JP5290372B2 - Transmitter and receiver - Google Patents

Description

  The present invention relates to a transmission apparatus and a reception apparatus of an access control system (Conditional Access System: CAS) in digital broadcasting.

  In recent years, with the spread of digital contents, digital rights management (DRM) technology has attracted attention. For example, in digital television broadcasting, broadcast waves are scrambled by CAS in conformity with the standard “ARIB STD-B25” (see Non-Patent Document 1) of the Association of Radio Industries and Businesses (ARIB). The content is copyright protected. Thereby, viewer limited reception is realizable. The introduction of CAS is also being considered in the future for digital television broadcasting for mobile terminals (commonly called “One Seg”) and digital radio broadcasting.

  FIG. 11 is a diagram showing a configuration of a conventional CAS (conforming to “ARIB STD-B25”). In CAS, in order to make it possible to view desired content, each receiver first receives an EMM (Entitlement Management Message) including a key Kw (work key) encrypted with a key Km (master key) for each receiver. The included broadcast wave is received from the broadcast station (step S1 in FIG. 11). Each receiver acquires the EMM from the broadcast wave and decrypts the key Kw with the key Km stored in the IC card of the receiver (step S2 in FIG. 11). Subsequently, each receiver receives a broadcast wave including an ECM (Entlement Control Message) including a key Ks (scramble key) encrypted with the key Kw from the broadcast station (step S3 in FIG. 11). Each receiver acquires the ECM from the broadcast wave, and decrypts the key Ks with the previously decrypted key Kw (step S4 in FIG. 11). Each receiver receives a broadcast wave including content encrypted with the key Ks by the block encryption method from the broadcasting station, and decrypts the content with the key Ks (step S5 in FIG. 11).

  As a similar DRM technique, an access control method (CAS) described in Non-Patent Document 2 is known. According to the technique described in Non-Patent Document 2, it is possible to realize viewer-limited reception in IPTV (Internet Protocol Television) broadcasting using a communication line.

"ARIB STD-B25", The Japan Radio Industry Association, 4.1, June 5, 2003 “Marlin IPTV End-point Service Specification”, Version 1.0, The Marlin Developer Community, July 20.2006.

  In the above-described conventional CAS, the block encryption method is adopted as the content encryption method, but the stream encryption method with a much lighter processing load is not particularly large in equipment, such as a portable terminal such as a mobile phone. When using as a receiver, the viewing environment can be improved by reducing the processing load. Also in IPTV broadcasting, it is possible to realize a more comfortable viewing environment by reducing the processing load on the receiver connected to the communication line.

  Therefore, it is conceivable to adopt the stream encryption method, but the conventional CAS does not support the stream encryption method. In addition, it is very expensive to newly develop a CAS for a stream encryption method. For this reason, it is desired to change to the stream encryption method based on the conventional CAS.

  The present invention has been made in view of such circumstances, and the object of the present invention is an access control system (CAS) in digital broadcasting, which can be easily changed to a stream encryption system based on the conventional CAS. It is to provide a transmission device and a reception device.

  In order to solve the above problems, a transmitting apparatus according to the present invention provides a scramble key as an initial value used for initializing a stream cipher algorithm in a transmitting apparatus of an access control method in digital broadcasting using a broadcast wave or a communication line. A stream encryption unit that initializes a stream encryption algorithm using the initial value and performs stream encryption using a work key; and a first encryption unit that encrypts the initial value using the work key. Encryption means, second encryption means for encrypting the work key using a common master key between the transmitting apparatus and the receiving apparatus, the stream cipher data, the initial cipher data, and the work key Transmission means for transmitting the encrypted data by broadcast waves or communication lines, respectively.

  The receiving apparatus according to the present invention is an access control system receiving apparatus in digital broadcasting using a broadcast wave or a communication line. The encrypted stream data, the initial value encrypted data, and the work key encrypted data are respectively transmitted through the broadcast wave or the communication line. Receiving means for receiving; first decrypting means for decrypting encrypted data of the work key using a common master key between the transmitting apparatus and the receiving apparatus; and encryption of the initial value using the decrypted work key Second decryption means for decrypting data; and stream cipher decryption means for initializing a stream cipher algorithm using the decrypted initial value and decrypting the stream cipher data using the decrypted work key; It is characterized by having.

  A transmission apparatus according to the present invention provides a fixed value as an initial value used for initializing a stream encryption algorithm in an access control system transmission apparatus in digital broadcasting using a broadcast wave or a communication line, and uses the initial value. Stream encryption means for initializing a stream encryption algorithm and performing stream encryption using a scramble key, first encryption means for encrypting the initial value and the scramble key using a work key, and the work key Second encryption means for encrypting the encrypted data using a common master key between the transmitting device and the receiving device, the stream cipher data, the initial cipher data, the scramble key cipher data, and the work key cipher Transmission means for transmitting data by broadcast waves or communication lines, respectively.

  The receiving apparatus according to the present invention is an access control system receiving apparatus in digital broadcasting using a broadcast wave or a communication line, and receives stream cipher data, initial cipher data, scramble key cipher data, and work key cipher data, respectively. Receiving means for receiving via broadcast wave or communication line; first decrypting means for decrypting encrypted data of the work key using a master key common between the transmitting apparatus and the receiving apparatus; and using the decrypted work key A second decryption means for decrypting the encrypted data of the initial value and the encrypted data of the scramble key, a stream encryption algorithm is initialized using the decrypted initial value, and the decrypted scramble key is used to initialize the stream encryption algorithm. And stream encryption / decryption means for decrypting the stream encryption data.

  A transmission apparatus according to the present invention uses a work key as an initial value used for initializing a stream encryption algorithm in an access control system transmission apparatus in digital broadcasting using a broadcast wave or a communication line, and uses the work key. Stream encryption means for initializing a stream encryption algorithm and performing stream encryption using a scramble key, first encryption means for encrypting the scramble key using the work key, and transmitting the work key Second encryption means for encrypting using a common master key between the apparatus and the receiving apparatus, and the stream cipher data, the scramble key cipher data, and the work key cipher data by a broadcast wave or a communication line, respectively. Transmitting means for transmitting.

  The receiving apparatus according to the present invention is an access control system receiving apparatus in digital broadcasting using a broadcast wave or a communication line. Receiving means for receiving; first decrypting means for decrypting encrypted data of the work key using a common master key between the transmitting apparatus and the receiving apparatus; and encryption of the scramble key using the decrypted work key Second decryption means for decrypting data; and stream encryption decryption means for initializing a stream cipher algorithm using the decrypted work key and decrypting the stream cipher data using the decrypted scramble key. It is characterized by having.

  According to the present invention, the stream encryption method can be easily changed based on the conventional CAS. As a result, in realizing CAS corresponding to the stream encryption method, an existing system can be used and a great cost reduction effect can be obtained.

It is a block diagram which shows the structure of the transmitter which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the stream encryption part 11 shown in FIG. It is a block diagram which shows the structure of the receiver which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the stream encryption / decryption part 31 shown in FIG. It is a figure which shows the structure of TS packet. It is a figure which shows the structure of an ECM section. It is a block diagram which shows the structure of the transmitter which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the receiver which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the transmitter which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure of the receiver which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure of the conventional CAS (conforms to "ARIB STD-B25").

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, a change is made based on “ARIB STD-B25”.

[First Embodiment]
1 to 4 are block diagrams showing configurations of a CAS transmission apparatus and reception apparatus according to the first embodiment of the present invention. 1 and 2 show the configuration of the transmission apparatus. 3 and 4 show the configuration of the receiving apparatus.

First, the transmission apparatus according to the first embodiment will be described with reference to FIG. 1 and FIG.
FIG. 1 is a block diagram showing a configuration of a transmission apparatus according to the first embodiment of the present invention. The transmission apparatus shown in FIG. 1 includes a stream encryption unit 11 and encryption units 12 and 13.

  The stream encryption unit 11 performs stream encryption as scramble for a TS (Transport Stream) packet. FIG. 5 shows the structure of the TS packet. The range of stream encryption is the payload portion of the TS packet. Content such as video and audio is stored in the payload portion. Further, when the value of the transport scramble control (transport_scramble_control) is “00”, there is no encryption, and when it is “10” or “11”, there is encryption.

  FIG. 2 is a block diagram showing the configuration of the stream encryption unit 11 shown in FIG. The stream encryption unit 11 includes a pseudo random number generator 21 and an exclusive OR calculator 22. The stream encryption unit 11 receives an initial value (Initial Vector: IV) used for initializing the stream encryption algorithm, a key used for stream encryption, and the content to be encrypted. The content to be encrypted is extracted from the payload portion of the TS packet whose transport scramble control value is “10” or “11”.

  The pseudorandom number generator 21 generates a pseudorandom number based on the key. The pseudo random number generator 21 is initialized with IV.

  The content data is encrypted by exclusive-ORing the pseudo-random number generated by the pseudo-random number generator 21 by the exclusive-OR calculator 22 for each bit. The encrypted content is stored in the payload portion of the original TS packet. The stream encryption unit 11 outputs a TS packet including encrypted content.

Returning to FIG.
The IV input to the stream encryption unit 11 corresponds to a scramble key (Ks) and is common to all viewers. For example, a scramble key (Ks) may be used as IV. The IV is updated at relatively short intervals, for example about every second.
The key input to the stream encryption unit 11 is a work key (Kw).

The encryption units 12 and 13 are the same as the conventional one.
The encryption unit 12 encrypts the IV with the key Kw. Encryption IV is stored in the ECM. The encryption unit 13 encrypts the key Kw with the key Km (master key). The encrypted key Kw is stored in the EMM.

  FIG. 6 is a diagram showing the structure of the ECM section. The encryption IV is stored in the scramble key area in the ECM section. There are two types of scramble keys: a scramble key (Odd) and a scramble key (Even). Similarly, there are two types of IV, IV (Odd) and IV (Even). The encryption IV (Odd) is stored in the scramble key (Odd) area in the ECM section. The encryption IV (Even) is stored in the scramble key (Even) area in the ECM section.

  The stream encryption unit 11 initializes the pseudo random number generator 21 using IV (Even) at the start of encryption of a TS packet whose transport scramble control value is “10”. On the other hand, at the start of encryption of a TS packet whose transport scramble control value is “11”, the pseudorandom number generator 21 is initialized using IV (Odd).

  The transmission device transmits TS packets, ECM, and EMM including encrypted content on broadcast waves.

Next, the receiving apparatus according to the first embodiment will be described with reference to FIG. 3 and FIG.
FIG. 3 is a block diagram showing the configuration of the receiving apparatus according to the first embodiment of the present invention. The receiving apparatus shown in FIG. 3 is paired with the transmitting apparatus in FIG. 1 and includes a stream encryption / decryption unit 31 and decryption units 32 and 33.

  The receiving device receives TS packets, ECM, and EMM including encrypted content by broadcast waves.

  The stream encryption / decryption unit 31 decrypts the stream cipher as descrambling for the TS packet. When the transport scramble control value of the TS packet is “00”, there is no encryption, and when it is “10” or “11”, there is encryption. The decryption range of the stream cipher is the payload portion of the TS packet. Encrypted content is stored in the payload portion of the encrypted TS packet.

  FIG. 4 is a block diagram showing a configuration of the stream encryption / decryption unit 31 shown in FIG. The stream encryption / decryption unit 31 has the same configuration as the stream encryption unit 11 in FIG. 2, and includes a pseudo-random number generator 21 and an exclusive OR calculator 22. The stream encryption / decryption unit 31 receives the IV used to initialize the stream encryption algorithm, the key used for decryption, and the encrypted content. The encrypted content is extracted from the payload portion of the TS packet whose transport scramble control value is “10” or “11”.

  The pseudorandom number generator 21 generates a pseudorandom number based on the key. The pseudo random number generator 21 is initialized with IV.

  The data of the encrypted content is decrypted by taking an exclusive OR for each bit of the pseudorandom number generated by the pseudorandom number generator 21 by the exclusive OR calculator 22. The decrypted content is stored in the payload portion of the original TS packet. The stream encryption / decryption unit 31 outputs a TS packet including the decrypted content.

Returning to FIG.
The decoding units 32 and 33 are the same as in the prior art.
The decryption unit 33 decrypts the encryption key (Kw) extracted from the EMM with the key Km. The key Km is a master key for each subscriber, and is common between the transmitting device and the receiving device. The decrypted key Kw is input to the stream encryption / decryption unit 31 and becomes a key used for decoding the stream encryption. The key Kw is also input to the decryption unit 32.

  The decryption unit 32 decrypts the encrypted IV extracted from the ECM with the key Kw. The decrypted IV is input to the stream encryption / decryption unit 31 and used to initialize the pseudorandom number generator 21.

  The stream encryption / decryption unit 31 initializes the pseudorandom number generator 21 using IV (Even) at the start of decryption of the TS packet whose transport scramble control value is “10”. On the other hand, at the start of decoding of a TS packet whose transport scramble control value is “11”, the pseudorandom number generator 21 is initialized using IV (Odd).

  The TS packet including the decrypted content is sent to the playback device, and the content is played back.

  According to the first embodiment described above, an IV corresponding to the scramble key is provided, the stream encryption algorithm is initialized using the IV, and the stream encryption is performed using the work key (Kw). Yes. As a result, the stream encryption method can be easily changed based on the conventional CAS. As a result, the existing system can be used for realizing CAS corresponding to the stream encryption method, and a very large cost reduction effect can be obtained.

  Further, since IV corresponding to the scramble key is used, IV is updated at a relatively short interval, so that the security in the stream encryption method is maintained.

[Second Embodiment]
FIG. 7 is a block diagram showing a configuration of a transmission apparatus according to the second embodiment of the present invention. FIG. 8 is a block diagram showing a configuration of a receiving apparatus according to the second embodiment of the present invention. 7 and 8, the same reference numerals are given to the portions corresponding to the respective portions in FIGS. 1 and 3, and the description thereof is omitted.

First, a transmission apparatus according to the second embodiment will be described with reference to FIG.
In the transmission device shown in FIG. 7, IV is a fixed value common to all viewers. The scramble key (Ks) is used as a key used for stream encryption. The scramble key (Ks) is updated at a relatively short interval, for example, about every second.

  The IV is input to the stream encryption unit 11 and used to initialize the stream encryption algorithm. The IV is encrypted by the encryption unit 12 with the key Kw and stored in the ECM. The encryption IV is stored in a variable part in the ECM section (see FIG. 6).

  The scramble key (Ks) is input to the stream encryption unit 11 and is used as a stream encryption key. The scramble key (Ks) is encrypted with the key Kw by the encryption unit 12 and stored in the ECM. The encrypted scramble key (Ks) is stored in a prescribed scramble key area in the ECM section (see FIG. 6).

  There are two types of scramble keys: a scramble key (Odd) and a scramble key (Even). The stream encryption unit 11 generates a pseudo-random number with the pseudo-random number generator 21 using a scramble key (Even) for encryption of a TS packet whose transport scramble control value is “10”. On the other hand, for encryption of a TS packet having a transport scramble control value “11”, a pseudo random number generator 21 generates a pseudo random number using a scramble key (Odd).

Next, a receiving apparatus according to the second embodiment will be described with reference to FIG.
The receiving apparatus shown in FIG. 8 is configured in a pair with the transmitting apparatus in FIG.
The decryption unit 32 decrypts the encrypted IV extracted from the ECM with the key Kw. The decrypted IV is input to the stream encryption / decryption unit 31 and used to initialize the pseudorandom number generator 21. The decrypting unit 32 decrypts the encrypted scramble key (Ks) extracted from the ECM with the key Kw. The decrypted scramble key (Ks) is input to the stream encryption / decryption unit 31 and is used by the pseudo random number generator 21 to generate pseudo random numbers.

  The stream encryption / decryption unit 31 generates a pseudo-random number with the pseudo-random number generator 21 using a scramble key (Even) for decoding a TS packet whose transport scramble control value is “10”. On the other hand, for decoding a TS packet having a transport scramble control value of “11”, a pseudo random number generator 21 generates a pseudo random number using a scramble key (Odd).

  Note that both the transmission device and the reception device initialize the stream encryption algorithm using IV at the start of processing of the TS packet with encryption. This establishes synchronization of initialization of the stream encryption algorithm between the transmission device and the reception device.

  According to the second embodiment described above, a fixed value IV is provided, the stream encryption algorithm is initialized using the IV, and the stream encryption is performed using the scramble key (Ks). . As a result, the stream encryption method can be easily changed based on the conventional CAS. As a result, the existing system can be used for realizing CAS corresponding to the stream encryption method, and a very large cost reduction effect can be obtained.

  Further, since the scramble key is used as the stream encryption key, the scramble key is updated at a relatively short interval, so that the security in the stream encryption method is maintained.

[Third Embodiment]
FIG. 9 is a block diagram showing a configuration of a transmission apparatus according to the third embodiment of the present invention. FIG. 10 is a block diagram showing a configuration of a receiving apparatus according to the third embodiment of the present invention. 9 and 10, the same reference numerals are given to the portions corresponding to the respective portions in FIGS. 1 and 3, and the description thereof is omitted.

First, a transmission device according to the third embodiment will be described with reference to FIG.
In the transmission apparatus shown in FIG. 9, the work key (Kw) is used as IV. The work key (Kw) is a key for each broadcaster common to all viewers, and is updated at relatively long intervals, for example, from January to every year. As in the second embodiment, the scramble key (Ks) is used as a key used for stream encryption.

  The work key (Kw) is input to the stream encryption unit 11 and used to initialize the stream encryption algorithm. The scramble key (Ks) is input to the stream encryption unit 11 and is used as a stream encryption key.

The scramble key (Ks) is encrypted with the key Kw by the encryption unit 12 and stored in the ECM. In the ECM, a message indicating that the work key (Kw) is used as IV is stored in the variable unit.
The work key (Kw) is encrypted with the key Km by the encryption unit 13 and stored in the EMM.

Next, a receiving device according to the third embodiment will be described with reference to FIG.
The receiving apparatus shown in FIG. 10 is configured in a pair with the transmitting apparatus in FIG.
The decryption unit 33 decrypts the encrypted work key (Kw) extracted from the EMM with the key Km. The decrypted work key (Kw) is input to the stream encryption / decryption unit 31 and used to initialize the pseudo random number generator 21.

The decryption unit 32 decrypts the encrypted scramble key (Ks) extracted from the ECM with the key Kw.
The decrypted scramble key (Ks) is input to the stream encryption / decryption unit 31 and is used by the pseudo random number generator 21 to generate pseudo random numbers.

  Note that both the transmission device and the reception device initialize the stream encryption algorithm using the work key (Kw) at the start of processing of the TS packet with encryption. This establishes synchronization of initialization of the stream encryption algorithm between the transmission device and the reception device. The receiving device uses the work key (Kw) as IV from the message in the ECM.

  According to the third embodiment described above, the work key (Kw) is used as the IV, the stream encryption algorithm is initialized using the IV, and the stream encryption is performed using the scramble key (Ks). It is composed. As a result, the stream encryption method can be easily changed based on the conventional CAS. As a result, the existing system can be used for realizing CAS corresponding to the stream encryption method, and a very large cost reduction effect can be obtained.

  Also, by using the work key (Kw) as IV, the amount of information transmitted from the transmission device to the reception device can be reduced.

  In addition, you may make it combine the access control system of 1st, 2nd or 3rd Embodiment. For example, the access control method to be used may be changed depending on the broadcast program or broadcast time. In this case, the access control method is designated from the transmission device to the reception device by storing information indicating which access control method is used in the variable part in the ECM.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.
For example, in the above-described embodiment, a digital broadcast system using broadcast waves has been described as an example, but the present invention can be similarly applied to a digital broadcast system using a communication line. For example, the present invention can be applied to an IPTV broadcast system using an IP (Internet Protocol) network. As a DRM technology related to the IPTV broadcasting system, “Marlin IPTV End-point Service Specification”, Version 1.0, The Marlin Developer Community, July 20.2006 (see Non-Patent Document 2) is known. The access control method described in Non-Patent Document 2 is the same as the CAS in FIG. 11 described above (compliant with “ARIB STD-B25”), but uses a communication line instead of the broadcast channels 1 and 2. Further, instead of the broadcast channel 3, SAC (Security Authentication Channel) that realizes secrecy of information on the communication line is used. In the access control method described in Non-Patent Document 2, the work key (Kw) and the contract information are not encrypted, but information concealment on the communication line is guaranteed by the SAC. By applying the present invention to such an IPTV broadcasting system, a stream encryption method can be easily adopted instead of the block encryption method. As a result, even in the IPTV broadcasting system, the existing system can be used for realizing CAS corresponding to the stream encryption method, and a great cost reduction effect can be obtained. Further, the receiver can also reduce the processing load, and can realize a more comfortable viewing environment.

DESCRIPTION OF SYMBOLS 11 ... Stream encryption part, 12, 13 ... Encryption part, 31 ... Stream encryption / decryption part, 32, 33 ... Decryption part

Claims (2)

In a transmission device of an access control method in digital broadcasting using a broadcast wave or communication line,
Use the work key as the initial value used to initialize the stream cipher algorithm,
Stream encryption means for initializing a stream encryption algorithm using the work key and performing stream encryption on the content using a scramble key;
First encryption means for encrypting the scramble key using the work key;
Second encryption means for encrypting the work key using a common master key between the transmitting device and the receiving device;
Transmission means for transmitting the stream encryption data that has been subjected to the stream encryption by the stream encryption means, the encryption data for the scramble key, and the encryption data for the work key, respectively, by broadcast waves or communication lines;
A transmission device comprising: In a receiving device of an access control method in digital broadcasting using a broadcast wave or a communication line,
Receiving means for receiving stream cipher data, scramble key cipher data and work key cipher data by broadcast waves or communication lines, respectively;
First decryption means for decrypting the encrypted data of the work key using a common master key between the transmission device and the reception device;
Second decryption means for decrypting the encrypted data of the scramble key using the decrypted work key;
A stream cipher decrypting means for initializing a stream cipher algorithm using the decrypted work key and decrypting the stream cipher data using the decrypted scramble key;
A receiving apparatus comprising:

Images