JP4703631B2 - Broadcast transmission / reception system, broadcast receiver - Google Patents

Description

This invention is a copyright protection system corresponding to the broadcasting reception system, a broadcast receiver.

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.

Specifically, the rights protection of the program in a digital broadcasting receiver or the like is as follows (1) to (3).
It is realized as described in.
(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 or 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 also 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.
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.

(1) Digital Copy Control Descriptor The ARIB standard ARIB STD-B10 “Program arrangement information used for digital broadcasting” has already been 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.

(2) Content usage descriptor Rights protection information newly introduced in the program arrangement information. For a copy-prohibited program, designation of whether or not temporary storage is possible and specification of temporary storage time (1) .5 hours, 3 hours ...
・ ・ One week, no limit) is possible, and when outputting a digital signal from the receiver, the “output protection bit” specification that specifies whether to protect the output data by encryption etc. Is also possible.

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.

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.

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.

In order to solve the problems noted above, the broadcast receiving system of the invention, the digital copy control unencrypted a protection information of the copyright protection system that is part of the service information used in digital broadcasting In a broadcast transmission / reception system in which a descriptor is transmitted together with a scrambled program by a broadcast transmission apparatus, and the transmitted signal is received by a broadcast reception apparatus, the broadcast transmission apparatus is configured such that the descriptor to be transmitted is altered in a transmission path. Means for generating a message digest as falsification detection data from the descriptor to detect presence / absence on the receiving device side, means for obtaining a scrambled program by scrambling the program with a scramble key, and the scramble key Means for multiplexing the message digest in an ECM (Entitlement Control Message); Means for encrypting an overlapped ECM, means for transmitting the encrypted ECM, the descriptor, and the scrambled program in a multiplexed manner, and the broadcast receiving apparatus includes the encrypted ECM. Means for receiving a signal obtained by multiplexing the ECM, the descriptor, and the scrambled program, and generating a message digest that is falsification detection data from the descriptor transmitted without encryption included in the received signal Means for obtaining the message digest by decrypting the ECM included in the received signal, the message digest generated from the descriptor included in the received signal, and obtaining the message digest by decrypting the ECM. Means for judging falsification of the descriptor in the transmission line by comparing the message digest Means for executing a copy control process according to the determination result, and descrambles the scrambled program included in the received signal using the scramble key and outputs it to the storage device regardless of the determination result And means for carrying out the above .

According to the above-mentioned means, it is detected whether or not the digital copy control descriptor, which is information for copyright protection, has been tampered with. Copyright protection is possible.

According to the present invention, it is possible to detect whether or not the digital copy control descriptor, which is information for copyright protection, has been tampered with, and when tampering is detected, control is performed such that viewing is not possible, and tampering can be suppressed. It becomes.

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.

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 sent to the message digest calculation unit 101.
The content digest descriptor 102 calculates a message digest, which is falsification detection data, in the message digest calculation unit 102, and the ECM (Entitlemen) common to all receiving apparatuses.
t Control Message) is input to the ECM multiplexing unit 103.

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.

In addition, as a specific example of the message digest that is falsification detection data, M
An AC (Message Authentication Code) is calculated and transmitted in the ECM.

Other specific examples of message digests include CRC (Cyclic Redundancy Check),
It is generated using a code capable of detecting an error without using secret information such as parity, BCH code, Reed-Solomon code, or a hash function without using a key. For example, the CRC calculated on the broadcast side is transmitted in the ECM.

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.

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.

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.

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.

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.

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.

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, the encryption / decryption unit, and the program arrangement information SI, PS
Blocks not directly related to the description of the present invention, such as a program table generation unit using I, a program table display unit, a user interface unit such as a remote control input unit, are omitted.

In the separation unit 201, program data and program arrangement information (SI, PSI) are received from the received broadcast signal.
, ECM and EMM (not shown) are separated. 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.

The digital copy control descriptor and the content use descriptor are given to the copyright protection processing unit 214, and the copyright protection processing unit 214 performs copyright protection according to the two descriptors.
The output signal of the receiver is controlled, 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.

FIG. 2 shows an example in which a key is not used for calculating a message digest. When a key is used, a message digest calculation unit 206, 2 from a key management unit (not shown) is used.
The key is input to 07. 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.

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.

The message digests of the two descriptors separated by the separation unit 204 are respectively compared with the comparison unit 2.
09 and 210 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.

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 not shown in MPE.
After code processing etc. by G (Moving Picture Coding Experts Group), Copyright Protection Department 2
14 to the viewer.

The viewing condition information regarding the program separated by the separation unit 204 is transmitted to the EM
It is compared with the individual contract information in the M memory 205, and it is determined whether or not viewing is possible.
When it is determined that viewing is possible, the switch 211 is turned on to allow passage of the scramble key.

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 the tampering has occurred, the switch 21
2 is turned OFF, and the scramble key for decrypting the scrambled program is not supplied to the descramble unit 213. Accordingly, the output signal remains scrambled, or the output signal is muted.

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.

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.

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 tampering is detected, descrambling is possible (viewing is possible) by the viewability determination process using ECM.
Even so, descrambling is impossible.

FIG. 3 is a block diagram for explaining another embodiment of the broadcasting side of the present invention. In this embodiment, the control mode information at the time of tampering detection is compared with that in FIG.
However, in the following description, the same components are denoted by the same reference numerals and are described in the following description.

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 A to C are used as control mode information when tampering is detected.
And bit 1 is designated as A, bit 2 as B, and bit 3 as C.

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.

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.

In FIG. 5, the separation unit 201 receives program data, program arrangement information (
SI, PSI), ECM, and EMM (not shown) are separated. Separated program arrangement information SI,
The PSI is further divided into program information array SI, a digital copy control descriptor and a content use descriptor which are part of the SPI information, and other program array 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.

The digital copy control descriptor and the content use descriptor are given to the copyright protection processing unit 214, and the copyright protection processing unit 214 performs copyright protection according to the two descriptors.
The output signal of the receiver is controlled, 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.

FIG. 5 shows an example in which a key is not used when calculating a message digest. When a key is used, a message digest calculation unit 206, 2 from a key management unit (not shown) is used.
The key is input to 07. 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.

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 the message digest calculation unit 2
The message digests calculated in 06 and 207 are compared with each other. The determination results are given to the copyright protection processing unit 214, respectively.

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.

The viewing condition information regarding the program separated by the separation unit 204 is transmitted to the EM
It is compared with the individual contract information in the M memory 205, and it is determined whether or not 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.

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 if there has been tampering, the separation unit 2
The receiver is controlled according to the control mode information at the time of tampering detection input from 04.

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.

That is, when descrambling is not possible, the copyright protection processing unit 214 sets the switch 212.
, And the scramble key is not supplied to the program descramble unit 213.
Therefore, the output signal is a scrambled program.

In the case of a warning message display, the copyright protection processing unit 214 displays the on-screen display unit 2.
16 is controlled 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.

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).

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.

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.

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.

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.

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.

The block diagram for demonstrating one Embodiment of the transmission side of this invention. The block diagram for demonstrating one Embodiment of the receiving side of this invention. The block diagram for demonstrating other embodiment of the transmission side of this invention. Explanatory drawing for demonstrating the control content at the time of the alteration detection of this invention. The block diagram for demonstrating other embodiment of the receiving side of this 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 ... decryption unit 213 ... descrambling unit 205 ... EMM Memory 208 ... Viewing permission / inhibition determination unit 209, 210 ... Comparison unit 211, 212 ... Switch 214 ... Copyright protection processing unit 215 ... MPEG decoding processing unit 216 ... On-screen display unit

Claims (2)

Transmitted by the broadcast transmitting apparatus with scrambled program the digital copy control descriptor that is not encrypted to a protection information of the copyright protection system that is part of the service information used in digital broadcasting, the transmitted In a broadcast transmission / reception system for receiving received signals by a broadcast receiver
The broadcast transmitting device is:
Means for 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;
It means for obtaining a scrambled program with a scramble key Nitesu crumble programs,
Some ECM (Entitlement Control Message) that includes the scan scrambling key, means for multiplexing the message Digest,
Means for encrypting the multiplexed ECM;
Means for multiplexing and transmitting the encrypted ECM, the descriptor, and the scrambled program;
The broadcast receiving device is:
Means for receiving a signal obtained by multiplexing the encrypted ECM, the descriptor, and the scrambled program;
Means for generating a message digest that is falsification detection data from the descriptor transmitted without encryption included in the received signal;
Means for obtaining the message digest by decrypting the ECM included in the received signal;
And message Digest generated from the descriptor contained in the received signal, means for determining the alteration of the descriptors in the transmission path by comparing the message digest obtained by decryption of the ECM,
Means for executing a copy control process according to the determination result ;
Means for descrambling the scrambled program included in the received signal regardless of the determination result using the scramble key and outputting the descrambled program to a storage device;
A broadcast transmission / reception system comprising: Digital copy control descriptor, which is copyright protection protection information that is part of the program sequence information used for digital broadcasting and is not encrypted, is transmitted together with the scrambled program by the broadcast transmission device, and this transmission is performed. Used in broadcast transmission / reception systems for receiving received signals by broadcast receivers,

The broadcast transmitting device is:
Means for 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;
Means for scrambling the program with a scramble key to obtain a scrambled program;
Means for multiplexing the message digest in an ECM (Entitlement Control Message) including the scramble key;
Means for encrypting the multiplexed ECM;
Means for multiplexing and transmitting the encrypted ECM, the descriptor, and the scrambled program;
In a broadcast receiving apparatus that receives a signal transmitted from the broadcast transmitting apparatus,
Means for receiving a signal obtained by multiplexing the encrypted ECM, the descriptor, and the scrambled program;
Means for generating a message digest that is falsification detection data from the descriptor transmitted without encryption included in the received signal;
Means for obtaining the message digest by decrypting the ECM included in the received signal;
And message Digest generated from the descriptor contained in the received signal, means for determining the alteration of the descriptors in the transmission path by the ECM is compared with the message digest obtained by decryption ,
Means for executing a copy control process according to the determination result ;
Means for descrambling the scrambled program included in the received signal regardless of the determination result using the scramble key and outputting the descrambled program to a storage device;
A broadcast receiving apparatus comprising:

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