center 30, and the signal separation section 11 scrambles the received video signal and the scrambled audio signal. Video descrambler 1 by separating signal and signal respectively
5 and the voice descrambler 16, and the scramble key Ks encrypted from the received signal.
And the billing type information are separated and input to the decryption unit 12.

The billing controller 19 is a card reader / writer 1
The remaining number is checked on the basis of the billing information recorded in the IC card 21 inputted from 8 and the operation permission signal (command) is sent to the PN generator 14 only when the remaining number is not zero. The PN generator 14 receives the scramble key K from the decryption unit 12 only when this operation permission signal is input.
A video descrambler 15 for generating a PN sequence based on s
And the audio descrambler 16 to output the video signal and the audio signal which are descrambled respectively.

Further, the billing control unit 19 discriminates whether the program currently being received is flat fee or pay per view based on the billing type information inputted from the decoding unit 12, and during the reception, it is for pay broadcast reception. For the IC card 21 held in the decoder 10 ',
Only when it is identified as pay-per-view, a prescribed charge is calculated according to the type of pay-per program or pay-per-time, and the frequency of the calculated prescribed charge is subtracted from the remaining count of the IC card 21 to write a new remaining count. repeat.

In this embodiment as well, as in the first embodiment, the master key Kmx has a different value after a certain period of time (for example, Km).
y) is changed. Therefore, even if the IC card 21 in which the information of the master key Kmx is recorded is used, the pay broadcast cannot be received. Therefore, the receiver desires to newly purchase another IC card in which the information of the new master key Kmy and the billing type information are recorded, and inserts this into the pay-broadcast receiving decoder 10 'to receive again. can do.

Therefore, in the present embodiment as well, even if the scramble key Ks or the master key Kmx is illegally decrypted by some means, it is possible to minimize the damage caused by unauthorized viewing, which is the same feature as the first embodiment. In addition to that, since the remaining number of the IC card 21 is updated and recorded, there is a feature that the charging can be surely performed.

The present invention is not limited to the above embodiment, and the recording medium for recording the master key Kmx and billing information may be a magnetic card other than an IC card, a compact disc, a magnetic disc or other recording medium. Often,
Further, instead of the master key file 34, a circuit for automatically generating a desired master key in response to a selection command may be used to eliminate the storage capacity limitation. Also,
It goes without saying that the present invention can also be applied to a pay broadcast transmission / reception system that performs scramble processing on only one of a video signal and an audio signal.

[0048]

As described above, according to the pay broadcast transmission / reception system of the present invention, the recording medium inserted into the decoder from the outside necessary for operating the decoder corresponds to the master key in the scrambled broadcast signal. Therefore, it is necessary to change to the recording medium in which the same master key is recorded every fixed period, so even if the scramble key or master key is illegally decrypted by some means, the structure of the decoder can be changed compared to the conventional one. It is possible to minimize the damage caused by unauthorized viewing without making it complicated, and it is possible to remove the complexity of the conventional master key file creation work for the receiver at the broadcasting center.

Further, according to the pay-broadcast receiving decoder of the present invention, the pay-broadcast receiving decoder is used by using the recording medium in which the same master key common to all the receivers (all the decoders) is recorded. Since the configuration can be made common to all the receivers, the decoder manufacturing cost can be made lower than in the past.

Further, according to the pay broadcast receiving decoder of the present invention, when the billing type is a predetermined type, the billing control unit calculates a new remaining number and the recording unit updates and records the remaining number on the recording medium. As a result, the transmitting side does not need to manage the remaining number and the pay broadcast can always be received based on the latest remaining number recorded in the recording medium.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a block diagram of an example of a conventional pay broadcast transmitting / receiving system.

[Explanation of symbols]

 10, 10 'Decoder for pay broadcast reception 11 Signal separation unit 12 Decoding unit 13 Card reader 14, 33 PN generator 15 Video descrambler 16 Audio descrambler 18 Card reader / writer 19 Billing control unit 20, 21 IC card 30 Broadcast center 34 Master Key File 35, 35 'Encryption Unit

Claims (4)

[Claims] 1. A scramble process for at least one of a video signal and an audio signal using a pseudo-random sequence, and a scramble key that defines an initial value of the pseudo-random sequence is encrypted using a master key as an encryption key. And at least one of them is multiplexed with a video signal and an audio signal that have been scrambled, and the multiplexed signal is transmitted as a scrambled broadcast signal. Separate the scrambling key, decrypt the encrypted scrambling key to determine the initial value of the pseudo-random sequence generator, and use the pseudo-random sequence to separate the video and audio signals separated after the reception. A pay-broadcast transmission / reception system for descramble processing, wherein the master key is used as the master key on the transmission side. A master key that is common to all reception decoders is used and the master key is changed at regular intervals, and in the reception decoder, a master key that is used as a decryption key for decrypting the encrypted scramble key, A pay broadcast transmission / reception system characterized by reading and inputting from a recording medium inserted from the outside. 2. A video signal and an audio signal, at least one of which has been scrambled, and a scramble key which is common to all reception decoders and which is encrypted with a master key changed at regular intervals as an encryption key. From a recording medium inserted from the outside, a signal separation unit that receives a scrambled broadcast signal that is a multiplex signal, and separates a video signal and an audio signal, at least one of which has been scrambled, and an encrypted scramble key. A first reading unit for reading the master key; a decoding unit for decoding the encrypted scramble key input from the signal separating unit using the master key from the first reading unit as a decoding key; Pseudo-random sequence generator whose initial value is set by the scramble key of Claim and having a descrambler for descrambling a video signal and / or audio signal is scrambled from the signal separating unit based on arm series 1
A decoder for pay broadcast reception used in the pay broadcast transmission / reception system described. 3. The scrambled broadcast signal separated by the signal separation unit includes accounting type information encrypted by the same master key as the scramble key, and the master key is inserted from a recording medium inserted from the outside. And a billing information, the master key is output to the decryption unit as a decryption key, and the billing information is read by the second reading unit.
The billing type information input from the signal separation unit is input, a signal indicating whether or not operation is permitted is output to the pseudo random sequence generator based on the billing information, and a predetermined value is based on the billing type information. The charging control unit that calculates a new remaining number in the case of the charging type and the recording unit that updates and records the new remaining number calculated by the charging control unit on the recording medium are replaced with the first reading unit. The pay broadcast receiving decoder according to claim 2, wherein the decoder is provided. 4. The pay-broadcast receiving decoder according to claim 2, wherein the recording medium is an IC card, and the pseudo-random sequence generator generates a PN sequence.