JP2008301219A - Digital broadcast receiver and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver of digital broadcast and a method which prevent unauthorized use of scramble key information when scramble key information transferred between an IC card and a CA module leaks. <P>SOLUTION: In the digital broadcast receiver 10, a CA module 20 which limited reception of the digital broadcast using th IC card 40 is performed is connected to the IC card 40 to transfer information, the IC card 40 includes a scramble key encryption circuit 56, the digital broadcast is descrambled with the scramble key by enciphering information regarding a scramble key transferred between the CA module 20 and the IC card 40 and received by being limited to a regular receiver. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a digital broadcast receiving apparatus and a receiving method thereof, and more particularly, to a receiving apparatus and a receiving method thereof capable of receiving digital broadcasting limitedly.

  Conventionally, in digital broadcasting such as satellite / terrestrial digital television broadcasting, a limited reception method has been adopted as one of content management methods for preventing unauthorized reception. For example, on the broadcast station side, broadcast information such as video and audio encrypted with a scramble key, common information including a scramble key and program information data encrypted with a work key, a work key encrypted with a master key, and each It multiplexes with individual information including the contract information data of the receiver and transmits it as a TS (Transport Stream) signal.

  On the other hand, for example, a CA (Conditional Access) module receives a TS signal and separates it into a broadcast information signal, an individual information (EMM: Entitlement Management Message) signal, and a common information (ECM: Entitlement Control Message) signal. To do. In addition, the EMM signal and ECM signal are sent to the electronic medium by connecting the electronic medium obtained in advance by the receiver through a regular procedure such as a contract to the receiving device, and the individual information is recorded by the master key recorded in advance in the electronic medium. Is decrypted. Using the work key extracted from the decrypted individual information, the common information is decrypted, the scramble key is extracted, and sent to the receiving apparatus again. On the receiving apparatus side, the broadcast information such as encrypted video and audio is decrypted by using this scramble key.

By the way, in the digital broadcasting system described in Patent Document 1, when the receiving device work key is leaked, the identifier (ID) of the receiving device that has been leaked can be specified, and the ID of the receiving device is invalidated. By doing so, a system capable of taking countermeasures against key leakage is disclosed.
JP 2005-110053 A

  In the conventional digital broadcast limited receiving apparatus and the receiving method thereof, the signal from the broadcasting station to the receiving apparatus is encrypted by the scramble key, but the scramble key transmitted from the receiving apparatus and decrypted by the electronic medium is encrypted. Is not sent to the receiving device. For this reason, a signal transmitted / received between the electronic medium and the receiving apparatus is observed by a person other than the authorized receiver, and there is a concern that the scramble key may leak. Furthermore, when this information is disclosed on the Internet, video and audio data may be viewed by an unspecified number of people.

  The present invention eliminates such drawbacks of the prior art, and even if a transmission / reception signal is observed between an electronic medium and a receiving device, it is used illegally and prevented from being viewed by an unspecified number of people. It is an object to provide a broadcast receiving apparatus and a digital broadcast receiving method.

  In order to solve the above-described problems, the present invention provides a CA module having a basic receiving function for receiving digital broadcasting, and an electronic device that is detachably connected to the CA module and has a function of sending and receiving encrypted signals. In the digital broadcast receiving apparatus including the medium, the CA module is supplied from the electronic medium by connecting the broadcast receiving means for receiving the signal including the scrambled broadcast information signal transmitted from the broadcasting station and the electronic medium. A scramble key decrypting means for decrypting an encrypted encrypted scramble key into a decrypted scramble key using a module encryption key, and a descramble means for descrambling a scrambled broadcast information signal using the decrypted scramble key. The electronic medium includes a scramble key supplied to the CA module and a predetermined electronic medium encryption key. Using, characterized in that it comprises a scrambling key encryption means for encrypting the encryption scramble key.

  Further, the digital broadcast receiving apparatus includes a CA module having a basic receiving function for receiving digital broadcasts and an electronic medium that is detachably connected to the CA module and has a function of sending and receiving encrypted signals. The CA module receives a signal including a scrambled broadcast information signal transmitted from a broadcasting station, and when the electronic medium is connected to the CA module, the encrypted signal supplied from the electronic medium is received. The scramble key decrypting step for decrypting the encrypted scramble key into the decryption scramble key using the module encryption key in the CA module, and the descrambling step for descrambling the scrambled broadcast information signal using the decryption scramble key in the CA module In order to supply the CA module with the electronic medium, the predetermined electronic medium encryption Using, characterized in that it comprises a scrambling key encryption step of encrypting the encryption scramble key to the scramble key.

  According to the digital broadcast receiving apparatus and the digital broadcast receiving method of the present invention, the encrypted scramble key transmitted from the electronic medium to the CA module is encrypted, for example, stream encrypted. Even if intercepted, it is impossible to descramble. Therefore, it is possible to prevent an unspecified number of people who have illegally obtained a scramble key from illegally viewing data such as video and audio.

  Next, embodiments of a digital broadcast receiving apparatus according to the present invention will be described in detail with reference to the accompanying drawings. For example, as shown in FIG. 1, the digital broadcast receiving apparatus 10 of this embodiment has a CA module 20 having a basic receiving function for receiving a digital broadcast, and is detachably connected to the CA module 20 and encrypted. An electronic medium having a function of transmitting / receiving signals, for example, an IC card 40 is included. Note that the basic reception function for receiving digital broadcasting is, for example, receiving a TS signal transmitted from a broadcasting station, separating it into a broadcast information signal, an EMM signal, and an ECM signal, and connected ICs. This function includes a function to send an EMM signal and an ECM signal to an electronic medium such as a card. Note that portions not directly related to understanding the present invention are not shown and redundant description is avoided.

  The CA module 20 includes a TS separation circuit 22, a descrambling circuit 24, a module ROM 26, a random number generation circuit 28, a random number encryption circuit 30, a module encryption key generation circuit 32, and a scramble key decryption circuit 34.

  The IC card 40 includes a storage medium such as a card ROM 42, an individual information (EMM) decryption circuit 44, a common information (ECM) decryption circuit 46, a viewability determination circuit 48, a nonvolatile memory 50, a card encryption key generation circuit 52, a random number A decryption circuit 54 and a scramble key encryption circuit 56 are included.

  The TS separation circuit 22 of the CA module 20 of this embodiment receives a TS signal 104 transmitted from the broadcast station side (not shown), and scrambles broadcast information including the scrambled video and audio. The signal 106, the EMM signal 108, and the ECM signal 110 are separated and then transmitted to the descrambling circuit 24, the EMM decoding circuit 44, and the ECM decoding circuit 46, respectively.

  The descrambling circuit 24 has a function of descrambling the scrambled broadcast information signal 106 and outputting a broadcast information signal 144 such as video and audio using the predetermined decryption scramble key 142 supplied. In this embodiment, the scramble key decoding circuit 34 is supplied with the decryption scramble key 142, and the decryption scramble key 142 is used to descramble the scramble broadcast information signal 106 supplied from the TS separation circuit 22 to broadcast video and audio. A function of outputting the information signal 144 is provided.

  The module ROM 26 has a function of storing identification information unique to the CA module, for example, a serial number 100. When the IC card 40 is connected to the CA module 20, the serial number 100 is transmitted to the nonvolatile memory 50 of the IC card 40. To do.

  The random number generation circuit 28 has a function of generating a random number 130, and transmits the random number 130 to the random number encryption circuit 30 and the module encryption key generation circuit 32.

  The random number encryption circuit 30 uses the random number encryption key 128 supplied from the module encryption key generation circuit 32, encrypts the random number 130 supplied from the random number generation circuit 28, and generates an encrypted random number 132. It has a function of transmitting to the random number decoding circuit 54.

  The module encryption key generation circuit 32 has a function of supplying the module encryption key 140 to the scramble key decryption circuit 34. In this embodiment, the module encryption key 140 has a function of generating using the random number 130 generated by the random number generation circuit 28 and the key generation information 126 received from the card encryption key generation circuit 52. Also, the key generation information 126 is received from the card encryption key generation circuit 52, a random number encryption key 128 is generated using the key generation information 126, and the random number encryption key 128 is supplied to the random number encryption circuit 30. .

  The scramble key decryption circuit 34 has a function of supplying the decryption scramble key 142 to the descramble circuit 24. This embodiment has a function of decrypting the encrypted scramble key 138 received from the IC card 40 into the decryption scramble key 142. In addition, in order to decrypt the encrypted scramble key 138, the module encryption key 140 generated by the module encryption key generation circuit 32 is used as a key.

  The card ROM 42 of the IC card 40 of this embodiment has a function of storing a master key 112 specific to the IC card 40 for decrypting the EMM signal 108, that is, a receiver-specific master key 112. Supply.

  The EMM decryption circuit 44 uses the master key 112 supplied from the card ROM 42 to convert the EMM signal 108 transmitted from the TS separation circuit 22 into the work key 114, the receiver-specific contract information 118, the serial number, and the random number encryption. A function for decrypting into individual information including encryption key generation information 122 having correspondence information between a key and key generation information, and supplying the individual information to the ECM decryption circuit 46, viewability determination circuit 48, and card encryption key generation circuit 52, respectively. It has the function to do.

  The ECM decryption circuit 46 has a function of decrypting the ECM signal 110 transmitted from the separation circuit 22 of the CA module 20 into ECM information including program information 116 using the work key 114 supplied from the EMM decryption circuit 44. The decoded program information 116 is supplied to the viewing permission / inhibition determination circuit 48.

  The viewing permission / non-permission determining circuit 48 has a function of determining whether or not the receiver can view and, when viewing is possible, generates a scramble key 120 and supplies the scramble key 120 to the scramble key encryption circuit 56. This embodiment has a function of determining whether or not viewing is possible from the contract information 118 supplied from the EMM decoding circuit 44 and the program information 116 supplied from the ECM decoding circuit 46.

  The nonvolatile memory 50 has a function of storing the serial number 100 transmitted from the module ROM 26 of the CA module 20.

  The card encryption key generation circuit 52 uses the serial number 102 stored in the non-volatile memory 50 and the encryption key generation information 122 supplied from the EMM decryption circuit 44 to generate key generation information 126 and a random number corresponding to the serial number 102 The decryption key 124 is generated and supplied to the module encryption key generation circuit 32 and the random number decryption circuit 54, respectively. Further, using the decryption random number 134 supplied from the random number decryption circuit 54 and the encryption key generation information 122 supplied from the EMM decryption circuit 44, for example, an electronic medium is obtained by exclusive OR of the decryption random number 134 and the encryption key generation information 122. An encryption key, that is, a card encryption key 136 is generated and supplied to the scramble encryption circuit 56.

  The random number decryption circuit 54 decrypts the encrypted random number 132 transmitted from the random number encryption circuit 30 of the CA module 20 into the decrypted random number 134 using the random number decryption key 124 supplied from the card encryption key generation circuit 52, and this decryption The random number 134 is supplied to the card encryption key generation circuit 52.

  The scramble key encryption circuit 56 has a function of transmitting the encryption scramble key 138 to the scramble key decryption circuit 34 of the CA module 20. The present embodiment has a function of encrypting the scramble key 120 supplied from the viewing permission determination circuit 48 into the encryption scramble key 138 using the card encryption key 136 supplied from the card encryption key generation circuit 52.

  Next, the operation when the receiver sets the IC card 40 in the digital broadcast receiving apparatus 10 in this embodiment will be described with reference to the flowchart of FIG.

  In the digital broadcast receiver 10 of the present embodiment, when the receiver IC card 40 is set (S200), the serial number 100 stored in the module ROM 26 of the CA module 20 is supplied to the IC card 40 and is nonvolatile. It is written in the memory 50 (S202).

  The TS signal 104 received by the CA module 20 is separated into the scrambled broadcast information 106, the EMM signal 108, and the ECM signal 110 by the TS separation circuit 22, and the EMM signal 108 and the ECM signal 110 are transferred to the IC card 40. The EMM signal 108 is decrypted into EMM information by the EMM decryption circuit 44, and the ECM signal 110 is decrypted by the ECM decryption circuit 46 into ECM information using the work key 114 included in the EMM information (S204).

  The reception information such as the decoded EMM information and ECM information is supplied to the viewing availability determination circuit 48, and the viewing availability determination circuit 48 compares the program information 116 of the reception information with the contract information 118 to determine whether viewing is possible. It is determined (S206).

  If it is determined that viewing is not possible, the process returns to the start, but if it is determined that viewing is possible, a scramble key 120 is generated (S208).

  On the other hand, the card encryption key generation circuit 52 generates a random number decryption key 124 using the encryption key generation information 122 decrypted by the EMM decryption circuit 44 and supplies it to the random number decryption circuit 54. Similarly, key generation information 126 corresponding to the serial number 102 stored in the nonvolatile memory 50 is generated using this encryption key generation information 122 and transmitted to the module encryption key generation circuit 32 of the module 20.

  In the module encryption key generation circuit 32, a random number encryption key 128 is generated using the key generation information 126 and supplied to the random number encryption circuit 30. The random number 130 generated by the random number generation circuit 28 is encrypted by the random number encryption key 128 and transmitted to the random number decryption circuit 54 of the IC card 40 as the encrypted random number 132.

  The transmitted encrypted random number 132 is decrypted into the decrypted random number 134 using the random number decryption key 124 already supplied by the random number decryption circuit 54 as a key, and is supplied to the card encryption key generation circuit 52 (S210).

  In the card encryption key generation circuit 52, a card encryption key 136 is generated from the decrypted random number 134 and the already supplied encryption key generation information 122, and is supplied to the scramble key encryption circuit 56 (S212).

  The scramble key encryption circuit 56 generates an encrypted scramble key 138 by encrypting the scramble key 120 with the card encryption key 136 (S214), and this encrypted scramble key 138 is the scramble key decryption circuit of the CA module 20. It is transmitted to 34 (S216).

  The module encryption key generation circuit 32 of the CA module 20 generates a module encryption key 140 using the random number 130 generated by the random number generation circuit 28 and the key generation information 126 received from the card encryption key generation circuit 52. Using this module encryption key 140, the scramble key decryption circuit 34 decrypts the encrypted scramble key 138 received from the scramble key encryption circuit 56 into the decrypt scramble key 142 (S218).

  When the decrypted scramble key 142 decrypted by the scramble key decryption circuit 34 is supplied to the descramble circuit 24, the scramble broadcast information signal 106 is descrambled, and the authorized receiver receives the broadcast information signal 144 such as video and audio. It can be viewed (S220).

  Thus, according to the present invention, the signal transmitted and received between the CA module 20 and the IC card 40 is in an encrypted state, and even if this signal is intercepted, it is encrypted as it is. Since the data cannot be descrambled, illegally obtaining the scramble key 120 can prevent the risk that an unspecified number of people will illegally view data such as video and audio. .

It is a block diagram which shows one Example of the digital broadcast receiver of this invention. It is a flowchart explaining the operation | movement procedure of the digital broadcast receiver shown in FIG.

Explanation of symbols

10 Digital broadcast receiver
20 CA module
22 TS separation circuit
24 Descramble circuit
26 Module ROM
28 Random number generator
30 Random number encryption circuit
32 Module encryption key generation circuit
34 Scramble key decryption circuit
40 IC card
42 Card ROM
44 EMM decoding circuit
46 ECM decoding circuit
48 Viewability judgment circuit
50 Nonvolatile memory
52 Card encryption key generation circuit
54 Random number decoding circuit
56 Scramble key encryption circuit

Claims (9)

In a digital broadcast receiving apparatus including a CA (Conditional Access) module having a basic receiving function for receiving a digital broadcast, and an electronic medium connected to the CA module in a detachable manner and having a function of sending and receiving an encrypted signal ,
The CA module includes an encrypted encrypted scramble key supplied from an electronic medium by connecting the electronic medium with broadcast receiving means for receiving a signal including a scrambled broadcast information signal transmitted from a broadcasting station, Scramble key decryption means for decrypting into a decryption scramble key using a module encryption key;
Descrambling means for descrambling the scrambled broadcast information signal using the decryption scramble key,
The digital broadcast receiving apparatus according to claim 1, wherein the electronic medium includes scramble key encryption means for encrypting a scramble key supplied to the CA module into the encrypted scramble key using a predetermined electronic medium encryption key. The digital broadcast receiver according to claim 1,
The CA module receives the scrambled broadcast information signal transmitted from the broadcast station, and separates the scrambled broadcast information signal, the individual information signal, and the common information signal,
A separate signal supply means for supplying the individual information signal of the separated signal and the common information signal to the electronic medium;
The electronic medium determines whether or not viewing is possible based on predetermined individual information and common information, and generates a scramble key when the electronic medium determines that viewing is possible.
Individual information decrypting means for decrypting the individual information signal transmitted from the CA module into the individual information by using a master key unique to the receiver that is preliminarily stored in the storage medium of the electronic medium,
Digital broadcast reception comprising: common information decoding means for decoding the common information signal supplied from the CA module into the common information using the receiver-specific work key included in the individual information apparatus. The digital broadcast receiver according to claim 1,
The CA module includes module encryption key generation means for generating the module encryption key from key generation information supplied from the electronic medium,
Including identification information storage means for storing identification information unique to the CA module,
The electronic medium includes electronic medium encryption key generation means for generating the electronic medium encryption key from the identification information supplied from the CA module and encryption key generation information included in the individual information. Digital broadcast receiver. The digital broadcast receiver according to claim 3, wherein
The CA module includes random number generation means for generating a random number;
Module encryption key generation means for generating the module encryption key from the random number and the key generation information;
Random number encryption key generation means for generating a random number encryption key from the key generation information;
Random number encryption means for encrypting the random number into an encrypted random number using the random number encryption key;
Encrypted random number supply means for supplying the encrypted random number to the electronic medium,
The electronic medium includes random number decryption key generation means for generating a random number decryption key from the encryption key generation information;
Random number decryption means for decrypting the encrypted random number supplied from the CA module into a decrypted random number using the random number decryption key;
An electronic medium encryption key generating means for generating the electronic medium encryption key using the decrypted random number. The digital broadcast receiver according to claim 1,
The CA module is composed of a semiconductor integrated circuit,
The digital broadcast receiving apparatus, wherein the electronic medium is formed of a semiconductor integrated circuit. Digital broadcasting is received by a digital broadcasting receiving apparatus including a CA module having a basic receiving function for receiving digital broadcasting and an electronic medium that is detachably connected to the CA module and has a function of sending and receiving encrypted signals. The method comprising:
Broadcast receiving step of receiving a signal including a scrambled broadcast information signal transmitted from a broadcasting station by the CA module;
When the electronic medium is connected to the CA module, a scramble key for decrypting the encrypted scramble key encrypted from the electronic medium into a decrypt scramble key using the module encryption key in the CA module Decryption step;
A descrambling step of descrambling the scrambled broadcast information signal using the decryption scramble key in the CA module;
A scramble key encryption step of encrypting a scramble key supplied to the CA module into the encrypted scramble key using the predetermined electronic medium encryption key in the electronic medium. Method. The digital broadcast receiving method according to claim 6, wherein the method includes:
The CA module receives the scrambled broadcast information signal transmitted from the broadcast station, and separates the scrambled broadcast information signal, the individual information signal, and the common information signal;
In the CA module, a separate signal supplying step of supplying the individual information signal of the separated signal and the common information signal to the electronic medium;
In the electronic medium, the individual information and the common information are used to determine whether or not viewing is possible, and when it is determined to be possible, a scramble key generation step of generating the scramble key;
An individual information decoding step of decoding the individual information signal supplied from the CA module into the individual information using a master key that is semi-fixed and stored in advance in the storage medium of the electronic medium;
A digital broadcast receiving method, comprising: a common information decoding step of decoding the common information signal supplied from the CA module into the common information using a work key included in the individual information. The digital broadcast receiving method according to claim 6, wherein the method includes:
In the CA module, a module encryption key generation step of generating the module encryption key from key generation information supplied from the electronic medium;
In the CA module, an identification information storage step of storing identification information unique to the receiver,
An electronic medium encryption key generating step for generating the electronic medium encryption key from the identification information supplied from the CA module and the encryption key generation information included in the individual information in the electronic medium; To receive digital broadcasts. 9. The digital broadcast receiving method according to claim 8, wherein the method includes:
In the CA module, a random number generation step for generating a random number;
In the CA module, a module encryption key generation step for generating the module encryption key from the random number and the key generation information;
In the CA module, a random number encryption key generation step of generating a random number encryption key from the key generation information;
A random number encryption step of encrypting the random number into an encrypted random number using the random number encryption key in the CA module;
In the CA module, an encrypted random number supply step of supplying the encrypted random number to the electronic medium;
A random number decryption key generation step for generating the random number decryption key from the encryption key generation information in the electronic medium;
A random number decryption step of decrypting the encrypted random number supplied from the CA module into a decrypted random number using the random number decryption key in the electronic medium;
A digital broadcast receiving method comprising: an electronic medium encryption key generating step for generating the electronic medium encryption key using the decrypted random number in the electronic medium.

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