JP2004088279A - Broadcast transmission method and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent piracy due to falsified copyright protection information. <P>SOLUTION: In order to prevent falsification of a digital copy control descriptor and a content utilization descriptor being the copyright protection information, a transmitter side calculates falsification detection data of each descriptor, attaches the data to an ECM and transmits the resulting ECM. A receiver side decides presence / absence of falsification on the basis of received digital copy control descriptor, content utilization descriptor and falsification detection data in the ECM. In the case of decision of the presence of falsification, control of disabled viewing or the like is executed to suppress the falsification thereby protecting the copyright. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a broadcast transmission method and a reception device compatible with a copyright protection system.
[0002]
[Prior art]
Under the “copyright protection method” under consideration for standardization by ARIB (Association of Radio Industries and Businesses), from the viewpoint of protecting the rights of program providers, only receivers that can use scramble to protect program rights are used. By enabling demodulation, it is possible to prevent unauthorized duplication of a broadcasted program.
[0003]
Specifically, the protection of the right of a program in a digital broadcast receiver or the like is realized as described in the following (1) to (3).
(1) The use conditions of the program, such as the number of times the program can be copied, 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 condition indicated in the rights protection information.
(3) A program can be output from a receiver to an externally connected device only when the externally connected device also operates in accordance with the program usage conditions indicated in the rights protection information. At this time, the right protection information is also output.
[0004]
Here, the usage conditions of the program, such as the number of times the 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. And the following two descriptors:
[0005]
(1) Digital Copy Control Descriptor 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 of copy permitted without limitation, copy permitted only for one generation (received broadcast signal can be recorded only once), and copy prohibited.
[0006]
(2) Content Use Descriptor This is rights protection information newly introduced in the program array information, and specifies temporary storage enable / disable and temporary storage time specification for a copy-prohibited program (1). .5 hours, 3 hours,..., 1 week, no limit), and if the signal is output digitally from the receiver, is the output data protected by encryption, etc.? It is also possible to specify "output protection bit" to specify 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 for standardization is progressing on the assumption that they are transmitted in an unencrypted state. If the above two descriptors are tampered with before the input to the receiver, even a legitimate receiver that operates according to the usage conditions indicated in the rights protection information operates according to the contents of the tampered descriptors. Would. Thus, the current standard has a disadvantage that it is vulnerable to fraud.
[0008]
[Problems to be solved by the invention]
As described above, the "copyright protection scheme" under consideration for standardization operates according to the contents of the falsified descriptor, and thus has a problem that the current standard is vulnerable to impropriety.
[0009]
An object of the present invention is to perform copyright protection by performing control of disabling viewing based on whether the copyright protection information has been tampered with.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, in the present invention, a digital copy control descriptor which is protection information on the transmission side and a digital copy control descriptor which is copyright protection information in order to prevent falsification of the content use descriptor. And / or Calculates tampering detection data of the content usage descriptor, and transmits it in ECM which is program information. The receiving side calculates tampering detection data from the received digital copy control descriptor and content usage descriptor, compares it with tampering detection data in the ECM, and determines whether or not tampering has occurred.
[0011]
According to the above-described means, it is detected whether or not the digital copy control descriptor and the content use descriptor, which are the information for copyright protection, have been tampered with. The copyright protection becomes possible by suppressing the above.
[0012]
BEST MODE FOR CARRYING OUT 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 a broadcast side according to the present invention, in which generation and multiplex blocks of EMM (Entitlement Management Message) as individual viewing contract information and blocks not directly related to the present invention are omitted. I have.
[0013]
In FIG. 1, the digital copy control descriptor and / or the content use descriptor, which are information for the copyright protection system positioned as a part of the information of the program information arrays SI and SPI, are other program array information SI, The multiplexing unit 106 multiplexes the broadcast signal with the PSI and broadcasts it. The digital copy control descriptor is processed by the message digest calculation unit 101, and the content usage descriptor is processed by the message digest calculation unit 102. Is calculated, and is input to the ECM multiplexing unit 103 together with an ECM (Entitlement Control Message) common to all receiving apparatuses.
[0014]
Here, in addition to the attribute information indicating whether the broadcast is paid or free, if the broadcast is a paid broadcast, the ECM can be compared with the EMM previously transmitted from the broadcast station and received and held by each receiver for viewing. This is information used to determine whether or not the program is broadcast, that is, program information indicating viewing conditions of the program.
[0015]
Further, as a specific example of the message digest that is the tampering detection data, a MAC (Message Authentication Code) is calculated on the transmission side, and is transmitted in the ECM.
[0016]
As another specific example of the message digest, the message digest is generated by using an error detectable code that does not use secret information such as CRC (Cyclic Redundancy Check), parity, BCH code, Reed-Solomon code, or a hash function that does not use a key. It was done. For example, the CRC calculated on the broadcast side is transmitted in the ECM.
[0017]
Another specific example of the message digest is generated using a hash function using a key or a block cipher. The key to be used shall be secretly shared between the broadcasting station and the receiver in advance. For example, the work key used when encrypting the ECM is secretly shared in advance. Is optimally managed safely in the block. In addition to the work key, any key can be used as long as the key can be shared by the broadcasting station and the receiver. The message digest used here is generated using a secret key, and the risk of being generated by someone who does not know the key is low, so it is necessary to encrypt and transmit the message digest calculated on the broadcast side 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 calculating a message digest. When a key is used, a key is input to a message digest calculating unit 101 or 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 key given to the encryption unit 105 is also input to the message digest calculation units 101 and 102, respectively.
[0019]
The ECM multiplexing unit 103 multiplexes an ECM used for scrambling a program such as video and audio data, in addition to the message digest. 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, and is generated and held by an EMM generation and management unit (not shown) and supplied to the encryption unit 105. The work key may be periodically updated at an update cycle of, for example, once a month for the purpose of preventing security deterioration. At the time of the update, a new work key scheduled to be updated to all viewing subscribers in advance is required. Is sent to the EMM. The broadcast station updates the work key at a time when almost all receivers receive the EMM containing the new work key.
[0021]
In the scrambler 104, programs such as video and audio data are scrambled and output to the multiplexer 16. The key used for this scramble is a scramble key multiplexed on the ECM.
[0022]
As described above, the message digests of the digital copy control descriptor and the content use descriptor are multiplexed on the ECM, encrypted, and transmitted to the receiver without being falsified.
[0023]
FIG. 2 is a block diagram for explaining one 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 generating unit using the program arrangement information SI and PSI, the program table display unit, the user interface unit such as a remote control input unit, and the like are provided. Blocks not directly related to the description 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 into a digital copy control descriptor and a content use descriptor which are part of the program information arrangement SI and SPI information, and other program arrangement information SI and PSI. It is separated into PSI. Here, the other program arrangement information SI and PSI are processed into a program guide by a program guide generation unit (not shown), and are presented to the user by on-screen display or the like, and are used for controlling the receiver as information at the time of channel selection. is there.
[0025]
The digital copy control descriptor and the content use 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 the copyright is protected according to the two descriptors. Alternatively, control is performed such that temporary storage can be performed only for a designated time in a storage device (not shown). The digital copy control descriptor and the content use descriptor are also provided to the message digest calculation units 206 and 207, and calculate the respective message digests.
[0026]
FIG. 2 shows an example in which no key is used in calculating the message digest. In the case where 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 decrypting the ECM and stored in the EMM memory 205 is used as the key in this case, the 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 on a program by the separation unit 204.
[0028]
The message digests of the two descriptors separated by the separation unit 204 are provided to comparison units 209 and 210, respectively, and compared with the message digests calculated by the message digest calculation units 206 and 207, respectively. The result of the determination is given to the copyright protection processing unit 214.
[0029]
The scramble key separated by the separation unit 204 is provided to the decryption unit 213 via the switches 211 and 212, and the program is decrypted. The decoded program is subjected to code processing or the like 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 separating unit 204 is compared with the individual contract information in the EMM memory 205 by the viewability determining unit 208 to determine whether or not viewing is possible. If it is determined that viewing is possible, the switch 211 is turned on to permit passage of the scramble key.
[0031]
The copyright protection processing unit 214 is notified of the falsification of the digital copy control descriptor and the content use descriptor from the comparison units 209 and 210, and if there is falsification, turns off the switch 212 and encrypts the scrambled program. The scramble key to be decrypted is not supplied to the descrambling unit 213. Therefore, the output signal is in a scrambled program or the output signal is in a mute state.
[0032]
Here, when the MAC is calculated on the transmitting side and transmitted in the ECM and transmitted, the MAC is calculated from the digital copy control descriptor and the content use descriptor received on the receiving side, and compared with the MAC in the ECM to perform falsification. This is for determining.
[0033]
Also, when the CRC calculated on the broadcast side is transmitted in the ECM and transmitted, the receiving side compares the CRC extracted from the ECM with the CRC calculated from the received descriptor, and if they match, there is no tampering, and if they do not match, there is no tampering. Judge that there is. Since the CRC calculated on the broadcast side is transmitted in an ECM protected by encryption, the risk of falsification of the CRC itself is low.
[0034]
Further, when the data generated by using the hash function using the key or the block cipher is transmitted in the ECM, the receiver uses the transmitted tampering detection data to transmit the digital copy control descriptor and the content usage. Detects descriptor tampering. If tampering is detected, it is determined that descrambling is not possible even if descrambling is possible (viewing is possible) by viewing permission / prohibition determination processing using the ECM.
[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 falsification detection is input to the ECM multiplexing unit 13 and transmitted as a part of the ECM information. The same components will be described with the same reference numerals.
[0036]
The control mode information at the time of tampering detection specifies a control method that the receiver should operate when the receiver detects that the digital copy control descriptor or the content use descriptor has been tampered with. As shown in FIG. 4, three bits are defined as A to C as control mode information at the time of falsification detection, and bit 1 is designated as A, bit 2 as B, and bit 3 as C.
[0037]
In other words, if "1" is assigned to A, descrambling is not possible, if "1" is assigned to B, the falsified descriptor is invalidated (copy prohibited or temporary storage disabled), and if C "1" is set Is to switch between displaying a warning message and performing nothing if "1" is not set in any of A to C. The control mode information at the time of falsification 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, the control mode information at the time of falsification detection multiplexed with other signals transmitted by the transmission method of FIG. 3 as compared with FIG. Are different from those of the first embodiment in that an on-screen display unit 206 for displaying a warning message is added. Further, 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, a separation unit 201 separates program data, program arrangement information (SI, PSI), ECM, and EMM (not shown) from a received broadcast signal. The separated program arrangement information SI and PSI are further separated by the separation unit 203 into a digital copy control descriptor and a content use descriptor which are part of the program information arrangement SI and SPI information, and other program arrangement information SI and PSI. It is 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), presented to the user on an on-screen display or the like, or used as information at the time of tuning to control the receiver. is there.
[0040]
The digital copy control descriptor and the content use 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 the copyright is protected according to the two descriptors. Alternatively, control is performed such that temporary storage can be performed only for a designated time in a storage device (not shown). The digital copy control descriptor and the content use descriptor are also given to the message digest calculation units 206 and 207, and calculate the respective message digests.
[0041]
FIG. 5 shows an example in which a key is not used in calculating the message digest. In the case where 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 decrypting the ECM and stored in the EMM memory 25 is used as the key in this case, the 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 decoded by the decoding unit 202, and is separated by the separation unit 204 into a message digest, control mode information upon tampering detection, a scramble key, and viewing condition information on a program. The message digests of the two descriptors separated by the separation unit 204 are provided to comparison units 209 and 210, respectively, and are compared with the message digests calculated by the message digest calculation units 206 and 207, respectively. The result of the determination is given to the copyright protection processing unit 214.
[0043]
The scramble key separated by the separation unit 204 is given to the program descramble unit 213 via the switches 211 and 212, and the descrambled program is decoded by the MPEG decode processing unit 215, and the like. 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 separating unit 204 is compared with the individual contract information in the EMM memory 205 by the viewability determining unit 208 to determine whether or not viewing is possible. If it is determined that viewing is possible, the switch 211 is turned on to permit passage of the scramble key.
[0045]
The copyright protection processing unit 214 notifies the digital copy control descriptor and the content use descriptor of the falsification from the comparison units 209 and 210 and, if falsified, inputs the falsification at the time of falsification detection input from the separation unit 204. The receiver is controlled according to the control mode information.
[0046]
As shown in FIG. 4, the control mode information at the time of falsification detection is defined as three bits A to C as control mode information at the time of falsification detection, bit 1 is A, bit 2 is B, and bit 3 is C. Specify corresponding to.
[0047]
That is, when descrambling is impossible, the copyright protection processing unit 214 turns off the switch 212 and does not supply the scramble key to the descramble unit 213 of the program. Therefore, the output signal is a program that has been scrambled.
[0048]
In the case of displaying a warning message, the copyright protection processing unit 214 controls the on-screen display unit 216 to display a warning message. The warning message may be stored in the copyright protection processing unit 214 in advance as a fixed message 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 and PSI may be stored. A part provided from the broadcasting side as a part may be separated and used by the separation unit 203.
[0049]
In the case of invalidating the falsified descriptor, the copyright protection processing unit 214 operates to invalidate the falsified descriptor. That is, when the digital copy control descriptor has been tampered with, the output signal is output after controlling copy prohibition. If the content usage descriptor has been tampered with, control is performed to disable temporary storage of the program 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, the message digest need not be transmitted in the ECM. In that case, the management unit that manages the encryption key, for example, an IC card used for the receiver, calculates the message digest from the digital copy control descriptor or the content usage descriptor, and the encryption key is disclosed to the public. Shall not be performed.
[0051]
Then, the IC card processes the ECM, and if there is a contract, the scramble key is output. At the same time, the calculation result of the message digest is compared with the transmitted message digest. The IC card performs processing such as not outputting the scramble key from the IC card.
[0052]
As described above, the falsification of the digital copy control descriptor or the content use descriptor related to the copyright protection method can be detected, so that the falsification of both descriptors can be detected. Tampering can be suppressed by performing control such as impossibility.
[0053]
In addition, since the message digest for falsification detection is encrypted and transmitted in the ECM together with the scramble key, the message digest itself is securely transmitted to the receiver without being falsified, and in parallel with the management of the scramble key. Then, the presence or absence of tampering is detected, so that if tampering occurs, it is possible to perform control such as disabling viewing.
[0054]
Further, by providing a plurality of types of receiver control methods when tampering is detected, and by enabling control using 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 or not the digital copy control descriptor and the content use descriptor, which are the information for copyright protection, have been tampered with. It becomes possible to control and prevent tampering.
[Brief description of the drawings]
FIG. 1 is a block diagram for explaining an embodiment of a transmitting side of the present invention.
FIG. 2 is a block diagram for explaining an embodiment of a receiving side of the present invention.
FIG. 3 is a block diagram for explaining another embodiment of the transmission side of the present invention.
FIG. 4 is an explanatory diagram for describing control contents at the time of falsification detection 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 units 201, 203, 204 separation unit 202: decoding unit 213: descrambling unit 205: EMM memory 208: viewability judging unit 209, 210 ... comparing units 211, 212 ... switch 214: copyright protection processing Unit 215: MPEG decode processing unit 216: On-screen display unit

Claims (6)

Transmit at least one of the digital copy control descriptor and the content use descriptor, which are protection information of the copyright protection system used as part of the program arrangement information used for digital broadcasting, together with the scrambled program Broadcast transmission method,
A falsification detection data is generated from the descriptor in order to detect whether the transmitted descriptor has been tampered with in the transmission path on the receiving device side, and a key or program attribute for descrambling a program common to all the receiving devices. A broadcast transmission method, comprising: multiplexing and encrypting information multiplexed with program information (ECM) referring to information together with the scrambled program, and transmitting the multiplexed information. When the descriptor transmitted by the receiving side is detected to have been tampered with, the control mode information at the time of tampering detection that specifies a control method to be operated by the receiving side is further multiplexed and transmitted. Item 2. The broadcast transmission method according to Item 1. A broadcast receiving apparatus that receives the descriptor and the program that are multiplexed and transmitted based on claim 1,
A broadcast receiving apparatus comprising: means for detecting the presence or absence of tampering on the transmission path of the transmitted descriptor and, when it is determined that tampering has occurred, means for disabling descrambling. A broadcast receiving apparatus that receives the descriptor and the program that are multiplexed and transmitted based on claim 1,
Descrambling means for descrambling the program,
The program is encrypted together with the non-encrypted descriptor included in the received signal and the program information (ECM) that refers to the key for descrambling the program common to all the receiving devices included in the received signal and the attribute information of the program. Means for determining tampering based on the result of calculating the tampering detection data;
A broadcast receiving apparatus comprising: means for performing control to disable descrambling by the descrambling means when it is determined by the means that there has been tampering. A broadcast receiving apparatus that receives the control mode information at the time of detecting the descriptor and the program and tampering multiplexed and transmitted based on claim 2,
Descrambling means for descrambling the program,
The program is encrypted together with the non-encrypted descriptor included in the received signal and the program information (ECM) that refers to the key for descrambling the program common to all the receiving devices included in the received signal and the attribute information of the program. Means for determining tampering based on the result of calculating the tampering detection data;
A broadcast receiving apparatus comprising: a means for controlling a reception state in accordance with control mode information at the time of tampering detection when the means determines that tampering has occurred. The ECM processing means for extracting a scramble key for descrambling the program scrambled from the ECM, the means for calculating the falsification detection data, and the means for determining the falsification shall be processed at least in an IC card. 6. The broadcast receiving apparatus according to claim 4, wherein the scramble key is not output from the IC card when the digital copy control descriptor or the content use descriptor is tampered.

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