JP2008205586A - Distribution server, client terminal and content distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distribution server capable of preventing fraudulent decoding and copying, etc., of contents and protecting the contents, a client terminal and a content distribution system. <P>SOLUTION: The distribution server distributes stream data, wherein kind specifying information specifying the kind of a reproduction object client terminal for respective contents and content selection information describing the selection procedure of the contents are included in stream data including the contents. The client terminal is provided with a stream data reception part for receiving the stream data, a content reproduction part for reproducing the contents and a content deciphering part for deciphering ciphered contents. The content deciphering part acquires content identification information and ECM identification information according to the selection procedure of the contents and deciphers the contents corresponding to the content selection information using a scramble key obtained from ECM corresponding to the ECM identification information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a distribution server that distributes stream data including content via a network, a client terminal that receives stream data and reproduces the content, and a content distribution system.

  In recent years, services for distributing content via a network have become widespread. The content is encrypted and distributed from the distribution server. A client terminal such as a set top box (hereinafter referred to as STB) or a personal computer (hereinafter referred to as PC) receives the encrypted content, and decrypts and reproduces the content. In order to protect the intellectual property of these distributed contents, the client terminal is desired to have a function of confirming the right to decrypt the contents and performing copy control (see Non-Patent Document 1).

  Non-Patent Document 2 describes a system for decrypting content encrypted at a client terminal. In this system, whether or not there is a right to decrypt the content is confirmed based on information stored in the attached IC card, and the content is decrypted if the right is confirmed. Further, the distribution server can control the decryption and copy execution of the content at the client terminal by distributing the right to decrypt the content and the copy control information (see Non-Patent Document 3).

Patent Document 1 describes a system that confirms the type of right for decrypting content held by a client terminal and gives permission to decrypt content at a bit rate corresponding to the type of right. A client terminal having the right to decrypt high bit rate content can decrypt the high bit rate content. A client terminal having only the right to decrypt a low bit rate content can decrypt only the low bit rate content.
"Digital Transmission Content Protection Specification Volume 1," Digital Transmission Licensing Administrator, February 28, 2005 "Common Interface Specification for Conditional Access and other Digital Video Broadcasting Decoder Applications", European telecommunications Standards Institute, February 1997 "Specification for Service Information (SI) in DVB systems", European telecommunications Standards Institute, February 1998 "IEC / ISO 13818-1 Information Technology-Generic coding of moving pictures and associated audio information Systems", International Organization for Standardization, December 1, 2000 JP 2004-31740 A

  As described above, in the system, it is assumed that the client terminal follows the right to decrypt the content from the distribution server and the copy control information. However, since a well-known operating system is used for a client terminal such as an STB or a PC, the client terminal can be easily modified. Therefore, the client terminal may be modified so as not to follow the right to decrypt the content from the distribution server and the copy control information.

  When the client terminal is modified so as not to follow the right to decrypt the content from the distribution server or the copy control information, the client terminal that does not have the right to decrypt the content can also decrypt the content. End up. Also, it becomes possible to copy content that is prohibited from being copied. Therefore, the content is illegally decrypted or the illegally copied content is leaked, and the content cannot be protected.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points. A distribution server, a client terminal, and a content distribution system capable of protecting contents by preventing unauthorized decryption of contents and outflow of illegally copied contents. The purpose is to provide.

  The distribution server of the present invention is a distribution server that distributes stream data including content to a client terminal via a network, and type designation information that designates a type of a client terminal to be played back for each content in the stream data; And content selection information describing a content selection procedure.

  The client terminal of the present invention receives a stream data receiving unit that receives stream data via a network, a content playback unit that plays back content, and a content that is encrypted from the stream data receiving unit, and decrypts the content. A content decrypting unit that transmits the content to the content playback unit, wherein the content decryption unit includes content identification information representing content permitted to be played in accordance with a content selection procedure described in the content selection information; Content selection means for acquiring ECM identification information representing ECM corresponding to the content, ECM acquisition means for acquiring ECM corresponding to the ECM identification information acquired by the content selection means from stream data, and ECM acquired by the ECM acquisition means Decrypt And having a ECM decoding means for obtaining a rumble key, and a content decryption means for decrypting the scrambling key content corresponding to the content identification information content selecting unit has acquired.

  The content distribution system of the present invention receives encrypted content from a stream data receiving unit that receives stream data including content via a network, a content reproduction unit that reproduces content, and a stream data receiving unit. A content distribution system comprising: a client terminal that includes a content decoding unit that decrypts and sends the content data to the content reproduction unit; and a distribution server that distributes stream data including the content to the client terminal via a network. The server includes type designation information for designating the type of client terminal to be reproduced for each content in the stream data, and content selection information describing the content selection procedure, and the content decoding unit is described in the content selection information The Corresponding to the ECM identification information acquired by the content selection means and the content selection means for acquiring the content identification information indicating the content permitted to be played back according to the content selection procedure and the ECM identification information indicating the ECM corresponding to the content. An ECM acquisition unit that acquires an ECM from the stream data, an ECM decoding unit that obtains a scramble key by decoding the ECM acquired by the ECM acquisition unit, and a content corresponding to the content identification information acquired by the content selection unit using the scramble key Content decrypting means for decrypting.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an embodiment of a distribution server, a client terminal and a content distribution system according to the present invention. The content distribution system includes a distribution server 1 that distributes stream data via the network 5 and a client terminal 2 that receives the stream data via the network 5 and reproduces the content. The distribution server 1 distributes the stream data to the client terminal 2 via the network 5. The stream data includes encrypted content, ECM, and a program map table (hereinafter referred to as PMT). The PMT includes type designation information that designates the type of client terminal to be played for each content and content selection information that describes a content selection procedure. The client terminal 2 receives stream data via the network 5 and reproduces content included in the stream data. The client terminal 2 includes an STB 3 and a content decoding unit 4. The client terminal can be configured using a PC or the like instead of the STB.

  The STB 3 receives stream data and reproduces content included in the stream data. The stream data receiving unit 31 receives stream data distributed from the distribution server 1 via the network 5. Further, the stream data receiving unit 31 sends the received stream data to the content decoding unit 4. The content reproduction unit 32 receives the decrypted content sent from the content decryption unit 4 and reproduces the received content. The terminal type information sending unit 33 sends terminal type information representing the type of the client terminal 2 to the content decrypting unit 4.

  The content decrypting unit 4 receives stream data including encrypted content, and decrypts the received encrypted content. The terminal type information receiving unit 41 receives the terminal type information sent from the terminal type information sending unit 33. The terminal type determination unit 42 determines whether the type of the client terminal represented by the terminal type information received by the terminal type information reception unit 41 matches the type specified by the type specification information included in the stream data. To do. The content selection unit 43 acquires content identification information representing content permitted to be played and ECM identification information representing ECM corresponding to the content according to the content selection procedure described in the content selection information. The content selection unit 43 acquires content identification information and ECM identification information when the terminal type determination unit 42 determines that the type of the client terminal matches the type specified in the type specification information. When the content selection unit 43 acquires the content identification information, the content selection unit 43 sends the acquired content identification information to the content decryption unit 47. Further, when acquiring the ECM identification information, the content selection unit 43 sends the acquired ECM identification information to the ECM acquisition unit 44. The ECM acquisition unit 44 receives the ECM identification information sent from the content selection unit 43, and acquires the ECM corresponding to the received ECM identification information from the stream data. Then, the ECM acquisition unit 44 sends the acquired ECM to the ECM decoding unit 46. The IC card 45 includes ECM decrypting means 46 that decrypts the ECM and obtains a scramble key. The scramble key is used for decrypting the encrypted content. The ECM decryption unit 46 receives the ECM sent from the ECM acquisition unit 44, decrypts the received ECM, and acquires a scramble key. Then, the ECM decryption unit 46 sends the acquired scramble key to the content decryption unit 47. The content decryption unit 47 decrypts the content corresponding to the content identification information received from the content selection unit 43 using the scramble key received from the ECM decryption unit 46. Then, the content decrypting unit 47 sends the decrypted content to the content playback unit 32 of the STB 3.

  FIG. 2 shows an example of the PMT. The PMT includes type designation information and content selection information. In the “CA_descriptor” of the PMT, information including type designation information, content selection information, and the like is described. Content identification information is described in “elementary_PID” of the PMT.

  FIG. 3 shows the contents of “CA_descriptor” of the PMT. In “CA_PID”, ECM identification information is described. In “private_data_byte”, type designation information and content selection information are described.

  FIG. 4 shows the contents of “private_data_byte”. “Private_data_byte” includes items “Cont_selector”, “Host_type”, and “Host_function”. In the item “Cont_selector”, content selection information is described. In “Host_type”, the type of the client terminal is described. In the item “Host_function”, a function of the client terminal is described. The type designation information includes an item “Host_type” and an item “Host_function”.

  FIG. 5 shows the contents of “Cont_selector” in which the content selection information is described. In the item “Cont_select_protocol”, a content selection procedure is described. In the item “ES_pid”, content identification information is described. In the item “ECM_pid”, ECM identification information is described.

  FIG. 6 shows a table indicating the correspondence between the value of “Host_type” and the type of client terminal. A value “01” of “Host_type” corresponds to an STB without a hard disk drive (hereinafter referred to as HDD). The value “02” of “Host_type” corresponds to the STB with HDD. The value “03” of “Host_type” corresponds to the PC. A value “04” of “Host_type” corresponds to the portable information terminal. A value “05” of “Host_type” corresponds to a mobile phone. The value “06” of “Host_type” corresponds to the gateway.

  FIG. 7 shows a table indicating the correspondence between the value of “Host_function” and the function of the client terminal. The first bit of “Host_function” corresponds to the copy protection function. The second bit of “Host_function” corresponds to the encryption function during stream accumulation. The third bit of “Host_function” corresponds to the encryption function at the time of file storage. The fourth bit of “Host_function” corresponds to the domain control function. The fifth bit of “Host_function” corresponds to the Ethernet (registered trademark) port. The sixth bit of “Host_function” corresponds to the security processor.

  FIG. 8 is a diagram illustrating an operation when the client terminal 2 decrypts and reproduces the encrypted content included in the received stream data.

  The terminal type information sending unit 33 of the STB 3 sends the terminal type information representing the type of the client terminal 2 toward the terminal type information receiving unit 41 of the content decrypting unit 4 (step S801). An example of the terminal type information transmitted at this time is shown in FIG. The terminal type information includes “authentication information” such as a password, “Host_type” indicating the type of the client terminal, and “Host_function” indicating the function of the client terminal. When receiving the terminal type information, the terminal type information receiving unit 41 sends the received terminal type information to the terminal type determining unit 42 (step S802).

  When receiving the stream data, the stream data receiving unit 31 of the STB 3 acquires the PMT from the received stream data and sends it to the content selection unit 43 of the content decoding unit 4 (step S803). The received stream data is sent to the ECM acquisition unit 44 and the content decryption unit 47 of the content decryption unit 4 (steps S804 to S805). Upon receiving the PMT, the content selection unit 43 determines whether to perform content selection processing based on the received PMT. Here, it is assumed that the content selection process is determined to be performed. In this case, the content selection unit 43 issues a terminal type determination command to the terminal type determination unit 42 so as to determine whether the type specified by the type specification information included in the PMT matches the type of the client terminal 2. (Step S806).

  Upon receiving the terminal type determination command, the terminal type determination unit 42 confirms that the content described in the “authentication information” item of the terminal type information received in S802 is correct. If it is confirmed that it is correct, it is determined whether the type of the client terminal indicated by the items “Host_type” and “Host_function” of the terminal type information matches the type specified in the type designation information. Then, the terminal type determination unit 42 sends the determination result to the content selection unit 43 (step S807). Here, it is determined that the type of the client terminal matches the type specified in the type specification information, and the determination result is sent to the content selection unit 43.

  Upon receiving the determination result that the types match, the content selection unit 43 performs content selection processing (step S808). In the content selection process, content identification information representing content permitted to be reproduced and ECM identification information representing ECM corresponding to the content are acquired in accordance with the content selection procedure of the content selection information included in the PMT. When acquiring the content identification information, the content selection unit 43 sends the acquired content identification information to the content decryption unit 47 (step S809). In addition, when acquiring the ECM identification information, the content selection unit 43 sends the acquired ECM identification information to the ECM acquisition unit 44 (step S810).

  When receiving the ECM identification information, the ECM acquisition unit 44 acquires an ECM corresponding to the received ECM identification information from the stream data. Then, the ECM acquisition unit 44 sends the acquired ECM to the ECM decoding unit 46 (step S811). When receiving the ECM, the ECM decrypting means 46 decrypts the received ECM and obtains a scramble key. Then, the ECM decryption unit 46 sends the acquired scramble key to the content decryption unit 47 (step S812).

  Upon receiving the content identification information and the scramble key, the content decryption unit 47 performs content decryption processing (step S813). In the content decryption process, the content corresponding to the received content identification information is decrypted using the received scramble key. Then, the content decrypting unit 47 sends the decrypted content to the content playback unit 32 of the STB 3 (step S814).

  Upon receiving the decrypted content, the content playback unit 32 of STB 3 plays back the received content (step S815).

  FIG. 10 shows the operation of the content selection routine executed by the content selection means 43 of the content decryption unit 4. The content selection routine is executed when the content selection unit 43 receives the PMT.

  The content selection unit 43 receives the PMT from the stream data receiving unit 31 of the STB 3 (step S1001). After receiving the PMT, the content selection unit 43 determines whether content selection is necessary (step S1002). Whether or not content selection is necessary is determined based on the value of “Cont_selector” in which content selection information is described. The content selection means 43 reads the item “Cont_selector” in the PMT and confirms the value. When the value of “Cont_selector” is “0”, it is determined that content selection is not necessary. If the value of “Cont_selector” is not “0”, it is determined that content selection is necessary.

  When it is determined that content selection is necessary, the content selection unit 43 issues a terminal type determination command to the terminal type determination unit 42 (step S1003). At this time, the content selection unit 43 reads the type designation information described in the items “Host_type” and “Host_function” of the PMT, and sends out the type designation information included in the terminal type determination command. When the terminal type determination unit 42 receives a command from the content selection unit 43, the type of the client terminal represented by the terminal type information sent from the terminal type sending unit 33 and the type specified by the type designation information are displayed. Judge whether they match. Then, the terminal type determination unit 42 sends the determination result to the content selection unit 43.

  When the content selection unit 43 receives the determination result from the terminal type determination unit 42, the content selection unit 43 determines whether or not the type of the client terminal matches the type specified in the type designation information based on the determination result (step S1004). . If a determination result indicating that the terminal types match is received, it is determined that the terminal types match. If a determination result indicating that the terminal types do not match is received, it is determined that the terminal types do not match.

  If it is determined that the terminal types match, the content selection unit 43 reads the item “Cont_select_protocol” of the PMT. Then, content is selected according to the content selection procedure described in the read “Cont_select_protocol”, and processing for acquiring content identification information and ECM identification information is performed (step S1005).

  FIG. 11 shows a table indicating the correspondence between the “Cont_select_protocol” value and the content selection procedure.

  When the first bit of “Cont_select_protocol” is “1”, the content identification information described in the item “ES_pid” of “Cont_selector” is set as the content identification information to be decrypted.

  When the second bit of “Cont_select_protocol” is “1”, the ECM identification information described in the item “ECM_pid” of “Cont_selector” is set as the ECM identification information to be acquired.

  When the third bit of “Cont_select_protocol” is “1”, the content identification information described in “element_PID” of the PMT and the content identification information described in the “ES_pid” item of “Cont_selector” Information indicating that the corresponding content is multiplexed is set as content identification information to be decrypted.

  When the fourth bit of “Cont_select_protocol” is “1”, the content identification information described in the “ES_pid” item of “Cont_selector” is included in the content identification information described in “elementary_PID” of the PMT. A value obtained by adding is used as content identification information to be decrypted. Also, a value obtained by adding the ECM identification information described in the item “ECM_pid” of “Cont_selector” to the ECM identification information described in “CA_PID” of “CA_descriptor” is used as the ECM identification information to be acquired.

  When the fifth bit of “Cont_select_protocol” is “1”, the content identification information described in the item “ES_pid” of “Cont_selector” in the content identification information described in “elementary_PID” of the PMT The value obtained by multiplying is used as the content identification information to be decrypted. In addition, a value obtained by multiplying the ECM identification information described in “CA_PID” of “CA_descriptor” by the ECM identification information described in the “ECM_pid” item of “Cont_selector” is used as the ECM identification information to be acquired.

  When the sixth bit of “Cont_select_protocol” is “1”, the content identification information described in the “element_PID” of the PMT and the content identification information described in the “ES_pid” item of the “Cont_selector” As a result, the result of calculating the exclusive OR is used as content identification information to be decrypted. The result of calculating the exclusive OR between the ECM identification information described in “CA_PID” of “CA_descriptor” and the ECM identification information described in the “ECM_pid” item of “Cont_selector” is obtained. Let it be ECM identification information.

  When the seventh bit of “Cont_select_protocol” is “1”, the content identification information described in the “element_PID” of the PMT and the content identification information described in the “ES_pid” item of the “Cont_selector” The result of calculating the logical product in the above is used as the content identification information to be decrypted. Also, the result of calculating the logical product of the ECM identification information described in “CA_PID” of “CA_descriptor” and the ECM identification information described in the “ECM_pid” item of “Cont_selector” is the target ECM identification Information.

  When the eighth bit of “Cont_select_protocol” is “1”, the content identification information described in the “elementary_PID” of the PMT and the content identification information described in the “ES_pid” item of the “Cont_selector” And the result of calculating the logical sum in the above is used as content identification information to be decrypted. Further, the ECM identification of the acquisition target is obtained by calculating the logical sum of the ECM identification information described in “CA_PID” of “CA_descriptor” and the ECM identification information described in “ECM_pid” of “Cont_selector”. Information.

  After performing the content selection according to the content selection procedure, the content selection unit 43 sends the content identification information as the content identification information to be decoded to the content decoding unit 47 (step S1006). Further, the content selection unit 43 sends the ECM identification information, which is the ECM identification information to be acquired, to the ECM acquisition unit 44 (step S1007).

  When it is determined that content selection is not necessary in the process of S1002 and when it is determined that the type of the terminal does not match in the process of S1004, the content selection unit 43 does not select the content, and the content identification information to be decrypted And the process which sets the ECM identification information of acquisition object is performed (step S1008). In this process, the content identification information described in “elementary_PID” of the PMT is set as the content identification information to be decrypted. Further, the ECM identification information described in “CA_PID” of “CA_descriptor” is set as the ECM identification information to be acquired.

  Then, the content selection unit 43 sends the content identification information, which is the content identification information to be decrypted, to the content decryption unit 47 (step S1006). Further, the content selection unit 43 sends the ECM identification information, which is the ECM identification information to be acquired, to the ECM acquisition unit 44 (step S1007).

  As described above, since the content selection is performed when the type of the client terminal 2 matches the type specified in the PMT type designation information, the decryption target is determined depending on whether the type matches or not. Can be different content. For example, when the type of the client terminal 2 matches the type specified by the type designation information of the PMT, decoding of the high bit rate content is permitted, and when the type does not match, only the low bit rate content is decoded. Can be disallowed.

  As described above, in the distribution server, client terminal, and content distribution system of the present invention, the content is selected by the content decoding unit according to the content identification information included in the stream data distributed from the distribution server. The content is being decrypted. Since the content decrypting unit does not need to use a well-known operating system such as STB or PC, it is difficult to modify the content decrypting unit. Therefore, the content can be protected by preventing the content from being illegally decrypted or outflowing the illegally copied content.

It is a block diagram which shows the delivery server which is an Example of this invention, a client terminal, and a content delivery system. It is a figure which shows the example of the program map table of the Example of FIG. It is a figure which shows the example of CA_descriptor of the Example of FIG. It is a figure which shows the example of private_data_byte of the Example of FIG. It is a figure which shows the example of Cont_selector of the Example of FIG. It is a figure which shows the example of the table showing the correspondence of Host_type of the Example of FIG. 1, and the classification of a client terminal. It is a figure which shows the example of the table showing the correspondence of Host_function of the Example of FIG. 1, and the function which a client terminal has. It is a sequence diagram which shows the operation | movement of decoding and reproduction | regeneration of the content of the Example of FIG. It is a figure which shows the example of the terminal classification information of the Example of FIG. It is a flowchart which shows operation | movement of the content selection routine of the Example of FIG. It is a figure which shows the example of the table showing the correspondence of Cont_select_protocol and the content selection procedure of the Example of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Distribution server 2 Client terminal 3 Set top box 31 Stream data receiving part 32 Content reproduction part 33 Terminal type information transmission means 4 Content decoding part 41 Terminal type information receiving means 42 Terminal type judgment means 43 Content selection means 44 ECM acquisition means 46 ECM Decryption means 47 Content decryption means

Claims (4)

A distribution server that distributes stream data including content to a client terminal via a network,
A distribution server characterized in that the stream data includes type designation information for designating a type of a client terminal to be reproduced for each content and content selection information describing a content selection procedure. A stream data receiving unit for receiving the stream data via the network; a content playback unit for playing back the content; and receiving the encrypted content from the stream data receiving unit to decrypt the content and A client terminal comprising: a content decrypting unit for sending to the playback unit;
The content decryption unit includes content selection means for acquiring content identification information representing content permitted to be played in accordance with a content selection procedure described in the content selection information, and ECM identification information representing ECM corresponding to the content; An ECM acquisition unit that acquires an ECM corresponding to the ECM identification information acquired by the content selection unit from the stream data, an ECM decryption unit that decrypts the ECM acquired by the ECM acquisition unit and obtains a scramble key, and the content A client terminal comprising: content decrypting means for decrypting content corresponding to the content identification information acquired by the screening means with the scramble key. The client terminal has terminal type information sending means for sending terminal type information representing its own type to the content decoding unit,
The content decoding unit includes a terminal type information receiving unit that receives the terminal type information, and a type designation information in which the type of the client terminal represented by the terminal type information received by the terminal type information receiving unit is included in the stream data A terminal type determination means for determining whether the type matches the type specified in
When the content selection unit determines that the terminal type determination unit matches, the content selection unit corresponds to the content identification information indicating the content permitted to be played according to the content selection procedure described in the content selection information and the content The client terminal according to claim 2, wherein ECM identification information representing ECM is acquired. A stream data receiving unit that receives stream data including content via a network, a content playback unit that plays back the content, and an encrypted content received from the stream data receiving unit, decrypts the content, and plays the content A content distribution system comprising: a client terminal including a content decrypting unit to be transmitted to a unit; and a distribution server that distributes stream data including content to the client terminal via a network,
The distribution server includes, in the stream data, type designation information for designating a type of a reproduction target client terminal for each content, and content selection information describing a content selection procedure,
The content decryption unit includes content selection means for acquiring content identification information representing content permitted to be played in accordance with a content selection procedure described in the content selection information, and ECM identification information representing ECM corresponding to the content; An ECM acquisition unit that acquires an ECM corresponding to the ECM identification information acquired by the content selection unit from the stream data, an ECM decryption unit that decrypts the ECM acquired by the ECM acquisition unit and obtains a scramble key, and the content A content distribution system comprising: content decrypting means for decrypting content corresponding to the content identification information acquired by the screening means with the scramble key.

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