JP2008278392A - Content encryption / decryption device, program, and data structure of media data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a content encryption/decryption apparatus, program and data structure of media data, wherein a copyright holder can deal with key information of the media data. <P>SOLUTION: A content encryption apparatus connected to a server for distributing media data includes: a scramble section that scrambles source media data using key information; an electronic watermark inserting means for embedding the key information in the scrambled media data through electronic watermarking; and a media data transmitting means for transmitting to the server the media data in which the key information has been embedded. On the other hand, a content decryption apparatus connected to a communication terminal device includes: an electronic watermark extracting means for extracting the key information from the media data through electronic watermarking; a descrambling means for descrambling the media data using the extracted key information; and a media data output means for outputting the descrambled media data to a playback device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a content encryption / decryption device, a program, and a data structure of media data.

  FIG. 1 is a system configuration diagram in the prior art.

  In the system of FIG. 1, a content distribution server 1 of a service providing facility and a set-top box (communication terminal device) 2 installed at home are connected via a network 5 such as the Internet. Connected to the set top box 2 are a television 3, an audio device 4, and the like (reproducing device).

  The content distribution server 1 distributes media data that can be viewed and viewed by the user. The media data is, for example, voice (music), still image, and moving image (video) data. Media data is obtained by digitizing content by a predetermined method (for example, MPEG (Moving Picture Experts Group)), and is stored in the content distribution server 1.

  A user at home uses the set top box 2 to request the desired media data from the content distribution server 1. At this time, the content distribution server 1 generates key information by random numbers, for example, and scrambles the media data using the key information.

  Scramble refers to a technique for making at least a part or all of media data unrecognizable. Accordingly, the scrambled media data cannot be viewed and viewed as it is, and thus has no commercial value. However, for media data that is partially scrambled, other portions may be viewable and viewable. Scramble is a reversible process, and the original media data can be completely restored using the key information.

  The content distribution server 1 transmits the scrambled media data to the set top box 2 via the network 5. At this time, the content distribution server 1 also transmits to the set top box 2 key information for descrambling. Since the key information also has a role of protecting the copyright of the media data, it must be transferred by a communication method in which confidentiality is ensured.

  The set top box 2 receives scrambled media data and key information from the content distribution server 1. Then, the set top box 2 uses the key information to release the scrambling of the media data. Thereby, the set top box 2 can output the decoded media data to the television 3 or the audio device 4.

JP 2003-195759 A JP 2005-142898 A

  However, according to the prior art, the content distribution server 1 and the set-top box 2 must always support the handling of key information and the scrambling method. That is, it is necessary to provide the set top box 2 corresponding to the media data and key information transmitted by the content distribution server 1.

  From the viewpoint of service provision, the set top box 2 had to be a device provided by the operator of the content distribution server 1. That is, the handling of the key information of the media data is managed by the network equipment provider that distributes the content.

  On the other hand, at present, contents are distributed from various copyright holders via the Internet. Then, the handling of the key information of the media data and the scramble method should be managed by the content creator who creates the content.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a content encryption / decryption device, a program, and a data structure of media data that can handle key information of media data by a copyright holder.

According to the present invention, a content encryption apparatus connected to a server for distributing media data,
Scrambling means for scrambling the original media data using the key information;
Digital watermark insertion means for embedding key information in digital data in scrambled media data;
Media data transmitting means for transmitting the media data in which the key information is embedded to the server. This is a content encryption apparatus based on the first embodiment.

According to the present invention, a content encryption apparatus connected to a server for distributing media data,
Scrambling means for scrambling the original media data using the key information;
A digital watermark inserting means for embedding key information and reproduction condition information in the scrambled media data with a digital watermark;
Media data transmitting means for transmitting the media data in which the key information is embedded to the server. This is a content encryption apparatus based on the second embodiment.

According to another embodiment of the content encryption device of the present invention,
Media data is MPEG (Moving Picture Experts Group) encoded data,
The watermark insertion means
Means for selecting a block from MPEG encoded data according to a template;
Means for decoding the selected block, dequantizing, and extracting an embedding position according to the template;
Means for embedding key information in the extracted embedding position;
It is also preferable to include means for quantizing and encoding the block in which the key information is embedded.

According to the present invention, there is provided a content decryption device connected to a communication terminal device that receives scrambled media data from a server connected to the content encryption device according to the first embodiment,
Digital watermark extraction means for extracting key information with digital watermark from media data output from the communication terminal device;
Using the extracted key information, descrambling means for descrambling the media data;
Media data output means for outputting the scrambled media data to a playback device. This is a content decrypting apparatus based on the first embodiment.

According to the present invention, there is provided a content decryption device connected to a communication terminal device that receives scrambled media data from a server connected to the content encryption device according to the second embodiment,
Digital watermark extraction means for extracting key information and reproduction condition information by digital watermark from media data output from a communication terminal device;
Reproduction condition determination means for determining whether or not the reproduction state information in the content decrypting apparatus satisfies the reproduction condition information;
Descrambling means for descrambling the media data using the extracted key information when it is determined that the playback state information satisfies the playback condition information;
Media data output means for outputting the scrambled media data to a playback device. This is a content decrypting apparatus based on the second embodiment.

According to another embodiment of the content decryption apparatus of the present invention,
The media data is MPEG encoded data,
The digital watermark extraction means
Means for selecting a block from MPEG encoded data according to a template;
Means for decoding the selected block, dequantizing, and extracting an embedding position according to the template;
Extraction means for extracting key information from the extracted embedding position;
It is also preferable to have

According to the present invention, there is provided a content encryption program for causing a computer mounted on a device connected to a server for distributing media data to function.
Scrambling means for scrambling the original media data using the key information;
Digital watermark insertion means for embedding key information in digital data in scrambled media data;
The computer is caused to function as media data transmitting means for transmitting media data in which key information is embedded to a server.

According to the present invention, there is provided a content encryption program for causing a computer mounted on a device connected to a server for distributing media data to function.
Scrambling means for scrambling the original media data using the key information;
A digital watermark inserting means for embedding key information and reproduction condition information in the scrambled media data with a digital watermark;
The computer is caused to function as media data transmitting means for transmitting media data in which key information is embedded to a server.

According to the present invention, content decryption that causes a computer mounted on a device connected to a communication terminal device that receives scrambled media data from a server connected to the content encryption device according to the first embodiment to function. A program,
Digital watermark extraction means for extracting key information with digital watermark from media data output from the communication terminal device;
Using the extracted key information, descrambling means for descrambling the media data;
The computer is caused to function as media data output means for outputting the scrambled media data to a playback device.

According to the present invention, content decryption that causes a computer mounted on a device connected to a communication terminal device that receives scrambled media data to function from a server connected to the content encryption device according to the second embodiment. A program,
Digital watermark extraction means for extracting key information and reproduction condition information by digital watermark from media data output from a communication terminal device;
Reproduction condition determination means for determining whether or not the reproduction state information in the content decrypting apparatus satisfies the reproduction condition information;
Descrambling means for descrambling the media data using the extracted key information when it is determined that the playback state information satisfies the playback condition information;
The computer is caused to function as media data output means for outputting the scrambled media data to a playback device.

According to the present invention, the data structure of the media data transmitted from the server connected to the content encryption device based on the first embodiment to the communication terminal device connected to the content decryption device based on the first embodiment Because
The original media data is scrambled with the key information,
The key information is embedded in the scrambled media data with a digital watermark.

According to the present invention, the data structure of the media data transmitted from the server connected to the content encryption device based on the second embodiment to the communication terminal device connected to the content decryption device based on the second embodiment Because
The original media data is scrambled with the key information,
The key information and the reproduction condition information are embedded in the scrambled media data with a digital watermark.

  According to the present invention, since the key information is embedded in the media data itself, the copyright owner can handle the key information of the media data without the operator of the content distribution server managing the key information. It becomes possible. Further, by embedding reproduction condition information, reproduction of the media data can be suppressed under a reproduction state that does not satisfy the condition of the reproduction condition information.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a system configuration diagram according to the present invention.

  The system of FIG. 2 includes a content encryption device 6 for transmitting media data to the content distribution server 1 and a content decryption device 7 connected to a set top box (communication terminal device) 2 as compared with FIG. ing. The content distribution server 1 and the set top box 2 are provided by a communication provider, while the content encryption device 6 and the content decryption device 7 are preferably managed by a content creation operator (copyright holder). .

  The original media data and key information are input to the content encryption device 6. The content encryption device 6 includes a scramble processing unit 61, a digital watermark insertion unit 62, and a media data transmission unit 63. These functional units can be realized by executing a content encryption program that causes a computer installed in the apparatus to function.

  The scramble processing unit 61 scrambles the original media data using the key information. The original media data is based on, for example, the MPEG system. Scramble refers to a technique for encrypting media data so that the original media data can be decrypted only by a specific decryption device. Only the right holder who can view the content holds the key information for decryption. This prevents a third party other than the right holder from browsing the content. The scramble processing unit 61 outputs the scrambled media data to the digital watermark insertion unit 62.

  The digital watermark insertion unit 62 embeds key information with a digital watermark at a specific position of the scrambled media data. Digital watermarking is a technique for embedding other information in media data, and is generally embedded so that it cannot be recognized by humans by utilizing human recognition characteristics.

  Further, the digital watermark inserting unit 62 may embed the reproduction condition information at a specific position of the scrambled media data and the key information with the digital watermark. The reproduction condition information may be a date and time range in which reproduction is permitted, for example. Therefore, reproduction of the media data can be prohibited at a date and time outside the date and time range.

  When the media data is MPEG encoded data, the digital watermark insertion unit 62 selects a block according to the template, decodes the block, performs inverse quantization, and extracts an embedding position according to the template. May be. Since the key information is embedded in a limited number of macro blocks and their positions in the template, the amount of calculation for embedding and extracting watermark data can be reduced. The block in which the key information is embedded is further quantized and encoded, and output to the media data transmission unit 63.

  The digital watermark inserting unit 62 may embed the key information and the reproduction condition information as they are in the scrambled media data. Further, the key information and the reproduction condition information may be encrypted and embedded in the scrambled media data. The master key for encrypting the key information and the reproduction condition information is also preferably an externally connected one such as an IC card. Thereby, the security effect regarding reproduction | regeneration of media data can be improved.

  The media data transmission unit 63 transmits the scrambled media data in which the key information (and reproduction condition information) is embedded to the content distribution server 1. The content encryption device 6 may be connected to the network 5 and configured to transmit the scrambled media data in which the key information is embedded to the content distribution server 1 via the network 5.

  The content decoding device 7 includes a digital watermark extraction unit 71, a scramble release unit 72, a media data output unit 73, a reproduction condition determination unit 74, and a watermark correction unit 75. These functional units can be realized by executing a content decryption program that causes a computer installed in the apparatus to function.

  The digital watermark extraction unit 71 receives the scrambled media data in which the key information is embedded from the set top box 2. This scrambled media data is compressed data. Then, key information is extracted from the scrambled media data by digital watermark. The digital watermark extraction unit 71 outputs the extracted key information to the descrambling unit 72.

  If the scrambled media data includes playback condition information, the digital watermark extraction unit 71 also extracts the playback condition information. In this case, the key information and the reproduction condition information are notified to the reproduction condition determination unit 74. When the playback condition information is not included in the scrambled media data, the digital watermark extraction unit 71 notifies the scramble release unit 72 of the key information.

  The descrambling unit 72 receives scrambled media data from the digital watermark extraction unit 71 (or a watermark correction unit 75 described later), and receives key information from the digital watermark extraction unit 71 (or a playback determination unit 74 described later). . Then, the scramble release unit 72 uses the key information to release scramble of the scramble media data. The unscrambled original media data is output to the media data output unit 73.

  The media data output unit 73 outputs the original media data to a playback device such as the television 3 and the audio device 4.

  Here, the descrambling unit 72 descrambles the scrambled media data in which the key information is embedded using the key information. Therefore, the original media data input to the scramble processing unit 61 of the content encryption device 6 and the original media data output from the descrambling unit 72 are completely restored 100% of the portion where the key information is inserted by the watermark. Not. However, since it is inserted with a watermark, it is not recognized by humans when played back by a playback device such as the television 3 and the audio device 4.

  The reproduction condition determination unit 74 receives the reproduction condition information from the digital watermark extraction unit 71 together with the key information. The reproduction condition determination unit 74 determines whether or not the reproduction state information in the content decrypting apparatus 7 satisfies the condition of the reproduction condition information. For example, if the playback condition information is a date and time range in which playback of the media data is permitted, the playback status information may be current date and time information. When the current date / time is not included in the date / time range of the playback condition information, the playback condition determination unit 74 does not notify the descrambling unit 72 of the key information. On the other hand, if it is included, the playback condition determination unit 74 notifies the scramble release unit 72 of the key information.

  The watermark correction unit 75 can improve the image quality after descrambling by determining the property of the media data modified along with the decoding of the digital watermark and correcting the media data. For example, the position of the embedded watermark on the MPEG encoded data is specified. Then, the DCT coefficient value is smoothed by performing a watermark erasing process which is a part of the watermark editing process.

  FIG. 3 is a functional configuration diagram of the digital watermark insertion unit of the content encryption apparatus according to the present invention.

  According to FIG. 3, the digital watermark insertion unit 62 includes a memory unit 621, a macroblock extraction unit 622, a template unit 623, a variable length decoding unit 624, an inverse quantization unit 625, and a DCT (Discrete Cosine Transform). The coefficient extraction unit 626, the watermark embedding unit 627, the quantization unit 628, and the variable length encoding unit 629 are included. These functional units can be realized by executing a program that causes a computer installed in the content encryption apparatus to function.

  For example, MPEG encoded frames Fn-1, Fn, Fn + 1,... Are sequentially read from the media data, and a plurality of frames are temporarily stored in the memory unit 621.

  The macroblock extraction unit 622 extracts a block (macroblock) in which the watermark data is to be embedded from the memory unit 621 based on an instruction from the template unit 623. A plurality of patterns for extracting a macroblock are prepared in the template unit 623, and a different macroblock extraction pattern is applied for each frame. When the application of the pattern is completed, the same pattern can be cyclically applied again.

  The variable length decoding unit 624 performs variable length decoding on the extracted macroblock. Next, the inverse quantization unit 625 inversely quantizes the decoded block and reproduces the DCT coefficient. The DCT coefficient is a numerical value obtained by performing discrete cosine transform (frequency decomposition) on macroblock data of an image.

  The DCT coefficient extraction unit 626 extracts a DCT coefficient at a position where the watermark data is embedded in accordance with an instruction from the template unit 623. In the DCT coefficient, a redundant component (a high-frequency component that does not affect image quality or the like even if deleted) is extracted.

  The watermark embedding unit 627 embeds key information as watermark data in the extracted DCT coefficient. Since the key information is embedded in the redundant component portion in the DCT coefficient, it is difficult for humans to recognize it.

  When the quantization step size of the DCT coefficient value to be embedded is Δ, Δ is added to the DCT coefficient value to be embedded in the direction in which the absolute value increases. Alternatively, when the quantization step size applied when the changed result is encoded at a lower bit rate is Δ ′, the ΔT is set to the DCT coefficient value to be embedded so that the absolute value becomes larger. to add.

  For example, when the DCT coefficient value to be embedded is A, Δ or Δ ′ is added to the absolute value of the quantization level value A ′. Note that “the result of the change is that the quantization step size applied when encoding at a lower bit rate is Δ ′” means that, for example, high bit rate image data for an optical fiber communication path is lower than that for a telephone line. An encoding process when converting to bit rate image data is conceivable.

  The quantization unit 628 requantizes the media data in which the key information is embedded. Next, the variable length coding unit 629 performs variable length coding of the media data, shapes the media data into an MPEG bit stream, and outputs the MPEG bit stream.

  FIG. 4 is a functional configuration diagram of the digital watermark extraction unit of the content decryption apparatus according to the present invention.

  According to FIG. 4, the digital watermark extraction unit 71 includes a memory unit 711, a macroblock extraction unit 712, a template unit 713, a variable length decoding unit 714, an inverse quantization unit 715, and a DCT coefficient extraction unit 716. And a watermark extraction unit 717. These functional units can be realized by executing a program that causes a computer installed in the content decrypting apparatus to function.

  The memory unit 711, the macroblock extraction unit 712, the template unit 713, the variable length decoding unit 714, the inverse quantization unit 715, and the DCT coefficient extraction unit 716 perform the same processing as described above with reference to FIG. To do. That is, since the template unit 713 of the content decryption device 7 and the template unit 623 of the content encryption device 6 use the same template, the macro block and the DCT coefficient in which the key information is embedded can be specified. The watermark extraction unit 717 extracts key information as watermark data from the extracted DCT coefficients. That is, the watermark extraction unit 717 performs the reverse process of the watermark embedding unit 627 of the content encryption device 6.

  According to FIGS. 3 and 4, since only the key information is embedded in a limited number of macroblocks and DCT coefficients in the template, the amount of calculation for embedding and extracting watermark data can be reduced.

  As described above in detail, according to the present invention, since the key information is embedded in the media data itself, the copyright holder himself can manage the key information without the operator of the content distribution server managing the key information. It becomes possible to handle key information of media data. Further, by embedding reproduction condition information, reproduction of the media data can be suppressed under a reproduction state that does not satisfy the condition of the reproduction condition information.

  According to the various embodiments of the present invention described above, various changes, modifications, and omissions within the scope of the technical idea and the viewpoint of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

It is a system block diagram in a prior art. It is a system configuration diagram in the present invention. It is a function block diagram of the electronic watermark insertion part of the content encryption apparatus in this invention. It is a function block diagram of the electronic watermark extraction part of the content decoding apparatus in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Content delivery server 2 Set top box, communication terminal device 3 Television 4 Audio apparatus 5 Network 6 Content encryption apparatus 61 Scramble processing part 62 Digital watermark insertion part 621 Memory part 622 Macroblock extraction part 623 Template part 624 Variable length decoding part 625 Inverse quantization unit 626 DCT coefficient extraction unit 627 Watermark embedding unit 628 Quantization unit 629 Variable length encoding unit 63 Media data transmission unit 7 Content decoding device 71 Digital watermark extraction unit 711 Memory unit 712 Macroblock extraction unit 713 Template unit 714 Variable Long decoding unit 715 Inverse quantization unit 716 DCT coefficient extraction unit 717 Watermark extraction unit 72 Scramble release unit 73 Media data output unit 74 Playback condition determination unit 75 Watermark correction unit

Claims (12)

A content encryption device connected to a server that distributes media data,
Scrambling means for scrambling the original media data using the key information;
A digital watermark inserting means for embedding the key information in the scrambled media data with a digital watermark;
A content encryption apparatus comprising: media data transmission means for transmitting the media data in which the key information is embedded to the server. A content encryption device connected to a server that distributes media data,
Scrambling means for scrambling the original media data using the key information;
A digital watermark inserting means for embedding the key information and reproduction condition information in the scrambled media data with a digital watermark;
A content encryption apparatus comprising: media data transmission means for transmitting the media data in which the key information is embedded to the server. The media data is MPEG (Moving Picture Experts Group) encoded data,
The digital watermark inserting means includes
Means for selecting a block from the MPEG encoded data according to a template;
Means for decoding the selected block, dequantizing, and extracting an embedding position according to the template;
Means for embedding the key information in the extracted embedding position;
The content encryption apparatus according to claim 1, further comprising: a unit that quantizes and encodes the block in which the key information is embedded. A content decryption device connected to a communication terminal device that receives the scrambled media data from a server connected to the content encryption device according to claim 1,
A digital watermark extraction means for extracting the key information with a digital watermark from the media data output from the communication terminal device;
Descrambling means for descrambling the media data using the extracted key information;
A content decoding apparatus, comprising: media data output means for outputting the media data that has been descrambled to a playback device. A content decryption device connected to a communication terminal device that receives the scrambled media data from a server connected to the content encryption device according to claim 2,
A digital watermark extraction means for extracting the key information and the reproduction condition information from the media data output from the communication terminal device with a digital watermark;
Reproduction condition determination means for determining whether reproduction state information in the content decrypting apparatus satisfies the reproduction condition information;
A descrambling means for descrambling the media data using the extracted key information when it is determined that the playback state information satisfies the playback condition information;
A content decoding apparatus, comprising: media data output means for outputting the media data that has been descrambled to a playback device. The media data is MPEG encoded data,
The digital watermark extracting means includes
Means for selecting a block from the MPEG encoded data according to a template;
Means for decoding the selected block, dequantizing, and extracting an embedding position according to the template;
Extraction means for extracting the key information from the extracted embedded position;
The content decryption apparatus according to claim 4, wherein the content decryption apparatus comprises: A content encryption program for causing a computer mounted on a device connected to a server for distributing media data to function,
Scrambling means for scrambling the original media data using the key information;
A digital watermark inserting means for embedding the key information in the scrambled media data with a digital watermark;
A content encryption program that causes a computer to function as media data transmission means for transmitting the media data in which the key information is embedded to the server. A content encryption program for causing a computer mounted on a device connected to a server for distributing media data to function,
Scrambling means for scrambling the original media data using the key information;
A digital watermark inserting means for embedding the key information and reproduction condition information in the scrambled media data with a digital watermark;
A content encryption program that causes a computer to function as media data transmission means for transmitting the media data in which the key information is embedded to the server. A content decryption program for causing a computer mounted on a device connected to a communication terminal device that receives the scrambled media data from a server connected to the content encryption device according to claim 1 to function,
A digital watermark extraction means for extracting the key information with a digital watermark from the media data output from the communication terminal device;
Descrambling means for descrambling the media data using the extracted key information;
A content decryption program that causes a computer to function as media data output means for outputting the media data that has been descrambled to a playback device. A content decryption program for causing a computer mounted on a device connected to a communication terminal device that receives the scrambled media data from a server connected to the content encryption device according to claim 2 to function,
A digital watermark extraction means for extracting the key information and the reproduction condition information from the media data output from the communication terminal device with a digital watermark;
Reproduction condition determination means for determining whether reproduction state information in the content decrypting apparatus satisfies the reproduction condition information;
A descrambling means for descrambling the media data using the extracted key information when it is determined that the playback state information satisfies the playback condition information;
A content decryption program that causes a computer to function as media data output means for outputting the media data that has been descrambled to a playback device. A data structure of media data transmitted from a server connected to the content encryption device according to claim 1 to a communication terminal device connected to the content decryption device according to claim 4,
The original media data is scrambled with the key information,
A data structure of media data, wherein the key information is embedded in the scrambled media data with a digital watermark. A data structure of media data transmitted from a server connected to the content encryption device according to claim 2 to a communication terminal device connected to the content decryption device according to claim 5,
The original media data is scrambled with the key information,
A data structure of media data, wherein the key information and reproduction condition information are embedded in the scrambled media data with a digital watermark.

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