JP4379895B2 - Digital broadcast receiving apparatus and method - Google Patents

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 conditional access system has been adopted as one of content management methods for preventing unauthorized reception. For example, on the transmitting 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, the receiving device side, for example, a CA (Conditional Access) module receives a TS signal, broadcast information signal, individual information (EMM: Entitlement Management Message) signal, common information (ECM: Entitlement Control Message) signal, To separate. 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 reception apparatus and the reception method thereof, the signal from the transmission station to the reception apparatus is encrypted by the scramble key, but the scramble key transmitted from the reception 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 be leaked. 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-mentioned problem, the present invention receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station, and descrambles the scrambled broadcast information signal using a predetermined scramble key. And a digital broadcast receiving apparatus for receiving a digital broadcast, wherein the electronic medium is generated, and is detachably connected to the CA module, generates a scramble key, further encrypts it, and transmits it to the CA module. A scramble key encryption unit that encrypts the scramble key using a predetermined encryption key and supplies the scramble key to the CA module; a scramble key storage unit that stores the generated scramble key and holds a predetermined number of scramble keys; The previous scramble key stored in the scramble key holding means during the previous reception process of the device The CA module receives an encrypted scramble key from an electronic medium, and obtains the scramble key from the scramble key holding means and includes an encryption key calculation means for calculating an encryption key based on the previous scramble key. A scramble key decrypting means for decrypting using a predetermined decryption key; a decryption scramble key holding means for storing a scramble key decrypted by the scramble key decryption means and retaining a predetermined number of decrypted scramble keys; A decryption key computing means for obtaining a previous scramble key stored in the decryption scramble key holding means during the previous reception process of the device from the decryption scramble key holding means, and calculating a decryption key based on the previous scramble key; It is characterized by including.

  Furthermore, a CA module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachably connected to the CA module, In a digital broadcast receiving apparatus for receiving a digital broadcast, the electronic medium is a receiver-specific serial number stored in advance in the electronic medium. A selection signal is generated based on a receiver-specific serial number stored in advance in the CA module, and a selection is made to select a scramble key from the scramble key holding means of the electronic medium and the decryption scramble key holding means of the CA module. Control means and generated scramble key using predetermined encryption key The scramble key encryption means for encrypting and supplying to the CA module, the scramble key holding means for storing the generated scramble key and holding a predetermined number of scramble keys, and the scramble key holding means according to the selection signal A scramble key obtained from the scramble key holding means, and an encryption key calculation means for calculating an encryption key based on the scramble key. The CA module receives the scramble key encrypted from the electronic medium and receives the scramble key A scramble key decrypting means for decrypting the key using a predetermined decryption key; a decryption scramble key retaining means for storing the scramble key decrypted by the scramble key decryption means and retaining a predetermined number of scramble keys; and a selection signal The scramble key stored in the decryption scramble key holding means is decrypted according to And a decryption key calculation means for calculating a decryption key based on the scramble key obtained from the key holding means.

  In addition, a CA module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachably connected to the CA module, A method of receiving a digital broadcast by a digital broadcast receiving apparatus that receives a digital broadcast including an electronic medium that generates a scramble key, further encrypts it, and transmits it to the CA module. The previous scramble key stored in the scramble key holding buffer is obtained from the scramble key hold buffer, and a predetermined encryption key is calculated based on the previous scramble key, and the generated scramble key is A scramble key holding step for storing and holding a predetermined number of scramble keys, and a scramble key A scramble key encryption process that encrypts using the encryption key and supplies it to the CA module, and the CA module decrypts and scrambles the previous scramble key stored in the decryption scramble key holding buffer during the previous reception process of the device. Obtains from the key holding buffer, stores the decryption key calculation step for calculating a predetermined decryption key based on the previous scramble key, and stores the scramble key decrypted in the scramble key decryption step, and holds a predetermined number of scramble keys A scramble key holding step, and a scramble key decryption step of receiving an encrypted scramble key from the electronic medium and decrypting the scramble key using the decryption key.

  Furthermore, a CA module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachably connected to the CA module, A method of receiving a digital broadcast by a digital broadcast receiving apparatus that receives a digital broadcast including an electronic medium that generates a scramble key, further encrypts it, and transmits it to a CA module is an electronic medium, which is stored in advance in the electronic medium A selection signal is generated based on the receiver-specific serial number and the receiver-specific serial number stored in advance in the CA module. From the scramble key holding buffer of the electronic medium and the decryption scramble key holding buffer of the CA module, respectively. The selection control process for selecting a scramble key and the selection signal Accordingly, the scramble key stored in the scramble key holding buffer is obtained from the scramble key hold buffer, and based on the scramble key, a predetermined encryption key is calculated, and the generated scramble key is stored, A scramble key holding step for holding a predetermined number of scramble keys, a scramble key encryption step for encrypting the scramble key using an encryption key and supplying the scramble key to the CA module, and a decryption scramble key holding buffer in accordance with the selection signal in the CA module The scramble key stored in the decryption scramble key holding buffer is obtained, a decryption key computation step for computing a predetermined decryption key based on the scramble key, and an encrypted scramble key received from the electronic medium, A scramble key decryption step of decrypting the scramble key using the decryption key, and the scramble key A scramble key holding step of storing the scramble key decrypted in the scramble key decryption step and holding a predetermined number of scramble keys.

  Next, embodiments of the digital broadcast receiving apparatus 10 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 (integrated circuit) card 40 is included. Note that portions not directly related to understanding the present invention are not shown and redundant description is avoided.

  The basic receiving 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 connecting the IC card 40 This function includes the function of sending EMM signals and ECM signals to electronic media.

  In a single reception process by the apparatus 10, a TS signal is received, a scramble key is generated from the EMM signal and the ECM signal, and a broadcast information signal is descrambled.

  The CA module 20 includes a TS separation circuit 22, a descrambling circuit 24, a decryption scramble key holding buffer 26, a decryption key operation circuit 28, and a decryption circuit 30.

  The IC card 40 includes a key register 42, an EMM decryption circuit 44, an ECM decryption circuit 46, a viewing determination circuit 48, a scramble key holding buffer 50, an encryption key operation circuit 52, and an encryption circuit 54.

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

  The descrambling circuit 24 uses the predetermined scramble key 128 supplied, in this embodiment, the scramble key 128 supplied from the decryption circuit 30, to de-scramble the scrambled broadcast information signal 106 into a broadcast information signal 134 such as video and audio. Scramble and output.

  The decryption scramble key holding buffer 26 temporarily holds the scramble key 128 decrypted by the decryption circuit 30 and supplies it to the decryption key calculation circuit 28 as necessary. Note that the decryption scramble key holding buffer 26 can hold a predetermined number of scramble keys 128. For example, in addition to the scramble key 128 decrypted by the decryption circuit 30 in the current process, the decryption circuit 30 performs the previous process. The decrypted scramble key 128 can also be held. As the decryption scramble key holding buffer 26, for example, a first-in first-out (FIFO) method may be used.

  The decryption key operation circuit 28 generates the decryption key 132 by operating the output 130 from the decryption scramble key holding buffer 26 by the same key generation operation method as the encryption key operation circuit 52, and supplies the decryption key 132 to the decryption circuit 30.

  The decryption circuit 30 generates the scramble key 128 using the decryption key 132 generated by the decryption key calculation circuit 28 using the encryption scramble key 126 received from the encryption circuit 54 of the IC card 40, and the descramble circuit 24 Send to.

  The key register 42 of the IC card 40 has a function of storing a master key 112 unique to the IC card 40 for decrypting the EMM signal 108, that is, a receiver-specific master key 112, and supplies the master key 112 to the EMM decryption circuit 44. .

  The EMM decryption circuit 44 decrypts the EMM signal 108 transmitted from the TS separation circuit 22 into the work key 114 and the EMM information 116 including the contract information using the master key 112 supplied from the key register 42, respectively. The data is supplied to the decoding circuit 46 and the viewing determination circuit 48.

  The ECM decryption circuit 46 decrypts the ECM signal 110 transmitted from the separation circuit 22 of the CA module 20 using the work key 114 supplied from the EMM decryption circuit 44 into ECM information 118 including program information, and determines whether or not to view the program. Supply to circuit 48.

  The viewing determination circuit 48 determines whether or not the receiver can view from the EMM information 116 including the contract information supplied from the EMM decoding circuit 44 and the ECM information 118 including the program information supplied from the ECM decoding circuit 46. If it can be viewed, a scramble key 120 is generated, and the scramble key 120 is supplied to the encryption circuit 54.

  The scramble key holding buffer 50 temporarily holds the scramble key 120 generated by the viewing determination circuit 48 and transmits it to the encryption key calculation circuit 52. The scramble key holding buffer 50 can temporarily hold a predetermined number of scramble keys 120. For example, in addition to the scramble key 120 generated by the viewing determination circuit 48 in the current process, the scramble key holding buffer 50 can be viewed in the previous process. The scramble key 120 generated by the determination circuit 48 can also be held. As the scramble key holding buffer 50, for example, a FIFO method may be used.

  The encryption key calculation circuit 52 generates the encryption key 124 by calculating the scramble key 122 supplied from the scramble key holding buffer 50 by the same key generation calculation method as the decryption key calculation circuit 28, and supplies the encryption key 124 to the encryption circuit 54. .

  The encryption circuit 54 has a function of transmitting the encryption scramble key 126 to the decryption circuit 30 of the CA module 20. In this embodiment, the scramble key 120 supplied from the viewing determination circuit 48 is encrypted to the encryption scramble key 126 using the encryption key 124 supplied from the encryption key calculation circuit 52.

  Next, the operation when the receiver sets the IC card 40 in the digital broadcast receiving apparatus 10 in the present embodiment will be described.

  In the digital broadcast receiving apparatus 10 of this embodiment, when the receiver IC card 40 is set in the CA module 20, the TS signal 104 received by the CA module 20 is scrambled by the TS separation circuit 22. The EMM signal 108 and the ECM signal 110 are separated, and the scrambled broadcast information signal 106 is transmitted to the descrambling circuit 24, and the EMM signal 108 and the ECM signal 110 are transmitted to the IC card 40.

  The EMM signal 108 sent to the IC card 40 is decrypted into EMM information 116 including contract information by using the master key 112 previously held in the key register 42 by the EMM decryption circuit 44, and the ECM signal 110 is decrypted by ECM. The circuit 46 uses the work key 114 included in the EMM information 116 to decrypt the ECM information 118 including the program information.

  The received reception information such as the decoded EMM information 116 and ECM information 118 is supplied to the viewing permission determination circuit 48, and the viewing permission determination circuit 48 compares the program information included in the reception information with the contract information. Whether it is possible is determined.

  If it is determined that viewing is possible, a scramble key 120 is generated and sent to the encryption circuit 54. In this way, in the current process, the scramble key 120 is also sent to the scramble key holding buffer 50 and temporarily held in the scramble key holding buffer 50 in order to calculate the next encryption key 124.

  The encryption circuit 54 uses the encryption key 124 calculated by the encryption key calculation circuit 52 based on the scramble key 122 generated by the viewing determination circuit 48 and held in the scramble key holding buffer 50 in the previous processing, to the scramble key 120. Is encrypted into the encryption scramble key 126 and transmitted to the CA module 20.

  In the decryption circuit 30 of the CA module 20, the decryption key 132 computed by the decryption key computation circuit 28 based on the scramble key 130 decrypted by the decryption circuit 30 and held in the decryption scramble key holding buffer 26 in the previous process, The encryption scramble key 126 transmitted from the IC card 40 is decrypted into the scramble key 128 and sent to the descramble circuit 24. In this way, in the current process, the scramble key 128 is also sent to the decryption scramble key holding buffer 26, and temporarily held in the decryption scramble key holding buffer 26 in order to calculate the next decryption key 132.

  The scramble key 120 held in the scramble key holding buffer 50 of the IC card 40 and the scramble key 128 held in the decryption scramble key holding buffer 26 of the CA module 20 are the same, and the encryption key of the IC card 40 Since the arithmetic circuit 52 and the decryption key arithmetic circuit 28 of the CA module 20 have the same arithmetic method, it goes without saying that the encryption key 124 and the decryption key 132 are the same.

  When the scramble key 128 decrypted by the decryption circuit 30 is supplied to the descramble circuit 24, the scramble broadcast information signal 106 is descrambled so that the authorized receiver can view the broadcast information signal 134 such as video and audio. Become.

  Next, a digital broadcast receiver 60 according to another embodiment of the present invention will be described with reference to FIG. However, the same elements as those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  In this embodiment, management of scramble keys is performed separately to further increase the security, and a new function is added to the previous embodiment.

  The CA module 20 includes a TS separation circuit 22, a descrambling circuit 24, a decryption scramble key holding buffer 26, a decryption key operation circuit 28, a decryption circuit 30, and a serial number register 32.

  The IC card 40 includes a key register 42, an EMM decryption circuit 44, an ECM decryption circuit 46, a viewing determination circuit 48, a scramble key holding buffer 50, an encryption key calculation circuit 52, an encryption circuit 54, a data selection control circuit 58, and a serial number register. Consists of 56.

  The serial number register 32 of the CA module 20 has a function of storing the serial number 202 unique to the receiver. When the IC card 40 is connected to the CA module 20, the serial number 202 is converted to the selection control circuit 58 of the IC card 40. Send to.

  The serial number register 56 of the IC card 40 has a function of storing a verification serial number 204 unique to the receiver for verification of the receiver. When the IC card 40 is connected to the CA module 20, the verification verification serial number 204 Is supplied to the selection control circuit 58.

  The selection control circuit 58 has a function of selecting and controlling the scramble key 120 and the scramble key 128, and is supplied from the serial number 202 transmitted from the serial number register 32 of the CA module 20 and the serial number register 56 of the IC card 40. A selection signal 206 is generated based on the serial number information 204 and sent to the decryption scramble key holding buffer 26 of the CA module 20 and the scramble key holding buffer 50 of the IC card 40. In this embodiment, the serial number 202 and the serial number information 204 are collated, and if they match, a selection signal 206 for selecting a scramble key to be used is output. Further, the selection signal 206 can be changed and output at regular intervals.

  The scramble key holding buffer 50 temporarily holds up to a predetermined number of scramble keys 120 sent subsequently from the viewability determination circuit 48, and is selected according to the selection signal 206 transmitted from the selection control circuit 58. One scramble key 122 is sent to the encryption key calculation circuit 52.

  The decryption scramble key holding buffer 26 temporarily holds up to a predetermined number of scramble keys 128 transmitted from the decryption circuit 30, and holds one scramble key 130 according to the selection signal 206 transmitted from the selection control circuit 58. Select and send to the decryption key calculation circuit 28.

  For example, in this embodiment, the scramble key holding buffer 50 of the IC card 40 holds a plurality of scramble keys, and the same scramble key as the plurality of scramble keys held in the decryption scramble key hold buffer 26 of the CA module 20 The scramble key 122 selected according to the selection signal 206 is the same as the scramble key 130 selected according to the selection signal 206.

  Next, the operation when the receiver sets the IC card 40 in the digital broadcast receiving apparatus 60 according to another embodiment of the present invention will be described. Except for the newly added function, the operation is the same as that of the previous embodiment, and a detailed description thereof will be omitted.

  In the digital broadcast receiver 60 of another embodiment, when the receiver IC card 40 is set in the CA module 20, the receiver-specific serial number 202 stored in advance in the serial number register 32 of the CA module 20 is It is transmitted to the selection control circuit 58 of the IC card 40.

  When the IC card 40 is connected to the CA module 20, the verification serial number information 204 unique to the receiver is stored in the selection control circuit 58 for verification of the receiver stored in advance in the serial number register 56 of the IC card 40. Supplied.

  The selection control circuit 58 generates a selection signal 206 based on the serial number 202 transmitted from the serial number register 32 of the CA module 20 and the serial number 204 supplied from the serial number register 56 of the IC card 40. In this embodiment, the serial number 202 and the serial number 204 are collated by the selection control circuit 58, and a selection signal 206 for selecting a scramble key to be used is output.

  This selection signal 206 is simultaneously sent to the decryption scramble key holding buffer 26 of the CA module 20 and the scramble key holding buffer 50 of the IC card 40.

  On the other hand, in the digital broadcast receiving apparatus 60, when the receiver's IC card 40 is set, the TS signal 104 received by the CA module 20 is sent to the EMM signal 108 by the TS separation circuit 22 as in the previous embodiment. And the ECM signal 110 are separated, transmitted to the IC card 40, decoded by the IC card 40, and then viewed / unviewable by comparing the program information included in the received information with the contract information in the viewability determination circuit 48. Is determined, and a scramble key 120 is generated.

  The generated scramble key 120 is sent to the encryption circuit 54 and also sent to the scramble key holding buffer 50, where it is temporarily held.

  In addition, the scramble key holding buffer 50 can temporarily hold up to a predetermined number of scramble keys 120 sent subsequently from the viewability determination circuit 48.

  Here, according to the selection signal 206 sent from the selection control circuit 58, one scramble key 122 is taken out from the plurality of scramble keys 120 held in the scramble key holding buffer 50, and the encryption key is based on the scramble key 122. Calculation is performed by the calculation circuit 52, and the encryption key 124 is output.

  The scramble key 120 sent from the viewing permission determination circuit 48 to the encryption circuit 54 is encrypted by the encryption key 124 sent from the encryption key calculation circuit 52, and the encrypted scramble key 126 is sent to the CA module 20.

  The encryption scramble key 126 transmitted from the IC card 40 is decrypted into the scramble key 128 by the decryption key 132 supplied from the decryption key calculation circuit 28 in the decryption circuit 30 of the CA module 20 and sent to the descramble circuit 24. In this way, the scramble key 128 is sent to the decryption scramble key holding buffer 26 and temporarily held in the decryption scramble key holding buffer 26.

  In addition, the decryption scramble key holding buffer 26 can temporarily hold the scramble key 128 transmitted from the decryption circuit 30 up to the same number as the scramble key holding buffer 50 of the IC card 40.

  Here, the decryption scramble key holding buffer 26 of the CA module 20 receives the same selection signal 206 transmitted from the selection control circuit 58 of the IC card 40 to the scramble key holding buffer 50 of the IC card 40, and receives the decryption scramble key. One scramble key 130 is taken out from the plurality of scramble keys 128 held in the holding buffer 26, calculated by the decryption key calculation circuit 28 based on the scramble key 130, and the decryption key 132 is output.

  The plurality of scramble keys held in the scramble key holding buffer 50 of the IC card 40 and the plurality of scramble keys held in the decryption scramble key holding buffer 26 of the CA module 20 are the same, and are extracted by the selection signal 206. The scramble key 122 and the scramble key 130 are the same. Also, since the encryption key operation circuit 52 of the IC card 40 and the decryption key operation circuit 28 of the CA module 20 have the same operation method, the encryption key 124 and the decryption key 132 are the same.

  When the scramble key 128 decrypted by the decryption circuit 30 is supplied to the descramble circuit 24, the scramble broadcast information signal 106 is descrambled so that the authorized receiver can view the broadcast information signal 134 such as video and audio. Become.

  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 block diagram which shows the other Example of the digital broadcast receiver of this invention.

Explanation of symbols

10 Digital broadcast receiver
20 CA module
22 TS separation circuit
24 Descramble circuit
26 Decryption scramble key holding buffer
28 Decryption key operation circuit
30 Decoding circuit
32 Serial number register
40 IC card
42 Key register
44 EMM decoding circuit
46 ECM decoding circuit
48 Viewing judgment circuit
50 Scramble key holding buffer
52 Cryptographic key operation circuit
54 Encryption circuit
56 Serial number register
58 Selection control circuit

Claims (6)

A CA (Conditional Access) module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachable from the CA module In a digital broadcast receiving apparatus for receiving a digital broadcast, including an electronic medium connected and generating the scramble key, further encrypting it and transmitting it to the CA module,
The electronic medium encrypts the generated scramble key using a predetermined encryption key, and supplies the CA module with scramble key encryption means;
Scramble key holding means for storing the generated scramble key and holding a predetermined number of scramble keys;
The previous scramble key stored in the scramble key holding means during the previous reception process of the device is obtained from the scramble key holding means, and the encryption key is calculated based on the previous scramble key. Encryption key calculation means,
The CA module receives the scramble key encrypted from the electronic medium, and scramble key decryption means for decrypting the scramble key using a predetermined decryption key;
Decoding scramble key holding means for storing the scramble key decoded by the scramble key decoding means and holding a predetermined number of decoded scramble keys;
Obtaining the previous scramble key stored in the decryption scramble key holding means from the decryption scramble key holding means during the previous reception process of the device, and calculating the decryption key based on the previous scramble key A digital broadcast receiving apparatus comprising: a decryption key calculation means. A CA module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachably connected to the CA module, In a digital broadcast receiving apparatus that receives a digital broadcast, including an electronic medium that generates a scramble key, further encrypts it, and transmits it to the CA module,
The electronic medium generates a selection signal based on a receiver-specific serial number stored in advance in the electronic medium and a receiver-specific serial number stored in advance in the CA module, and scrambles the electronic medium. Selection control means for selecting a scramble key from the key holding means and the decryption scramble key holding means of the CA module,
Scramble key encryption means for encrypting the generated scramble key using a predetermined encryption key and supplying the scramble key to the CA module;
Scramble key holding means for storing the generated scramble key and holding a predetermined number of scramble keys;
In accordance with the selection signal, the scramble key stored in the scramble key holding means is obtained from the scramble key holding means, and based on the scramble key, encryption key calculation means for calculating the encryption key,
The CA module receives the scramble key encrypted from the electronic medium, and scramble key decryption means for decrypting the scramble key using a predetermined decryption key;
Decryption scramble key holding means for storing the scramble key decoded by the scramble key decoding means and holding a predetermined number of scramble keys;
A decryption key computing means for obtaining the scramble key stored in the decryption scramble key holding means in accordance with the selection signal from the decryption scramble key holding means and computing the decryption key based on the scramble key. A digital broadcast receiver characterized by the above. The digital broadcast receiver according to claim 1 or 2,
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. A CA module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachably connected to the CA module, In a method of receiving a digital broadcast by a digital broadcast receiving apparatus that receives a digital broadcast including an electronic medium that generates a scramble key, further encrypts it, and transmits it to the CA module, the method comprises:
In the electronic medium, the previous scramble key stored in the scramble key holding buffer at the time of the previous reception process of the device is obtained from the scramble key holding buffer, and based on the previous scramble key, a predetermined value is obtained. An encryption key calculation step for calculating an encryption key;
A scramble key holding step for storing the generated scramble key and holding a predetermined number of scramble keys;
A scramble key encryption step that encrypts the scramble key using the encryption key and supplies the scramble key to the CA module;
The CA module obtains the previous scramble key stored in the decryption scramble key holding buffer during the previous reception process of the device from the decryption scramble key hold buffer, and uses the predetermined scramble key based on the previous scramble key. A decryption key computation step for computing the decryption key of
A scramble key holding step for storing the scramble key decrypted in the scramble key decryption step and holding a predetermined number of scramble keys;
A digital broadcast receiving method comprising: a scramble key decryption step of receiving the encrypted scramble key from the electronic medium and decrypting the scramble key using the decryption key. A CA module that receives a received signal having a scrambled broadcast information signal transmitted from a transmitting station and descrambles the scrambled broadcast information signal using a predetermined scramble key, and is detachably connected to the CA module, In a method of receiving a digital broadcast by a digital broadcast receiving apparatus that receives a digital broadcast including an electronic medium that generates a scramble key, further encrypts it, and transmits it to the CA module, the method comprises:
The electronic medium generates a selection signal based on a receiver-specific serial number stored in advance in the electronic medium and a receiver-specific serial number stored in advance in the CA module, and scrambles the electronic medium. A selection control step of selecting each of the scramble keys from a key hold buffer and a decryption scramble key hold buffer of the CA module;
In accordance with the selection signal, the scramble key stored in the scramble key holding buffer is obtained from the scramble key hold buffer, and an encryption key calculation step of calculating a predetermined encryption key based on the scramble key;
A scramble key holding step for storing the generated scramble key and holding a predetermined number of scramble keys;
A scramble key encryption step that encrypts the scramble key using the encryption key and supplies the scramble key to the CA module;
In the CA module, the scramble key stored in the decryption scramble key holding buffer is obtained from the decryption scramble key holding buffer according to the selection signal, and a predetermined decryption key is calculated based on the scramble key. A key operation process;
A scramble key decryption step of receiving the scramble key encrypted from the electronic medium and decrypting the scramble key using the decryption key;
A digital broadcast receiving method, comprising: a scramble key holding step of storing the scramble key decoded in the scramble key decoding step and holding a predetermined number of scramble keys. The digital broadcast receiving method according to claim 4 or 5, wherein the method includes:
A selection signal that outputs the selection signal in which the selection signal for selecting the scramble key is changed at regular intervals in the electronic medium, and transmits the selection signal to the scramble key holding buffer and the scramble key holding buffer of the CA module. A digital broadcast receiving method comprising a transmitting step.

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