JP4127778B2 - Broadcast transmission / reception method, broadcast reception method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a broadcast transmission method and a receiving apparatus corresponding to a copyright protection system.
[0002]
[Prior art]
In the “copyright protection method” under standardization by ARIB (Radio Industry Association), etc., only receivers that can protect the rights of programs using scramble from the viewpoint of protecting the rights of program providers. By making it possible to demodulate, it is possible to prevent unauthorized duplication of broadcasted programs.
[0003]
Specifically, program right protection in a digital broadcast receiver or the like is realized as described in the following (1) to (3).
(1) Program usage conditions such as the number of times a program can be duplicated are transmitted together with the program by broadcast waves.
(2) The broadcast sender manages a key for scrambling a program and the like, and assigns the key to a receiver that operates according to the use conditions indicated in the right protection information.
(3) The program can be output from the receiver to the externally connected device only when the externally connected device operates according to the program usage conditions indicated in the right protection information. At that time, the rights protection information is also added and output.
[0004]
Here, program usage conditions such as the number of times a program can be copied are already defined or additionally defined as part of program arrangement information (SI (Service Information), PSI (Program Specific Information)) used for digital broadcasting. These are the following two descriptors.
[0005]
(1) Digital Copy Control Descriptor The ARIB standard ARIB STD-B10 “Program arrangement information used for digital broadcasting” is already defined as rights protection information for pay broadcasting. It is possible to specify three states: copying is possible without restriction conditions, copying is possible only for one generation (the received broadcast signal can be recorded only once), and copying is prohibited.
[0006]
(2) Content protection descriptor This is the right protection information newly introduced in the program arrangement information. For the copy-prohibited program, designation of whether or not temporary storage is possible and specification of temporary storage time (1) .5 hours, 3 hours,..., 1 week, no limit), and when outputting a digital signal from the receiver, is the output data protected by encryption or the like? It is also possible to specify an “output protection bit” that specifies whether or not.
[0007]
However, the standardization of the digital copy control descriptor and the content use descriptor in the “copyright protection method” under consideration of standardization is progressing on the premise that they are transmitted in an unencrypted state. If the above two descriptors are tampered with before being input to the receiver, even if it is a legitimate receiver that operates according to the usage conditions indicated in the rights protection information, it operates according to the contents of the tampered descriptor. End up. Thus, the current standard has a drawback of being vulnerable to fraud.
[0008]
[Problems to be solved by the invention]
As described above, the “copyright protection system” under consideration for standardization operates according to the contents of the falsified descriptor, and thus there is a problem that the current standard is vulnerable to fraud.
[0009]
An object of the present invention is to perform copyright protection by controlling viewing prohibition depending on whether or not the copyright protection information has been altered.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, a broadcast transmission / reception method of the present invention is a copyright protection method protection information which is a part of program arrangement information used for digital broadcasting, and is an unencrypted digital copy control description. In a broadcast transmission / reception method in a broadcast transmission / reception system in which a child and a content usage descriptor are transmitted together with a scrambled program by a broadcast transmission apparatus, and the transmitted signal is received by the broadcast reception apparatus, the broadcast transmission apparatus is transmitted Generating a message digest that is falsification detection data from the descriptor to detect whether the descriptor is falsified in the transmission path, obtaining a scrambled program by scrambling the program, ECM (Entitlement Control Messa) containing the scramble key used to scramble ge), the message digest, the step of encrypting the multiplexed ECM, the encrypted ECM, the descriptor, and the scrambled program. The broadcast receiving device receives a signal obtained by multiplexing the encrypted ECM, the descriptor, and the scrambled program, and the encrypted signal included in the received signal. Generating a message digest that is tampering detection data from the transmitted descriptor, obtaining the message digest and the scramble key by decrypting an ECM included in the received signal, and from the received signal The message digest and the message obtained by decrypting the ECM A step of determining falsification of the descriptor in the transmission path by comparing with a sage digest, a step of executing a copy control process according to the determination result, and included in the received signal regardless of the determination result a step of descrambling by descrambling means using the scramble key to the scrambled program is characterized by a run.
In order to solve the above-described problem, the broadcast receiving method of the present invention is a digital copy that is protection information of a copyright protection system that is a part of program arrangement information used for digital broadcasting and is not encrypted. In a broadcast reception method in which a control descriptor is transmitted by a broadcast transmission device together with a scrambled program, and the transmitted signal is received by a broadcast reception device,
A step of generating a message digest as falsification detection data from the descriptor in order for the broadcast transmission apparatus to detect whether the descriptor to be transmitted is falsified in the transmission path, and scrambling the program; A step of obtaining a scrambled program, a step of multiplexing an ECM (Entitlement Control Message) including a scramble key used to scramble the program, and a step of encrypting the multiplexed ECM. Receiving a signal transmitted in a multiplexed manner on the basis of a broadcast transmission method for executing the step of multiplexing and transmitting the encrypted ECM, the descriptor, and the scrambled program. In the method, the broadcast receiving apparatus includes the encrypted ECM, the descriptor, and the script. Included in the received signal, a step of receiving a signal multiplexed with the mbled program, a message digest that is falsification detection data from the descriptor transmitted without encryption included in the received signal, and The transmission path is obtained by comparing the message digest and the scramble key obtained by encrypting and decrypting the ECM, and the message digest generated from the received signal and the message digest obtained by decrypting the ECM. Determining whether the descriptor has been tampered with, performing a copy control process in accordance with the determination result, and using the scramble key for the scrambled program included in the received signal regardless of the determination result. the descrambling means using And executes the steps of: descrambling me.
[0011]
According to the above means, to detect whether there is falsification in the digital copy control descriptor is information for copyright protection, if there is tampering performs control such watchable, by inhibiting the tampering Copyright protection is possible.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram for explaining the broadcasting side according to the present invention, in which generation of EMM (Entitlement Management Message) that is individual viewing contract information, multiple blocks, and blocks not directly related to the present invention are omitted. It is.
[0013]
In FIG. 1, the digital copy control descriptor and / or the content usage descriptor, which is information for the copyright protection system positioned as a part of the information of the program information array SI, SPI, is the other program array information SI, In addition to the PSI, the multiplexing unit 106 multiplexes the broadcast signal with the broadcast signal, and the digital copy control descriptor is the message digest calculation unit 101. The content digest descriptor is the message digest calculation unit 102. Are respectively input to the ECM multiplexing unit 103 together with an ECM (Entitlement Control Message) common to all receiving apparatuses.
[0014]
Here, in addition to attribute information indicating whether the broadcast is paid or free, the ECM can be viewed in comparison with the EMM that is received and held by each receiver in advance when the broadcast is a paid broadcast. This is information used to determine whether or not the program has been received, that is, program information indicating program viewing conditions.
[0015]
Further, as a specific example of the message digest that is tampering detection data, a MAC (Message Authentication Code) is calculated on the transmission side, and transmitted in the ECM.
[0016]
Other specific examples of message digests are generated using error detection codes that do not use secret information such as CRC (Cyclic Redundancy Check), parity, BCH code, Reed-Solomon code, and hash functions that do not use keys. It is a thing. For example, the CRC calculated on the broadcast side is transmitted in the ECM.
[0017]
Another specific example of the message digest is one generated by using a hash function using a key or a block cipher. The key used is assumed to be secretly shared beforehand between the broadcasting station and the receiver. For example, the work key used when encrypting the ECM is secretly shared beforehand, and the IC card or the like is also used in the receiver. It is optimally managed in a safe block. Other than the work key, any key that can be shared by the broadcasting station and the receiver may be used. The message digest used here is generated using a secret key, and since the risk of generation by a person who does not know the key is low, it is necessary to encrypt and transmit the message digest calculated on the broadcast side However, the information may be transmitted as information other than the ECM, or may be transmitted in the ECM.
[0018]
FIG. 1 shows an example in which a key is not used for calculation of a message digest. When a key is used, the key is input to the message digest calculation units 101 and 102 from a key management unit (not shown). When a work key used for ECM encryption is used as the key in this case, the keys given to the encryption unit 105 are also input to the message digest calculation units 101 and 102, respectively.
[0019]
In addition to the message digest, an ECM used for scrambling a program such as video / audio data is multiplexed in the ECM multiplexing unit 103. The ECM output from the ECM multiplexing unit 103 is encrypted by the encryption unit 105 and output to the multiplexing unit 106.
[0020]
A key used for encryption in the encryption unit 105 is called a work key, generated and held by an EMM generation and management unit (not shown), and supplied to the encryption unit 105. For the purpose of preventing security degradation, this work key may be updated periodically, for example, once a month, with a new work key scheduled to be updated for all viewing subscribers in advance. Is sent to EMM. The broadcasting station updates the work key in anticipation of when almost all receivers have received the EMM containing the new work key.
[0021]
The scramble unit 104 scrambles a program such as video / audio data and outputs the scrambled program to the multiplexing unit 106 . The key used for this scramble is a scramble key multiplexed in the ECM.
[0022]
As described above, the message digests of the digital copy control descriptor and the content usage descriptor are multiplexed on the ECM, encrypted, and transmitted without being altered to the receiver.
[0023]
FIG. 2 is a block diagram for explaining an embodiment of the broadcast receiving apparatus of the present invention. In FIG. 2, the EMM receiving unit and the encryption / decryption unit, the program table generation unit using the program sequence information SI and PSI, the program table display unit, the user interface unit such as the remote control input unit, etc. Blocks not directly related to the explanation are omitted.
[0024]
The separation unit 201 separates program data, program arrangement information (SI, PSI), ECM, and EMM (not shown) from the received broadcast signal. The separated program arrangement information SI and PSI are further separated by the separation unit 203 in the digital copy control descriptor and the content use descriptor which are part of the information of the program information arrangement SI and SPI, and other program arrangement information SI, Separated into PSI. Here, the other program arrangement information SI and PSI are processed into a program table by a program table generation unit (not shown) and presented to the user by an on-screen display or used for control of the receiver as information at the time of channel selection. is there.
[0025]
The digital copy control descriptor and the content usage descriptor are given to the copyright protection processing unit 214. The copyright protection processing unit 214 controls the output signal of the receiver so that copyright protection is performed according to the two descriptors. Or a storage device (not shown) is controlled so that temporary storage can be performed only for a specified time. The digital copy control descriptor and the content use descriptor are also given to the message digest calculation units 206 and 207 to calculate the respective message digests.
[0026]
FIG. 2 shows an example in which a key is not used for calculating a message digest. When a key is used, the key is input to the message digest calculation units 206 and 207 from a key management unit (not shown). is there. When a work key used for ECM decryption and stored in the EMM memory 205 is used as a key in this case, this work key is also given to the message digest calculation units 206 and 207, respectively.
[0027]
Next, the ECM separated by the separation unit 201 is decrypted by the decryption unit 202, and is separated into a message digest, a scramble key, and viewing condition information regarding the program by the separation unit 204.
[0028]
The message digests of the two descriptors separated by the separation unit 204 are given to the comparison units 209 and 210, respectively, and compared with the message digests calculated by the message digest calculation units 206 and 207, respectively. The determination results are given to the copyright protection processing unit 214, respectively.
[0029]
The scramble key separated by the separation unit 204 is given to the decryption unit 213 via the switch 211 and the switch 212, and the program is decrypted. The decrypted program is code-processed by MPEG (Moving Picture Coding Experts Group) (not shown) and then provided to the viewer via the copyright protection unit 214.
[0030]
The viewing condition information related to the program separated by the separation unit 204 is compared with the individual contract information in the EMM memory 205 by the viewing availability determination unit 208 to determine whether viewing is possible. When it is determined that viewing is possible, the switch 211 is turned on to allow passage of the scramble key.
[0031]
The copyright protection processing unit 214 is notified of whether the digital copy control descriptor and the content use descriptor have been tampered with from the comparison units 209 and 210, and when tampered, the switch 212 is turned off to encrypt the scrambled program. The scramble key to be solved is not supplied to the descramble unit 213. Accordingly, the output signal remains scrambled, or the output signal is muted.
[0032]
Here, when the MAC is calculated on the transmission side and transmitted in the ECM, the MAC is calculated from the digital copy control descriptor and the content usage descriptor received on the reception side, and compared with the MAC in the ECM and falsified. It is for judging.
[0033]
When the CRC calculated on the broadcast side is transmitted in the ECM, the reception side compares the CRC extracted from the ECM with the CRC calculated from the received descriptor, and if they match, there is no falsification. Judge that there is. Note that the CRC calculated on the broadcast side is transmitted in an ECM protected by encryption, so that the risk of falsification of the CRC itself is low.
[0034]
Further, when a hash function using a key or a block cipher generated using ECM is transmitted in the ECM, the receiver uses the tampering detection data transmitted to use the digital copy control descriptor and content. Detects falsification of descriptors. If it is detected that there has been tampering, even if descrambling is possible (viewing is possible) by the viewing possibility determination process using the ECM, descrambling is not possible.
[0035]
FIG. 3 is a block diagram for explaining another embodiment of the broadcasting side of the present invention. This embodiment is different from FIG. 1 only in that control mode information at the time of tampering detection is input to the ECM multiplexing unit 13 and transmitted as a part of the ECM information. Therefore, in the following description, The same components will be described with the same reference numerals.
[0036]
The control mode information at the time of tampering detection defines the control method that the receiver should operate when the receiver detects that the digital copy control descriptor or the content usage descriptor has been tampered with. As shown in FIG. 4, 3 bits are defined as A to C as control mode information when tampering is detected, bit 1 is designated as A, bit 2 as B, and bit 3 as C.
[0037]
In other words, descrambling is not possible when A is “1”, descriptors that have been falsified are invalidated (copying prohibited or temporary storage is impossible), and C “1” is hit. Is a warning message display, and switches between "no action" if none of "A" to "C" is hit. Further, the control mode information at the time of tampering detection is, for example, a bitmap designation method so that A to C can be used together.
[0038]
Another embodiment of the broadcast receiving apparatus of the present invention will be described with reference to FIG. In this embodiment, compared with FIG. 2, control mode information at the time of tampering detection multiplexed with other signals transmitted by the transmission method of FIG. 3 is separated by the separation unit 204 and the copyright protection processing unit 214. The part to be input to the screen is different from the part added to the on-screen display unit 206 for displaying a warning message. For convenience of explanation, an MPEG decode processing unit 205 is also added. Hereinafter, the same components as those in FIG.
[0039]
In FIG. 5, the separation unit 201 separates program data, program arrangement information (SI, PSI), ECM, and EMM (not shown) from the received broadcast signal. The separated program arrangement information SI and PSI are further separated by the separation unit 203 in the digital copy control descriptor and the content use descriptor which are part of the information of the program information arrangement SI and SPI, and other program arrangement information SI, Separated into PSI. Here, the other program arrangement information SI and PSI are processed into a program table by a program table generation unit (not shown) and presented to the user by an on-screen display or used for control of the receiver as information at the time of channel selection. is there.
[0040]
The digital copy control descriptor and the content usage descriptor are given to the copyright protection processing unit 214. The copyright protection processing unit 214 controls the output signal of the receiver so that copyright protection is performed according to the two descriptors. Or a storage device (not shown) is controlled so that temporary storage can be performed only for a specified time. The digital copy control descriptor and the content use descriptor are also given to the message digest calculation units 206 and 207 to calculate the respective message digests.
[0041]
FIG. 5 shows an example in which a key is not used for calculating a message digest. When a key is used, the key is input to the message digest calculation units 206 and 207 from a key management unit (not shown). is there. When a work key used for ECM decryption and stored in the EMM memory 25 is used as a key in this case, this work key is also given to the message digest calculation units 206 and 207, respectively.
[0042]
Next, the ECM separated by the separation unit 201 is decrypted by the decryption unit 202, and is separated by the separation unit 204 into message digest, control mode information at the time of tampering detection, a scramble key, and viewing condition information regarding the program. The message digests of the two descriptors separated by the separation unit 204 are given to the comparison units 209 and 210, respectively, and compared with the message digests calculated by the message digest calculation units 206 and 207, respectively. The determination results are given to the copyright protection processing unit 214, respectively.
[0043]
The scramble key separated by the separation unit 204 is given to the program descrambling unit 213 via the switches 211 and 212, and the descrambled program is decoded by the MPEG decoding processing unit 215, etc. It is provided to the viewer via the on-screen display unit 216 and the copyright protection unit 214.
[0044]
The viewing condition information related to the program separated by the separation unit 204 is compared with the individual contract information in the EMM memory 205 by the viewing availability determination unit 208 to determine whether viewing is possible. As a result of the determination, when it is determined that viewing is possible, the switch 211 is turned on to allow passage of the scramble key.
[0045]
The copyright protection processing unit 214 is notified of whether the digital copy control descriptor and the content usage descriptor have been tampered with from the comparison units 209 and 210, and when tampering has occurred, The receiver is controlled according to the control mode information.
[0046]
As shown in FIG. 4, the control mode information at the time of tampering detection is defined as 3 bits A to C as control mode information at the time of tampering detection, bit 1 is A, bit 2 is B, bit 3 is C Specify according to.
[0047]
That is, when descrambling is not possible, the copyright protection processing unit 214 turns off the switch 212 and does not supply the scramble key to the program descrambling unit 213. Therefore, the output signal is a scrambled program.
[0048]
In the case of a warning message display, the copyright protection processing unit 214 controls the on-screen display unit 216 to display a warning message. The warning message may be stored as a fixed message in advance in the copyright protection processing unit 214 at the time of manufacture or the like, and data may be presented to the copyright protection processing unit 214, or the program arrangement information SI, PSI What is provided from the broadcast side as a part may be separated by the separation unit 203 and used.
[0049]
In the case of invalidation of a falsified descriptor, the copyright protection processing unit 214 operates to invalidate the falsified descriptor. That is, when the digital copy control descriptor is falsified, the output signal is output after the copy prohibition is controlled. In addition, when the content use descriptor is falsified, control is performed to disable temporary storage of programs in a storage device (not shown).
[0050]
In the example described above, the message digest is transmitted in the ECM. However, if the message digest is calculated using an encryption key such as a work key, it is not necessary to transmit the message digest in the ECM. In that case, the management unit that manages the encryption key, for example, the IC digest used for the receiver, calculates the message digest from the digital copy control descriptor or content usage descriptor, and the encryption key is disclosed. Shall not be done.
[0051]
The IC card is processed with ECM, and if there is a contract, the scramble key is output, and the message digest calculation result is compared with the transmitted message digest. The scramble key is not output from the IC card.
[0052]
As described above, it is possible to detect falsification of both descriptors by detecting falsification of the digital copy control descriptor or content usage descriptor related to the copyright protection method. Tampering can be suppressed by performing improper control.
[0053]
Further, since the message digest for tampering detection is encrypted and transmitted in the ECM together with the scramble key, the message digest itself is safely transmitted to the receiver without being tampered with, and in parallel with the management of the scramble key. Since the presence / absence of tampering is detected, it is possible to control such that viewing is not possible when tampering occurs.
[0054]
Furthermore, by providing a plurality of types of receiver control methods when tampering is detected and enabling control by broadcast waves, it becomes possible to switch the penalty level when tampering occurs.
[0055]
【The invention's effect】
As described above, according to the present invention, it is detected whether the digital copy control descriptor, which is copyright protection information, has been tampered with, and if tampering is detected, control is performed such that viewing is not possible, and tampering is performed. Can be suppressed.
[Brief description of the drawings]
FIG. 1 is a block diagram for explaining an embodiment of a transmission side of the present invention.
FIG. 2 is a block diagram for explaining an embodiment of the receiving side of the present invention.
FIG. 3 is a block diagram for explaining another embodiment of the transmitting side of the present invention.
FIG. 4 is an explanatory diagram for explaining control contents when tampering is detected according to the present invention.
FIG. 5 is a block diagram for explaining another embodiment of the receiving side of the present invention.
[Explanation of symbols]
101, 102, 206, 207 ... message digest calculation unit 103 ... ECM multiplexing unit 104 ... scramble unit 105 ... encryption unit 106 ... multiplexing unit 201, 203, 204 ... separation unit 202 ... Decoding unit 213 ... Descramble unit 205 ... EMM memory 208 ... Viewing permission / non-permission judgment unit 209, 210 ... Comparison unit 211, 212 ... Switch 214 ... Copyright protection processing Unit 215... MPEG decode processing unit 216... On-screen display unit

Claims (2)

Digital copy control descriptors and content usage descriptors, which are copyright protection system protection information that is part of the program sequence information used for digital broadcasting, and are transmitted together with the scrambled program by the broadcast transmitter. In the broadcast transmission / reception method in the broadcast transmission / reception system for receiving the transmitted signal by the broadcast reception device,
The broadcast transmitting device is
Generating a message digest that is falsification detection data from the descriptor in order to detect whether or not the descriptor to be transmitted is falsified in the transmission path;
Scrambled the program to obtain a scrambled program;
Multiplexing an ECM (Entitlement Control Message) including a scramble key used to scramble a program and the message digest;
Encrypting the multiplexed ECM;
Performing the step of multiplexing and transmitting the encrypted ECM, the descriptor, and the scrambled program;
The broadcast receiving device is
Receiving a signal obtained by multiplexing the encrypted ECM, the descriptor, and the scrambled program;
Generating a message digest that is falsification detection data from the descriptor transmitted without encryption included in the received signal;
Obtaining the message digest and the scramble key by decrypting an ECM included in the received signal;
Determining falsification of the descriptor in the transmission path by comparing a message digest generated from the received signal and a message digest obtained by decrypting the ECM;
Executing a copy control process according to the determination result;
A step of descrambling by descrambling means using said regardless of the determination result, the scramble key of the scrambled programs are included in the reception signal,
A broadcast transmission / reception method characterized by: This is copyright protection protection information that is part of the program sequence information used for digital broadcasting, and is transmitted by the broadcast transmission device together with the scrambled program with the unencrypted digital copy control descriptor. In a broadcast receiving method for receiving a received signal by a broadcast receiving device,
The broadcast transmitting device is
Generating a message digest that is falsification detection data from the descriptor in order to detect whether or not the descriptor to be transmitted is falsified in the transmission path;
Scrambled the program to obtain a scrambled program;
Multiplexing an ECM (Entitlement Control Message) including a scramble key used to scramble a program and the message digest;
Encrypting the multiplexed ECM;
Multiplexing and transmitting the encrypted ECM, the descriptor, and the scrambled program;
In a broadcast reception method for receiving a signal transmitted in a multiplexed manner based on a broadcast transmission method for executing
The broadcast receiving device is
Receiving a signal obtained by multiplexing the encrypted ECM, the descriptor, and the scrambled program;
Generating a message digest that is falsification detection data from the descriptor transmitted without encryption included in the received signal;
Obtaining the message digest and the scramble key by decrypting an ECM included in the received signal;
Determining falsification of the descriptor in the transmission path by comparing a message digest generated from the received signal and a message digest obtained by decrypting the ECM;
Executing a copy control process according to the determination result;
A step of descrambling by descrambling means using said regardless of the determination result, the scramble key of the scrambled programs are included in the reception signal,
The broadcast receiving method characterized by performing.

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