JP2006279804A - Scrambling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the number of scramble-processable services by reducing load on a CPU. <P>SOLUTION: The scrambling device is provided with a PID-searching section 1 for using a PID of an input TS packet to search a service to which an input TS packet belongs to, and adding the service ID, corresponding to the searched service to the input TS packet and outputting the packet; a CPU 3 for determining the service, to which the TS packet belongs, on the basis of the service ID of the TS packet added with the service ID, and outputting an instruction signal for instructing the propriety of encryption and allocation of encryption keys different for each of services, on the basis of a result of determination; and a TS packet scrambler 6 for performing encryption processing to the TS packet, in accordance with the instruction signal from the CPU 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a scrambler used in a conditional access system that permits viewing of a service composed of a specific channel, a specific program, etc. only for a specific viewer who has contracted in digital broadcasting, and in particular, an input transport stream packet The present invention relates to a scramble apparatus that scrambles and transmits TS packets belonging to a required service (hereinafter referred to as TS packets).

  In a conditional access (CA) system for digital broadcasting in cable television, satellite broadcasting, terrestrial broadcasting, etc., a service that broadcasts on the transmission side so that only contract viewers can receive limited broadcasting for paid broadcasting (CA) (Encrypted with a different key for each channel or program), and on the receiving side, only the receiving device that obtains the key information for releasing the encryption by contract must release the encryption and view each service Can be done. Therefore, in a scrambler used in this type of broadcasting station, the service to which the input TS packet belongs is identified, and the scramble process is performed based on the identification result.

  In digital broadcasting, the MPEG-2 system standard is adopted as a standard as a packet multiplexing method. Components included in services such as video and audio digitally encoded according to the MPEG-2 system standard are packetized and transmitted. This packet stream is called a transport stream (TS), and each packet is called a TS packet. Each TS packet includes a packet identifier (hereinafter referred to as PID). The TS includes transmission control information in addition to components included in each service such as an elementary stream (ES) such as an image and sound and a program clock reference (PCR) as time information. The transmission control information includes program arrangement information (SI: Service Information), and information defined in the MPEG-2 system standard in SI is referred to as program specification information (PSI: Program Specification Information).

  The PSI includes a program association table (PAT), a program map table (PMT), a conditional access table (CAT), and a network information table (NIT). The PMT stores the PID of a TS packet that transmits ES such as video and audio included in the service, and also transmits a TS packet that is time information necessary for reproducing the service by the receiver. The PID is described. The PAT is transmitted in a TS packet with a PID of “0000” in hexadecimal, and a list of services included in the TS (a list of correspondence between each service and the PMT PID) is described.

  FIG. 1 shows a conventional configuration of this type of scrambler. In FIG. 1, a TS packet in which a plurality of services are multiplexed is input to the CPU 102 via the input buffer 101. In the PID table 103, as shown in FIG. 2, the PID value of the PMT of each service and the PID value of the TS packet that transmits ES (VES is video, AES is audio) such as video and audio belonging to each service. In this case, each PID value belonging to 12 services can be defined, and four VESs and AESs can be defined for each service.

The CPU 102 executes the following two processes in addition to various processes for controlling other components.
(A) If the PID of the input TS packet is PAT or PMT, the version is confirmed to determine whether or not there is an update, and if it is updated, the analysis result is reflected in the PID table 103.
(B) As shown in FIG. 2, by searching the PID table 103 based on the PID value of the input TS packet, it is identified which service the input TS packet belongs to, and a scramble key different for each service Execute the process to scramble with. In addition, a service that is not instructed to be scrambled is transmitted without being scrambled.

  The CPU 102 adds a scramble instruction signal corresponding to the search result of (b) to the TS packet and outputs it to the output buffer 104. The TS packet scrambler 105 reads the TS packet to which the scramble instruction signal is added from the output buffer 104, scrambles the TS packet in accordance with the scramble instruction signal, and sends it out.

  On the other hand, in Patent Document 1, a PID of a program packet is converted into a service ID using a service ID-PID mapping table, and the converted service ID is converted into a scramble key using a service ID-scramble key mapping table. It is shown that a program packet is scrambled and output using the converted scramble key.

JP 2004-363976 A

  By the way, the process of one input TS packet needs to be included within the prescribed transmission time of one TS packet including the PID table search process. However, in the prior art shown in FIG. 1, since the CPU 102 is configured to execute various processes including the PID table search process, the CPU 102 has a processing capacity limit of about 10 per scrambler. One problem is that only services can be processed. The bottleneck is the PID search process. The larger the number of services, the larger the PID table, and the longer the search time. If the search time becomes longer, processing of one TS packet cannot be completed within the transmission time of one TS packet. In cable television digital broadcasting, currently, the number of TV services that can be transmitted with one 64QAM wave is 12 or less in actual operation, but it is assumed that a higher compression video compression method will be used in the future. In this case, it is required to scramble more services than 12 services.

  In Patent Document 1, as in the prior art shown in FIG. 1, PID-service ID conversion is performed by searching a service ID-PID mapping table, and service ID-scramble key mapping table is further searched for service ID. -It is only disclosed that scramble key conversion is performed, and there is no disclosure about the above-described problem when these conversion processes are processed by one CPU.

  The present invention has been made in view of the above, and provides a scramble apparatus capable of reducing the load on the CPU and increasing the number of services that can be scrambled by distributing the load on the CPU. With the goal.

  The invention according to claim 1 searches for a service to which an input TS packet belongs using the packet identifier of the input TS packet, adds a service identifier corresponding to the searched service to the input TS packet, and outputs the packet identifier search unit And an instruction instructing whether the TS packet belongs based on the service identifier of the TS packet to which the service identifier is added, and assigning different encryption keys for each service according to the determination result And a scramble unit that performs encryption processing on the TS packet in accordance with an instruction signal from the overall control unit.

  Exemplary embodiments and examples of a scrambler according to the present invention will be described below in detail with reference to the accompanying drawings.

[Embodiment]
In this scrambler, a so-called PID search process is performed in which a packet identifier search unit (PID search unit) provided on the front side of the CPU as the overall control unit identifies to which service the input TS packet belongs. Let

  The PID search unit has, for example, a packet identifier table (PID table) in which correspondences between a plurality of service identifiers (service IDs) and packet identifiers (PIDs) of components belonging to each service are registered. By searching the PID table using the PID, the service ID of the service to which the input TS packet belongs is selected. The PID search unit adds the selected service ID to the input TS packet and outputs it.

  The CPU extracts the service ID from the TS packet to which the service ID is added, determines the service to which the TS packet belongs based on the service ID, and determines whether encryption is possible and different encryption keys for each service according to the determination result. Determine the assignment. Then, the CPU outputs a scramble instruction signal indicating whether encryption is possible and a different encryption key for each service to the scramble unit. The scrambler performs encryption processing on the TS packet in accordance with a scramble instruction signal from the CPU.

  As described above, according to this embodiment, the PID search process that is conventionally performed by the CPU is executed by the PID search unit provided on the front stage side of the CPU, and the CPU displays the search result of the PID search process by the PID search unit. Since it is only necessary to determine whether or not encryption is possible and to assign different encryption keys for each service, it is not necessary for the CPU to perform PID search processing, and the load on the CPU can be reduced. Therefore, the number of services that can be scrambled can be increased.

  Next, a first embodiment of the scrambler according to the present invention will be described with reference to FIGS. FIG. 3 shows the configuration of the scrambler according to the first embodiment. This scrambler includes a PID search unit 1, an input FIFO as an input buffer, a CPU 3, a memory 4, an output FIFO as an output buffer, a TS packet scrambler 6, a random number generator 7, and an ECM (Entitlement). Control Message) generation unit 8.

  A TS signal in which a plurality of services are multiplexed is input to the PID search unit 1. The PID search unit 1 has a PID table 1a. In this PID table 1a, at least a correspondence between a service identifier (service ID) and a PID of a component belonging to each service is registered.

  FIG. 4 shows an example of a conceptual configuration of the PID table 1a. In this case, the PID table 1a is composed of 25 columns and 24 rows. Version information is also registered in each column. In column “0”, PIDs of PMTs corresponding to 24 services, which are PAT analysis results, and version information thereof are registered. In the column “1”, PIDs of 12 components (ESs such as video and audio and PCRs as time information) belonging to the service 1 and version information thereof, which are the analysis results of the PMT of the service 1, are registered. ing. In the column “2”, PIDs of twelve components belonging to the service 2 and version information thereof, which are PMT analysis results of the service 2, are registered. Similarly, in the column “24”, PIDs of 12 components belonging to the service 24 and version information thereof, which are PMT analysis results of the service 24, are registered.

  The registration data of the PID table 1a is obtained from the result of the CPU 3 analyzing the PAT and PMT. That is, every time the version is updated, the CPU 3 analyzes the PAT and PMT and inputs the analysis result to the PID search unit 1. When the PAT and PMT analysis results are input from the CPU 3, the PID search unit 1 registers the analysis results in the PID table 1a.

  The PID search unit 1 extracts a PID from the TS packet of the input TS signal, selects a PID that matches the extracted PID by searching the PID table 1a using the extracted PID, and selects the PID that matches the PID. Extract the corresponding column number, row number, and version information. The column number, row number, and version information are included in the scramble management information.

  In this case, the column number of the scramble management information includes information for identifying whether it is a PMT or one of the services 1 to 24. That is, if the column number is “0”, it can be identified as a PMT TS packet, and if the column number is “1”, it can be identified as a TS packet of service 1, and the column number “2” can be identified. "Can be identified as a TS packet of service 2, ..., and column number" 24 "can be identified as a TS packet of service 24. Therefore, it can be said that the column number includes a service ID for identifying the service.

  In this case, the row number of the scramble management information includes information identifying which service the PMT is and information identifying whether the service is a video or an image. That is, in the case of the column number “0”, it is possible to identify which service the PMT is by identifying the row number. In the case of the column numbers “1” to “24”, if the video, audio, or time information is determined in advance according to the row number, it is possible to identify video or image or time information by identifying the row number. Can be identified.

  In the PID search unit 1, the scramble management information including the column number, row number, and version information obtained by the above-described search of the PID table 1a is added to the TS packet and output to the input FIFO 2 as shown in FIG. To do.

  The input FIFO 2 is a buffer capable of temporarily storing a plurality of TS packets with scramble management information. When all data constituting one TS packet with scramble management information is input, the CPU 3 generates an interrupt.

  When the CPU 3 receives an interrupt request from the input FIFO 2, it reads a TS packet with scramble management information from the input FIFO 2. The CPU 3 only analyzes the scramble management information of the read TS packet with the scramble management information and does not perform a PID table search as in the conventional case, and what type (PMT) the input TS packet belongs to which service. It is possible to determine whether it is a TS packet of whether it is video, image or time information. That is, the correspondence relationship between the column number and row number and the service ID (service number) is registered in the CPU 3 in advance. For example, when the column number is “1” and the row number is “2”, It can be identified as a component of service 1, and when the column number is “0” and the row number is “2”, it can be identified as a PMT of service 2. In this way, when the CPU 3 determines which service the input TS packet belongs to, according to the determination result, information indicating whether or not to perform the scramble processing for the TS packet and the scramble used for the scramble A scramble instruction signal including information indicating the key number is added to the TS packet and written to the output FIFO 5. The scramble key number is equivalent to the service ID, and in the case of a TS packet belonging to the service 3, the scramble key number is “3”. Whether or not the service is a service for scrambling is preset in the CPU 3 by the host device.

  In addition to the above processing, when the CPU 3 determines that the input TS packet is PAT or PMT, the CPU 3 checks the version information to check whether it has been updated. A process of reflecting the updated analysis result reflected in the PID table stored in the memory 4 to the PID search unit 1 as described above, and performing overall control of other components is executed. When it is determined that the input TS packet is a PMT, or when the input PAT or PMT version is confirmed, the scramble management information added by the PID search unit 1 is used. Yes.

  The output FIFO 5 is a buffer capable of temporarily storing a plurality of TS packets with a scramble command signal, and outputs the temporarily stored TS packets with a scramble command signal to the TS packet scrambler 6.

  The TS packet scrambler 6 reads a TS packet with a scramble command from the output FIFO 5, performs a scramble process of the TS packet according to the content of the added scramble command signal, multiplexes the scrambled TS packet and outputs it as a TS signal To do. The scramble key has a different value for each service in order to enhance security. In the TS packet scrambler 6, a scramble key table in which the correspondence between the scramble key number (service ID) and the scramble key is set. Is provided. In this case, as shown in FIG. 4, since the number of services is 24, correspondence relations of 24 scramble key numbers and scramble keys are set in the scramble key table. Therefore, the TS packet scrambler 6 determines whether or not to scramble the packet based on information indicating whether or not to perform the scramble process in the scramble command signal, and when performing the scramble, The required scramble key is extracted from the scramble key table using the information indicating the scramble key number, and the TS packet is scrambled using the extracted scramble key, and the scrambled TS packet is multiplexed and output as a TS signal. .

  Here, each scramble key registered in the scramble key table is generated by the random number generator 7 and registered in the scramble key table. From the random number generator 7, scramble keys having different values are generated at regular time intervals, and the scramble key table in the TS packet scrambler 6 is also updated at regular time intervals.

  The scramble key generated by the random number generator 7 is input to the ECM generation unit 8. The ECM generation unit 8 encrypts the scramble key using the work key designated by the host device of the scramble device, and outputs it to the TS packet scrambler 6. The TS packet scrambler 6 replaces the scramble key encrypted with the work key with a null packet in the TS signal output as an ECM. Here, the null packet is a TS packet having a PID value of “1FFF” in hexadecimal, and is a TS packet used for adjusting the transmission rate of the TS.

  In this way, the TS packet scrambler 6 outputs a TS signal in which a component (video, audio, time information, etc.) encrypted with a scramble key and a scramble key encrypted with a work key are multiplexed. Is done. Note that the work key is encrypted with the master key and sent in a TS packet called EMM separately from the sending of the program.

  Incidentally, when the receiving device receives the work key encrypted with the master key, the receiving device decrypts the work key encrypted with the master key using the master key registered in the receiving device, and holds this. Keep it. When receiving a TS signal in which a scramble key encrypted with a component and a work key is received, the receiving device decrypts the scramble key encrypted with the work key using the held work key, and The component is decrypted using the decrypted scramble key.

  In the above description, as shown in FIG. 4, the PAT analysis result is also registered in the PID table 1a. However, the PAT analysis result and the version information may be deleted from the PID table 1a. .

  As described above, in the first embodiment, the PID search unit 1 provided on the front side of the CPU 3 performs PID search processing to identify the service to which the TS packet belongs, and scramble management information including the identified service ID is added. Since the processed TS packet is output to the CPU 3, the CPU 3 only has to determine whether or not to scramble and assign different scramble keys for each service using the scramble management information, so the CPU 3 performs PID search processing. This eliminates the need for the CPU load. Therefore, the number of services that can be scrambled can be increased.

  Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment shows a specific configuration example of the PID search unit 1. The PID search unit 1 according to the second embodiment includes a PID extraction unit 10, a plurality of PID comparison units 11-1 to 11-n, a scramble management information selection unit 12, a PID table 1a, and a scramble management information addition unit 14. It has.

  In the PID table 1a, at least the analysis result of the PMT shown in FIG. 4 is registered. The PID extraction unit 10 extracts a PID value from the input TS packet, and inputs the extracted PID value to all the PID comparison units 11-1 to 11-n. A plurality of different PID values registered in the PID table 1a are preset in the PID comparison units 11-1 to 11-n. Each of the comparison units 11-1 to 11-n simultaneously compares the set PID value with the PID value input from the PID extraction unit 10, and outputs a match signal to the scramble management information selection unit 12 if they match. To do.

  The scramble management information selection unit 12 selects scramble management information corresponding to the matched PID value from the PID table 1 a based on the input match signal, and outputs the selected scramble management information to the scramble management information addition unit 14. . As shown in FIG. 5, the scramble management information adding unit 14 adds the scramble management information to the input TS packet and outputs it.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. The third embodiment shows another specific configuration example of the PID search unit 1. The PID search unit 1 according to the second embodiment includes a PID extraction unit 10, a scramble management information selection unit 20, a PID table 1a, and a scramble management information addition unit 14.

  In this case, as shown in FIG. 8, the PID table 1a uses a memory whose address is 2 bytes from “0000” to “1FFF” in hexadecimal which is a range of values that the PID can take. That is, a memory area corresponding to the PID value is prepared one by one, and the scramble management information of the PID value is stored in the memory area of the address corresponding to the PID value.

  The PID extraction unit 10 extracts a PID value from the input TS packet and outputs the extracted PID value to the scramble management information selection unit 12. The scramble management information selection unit 12 performs a read operation on the PID table using the input PID value as an address signal. As a result, the scramble management information corresponding to the PID value is read from the memory area corresponding to the accessed address. In the case of FIG. 8, the PMT table 1a address “0100” (hexadecimal) stores the scramble management information of the service 1 PMT. The PTS value “0100” of the input TS packet is “PID value“ 0100 ”. A state in which read access is performed using 0100 "(hexadecimal) is shown.

  The scramble management information selecting unit 12 outputs the read scramble management information to the scramble management information adding unit 14. As shown in FIG. 5, the scramble management information adding unit 14 adds the scramble management information to the input TS packet and outputs it. As described above, in the third embodiment, the scramble management information can be obtained only by extracting the PID value of the TS packet and reading the memory area at the address corresponding to the PID value.

It is a block diagram which shows the structure of the conventional scramble apparatus. It is a conceptual diagram explaining the conventional PID search process. It is a block diagram which shows the structure of the scramble apparatus of Example 1. FIG. It is a figure which shows notionally the memory content of a PID table. It is a figure which shows TS packet to which scramble management information was added. It is a block diagram which shows the example of an internal structure of a PID search part. It is a block diagram which shows the other internal structural example of a PID search part. It is a figure which shows notionally the memory content of the PID table in the PID search part shown in FIG.

Explanation of symbols

1 PID search part 1a PID table 2 Input FIFO
3 CPU (overall control unit)
4 memory 5 output FIFO
6 TS packet scrambler 7 Random number generator 8 ECM generation unit 10 PID extraction unit 11 Comparison unit 12 Scramble management information selection unit 14 Scramble management information addition unit 20 Scramble management information selection unit

Claims (5)

A packet identifier search unit that searches for a service to which the input TS packet belongs using the packet identifier of the input TS packet, adds a service identifier corresponding to the searched service to the input TS packet, and outputs the service identifier;
Based on the service identifier of the TS packet to which the service identifier is added, a service to which the TS packet belongs is determined, and an instruction signal for instructing whether encryption is possible and assigning a different encryption key for each service according to the determination result An overall control unit to output,
A scrambler that performs encryption processing on the TS packet in accordance with an instruction signal from the overall controller,
A scramble device comprising: The packet identifier search unit
A packet identifier table in which correspondence between a plurality of service identifiers and packet identifiers of components belonging to each service is registered;
The scrambler according to claim 1, wherein a service to which the input TS packet belongs is determined by searching the packet identifier table using a packet identifier of the input TS packet.   The scramble apparatus according to claim 1 or 2, wherein the component includes video, audio, and time information. The packet identifier search unit
A plurality of comparison units for simultaneously comparing a packet identifier of the input TS packet and a packet identifier of each component of each service registered in the packet identifier table;
As a result of comparison by the plurality of comparison units, a service identifier adding unit that adds a service identifier corresponding to a packet identifier as a comparison target in the comparison unit that outputs a match signal to the input TS packet and outputs the service identifier,
The scramble apparatus according to claim 2, further comprising: The packet identifier table stores service identifiers corresponding to the packet identifiers in memory areas of addresses corresponding to the packet identifiers of components belonging to each service,
A service identifier adding unit for acquiring a service identifier corresponding to the packet identifier of the input TS packet from a memory area of an address corresponding to the packet identifier of the input TS packet, and adding the acquired service identifier to the input TS packet and outputting the same; The scrambler according to claim 2 or 3, wherein

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