JP2003078515A - Contents distributing system, decoding device, encrypting device, decoding program, and encrypting program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it much more difficult to illegally decode encrypted contents by preventing any information embedded in an electronic watermark from being illegally erased in the distribution system of digital contents. SOLUTION: A decoding device 100 is provided with an encrypted contents reading part 10 for successively reading the data of digital contents by each decided block from the top of the data, an initial parameter holding part 30 for holding an encryption parameter being information for decoding the leading block of the encrypted contents, a decoding processing part 20 for decoding each block of the encrypted contents, an electronic watermark detecting part 40 for detecting electronic watermark information embedded in the block from the data of the block decoded by the decoding processing part 20, and a detected information processing part 60 for generating the encryption parameter being information for decoding the next block based on the electronic watermark information detected by the electronic watermark detecting part 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to copyright protection of digital contents, and more particularly, to a contents distribution system that allows only authorized users to view digital contents distributed to users and prohibits unauthorized use thereof. The present invention relates to a decryption device, an encryption device, a decryption program, and an encryption program.

[0002]

2. Description of the Related Art An example of a conventional content distribution system is disclosed in Japanese Patent Application No. 11-253522. In this conventional content distribution system, information used for user authentication is embedded in digital content such as video by using a technique called digital watermark. The user terminal device that reproduces the content extracts the information used for the embedded authentication, sends the information to the center that manages the content, and the center sends back the authentication information to obtain the authentication information correctly. Only if
It is configured to play digital contents.

In the digital watermark technology, information about the copyright holder of the content and permission / non-permission of copying is added in a format that cannot be discriminated by the user, and the added information is read as necessary. It is possible. Therefore, the content to which the digital watermark is added is normally in a format that can be used as it is. In addition, the digital watermark is a technique for detecting illegal use, not a technique for prohibiting illegal use.

On the other hand, in order to prohibit illegal use, it is said that a method of encrypting digital contents and distributing an encryption key for decryption to users is effective. For example, 2
Information Media Study Group Report 3 published in January 2000
On pages 6-3 and 22, an example is described in a paper by Ueno et al. Entitled “Content Sales System Considering Prevention of Unauthorized Copy”. In this example, the digital content is reproduced as follows.

FIG. 19 is a block diagram showing the structure of this conventional content distribution system. The encrypted content is delivered from the content server 81 to the user's personal computer (PC) 82 through the CDROM or the Internet. Then, the user's personal computer 82 transmits the ID information of the medium 83 holding the delivered data to the encryption key server 84, and the encryption key server 84 receives the ID.
Using the information, the encryption key for decrypting the content is subjected to the second encryption and returned to the personal computer 82.

In the reproducing section 85 of the user's personal computer 82,
Using the encryption key associated with the ID information, the second encryption is decrypted and the encryption key for decrypting the content is retrieved. Further, the content is decrypted and reproduced by using the encryption key.

Further, when a block cipher is applied to a long data such as video data, the original data is divided into blocks having a predetermined length (block length), and the encryption process is repeated for each block. Is generally known. As an example, there is a method called OFB mode.

FIG. 20 schematically shows a conventional data encryption process according to the OFB mode.

First, the original data (plaintext) P and the encryption key K
In addition to the above, the initial vector IV is determined in advance. Then, the initial vector IV is encrypted with the encryption key K, and the result is used as the first encryption key K1. Next, a partial value for the number of bits corresponding to the above-mentioned block length is calculated from the beginning of K1. Then, the exclusive OR is calculated for the partial value and the first plaintext block P1 obtained by dividing P into blocks as described above, and the calculated value is set as the first cipher block C1.

Next, the first encryption key K1 is encrypted with the encryption key K, and the result is the second encryption key K1.
2 and the second plaintext block P in the same manner as the first-stage processing.
The second cipher block C2 is calculated from 2. Thereafter, similarly, the cipher blocks are sequentially calculated from all the plaintext blocks.

Further, in the decryption process for the sequence of cipher blocks obtained in this way, each block is encrypted by similarly performing the above-mentioned encryption process using the initial vector IV and the encryption key K. An encrypted encryption key can be obtained, and a plaintext block can be obtained by using each encryption key.

However, in such a conventional encryption method, since the decryption key is different for each cipher block Cn, although the security is slightly improved, the key sequence Kn
Is uniquely determined for K and IV binary,
Parameters related to block ciphers (algorithm /
Regarding the key length / block length, etc.), there was no choice but to use a fixed value.

[0013]

As described above, the conventional technique has the following problems.

First, there is a problem in the related art that there is a high risk that information embedded as a digital watermark will be lost in digital contents to be distributed. The reason is that the digital watermark information is destroyed by image processing such as color reduction processing.

Secondly, conventionally, there is a problem that the distributed digital contents are easily copied, and there is a high risk that the copyright of the digital contents is infringed. The reason is that conventionally, because of the method of encryption with one encryption key, all the data of the content can be decrypted by discovering that one encryption key. Furthermore, if the location of the encryption key is clear and the algorithm for decrypting the encryption leaks, all contents can be decrypted.

Third, in order to prevent illegal copying,
When the encryption is strengthened using a plurality of encryption keys, a storage area for holding the plurality of encryption keys is required, and further, processing for safely managing the plurality of encryption keys is required. There is a problem that many storage areas are required.

A first object of the present invention is to solve the above-mentioned drawbacks of the prior art, reproduce digital contents exactly as intended by the copyright holder / provider, and illegally embed information embedded in a digital watermark. It is to provide a content distribution system, a decryption device, an encryption device, a decryption program, and an encryption program that are not erased.

A second object of the present invention is to solve the above-mentioned drawbacks of the prior art, to make illegal decryption of encrypted content more difficult, and to protect the copyright of the content. To provide an encryption device, a decryption program, and an encryption program.

A third object of the present invention is to solve the above-mentioned drawbacks of the prior art and to realize a complicated decryption process in a smaller storage area, a content distribution system, a decryption device, an encryption device, a decryption program, an encryption program. To provide.

[0020]

In order to achieve the above object, a content distribution system of the present invention is a content distribution system for encrypting digital content to generate encrypted content and distributing the encrypted content to a decryption device which is a terminal of a user. In the above, the data of the digital content is divided into a plurality of blocks from the beginning based on a predetermined method, an encryption method for encrypting the data of the block is determined for each block, and each block is By embedding a cryptographic parameter, which is information for decoding the encryption by the encryption method defined for the subsequent block, by a digital watermark, and then encrypting by the encryption method defined for the block And generating the encrypted content.

According to another aspect of the present invention, in the content distribution system of the present invention, the decryption device includes an initial parameter retaining unit that retains the encryption parameter for decrypting the first block of the encrypted content, and the encryption. A decryption processing unit that decrypts each of the blocks of the content based on the encryption parameter for decrypting the block,
From the data of the block decoded by the decoding processing unit to a digital watermark detection unit that detects the digital watermark information embedded in the block with a digital watermark, and the digital watermark information detected by the digital watermark detection unit. It is characterized by comprising a detection information processing unit for generating the encryption parameter based on the above.

According to a third aspect of the present invention, there is provided a content distribution system including a content management server that manages information for decrypting the encrypted content, wherein the decryption device comprises:
It is characterized by communicating with the content management server via a network and acquiring information necessary for decrypting the encrypted content.

In the content distribution system according to the present invention of claim 4, when the decoding device fails to detect the digital watermark information, the decoding device acquires information for detecting the digital watermark information from the content management server. It is characterized by doing.

According to a fifth aspect of the present invention, there is provided a content distribution system including an encryption device for encrypting digital content to generate encrypted content, wherein the decryption device includes a reproduction section for reproducing the decrypted encrypted content. It is characterized in that the encrypted content generated by the encryption device is distributed to the decryption device via a network and reproduced.

According to a sixth aspect of the present invention, there is provided a decryption device for decrypting encrypted content, which is encrypted digital content, wherein the encrypted content is a plurality of blocks from the beginning based on a predetermined method. Each block is embedded with digital watermark information and then encrypted based on the encryption method defined for the block, and the digital watermark information embedded in each block is , And includes a cryptographic parameter which is information for decrypting the encryption by the encryption method defined for the block following the block.

According to a seventh aspect of the present invention, there is provided a decryption device for storing an initial parameter holding unit for holding the encryption parameter for decrypting the first block of the encrypted content, and each block of the encrypted content. , A decryption processing unit that decrypts the block based on the encryption parameter for decrypting the block, and the digital watermark information embedded in the block with a digital watermark from the data of the block decrypted by the decryption processing unit And a detection information processing unit that generates the encryption parameter based on the digital watermark information detected by the digital watermark detection unit.

In the decryption device of the present invention of claim 8, the decryption processing unit decrypts the block at the beginning of the encrypted content by the encryption parameter held in the initial parameter holding unit, The second and subsequent blocks of the encrypted content are decrypted by the encryption parameter generated by the detected information processing unit.

According to a ninth aspect of the present invention, in the decryption apparatus of the present invention, the electronic watermark information embedded in each block includes information on the position and range of encrypted data, and the decryption processing unit includes the electronic watermark. It is characterized in that the position and range of the encrypted data indicated by the information are decrypted.

According to a tenth aspect of the present invention, in the digital watermark information embedded in each block,
The encryption parameter includes identification information for uniquely identifying the encryption method defined for the block at a defined position after the block.

According to the decoding apparatus of the present invention of claim 11, in the electronic watermark information embedded in each of the blocks,
The encryption parameter includes data of a computer program that executes an encryption algorithm for decrypting the encryption method defined for the block at a defined position after the block.

According to a twelfth aspect of the present invention, in the digital watermark information embedded in each block,
It is characterized in that the encryption parameter includes information on the number of times and the value of the agitation coefficient of the encryption algorithm in the encryption method determined for the block at a determined position after the block.

According to a thirteenth aspect of the present invention, in the digital watermark information embedded in each block,
In the block at a predetermined position after the block, including the hint information indicating the position where the electronic watermark information is embedded, the electronic watermark detection unit indicates the electronic watermark information of each block in the hint information. It is characterized by detecting by referring to the position.

According to a fourteenth aspect of the present invention, in the digital watermark information embedded in each block,
The block includes a detection key for detecting digital watermark information in the block at a predetermined position after the block, and the digital watermark detecting unit detects the digital watermark information of each block using the detection key. Is characterized by.

The decoding apparatus of the present invention according to claim 15 is characterized by comprising a reproducing section for reproducing the data of each block decoded by the decoding processing section.

According to a sixteenth aspect of the present invention, there is provided a decoding device which stores and references the digital watermark information detected by the digital watermark detecting unit, and the detection information holding unit according to a user's operation. Using the digital watermark information stored in the above, restarting decryption from the block decrypted by the encryption parameter included in the digital watermark information, and reproducing by the reproducing unit. To do.

According to a seventeenth aspect of the present invention, when the digital watermark detecting section fails to detect the digital watermark information, the digital watermark detecting section refers to the digital watermark information stored in the detection information holding section. Thus, the apparatus is provided with means for continuing the reproduction by the reproducing unit.

According to the decrypting apparatus of the present invention of claim 18, the user receives an input of ticket information indicating a level permitted to browse the encrypted content, and based on the ticket information, the reproducing unit. Is provided with a content reproduction management unit for controlling the content to be reproduced.

A decryption device of the present invention according to claim 19 comprises a content management server that manages information for decrypting the encrypted content, and a communication unit that communicates via a network to decrypt the encrypted content. It is characterized in that the information necessary for this is acquired from the content management server and decrypted.

[0039] An encryption apparatus according to a twentieth aspect of the present invention is an encryption apparatus for encrypting digital content to generate encrypted content, wherein the data of the digital content is recorded in a plurality of data from the head based on a predetermined method. To divide into blocks, determine an encryption method for encrypting the data of the block for each of the blocks, and decrypt each of the blocks by the encryption by the encryption method defined for the subsequent block The encrypted content is generated by embedding a cryptographic parameter, which is information, by a digital watermark and then encrypting the block by the encryption method defined for the block.

According to a twenty-first aspect of the present invention, in the encryption device of the present invention, an initial parameter holding section for holding the encryption parameter for decrypting the first block of the encrypted content, and the encryption parameter of each block are stored. A cryptographic parameter generation unit that generates a digital watermark embedding unit that embeds, as digital watermark information for each block, the cryptographic parameter defined for the block at a predetermined position after the block by a digital watermark,
It is characterized by comprising a content encryption unit for encrypting the block in which the digital watermark information is embedded by the encryption method defined for the block.

The decoding program of the present invention according to claim 22 is
In a decryption program for decrypting encrypted content that is encrypted digital content by controlling a computer, the encrypted content is divided into a plurality of blocks from the beginning based on a predetermined method, and each of the blocks is Is embedded in the digital watermark information and then encrypted based on the encryption method defined for the block. The digital watermark information embedded in each block is a block that follows the block. It is characterized in that it includes a cryptographic parameter which is information for decrypting the encryption by the cryptographic method defined for.

The decoding program of the present invention according to claim 23 is
An initial parameter holding function for holding the encryption parameter for decrypting the block at the beginning of the encrypted content, and each block of the encrypted content based on the encryption parameter for decrypting the block. A decoding processing function of decoding, a digital watermark detection function of detecting the digital watermark information embedded in the block by a digital watermark from the data of the decoded block, and the digital watermark information detected based on the detected digital watermark information. It is characterized by having a detection information processing function for generating a cryptographic parameter.

The decoding program of the present invention according to claim 24 is
In the decryption processing function, the first block of the encrypted content is decrypted by the encryption parameter held by the initial parameter holding function, and the second and subsequent blocks of the encrypted content are It is characterized in that it is decrypted by the encryption parameter generated by the detection information processing function.

According to a twenty-fifth aspect of the present invention, there is provided an encryption program for encrypting digital content to generate encrypted content, wherein the data of the digital content is a plurality of data from the beginning based on a predetermined method. The function of dividing into blocks, the function of determining the encryption method for encrypting the data of the block for each block, and the encryption of each block by the encryption method defined for the succeeding block. It is characterized by having a function of generating the encrypted content by embedding an encryption parameter, which is information for decryption, with a digital watermark and then encrypting the block by the encryption method defined for the block. .

According to a twenty-sixth aspect of the present invention, an encryption program stores an initial parameter holding function for holding the encryption parameter for decrypting the block at the head of the encrypted content, and the encryption parameter for each block. A cryptographic parameter generating function for generating, and a digital watermark embedding function for, for each of the blocks, as a digital watermark information, embedding the cryptographic parameter defined for the block at a predetermined position after the block by a digital watermark, It is characterized by comprising a content encryption function of encrypting the block in which the digital watermark information is embedded by the encryption method defined for the block.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a decryption apparatus 100 for decrypting encrypted content according to the first embodiment of the present invention. Referring to FIG. 1, a decoding device 100 according to the present embodiment is a program-controlled CP.
It is realized by U or the like, and includes an encrypted content reading unit 10, a decryption processing unit 20, an initial parameter holding unit 30, a digital watermark detection unit 40, a reproduction unit 50, and a detection information processing unit 60.

The decoding device 100 can be realized by the personal computer of the user or other electronic equipment. In addition, the decryption device 100 of the present embodiment also includes a reproduction unit 50 that reproduces the decrypted content.

In the present invention, the encrypted contents are
It is characterized in that, for each data block of a predetermined size, information (encryption parameter) for decrypting the subsequent blocks is sequentially embedded from the first block by a digital watermark. The information embedded in each block by a digital watermark will be referred to as digital watermark information hereinafter.

Here, the block of encrypted content is a section for embedding a digital watermark in each predetermined section of the content.

FIG. 2 shows a decoding device 10 according to this embodiment.
It is a figure which shows an example of the data structure of the encrypted content 110 which 0 decrypts. As shown in FIG. 2, the encrypted content 110 includes the first block 120-
The second block 120-2 is divided into a plurality of blocks. Further, in the example of FIG. 2, in each block, a cryptographic parameter is embedded by a digital watermark in order to decrypt the next block. For example, the nth
In the block 120-n, the cryptographic parameter 130-n for decrypting the next n + 1th block is embedded.

Here, in each block of the encrypted content, the digital watermark information, which is the information to be embedded by the digital watermark, is simply used as the encryption parameter for decrypting the next block, and the position determined after the next block. Method to use as the encryption parameter for decrypting the block, or a method to use as the data to calculate the encryption parameter to decrypt all the blocks after the next (or a predetermined number of blocks after the next) it can.

Therefore, the decryption device 100 for decrypting and reproducing this encrypted content, as shown in FIG.
It is characterized in that a digital watermark detecting unit 40 for detecting a digital watermark and a detection information processing unit 60 for generating a cryptographic parameter of the next block based on the detected digital watermark information are provided.

The decrypting apparatus 100 of the present embodiment first decrypts the first block of the encrypted content using the encryption parameter held in the initial parameter holding unit 30 by the same method as the conventional method. In the decrypted content, cryptographic parameters for decrypting the subsequent blocks are embedded as a digital watermark.

Then, the following processes (1) to (3) are sequentially executed. (1) The digital watermark detection unit 40 detects embedded digital watermark information. (2) The detection information processing unit 60 generates an encryption parameter for decrypting the next block based on the detected electronic watermark information. (3) The decryption processing unit 20 decrypts the next block using the generated encryption parameter.

Then, the process of (1) for detecting the digital watermark information from the decrypted block is executed again, and thereafter, the processes of (1) to (3) are repeated, whereby all the encrypted contents are obtained. Of blocks are sequentially decoded.

As the encrypted content, for example, music content or moving image content can be used. These contents decrypted by the decryption processing unit 20 are sequentially reproduced by the reproducing unit 50 included in the decoding device 100 of the present embodiment.

As a result, in the encrypted content of this embodiment, if the electronic watermark information of the content is lost, the content cannot be decrypted and the content cannot be reproduced. Therefore, the user needs to retain the digital watermark without destroying it in order to reproduce the content, and the information embedded in the digital watermark can be protected.

Further, since the content is encrypted with a different encryption key for each block, illegally decrypting all the encrypted content requires a lot of time and effort, so that It is possible to prevent illegal copying and protect copyright.

Further, since the encryption key is embedded in the digital watermark, it is difficult to find where the encryption key is, making it difficult to obtain the encryption key illegally.

Since the encryption processing parameters are embedded in the contents, the usage information and the decryption information are
Since it is not necessary to hold or distribute the content separately from the content, it is possible to obtain an effect of requiring a smaller storage area.

Next, the function of each section of the decoding apparatus 100 of the present invention will be described.

The encrypted content reading unit 10 uses the DV
Data of encrypted content is read from a predetermined medium such as D or the Internet. Here, the encrypted content read by the encrypted content reading unit 10 is
A user purchases a DVD medium on which encrypted content is recorded, or downloads it from a website that distributes encrypted content via the Internet.
It can be obtained by various methods such as receiving streaming distribution.

The decryption processing unit 20 performs a decryption process on the encrypted content read by the encrypted content reading unit 10. Decryption of the encrypted content is executed block by block from the beginning of the content, and the cryptographic parameters that are information such as the cryptographic key necessary for decrypting each block are acquired from the initial parameter holding unit 30 and the detection information processing unit 60. It is executed by

The initial parameter holding unit 30 holds encryption parameters such as an encryption key used by the decryption processing unit 20 for decryption processing. In particular, it holds cryptographic parameters for decrypting the first block of encrypted content.

The digital watermark detecting section 40 includes a decoding processing section 20.
The digital watermark embedded in the content is detected from the digital content such as video and music decrypted by. Then, the detected information is passed to the detection information processing unit 60 as digital watermark information.

The reproducing section 50 reproduces the digital contents such as video and music decoded by the decoding processing section 20.

The detection information processing unit 60 uses the digital watermark information detected by the digital watermark detection unit 40 to decode the decoding processing unit 2.
0 generates cryptographic parameters for decrypting the next block of encrypted content.

Next, the operation of the reproduction processing of the encrypted content of this embodiment will be described. FIG. 3 is a flowchart for explaining the operation of content reproduction according to this embodiment.

First, the encrypted content reading unit 10
Reads a predetermined block of encrypted content data from a medium such as a DVD or the Internet and sends it to the decryption processing unit 20 (step 201).

The decryption processing section 20 further extracts the encryption parameter used for the decryption processing of the encrypted content held in the initial parameter holding section 30 (step 20).
2). Then, the block of the encrypted content read by the encrypted content reading unit 10 is decrypted using this encryption parameter, and the decrypted content is sent to the digital watermark detection unit 40 (step 203).

The digital watermark detector 40 attempts to detect a digital watermark from the decrypted content data (step 204). If the digital watermark cannot be detected from the decrypted content (step 205), the process proceeds to the content data reproduction check (step 208).

If the digital watermark can be detected (step 205), it is checked whether the digital watermark information is related to cryptographic processing (step 20).
6) If the digital watermark information is related to cryptographic processing, it is sent to the detection information processing unit 60 and stored as cryptographic parameters (step 207). Also, step 2
In 07, the detection information processing unit 60 is not limited to the method of storing the digital watermark information itself as the encryption parameter, and may execute the process of generating the encryption parameter from the digital watermark information if necessary.

Then, the process proceeds to a check for reproduction of the decrypted content data (step 208). Step 20
8, whether the decrypted content data is in a reproducible format, whether the data is over, etc.
It is checked whether the content data can be reproduced (step 208). If the content can be reproduced, the reproducing unit 50 reproduces the content (step 20).
9). On the other hand, if the reproduction is impossible, an error message indicating that the reproduction is impossible (or a reproduction end message is displayed) and the like are performed, and the process ends (step 210).

Then, returning to step 201, the series of processing from step 201 to step 209 is repeatedly executed until the reproduction of the content is completed.

In this iterative process, the cryptographic parameters saved in step 207 of the previous (or up to the previous) series of iterative processes are used for the second and subsequent times in the extraction of the cryptographic parameters in step 202.

In the above embodiment, the encryption / decryption processing parameters are called encryption parameters, but the following concrete parameters can be assumed.

First, the encryption key and the encryption key length are the most well-known encryption parameters. In this case, the cryptographic algorithm is constant.

Next, the function of changing the cryptographic algorithm used for decryption is to implement a plurality of cryptographic algorithms in the decryption processing unit 20, and to encrypt the cryptographic algorithm used for decryption (for example, a character string or identification information). It is possible to change the encryption algorithm based on the encryption parameter by a method such as changing based on the parameter.

Further, although the normal encryption algorithm performs the repeating process and the bit shift process, the number of repetitions and the bit shift value can be processed as a cryptographic parameter called the number of times of stirring and the stirring coefficient.

On the other hand, it is also possible to specify the encrypted area by using the encryption parameter. For example, it is possible to specify the position and length of the data in the encrypted area in byte units, frame units, and songs (content units).

As described above, according to the present embodiment, in the encrypted content, different encryption processing is performed for each block of the content, and the encryption key of each block is located in the front (or one block). Embedded as a watermark in the (previous) block. Therefore, in order to reproduce this encrypted content, it is necessary to retain the digital watermark information without destroying it, and the information embedded in the digital watermark can be protected.

Furthermore, since the encrypted content is encrypted for each block by a plurality of types of encryption parameters, even if some encryption keys are illegally acquired,
Only the block corresponding to the encryption key can be decrypted, and the illegal copy of the content can be prevented. Moreover, each of the cryptographic parameters is embedded in the content by a digital watermark, which makes it difficult to illegally extract the cryptographic parameters.

Further, since the encryption parameter is embedded in the content as a digital watermark, it is not necessary to secure a special data size for the encryption parameter as in the conventional method, and the same amount of encryption parameter is used in the conventional method. The storage area and communication data size can be greatly reduced compared to the case of using. Further, since the encrypted content and the encryption parameter are integrated, there is also an effect that the management of the encryption parameter is easy.

Further, since a method of embedding a digital watermark in the encrypted content so that the encryption parameter is sequentially changed for each block, the content reproduction method can be controlled by utilizing this method. For example, it is possible to realize control such that reproduction by fast-forwarding is prohibited, or only sequential reproduction from the beginning of the content is permitted. Educational content,
There are advertisements and games before the main part is played.

Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram showing the configuration of the decoding device 100a according to the second embodiment of the present invention.

The decoding apparatus 100a of the present embodiment has the same basic configuration as that of the first embodiment, but controls the content reproduction method between the detection information processing section 60a and the reproduction section 50. The difference is that a content reproduction management unit 61 is added.

The content reproduction management section 61 of the present embodiment
Controls the content reproduction method according to the ticket information indicating the level at which the user can reproduce the content and the information detected by the digital watermark. here,
The ticket information is information for reproducing the content at the reproduction level indicated in the ticket information by inputting it to the decryption device 100a, and is obtained by the user by purchasing from the content provider.

On the other hand, the digital watermark information newly includes reproduction parameters such as display quality, display area, and display length for each level. FIG. 6 is a diagram showing a data structure of the block 130-1a of the encrypted content 110a decrypted by the decryption apparatus 100a according to the present embodiment. As shown in FIG. 6, in the present embodiment, encrypted content 1
In the block 10a, a reproduction parameter is stored as electronic watermark information in addition to the encryption parameter.

FIG. 7 is a reproduction parameter 1 of this embodiment.
It is a figure which shows an example of the data structure of 40. In the example of FIG. 7, the content reproduction management unit 61 defines the content to control the content reproduction according to the content reproduction level (A, B, C, D) indicated by the ticket information purchased by the user. ing.

Next, the operation of this embodiment will be described. FIG. 5 is a flowchart for explaining the operation of the content reproduction management unit 61 of this embodiment.

The content reproduction management unit 61 receives the input of the ticket information of the user (step 301). Then, when the digital watermark detection unit 40 detects the reproduction parameter (step 302), referring to the ticket information purchased by the user, as shown in the example of FIG. 7, the appropriate display quality, display area, and display length are displayed. Accordingly, the content reproduction of the reproduction unit 50 is controlled (step 303).

If the user has not purchased the ticket, the reproduction is stopped or the reproduction is performed at a level of trial use.

The display quality includes the image resolution, the number of colors,
Playback frame rate, playback frequency (audio), monaural
A method of designating the distinction of stereo is possible. Also,
As the display area, it is possible to specify a size of an image, a heading level of a structured document such as HTML, a media type such as audio only or video only, and a number of objects of an object unit type reproduction medium such as MPEG4 and VRML. . The display length can be specified by the number of frames to be displayed, time, and the like.

In the present embodiment, the ticket is thus used for the user to browse the contents. For example, the user who purchased the ticket is notified of the password and the personal identification number and used. A method of reproducing content only when a person inputs the password or the like into the decryption device 100a, or a user who sells a ticket with a magnetic card to the user and purchases the ticket has a function of a card reader. It is possible to play back the content only when the ticket card is inserted into the.

In the embodiment of the present embodiment described above, the content reproduction management unit 61 has been described by way of example of the method of checking the ticket purchased by the user, but the invention is not limited to this. In addition, for example, by detecting the processing capability of the decryption device 100a and describing the reproduction method setting for each of the determined processing capabilities of the decryption device 100a as the reproduction level information in the digital watermark of the encrypted content. By collating this with the content reproduction management unit 61, the content can be reproduced with the display quality, the display area, and the display length according to the processing capability of the decoding device 100a.

As described above, in the present embodiment, in addition to the effect of the first embodiment, the reproduction level information embedded in the electronic watermark and the ticket purchased by the user are collated to check the contents. Playback can be controlled. In addition, the storage area for the ticket and the communication data size can be reduced as compared with the conventional one, and since the content and the reproduction level information are integrated, it is easy to manage the reproduction level information. is there.

Next, a third embodiment of the present invention will be described. FIG. 8 is a block diagram showing the configuration of the decoding device 100b according to the third embodiment of the present invention.

The encrypted content of the present embodiment is characterized in that information such as the position of the digital watermark used for detecting the digital watermark in each block is embedded in the digital watermark information in the previous block. this,
The information used to detect the digital watermark will be referred to as hint information below.

In the first embodiment, if the detection of the digital watermark fails, the decoding of the next block will fail, and the content cannot be reproduced thereafter. Although the digital watermark is not a technique that succeeds in its detection, the detection accuracy can be improved by specifying the detection key for detecting the digital watermark, the position, and the range.

Therefore, in the present embodiment, hint information (detection key, position, position, etc.) for detecting the digital watermark of the next block (or of the next and subsequent blocks) is added to the digital watermark information of each block. Including the range), the hint information is applied to the next digital watermark detection process to improve the detection accuracy.

FIG. 10 shows a decoding device 1 according to this embodiment.
It is a figure which shows the data structure of the block 130-1b of the encrypted content 110b which 00b decrypts. As shown in FIG. 10, in the present embodiment, encrypted content 1
In the block 10b, hint information is stored as electronic watermark information in addition to encryption parameters.

The first part of the decoding device 100b of this embodiment is
The difference from the above embodiment lies in the digital watermark detection unit 40b and the detection information processing unit 60b.
Acquires hint information for detecting the digital watermark of the next block (along with the encryption parameter) from the digital watermark information detected by the digital watermark detection unit 40b, and the digital watermark detection unit 40b uses this hint information. The digital watermark of the next block is detected with high accuracy.

FIG. 9 is a flow chart for explaining the operation of the digital watermark detecting section 40b of this embodiment.

The digital watermark detecting section 40b of the present embodiment
The electronic watermark information is sent to the detected information processing unit 60b, so that the hint information extracted from the electronic watermark information is transmitted from the detected information processing unit 60b (step 401). And the hint information (detection key, position,
Based on the range), the digital watermark information is detected from the decoded block sent from the decoding processing unit 20 (step 402). Then, the detected digital watermark information is sent to the detected information processing unit 60b (step 403), and then step 401 until the end of this encrypted content.
~ The process of step 403 is repeated.

At the time of the first block of the encrypted content, there is no hint information from the detected information processing unit 60b, but in this case, for example, the initial parameter holding unit 30 stores the hint information of the first block. It is also possible to use a method such as a method used by the digital watermark detector 40b or a method in which the digital watermark detector 40b detects digital watermark information without using hint information (similarly to the first embodiment).

As described above, in this embodiment, in addition to the effects of the first embodiment, it is possible to detect a digital watermark with high accuracy.

Next, a fourth embodiment of the present invention will be described. FIG. 11 is a block diagram showing the configuration of the decoding device 100c according to the fourth embodiment of the present invention.

The difference of the decryption apparatus 100c of the present embodiment from the first embodiment is that instead of the initial parameter holding unit 30, in addition to the encryption parameter (initial parameter) of the first block, digital watermark detection is performed. Detection information holding unit 30c that holds the digital watermark information detected by the unit 40
It is a point to have.

FIG. 13 is a diagram showing an example of the data structure of data recorded in the detection information holding unit 30c of this embodiment. In FIG. 13, in the detection information holding unit 30c,
Watermark information for each block of encrypted content (A, B,
...) is recorded.

The decoding apparatus 100c of the present embodiment holds the digital watermark information detected in the previous block in the detection information holding unit 30c, and extracts it as necessary. This makes it possible to perform rewinding reproduction, reproduction from a previously browsed position, and the like. Further, even when the detection of the digital watermark fails, the digital watermark information detected in the previous block can be used to smoothly continue the reproduction.

FIG. 12 is a flow chart for explaining the operation of the detected information processing unit 60c of this embodiment.
FIG. 12 illustrates an operation of performing reproduction from the specified position when the user specifies the position to start reproducing the content.

First, when the user performs an operation of designating the position where the reproduction of the content is started, the detected information processing section 6
0c accepts this operation (step 501), and extracts the electronic watermark information for decoding the block at the designated reproduction start position from the detection information holding unit 30c (step 502).

Then, an encryption parameter is generated from the extracted digital watermark information and sent to the decryption processing unit 20 (step 503). Then, in the decryption processing unit 20, the decryption of the block of the encrypted content is started from the block designated by the user, and similarly to the first embodiment, the detection information processing unit 60c includes the electronic watermark detection unit. The electronic watermark information detected by 40 is sent.

Further, the detection information processing unit 60 of the present embodiment
c stores the digital watermark information sent from the digital watermark detection unit 40 in the detection information holding unit 30c (step 50).
4) And the encryption parameter is generated from the electronic watermark information and sent to the decryption processing unit 20 (step 503). Less than,
The processes of step 503 and step 504 are repeated until the reproduction of the content ends.

The detection information holding unit 30c in the example of FIG.
Then, since it is a method of holding the initial encryption parameter, it is not necessary to provide the initial parameter holding unit 30, but
As in the first embodiment, a method in which the decoding device 100c is provided with the initial parameter holding unit 30 and only the digital watermark information is held in the detection information holding unit 30c can be similarly implemented.

As described above, in the present embodiment, in addition to the effects of the first embodiment, a function of holding digital watermark information is provided, so that even if digital watermark detection fails, It is possible to smoothly continue the reproduction by using the digital watermark information detected in the block.

Next explained is the fifth embodiment of the invention. FIG. 14 is a block diagram showing the configuration of the decoding device 100d according to the fifth embodiment of the present invention.

The decryption apparatus 100d of the present embodiment communicates with the content management server 400 that manages the copyright information of the content and the encryption key via the network 300, so that the encrypted content of the next block If the parameters are insufficient in the processes of decryption, detection of digital watermark, and reproduction of data, the content management server 400 is inquired about the values of the parameters and acquired.

Therefore, the decoding apparatus 100 according to the present embodiment
In addition to the configuration of the first embodiment, d includes a communication unit 62 for communicating with the content management server 400 via the network 300.

The communication unit 62 communicates with the server using secure encrypted communication such as SSL communication, and when it is authenticated that the content is distributed by a legitimate user and a legitimate route, an inquiry is made. Returns the value of the existing parameter.

FIG. 15 is a flow chart for explaining the operation of the detected information processing unit 60d of this embodiment.
FIG. 15 illustrates an operation in which the digital watermark detection unit 40 acquires the digital watermark information from the content management server 400 and continues the reproduction of the content when the digital watermark detection fails.

When the detection information processing unit 60d recognizes that the digital watermark detection unit 40 has failed to detect the digital watermark (step 601), it communicates with the content management server 400 using the communication unit 62, and the detection fails. The electronic watermark information is requested and transmitted (step 602).

Then, an encryption parameter is generated using the acquired digital watermark information and is sent to the decryption processing unit 20 (step 603), so that the content reproduction can be continued.

If the digital watermark detection unit 40 correctly detects the digital watermark information in step 601, the detected information processing unit 60d accepts the digital watermark information from the digital watermark detection unit 40, and proceeds to step 603. The encryption parameter is generated using the acquired digital watermark information and sent to the decryption processing unit 20.

As described above, according to the present embodiment, in addition to the effects of the first embodiment, the decryption of the content is performed only when the secure communication such as the SSL communication is authenticated as the normal use. Information for detecting a digital watermark and reproducing a content is provided to the content management server 4
00, it is possible to fast-forward the content and play it from the middle, or to continue playing smoothly even if a part of the medium is damaged.

Further, the decoding devices 100, 100a, 100b, 100c, 10 according to the first to fifth embodiments described above.
0d can be implemented in any combination with each other.

Next, an embodiment of the encryption device for generating the encrypted content of the present invention will be described. FIG. 16 is a block diagram showing the configuration of an embodiment of the encryption device 200 of the present invention. The encryption device 200 shown in FIG.
The decoding devices 100, 100a, 100 according to the first to fifth embodiments are realized by a program-controlled CPU or the like.
b, 100c, and 100d generate encrypted contents to be decrypted.

The encryption device 200 includes a content reading section 71 for reading raw data of digital content such as video and music from a medium before encryption, and an encryption used for encrypting each block of the content. A cryptographic parameter generation unit 72 that generates cryptographic parameters such as a key, an initial parameter holding unit 73 that holds initial data of the cryptographic parameters, and information that adds information such as cryptographic parameters to the content is digitally watermarked in a predetermined block of the content. A digital watermark embedding unit 74 to be embedded as a content and a content encryption unit 75 to encrypt the block according to the encryption parameter of each block of the content.
And an encrypted content storage unit 76 that stores the encrypted encrypted generated content in a medium.

FIG. 17 is a flow chart for explaining the operation of the embodiment of the present invention for generating the encrypted content of the encryption device 200 of the present invention.

First, the content reading unit 71 reads out raw data of digital content such as video and music before encryption from a medium (medium) and sends it to the digital watermark embedding unit 74 (step 801).

The cryptographic parameter generation unit 72 acquires the initial data of the cryptographic parameters from the initial parameter storage unit 73 and sends it to the content encryption unit 75 (step 80).
2). Here, the initial data of the cryptographic parameter held in the initial parameter holding unit 73 is the same as the cryptographic parameter incorporated in the initial parameter holding unit 30 of the decryption device 100.

Then, the encryption parameter generation unit 72 generates the encryption parameter of the next block and sends it to the digital watermark embedding unit 74 and the content encryption unit 75 (step 803).

The digital watermark embedding unit 74 embeds the encryption parameter of the next block sent from the encryption parameter generating unit 72 as a digital watermark in the block of the content currently held (step 804).

Then, the content encryption unit 75 encrypts the data of the block in which the digital watermark is embedded, based on the encryption parameter of the block (in this case, the initial data) (step 805).

Then, if the encryption of all blocks of the content is not completed yet, the step 80 is executed again.
Returning to step 3, the series of processing from step 803 to step 805 is repeatedly executed until the reproduction of the content ends (step 806).

That is, after the second time, the following (1) to
The process of (3) is repeated until the encryption of all blocks of the content is completed. (1) The cryptographic parameter generation unit 72 generates a cryptographic parameter of the next block (step 803). (2) The electronic watermark embedding unit 74 embeds the encryption parameter of the next block in the currently held content block as an electronic watermark (step 804). (3) The content encryption unit 75 encrypts the data of the block in which the digital watermark is embedded, based on the encryption parameter of the block (step 805).

Further, in the flowchart of FIG. 17, the encrypted content storage unit 76 stores the encrypted content after all the content is encrypted (step 807), but the method is not limited to this, but step 80
5, when each block of the content is encrypted, the encrypted content storage unit 76 may store the data of the encrypted block.

Also, the digital watermark embedding unit 74
The reproduction parameter used by the content reproduction management unit 61 of the decoding apparatus 100a according to the third embodiment to control the reproduction of the content, and the digital watermark detection unit b of the decoding apparatus 100b according to the third embodiment detects the digital watermark. Various information such as hint information that is referred to for this purpose is embedded in a predetermined block of the content as a digital watermark together with encryption parameters as necessary.

Further, in the above description, as the initial data of the encryption parameter, the same data as the encryption parameter held in the initial parameter holding unit 30 of the decryption apparatus side is incorporated in the initial parameter holding unit 73, but the description has been given as an example. Not limited to this method, the initial data of the encryption parameter may be variably configured.

In this case, for example, communication (usually encrypted communication is used to safely transfer data)
Depending on the method used to synchronize the initial data of the decryption device before playback of the encrypted content, or by using a rewritable memory such as a flash ROM as a means for holding the initial data of the encryption parameter, the initial data may be transferred by communication or a software program. A method to rewrite cryptographic parameters at any time,
A method of providing the encrypted content to the user by including the initial encryption parameter in a medium different from the medium providing the encrypted content or in a different area of the same medium can be considered. The above-mentioned encrypted communication processing and authentication processing are well known to those skilled in the art and are not directly related to the present invention, and therefore detailed description thereof will be omitted.

As described above, according to the encryption device 200, the decryption device 10 of each of the above-described first to fifth embodiments.
It is possible to generate encrypted content that is decrypted by 0, 100a, 100b, 100c, and 100d.

That is, the encryption device 200 protects the information embedded in the digital watermark from being erased illegally,
An encrypted content is generated that makes it difficult to perform illegal decryption and can perform complicated decryption processing in a small storage area.

Next, the content distribution system of the present invention will be described. FIG. 18 is a block diagram showing an example of the configuration of the content distribution system of the present invention.

In the above-described embodiment of the encryption device 200, the method of storing the generated encrypted content in the medium such as DVD and providing it to the user has been described as an example.
The generated encrypted content can be directly sent to the decryption device 100 via the Internet, a broadcasting station, or another communication network.

In the content distribution system of the present invention shown in FIG. 18, the encrypted content generated in the encryption device 200 is transferred from the distribution server 500 to the network 3.
The configuration is such that the content is directly delivered to the decryption device 100 which is the user's terminal via 00.

As the distribution server 500, for example, an Internet web server or the like can be used.

Further, in FIG. 18, the content management server 400 described in the fifth embodiment is also connected to the same network 300, and provides the value of the parameter that the user's decryption apparatus 100 lacks. can do. Further, the function of the content management server 400 may be included in the distribution server 500.

Further, in each of the above-described embodiments, the method of dividing the encrypted content block into blocks each having a predetermined size from the beginning of the encrypted content has been described as an example, but the present invention is not limited to this method. The size of each block does not necessarily have to be fixed. For example, the encrypted content can be correctly divided into blocks of various sizes in the decryption device by a method such as embedding a code indicating a block division of each block in the encrypted content.

In each of the above embodiments, the decoding devices 100, 100a, 100b, 100c, 100d.
In the decoding processing unit 20, the digital watermark detection units 40, 4
0b, reproduction unit 50, detection information processing units 60, 60a, 60
b, 60c, 60d, the functions of the content reproduction management unit 61, the functions of the encryption parameter generation unit 72, the digital watermark embedding unit 74, the content encryption unit 75, and other functions of the encryption device 200 in terms of hardware. Of course, the decryption programs 90, 90a, 90b, 9 which are computer programs having the respective functions are realized.
0c, 90d and the encryption program 91 can be realized by being loaded in the memory of the computer processing device. This decryption program 90, 90a, 90b,
90c, 90d and the encryption program 91 are stored in a magnetic disk, a semiconductor memory, or another recording medium. Then, it is loaded from the recording medium to the computer processing device and controls the operation of the computer processing device to realize the above-described functions.

Although the present invention has been described with reference to the preferred embodiments and examples, the present invention is not necessarily limited to the above-described embodiments and examples, and various modifications are possible within the scope of the technical idea. It can be modified and implemented.

[0152]

As described above, the content distribution system, the decoding device, the generating device, the reproducing program of the present invention,
According to the generation program, the following effects are achieved.

First, the information embedded in the digital watermark can be protected. The reason is that different encryption processing is performed for each block, and the encryption key is embedded in the content data of the previous block as a digital watermark, so it is necessary to retain the digital watermark information as it is in order to reproduce the content. Because there is.

Secondly, the encryption for encrypting the contents can be made stronger. The reason is that the content is encrypted with multiple types of encryption parameters, so even if the encryption key is obtained illegally, the entire content cannot be decrypted, and thus illegal copying can be prevented. . Moreover, since the cryptographic parameter is embedded in the content by the digital watermark, it is difficult to illegally acquire and obtain the cryptographic parameter.

Thirdly, the storage area and communication data size required for encryption parameters, reproduction parameters, etc.
The amount can be reduced more than the amount required in the conventional method. The reason is that the encryption parameter, the reproduction parameter, etc. are embedded in the encrypted content as a digital watermark, instead of being passed to the user separately from the encrypted content.

Fourth, it is possible to easily manage encryption parameters, reproduction parameters and the like. The reason is that the encrypted content is integrated with the encryption parameter, the reproduction parameter, and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a decoding device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a data configuration of encrypted content decrypted by the decryption device according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of content reproduction according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a decoding device according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of a content reproduction management unit according to the second embodiment of this invention.

FIG. 6 is a diagram showing a data structure of a block of encrypted content decrypted by a decryption device according to a second embodiment of the present invention.

FIG. 7 is a diagram showing an example of a data structure of reproduction parameters according to the second embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a decoding device according to a third embodiment of the present invention.

FIG. 9 is a flowchart illustrating an operation of a digital watermark detection unit according to the third embodiment of this invention.

FIG. 10 is a diagram showing a data structure of a block of encrypted content decrypted by a decryption device according to a third embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a decoding device according to a fourth embodiment of the present invention.

FIG. 12 is a flowchart illustrating an operation of a detected information processing unit according to the fourth embodiment of this invention.

FIG. 13 is a diagram showing an example of a data structure of data recorded in a detection information holding unit according to the fourth embodiment of the present invention.

FIG. 14 is a block diagram showing a configuration of a decoding device according to a fifth embodiment of the present invention.

FIG. 15 is a flowchart illustrating an operation of a detected information processing unit according to the fifth embodiment of this invention.

FIG. 16 is a block diagram showing a configuration of an embodiment of an encryption device of the present invention.

FIG. 17 is a flowchart for explaining an example of an operation of generating encrypted content according to the present invention.

FIG. 18 is a block diagram showing an example of a configuration of a content distribution system of the present invention.

FIG. 19 is a block diagram showing a configuration of a conventional content distribution system.

FIG. 20 is a diagram for explaining a conventional content encryption process.

[Explanation of symbols]

100, 100a, 100b, 100c, 100d Decryption device 10 Encrypted content reading unit 20 Decryption processing unit 30 Initial parameter storage unit 30c Detection information storage unit 40, 40b Digital watermark detection unit 50 Playback unit 60, 60a, 60b, 60c, 60d Detection information processing unit 61 Content reproduction management unit 62 Communication unit 200 Encryption device 71 Content reading unit 72 Cryptographic parameter generation unit 73 Initial parameter storage unit 74 Digital watermark embedding unit 75 Content encryption unit 76 Encrypted content storage units 90, 90a, 90b, 90c, 90d Decryption program 91 Encryption program 110 Encrypted content 120-n Block 130-n Cryptographic parameter 140, 140-n Playback parameter 150-n Hint information 300 Network 400 Content management Over bus 500 distribution server

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // H04N 7/16 F term (reference) 5C063 AB03 AB05 CA12 CA23 DA07 DA20 DB09 5C064 BA07 BB02 BB05 BC06 BC18 BC20 BC23 BD08 BD09 5J104 AA01 AA14 AA16 EA01 EA04 EA06 EA17 NA02

Claims (26)

[Claims] 1. A content distribution system that encrypts digital content to generate encrypted content and distributes the encrypted content to a decryption device, which is a user's terminal, wherein data of the digital content is recorded from the beginning based on a predetermined method. It is divided into a plurality of blocks, the encryption method for encrypting the data of the block is determined for each block, and each block is decrypted by the encryption method defined for the succeeding block. The content distribution system is characterized in that the encrypted content is generated by embedding a cryptographic parameter, which is information for the above, by a digital watermark and then encrypting the block by the encryption method defined for the block. 2. The decryption device includes an initial parameter storage unit for storing the encryption parameter for decrypting the block at the beginning of the encrypted content, and each block of the encrypted content for the block. A decryption processing unit for decrypting based on the encryption parameter for decryption, and a digital watermark detection for detecting the digital watermark information embedded in the block by a digital watermark from the data of the block decrypted by the decryption processing unit The content distribution system according to claim 1, further comprising: a unit, and a detection information processing unit that generates the encryption parameter based on the digital watermark information detected by the digital watermark detection unit. 3. A content management server that manages information for decrypting the encrypted content, wherein the decryption device communicates with the content management server via a network to decrypt the encrypted content. The content distribution system according to claim 2, wherein necessary information is acquired. 4. The decoding device acquires information for detecting the digital watermark information from the content management server when the detection of the digital watermark information fails. Content distribution system described. 5. An encryption device for encrypting digital content to generate encrypted content, wherein the decryption device includes a reproduction unit for reproducing the decrypted encrypted content, and the decryption device generates the encrypted content. The content distribution system according to any one of claims 1 to 3, wherein encrypted content is distributed to the decryption device via a network and reproduced. 6. A decryption device for decrypting encrypted content, which is encrypted digital content, wherein the encrypted content is divided into a plurality of blocks from the beginning based on a predetermined method, and each block includes: The digital watermark information is embedded and then encrypted based on the encryption method specified for the block, and the digital watermark information embedded in each block is for the blocks following the block. A decryption device including an encryption parameter that is information for decrypting the encryption by the encryption method defined by the above. 7. An initial parameter holding unit for holding the encryption parameter for decrypting the block at the head of the encrypted content, and each block of the encrypted content for decrypting the block. A decryption processing unit for decrypting based on an encryption parameter; a digital watermark detection unit for detecting the digital watermark information embedded in the block by a digital watermark from the data of the block decrypted by the decryption processing unit; The decryption device according to claim 6, further comprising a detection information processing unit that generates the encryption parameter based on the digital watermark information detected by the watermark detection unit. 8. The decryption processing unit decrypts the block at the beginning of the encrypted content by the encryption parameter held in the initial parameter holding unit, and the second and subsequent ones of the encrypted content are decrypted. Block
The decryption device according to claim 7, wherein decryption is performed using the encryption parameter generated by the detection information processing unit. 9. The digital watermark information embedded in each of the blocks includes information on a position and a range of encrypted data, and the decryption processing unit includes the encrypted watermark information indicated by the digital watermark information. 9. The decoding device according to claim 8, wherein the position and range of the existing data are decoded. 10. In the digital watermark information embedded in each block, identification information for uniquely identifying, as the encryption parameter, the encryption method defined for the block at a specified position after the block. The decoding device according to claim 8 or 9, comprising: 11. In the digital watermark information embedded in each of the blocks, an encryption algorithm for decrypting the encryption method defined for the block at a specified position after the block is executed as the encryption parameter. 10. The decoding device according to claim 8 or 9, wherein the decoding device includes data of a computer program to be executed. 12. In the digital watermark information embedded in each block, as the encryption parameter, the number of times the encryption algorithm is agitated in the encryption method defined for the block at a predetermined position after the block, and The decoding device according to claim 8 or 9, wherein the decoding device includes information on a value of a stirring coefficient. 13. The electronic watermark information embedded in each of the blocks includes hint information indicating a position where the electronic watermark information is embedded in the block at a predetermined position after the block, and the electronic watermark detecting unit includes The decoding device according to any one of claims 8 to 12, wherein the electronic watermark information of each block is detected with reference to a position indicated by the hint information. 14. The digital watermark information embedded in each of the blocks includes a detection key for detecting digital watermark information in the block at a predetermined position after the block, and the digital watermark detecting unit includes The electronic watermark information of a block is detected using the detection key.
3. The decoding device according to any one of 3. 15. The decoding device according to claim 8, further comprising a reproducing unit that reproduces the data of each block decoded by the decoding processing unit. 16. A detection information holding unit for recording and referring to the digital watermark information detected by the digital watermark detecting unit, and the digital watermark information held in the detection information holding unit according to a user's operation. 16. The decryption apparatus according to claim 15, further comprising means for resuming decryption from the block decrypted by the encryption parameter included in the electronic watermark information, and reproducing by the reproducing unit, using . 17. When the digital watermark detector fails to detect the digital watermark information, the reproduction by the reproducing unit is performed by referring to the digital watermark information stored in the detection information holding unit. The decoding device according to claim 15 or 16, further comprising means for continuing. 18. A content reproduction for controlling the content reproduced by the reproducing unit based on the ticket information when a user accepts input of ticket information indicating a level permitted to browse the encrypted content. The decoding device according to claim 15, further comprising a management unit. 19. A content management server that manages information for decrypting the encrypted content, and a communication unit that communicates via a network, the information necessary for decrypting the encrypted content,
The decoding device according to any one of claims 8 to 14, wherein the decoding device acquires and decodes the content management server. 20. An encryption device for encrypting digital content to generate encrypted content, wherein the data of the digital content is divided into a plurality of blocks from the beginning based on a predetermined method, and for each block, Determine the encryption method for encrypting the data of the block, and embed the encryption parameter, which is the information for decrypting the encryption by the encryption method defined for the succeeding block, with a digital watermark in each block. In addition, the encryption device is characterized in that the encrypted content is generated by encrypting the block with the encryption method defined. 21. An initial parameter holding unit that holds the encryption parameter for decrypting the block at the head of the encrypted content; an encryption parameter generation unit that generates the encryption parameter of each block; For the block, a digital watermark embedding unit that embeds, as a digital watermark information, the encryption parameter defined for the block at a predetermined position after the block by a digital watermark, and a block in which the digital watermark information is embedded. 21. A content encryption unit that encrypts the block according to the encryption method defined for the block.
The encryption device described in. 22. By controlling a computer,
In a decryption program for decrypting encrypted content that is encrypted digital content, the encrypted content is divided into a plurality of blocks from the beginning based on a predetermined method, and each block is embedded with digital watermark information. Then, the digital watermark information embedded in each block is encrypted based on the encryption method defined for the block, and the digital watermark information embedded in each block is A decryption program including an encryption parameter that is information for decrypting encryption by an encryption method. 23. An initial parameter holding function for holding the encryption parameter for decrypting the block at the head of the encrypted content, and each of the blocks of the encrypted content for decrypting the block. A decryption processing function of decrypting based on an encryption parameter, a digital watermark detection function of detecting the digital watermark information embedded in the block by a digital watermark from the data of the decrypted block, and the detected digital watermark information 23. The decryption program according to claim 22, further comprising a detection information processing function for generating the encryption parameter based on the. 24. In the decryption processing function, the first block of the encrypted content is decrypted by the encryption parameter held by the initial parameter holding function, and the second and subsequent blocks of the encrypted content are decrypted. The block
24. The decryption program according to claim 23, wherein the decryption program decrypts with the encryption parameter generated by the detection information processing function. 25. An encryption program for encrypting digital content to generate encrypted content, the function of dividing the data of the digital content into a plurality of blocks from the beginning based on a predetermined method, and each of the blocks. , The function of determining the encryption method for encrypting the data of the block, and the encryption parameter that is the information for decrypting the encryption by the encryption method defined for each subsequent block for each block. An encryption program having a function of generating the encrypted content by embedding a digital watermark and then encrypting the block with the encryption method defined. 26. An initial parameter holding function of holding the encryption parameter for decrypting the block at the head of the encrypted content, an encryption parameter generation function of generating the encryption parameter of each block, For a block, a digital watermark embedding function of embedding, as a digital watermark information, the encryption parameter defined for the block at a predetermined position after the block by a digital watermark, and a block in which the digital watermark information is embedded, 3. A content encryption function for encrypting the block by the encryption method defined for the block.
The encryption program according to item 5.