JP5718856B2 - DIGITAL CONTENT LICENSE GENERATION SYSTEM, DIGITAL CONTENT LICENSE GENERATION METHOD, AND DIGITAL CONTENT LICENSE GENERATION PROGRAM - Google Patents

Description

  The present invention relates to a technique for generating digital content used in a user terminal and a license thereof.

  In order to view the distributed encrypted digital content on a user terminal, there is a technique for generating a decryption license capable of decrypting the encrypted digital content using a user ID and a license ID transmitted from the user terminal.

  In particular, in order to prevent impersonation of the user, when an encryption key unique to the user terminal (hereinafter referred to as user key) is pre-registered in the server and a license acquisition request comprising a plaintext part and an encryption part is received from the user terminal The encryption part is decrypted to confirm the identity with the plaintext part. It is also possible to generate a decryption license unique to the user terminal by generating a decryption license and then encrypting it with the user key.

  In Patent Document 1, considering the case where there are a plurality of service providers providing digital content licenses to a user terminal, a process for generating a license, a highly confidential user key, and an encryption key for encrypting digital content (Hereinafter referred to as “content key”), the encryption / decryption process is divided, and the encryption / decryption process can be executed only by the encryption / decryption service provider. A license generation system with improved security has been realized without sharing highly confidential encryption keys among service providers that issue licenses.

  Hereinafter, a conventional license generation system disclosed in Patent Literature 1 will be described. FIG. 8 is a diagram showing an overall configuration of a conventional license generation system. FIG. 9 is a diagram illustrating a functional block configuration of the license generation device and the data encryption / decryption device.

  When the license generation apparatus 100a that exists for each service provider and the data encryption / decryption apparatus 100b that exists for a single encryption / decryption provider receive a license acquisition request from the user terminal 300 In addition, the following processing is performed using the plaintext part (user ID, license ID, business ID) and the encryption part (user ID, license ID) included therein, and the generated decryption license is stored in the user terminal 300. To issue.

  Here, the user ID is an ID for identifying the user terminal 300, the license ID is an ID for identifying a license of digital content, and the user key is an encryption key of the user terminal associated with the user terminal 300.

  The operation of the conventional license generation system will be described with further reference to FIG.

  First, the plaintext part (user ID, license ID, business ID) transmitted from the user terminal 300 by the transmission / reception part 11 of the license generation device 100a and the encryption encrypted with the user key of the user terminal 300 are encrypted. A license acquisition request having a part (user ID, license ID) is received (S501).

  Next, the search / determination unit 12 searches the contract DB 15 using the user ID and license ID of the plaintext part received in S501 as keys, and determines whether or not a corresponding record exists (S502). As a result of searching the contract DB 15, if there is no corresponding record, the process proceeds to S514-2.

  Next, if there is a corresponding record as a result of the determination in S502, the search / acquisition unit 13 searches the license information DB 16 using the license ID of the plaintext part received in S501 as a key, and corresponds to the license ID. License information is acquired (S503). If the license information does not exist as a result of searching the license information DB 16, the process proceeds to S514-2.

  Next, the license A is generated by combining the license information acquired in S503 and the plaintext part user ID received in S501 by the generating unit 14 (S504).

  Next, the transmission / reception unit 11 causes the license A generated in S504, the plaintext part (user ID, license ID, business ID) received in S501, and the encryption part (user ID, license ID) to be data encrypted / The data is transmitted to the decryption device 100b (S505).

  Next, the license A, the plaintext part (user ID, license ID, business ID) and the encryption part (user ID, license) transmitted from the license generation apparatus 100a by the transmission / reception part 31 of the data encryption / decryption apparatus 100b. ID) is received (S506).

  Next, the search / acquisition unit 32 searches the user key DB 35 using the plaintext part user ID received in S506 as a key, and acquires the user key of the user terminal 300 (S507). If the user key does not exist as a result of searching the user key DB 35, the process proceeds to S514-2.

  Next, the decryption / determination unit 33 uses the user key acquired in S507 to decrypt the encryption unit (user ID, license ID) received in S506 to extract the user ID and license ID. It is determined whether or not the user ID and the license ID are the same (whether or not they match) (S508). If the user ID and the license ID are not the same, the validity of the license acquisition request is denied, and the process proceeds to S514-2.

  Next, when the user ID and the license ID are the same as a result of the determination in S508, the searcher / acquisition unit 32 confirms the business operator ID received in S506 (S509). If the business ID is 1, the process proceeds to S510-1, and if the business ID is 2, the process proceeds to S510-2. The provider ID is an ID for identifying a service provider that provides digital content, and a different content key DB is prepared for each ID.

  Next, when the search / acquisition unit 32 confirms S509 that the provider ID is 1, immediately after decryption of S508, the license ID of the plaintext part received in S506 is used as a key for the content key DB (1) 36a is searched, and the content key A corresponding to the license ID is acquired (S510-1). As a result of searching the content key DB (1) 36a, if there is no content key, the process proceeds to S514-2.

  On the other hand, if the operator ID is 2 as a result of the confirmation in S509, the content key DB (2) 36b is searched using the plaintext part license ID received in S506 as a key immediately after the decryption in S508, and the license The content key B corresponding to the ID is acquired (S510-2). If the content key does not exist as a result of searching the content key DB (2) 36b, the process proceeds to S514-2.

  Next, immediately after acquisition of S510-1 or S510-2 by the encryption / generation unit 34, the content key A acquired in S510-1 or the content key B acquired in S510-2 is added to the license A received in S506. The license B is generated by performing encryption using the user key that has been combined and acquired in S507 and used for decryption (S511).

  Next, the transmission / reception unit 31 transmits the license B generated in S511 to the license generation apparatus 100a (S512).

  Next, the transmission / reception unit 11 of the license generation device 100a receives the license B transmitted from the data encryption / decryption device 100b (S513).

  Next, the generation unit 14 combines the user ID and the license ID with the license B received in S513 to generate a decryption license (S514-1).

  On the other hand, if the corresponding record does not exist in S502, the license information does not exist in S503, the user key does not exist in S507, the user ID and the license ID do not match (does not match) in S508, S510-1 or If the content key does not exist in S510-2, the generation unit 14 generates a message indicating that the decryption license cannot be issued using the plaintext part user ID and license ID (S514-2). .

  Finally, the transmission / reception unit 11 transmits the decryption license generated in S514-1 or the message generated in S514-2 to the user terminal 300 (S515-1, S515-2).

  Through the above processing, the user terminal 300 uses the content key obtained by decrypting the decryption license with the user key of the user device 300 to decrypt the encrypted digital content transmitted on the broadcast wave. Thus, the digital content can be used.

JP 2012-94034 A

  However, if the content key stored in the data encryption / decryption device is leaked, the content key is received by receiving the digital content from the broadcast wave, even if the corresponding digital content license is not obtained. Since the digital content is easily decrypted and used by the user terminal that has acquired the license without making a license purchase contract, there is a possibility that the service provider that is the content provider may be seriously damaged.

  To solve such a problem, a method of encrypting the entire content in a multiplexed manner with a plurality of content keys and managing each content key with another server of a different provider can be considered. However, the process of encrypting / decrypting large-capacity content has a high load, and the keying to multiplex makes the high-load process on the server side and the user terminal side multiple times.

  Therefore, it is necessary to prevent the digital content from being decrypted only by the information leaked from the data encryption / decryption device and not to increase the processing load on the server or user terminal.

  The present invention has been made in view of the above, and even if a content key is leaked, a user terminal having no license uses digital content without greatly increasing encryption / decryption processing. The challenge is to increase security so that it cannot be done.

  The digital content / license generation system according to claim 1 includes a digital content generation device, a license generation device, and a data encryption / decryption device that are communicably connected via a communication network, and are used in a user terminal. In the digital content / license generating system for generating digital content and its license, the digital content generating device is configured to encrypt the digital content with a content key and to divide the encrypted digital content into a plurality of fragments. Generating fragment content by combining a part of the fragment and adding the restoration information to the digital content, and generating a fragment missing content by combining the rest of the plurality of fragments excluding the part of the fragment Generating means for generating and generating the license Transmitting the fragment content to a user terminal and transmitting the fragment missing content to a device that distributes the content to the user terminal, wherein the license generation device identifies a license of the digital content First storage means for storing a license ID and license information defining the license usage conditions in association with each other, and receiving the fragment content from the digital content generation device and storing the fragment content in association with the license ID. Second storage means for receiving, a receiving means for receiving from the user terminal a license acquisition request including at least a plain text user ID and license ID and a user ID and license ID encrypted with the user key of the user terminal; The license information and fragment code corresponding to the plaintext license ID Tents are acquired from the first storage means and the second storage means, respectively, the license information, the fragment content, the plain text user ID and license ID, and the encrypted user ID and license. A transmission means for transmitting the ID to the data encryption / decryption device, a content key and license information encrypted with the user key, and a fragment content are received from the data encryption / decryption device; A decryption license for decrypting the encrypted digital content is generated using the content key and the license information, and a restoration fragment content for restoring the digital content before the fragmentation is generated using the fragment content. Generating means, and transmitting the decryption license and the fragment content for restoration to the user terminal Transmitting means, and the data encryption / decryption device associates and stores a user ID for identifying the user terminal and a user key of the user terminal, and Fourth storage means for storing the license ID and the content key in association with each other, the license information, the fragment content, the plain text user ID and license ID, and the encrypted user ID and license Receiving means for receiving the ID from the license generating device; and decrypting the encrypted user ID and license ID by obtaining a user key corresponding to the plaintext user ID from the third storage means And when the decrypted user ID and license ID match the plain text user ID and license ID, An encryption unit that obtains a content key corresponding to the license ID from the fourth storage unit, combines it with the license information and encrypts it with the user key, and encrypts the fragment content with the user key; and the user key And a transmission means for transmitting the content key and license information encrypted in step 1 and the fragment content to the license generation apparatus.

  The digital content / license generation method according to claim 2 comprises a digital content generation device, a license generation device, and a data encryption / decryption device that are communicably connected via a communication network, and are used in a user terminal. In the digital content / license generation method for generating digital content and its license, the digital content generation device encrypts the digital content with a content key and divides the encrypted digital content into a plurality of fragments A fragmentation step of combining a part of the fragments to generate fragment content to which the restoration information is added to the digital content, and generating a fragment missing content by combining the rest of the plurality of fragments excluding the part of the fragments A generating step for generating the license Transmitting the fragment content to a device for generating content, and transmitting the fragment missing content to a device for delivering the content to the user terminal. The license generating device licenses the digital content. A storage step of associating the license ID to be identified with the license information defining the license usage conditions in the first storage means; receiving the fragment content from the digital content generation device; A license acquisition request including a storage step stored in the second storage means in association with the user ID, a license ID, and at least a user ID and a license ID encrypted with a user key of the user terminal. A reception step of receiving from the terminal, and the plaintext Obtaining license information and fragment content corresponding to the license ID from the first storage unit and the second storage unit, respectively, the license information, the fragment content, the plain text user ID and license ID, A transmission step of transmitting the encrypted user ID and license ID to the data encryption / decryption device, and a user ID for identifying the user terminal by the data encryption / decryption device; A storage step of associating and storing the user key of the user terminal in the third storage unit, a storage step of associating and storing the license ID and the content key in the fourth storage unit, The license information, the fragment content, the plaintext user ID and license ID, and the encrypted user. Receiving the user ID and license ID from the license generating device; obtaining a user key corresponding to the plaintext user ID from the third storage means; and obtaining the encrypted user ID and license ID. When the decrypting step for decrypting and the decrypted user ID and license ID match the plain text user ID and license ID, the content key corresponding to the license ID is obtained from the fourth storage means. And encrypting with the user key in combination with the license information, and encrypting the fragment content with the user key, and the content key and license information encrypted with the user key and the fragment content A transmission step of transmitting to the license generation apparatus, and the license generation apparatus Receiving the content key and license information encrypted with the user key and the fragment content from the data encryption / decryption device, and using the content key and the license information to convert the encrypted digital content Generating a decryption license to be decrypted and generating a fragment content for restoration to restore the digital content before fragmentation using the fragment content; and the decrypting license and the fragment content for restoration are A transmission step of transmitting to the user terminal.

  A digital content license generation program according to claim 3 causes a computer to execute the digital content license generation method according to claim 2.

  According to the present invention, the digital content generating apparatus encrypts the digital content with the content key, divides the encrypted digital content into a plurality of fragments, and a fragment obtained by combining the remainder excluding some fragments from the plurality of fragments. Since missing content is generated and distributed to the user terminal, in order to restore / decrypt the original digital content, a part of the fragment is required in addition to the content key. The digital content cannot be restored, and the security of digital content protection can be improved.

  Further, according to the present invention, since the license generation device stores the fragment content generated by the digital content generation device and the data encryption / decryption device stores the content key, the original digital Since the fragment content and the content key necessary for restoring / decrypting the content are distributed and stored in different devices, the security against leakage of information necessary for restoring the digital content can be improved.

  Further, according to the present invention, compared to the conventional method described in the background art, the processing added by the data encryption / decryption device is only the encryption processing with the user key for the fragment content. Compared to a method in which multiple keys are applied to the entire content and each key is managed separately, the security of digital content protection can be improved without greatly increasing the processing load of encryption / decryption.

  According to the present invention, even when a content key is leaked, without increasing the encryption / decryption processing greatly, security can be improved so that a user terminal having no license cannot use digital content. it can.

It is a figure which shows the whole structure of a digital content license production system. It is a figure explaining the production | generation procedure of a fragment content and a fragment missing content. It is a figure which shows the processing flow of a digital content production | generation apparatus. It is a figure which shows the functional block structure of a license production | generation apparatus and a data encryption / decryption apparatus. It is a figure which shows the processing flow of a license production | generation apparatus and a data encryption / decryption apparatus. It is a figure which shows the conventional whole image until it decodes digital content. It is a figure which shows the whole image until it decodes digital content. It is a figure which shows the whole structure of the conventional license generation system. It is a figure which shows the functional block structure of the conventional license production | generation apparatus and data encryption / decryption apparatus. It is a figure which shows the processing flow of the conventional license generation system.

  The present invention fragments digital content encrypted with a content key, and further distributes and stores the content key and a part of the fragment necessary for restoring / decrypting the original digital content with different devices, The main feature is that even if either one leaks, the original digital content cannot be restored / decrypted.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes and should not be construed as being limited to the description of the present embodiment.

[Overall configuration of digital content license generation system]
FIG. 1 is a diagram showing an overall configuration of a digital content / license generation system according to the present embodiment. This digital content / license generation system is a configuration example in the case of being used in a paid content viewing service in digital broadcasting, and a digital content generation apparatus 100d connected to be communicable with each other via an IP network 500, and a license The generation apparatus 100a, the data encryption / decryption apparatus 100b, and the user terminal 300 are mainly configured.

  Although a plurality of license generation apparatuses 100a are shown in FIG. 1, the functions of the license generation apparatuses 100a are the same. It is assumed that each license generation device 100a is used by a different service provider, and one data encryption / decryption device 100b is used by a single encryption / decryption operator.

  The reason why the functions of the license generation device 100a are shared and the number of the license generation apparatuses 100a is plural is that the processing policy for generating and issuing the decryption license and restoration fragment content, which will be described later, is shared by the service policy for generating them. This is because different cases are assumed for each company.

  Each of the above devices constituting the digital content / license generation system is realized by a computer including a storage unit such as a memory, a calculation / control unit such as a CPU, a screen display unit such as a monitor. The processing of each device is executed by a program. Hereinafter, each device will be described.

[About digital content generator]
First, the digital content generation device 100d will be described.

  The digital content generation device 100d generates and encrypts digital content provided to the user terminal 300, and transmits the digital content from which fragments are deleted (hereinafter referred to as fragment-deleted content) to the broadcasting facility 200 via the IP network 500. And the digital content of the fragment (hereinafter referred to as fragment content) is transmitted to the license generation apparatus 100a by the broadcast wave and accumulated. Details will be described below.

  As shown in FIG. 1, the digital content generation apparatus 100d includes an encryption unit 101d that encrypts digital content to be provided with a content key, and divides the encrypted digital content into a plurality of fragments. The fragmentation / generation unit 102d that generates the fragment missing content and the transmission / reception unit 103d that transmits the fragment content to the license generation apparatus 100a via the IP network 500 and transmits the fragment missing content to the broadcast facility 200 by broadcast waves. Configured.

  The broadcast facility 200 is a device that distributes digital content to the user terminal 300 by digital broadcast waves. Further, transmission to the broadcasting facility 200 can be performed via the IP network 500.

  FIG. 2 is a diagram for explaining a procedure for generating fragment content and fragment lack content by dividing encrypted digital content.

  First, information on fragment positions P1, P2,..., Pn (n is a natural number) and fragment widths L1, L2,..., Ln is given to the encrypted digital content, and the digital content is divided into a plurality of fragments C1, C2. ... Divide into C2n + 1.

  Next, the even-numbered fragments C2, C4,..., C2n are combined, and the number of fragments n and fragment positions P1, P2,..., Pn and fragment widths L1, L2,. ..., data with the restoration information consisting of Ln added to the head is generated and transmitted as fragment content to the license generation apparatus 100a.

  Since the fragment content is transmitted via the communication on the IP network 500, the fragment content is generated in the size from the same level as the decryption license transmitted by the communication to several kilobytes and several megabytes.

  Finally, the remaining odd-numbered fragments C1, C3,..., C2n + 1 are combined and transmitted to the broadcast facility 200 as fragment-missing content.

  Next, the operation of the digital content generation device 100d will be described. FIG. 3 is a diagram illustrating a processing flow of the digital content generation device 100d.

  First, the digital content main body before encryption, the business operator ID for identifying the service business operator, the license ID determined by the combination of the business operator ID and the digital content, the content key corresponding to the business operator ID, The number n of fragments when the digital content is fragmented, the fragment position Pn of each fragment, and the fragment width Ln are designated (S101).

  Next, the digital content body designated in S101 is encrypted by the encryption unit 101d with the content key designated in S101 (S102).

  Next, the fragmentation / generation unit 102d determines whether to fragment the encrypted digital content based on whether the designated fragment number n is 0 or 1 or more (S103). Here, when it is determined that the fragmentation is not performed because the fragment number n is 0, the digital content encrypted in S102 is transmitted to the broadcast facility 200 as in the conventional case, and this process is terminated (S107-). 2).

  On the other hand, if it is determined that the fragmentation is performed because the number of fragments n is 1 or more, the fragmentation / generation unit 102d performs encryption based on the information on the designated number of fragments n, fragment position Pn, and fragment width Ln. The digital content is divided into a plurality of fragment data (S104).

  Next, the even numbered fragments are combined by the fragmentation / generation unit 102d, and the restoration information (the number of fragments n, the fragment position Pn, the fragment width Ln) necessary for restoring the original encrypted digital content starts. The fragment content added to is generated (S105).

  Next, the transmission / reception unit 103d adds the license ID specified in S101 to the fragment content, and transmits it to the license generation device 100a (S106). In the license generation apparatus 100a, the received license ID and the fragment content are associated with each other and stored in the fragment content DB 17 in the device itself to be described later.

  Finally, the fragmentation / generation unit 102d combines the remaining portions after the fragments are deleted, and the transmission / reception unit 103d transmits the fragmented content to the broadcast facility 200 (S107-1). In the broadcasting facility 200, the received fragment missing content is stored in a fragment content DB (not shown in FIG. 1) in its own device. As a result, the user terminal 300 can be provided.

  Note that S107-1 may be executed before or in parallel with the processing of S105 to S106.

[User terminal]
Next, the user terminal 300 will be described before describing the license generation device 100a and the data encryption / decryption device 100b.

  The user terminal 300 receives a desired digital content (fragment missing content) from the broadcasting facility 200 by a digital broadcast wave, and sends it to the license generation device 100a and the data encryption / decryption device 100b in order to view the digital content. A license acquisition request is made, and the digital content is restored / decrypted using the decryption license and restoration fragment content returned in response to the request, and displayed on the screen. Details will be described below.

  As shown in FIG. 1, the user terminal 300 receives a fragment missing content from the broadcast facility 200, and receives a decryption license and a restoration fragment content corresponding to the fragment missing content from the license generation device 100a. 51, a restoration unit 52 that restores fragment missing content with restoration fragment content, a decryption unit 53 that decrypts the restored encrypted digital content with a decryption license, and the decrypted original digital content It is mainly comprised by the display part 54 to output.

  Next, the operation of the user terminal 300 will be described.

  First, the digital content (fragment missing content) that the user intends to view is received by the transmission / reception unit 51 from the broadcast facility 200 by digital broadcast waves (S201).

  Next, since the received digital content is encrypted and a fragment is missing, the transmission / reception unit 51 uses the user ID, license ID, and business ID to obtain a plaintext part (user ID, license ID, business ID). A license acquisition request including the encryption unit (user ID, license ID) is transmitted to the license generation apparatus 100a via the IP network 500 (S202).

  The user ID is an ID for identifying the user terminal 300. The license ID is an ID for identifying a license of digital content. The provider ID is an ID for identifying the service provider, and is delivered in advance to the user of the user terminal 300 from the service provider as a set with the license ID.

  Next, as a response to the license acquisition request transmitted in S202, the transmission / reception unit 51 receives the decryption license and the restoration fragment content corresponding to the fragment missing content received in S201 (S203).

  Next, the decryption unit 53 decrypts the decryption license and the restored fragment content received in S203 with the user key in the own device, and at least the content key and the fragment content are acquired (S204).

  Next, the restoration unit 52 combines the fragment missing content received in S201 and the fragment content decrypted in S204 based on the restoration information in the fragment content, and restores the encrypted digital content (S205).

  Subsequently, the decryption unit 53 decrypts the encrypted digital content restored in S205 with the content key acquired in S204 (S206).

  Finally, the display unit 54 outputs the decrypted original digital content from a monitor or a speaker (S207).

[License generation device and data encryption / decryption device]
Next, the license generation device 100a and the data encryption / decryption device 100b will be described.

  The license generation device 100a and the data encryption / decryption device 100b accumulate the fragment content transmitted from the digital content generation device 100d, and when there is a license acquisition request from the user terminal 300, based on the request It returns a decryption license and restoration fragment content necessary for viewing the digital content. Details will be described below.

  FIG. 4 is a diagram illustrating a functional block configuration of the license generation device 100a and the data encryption / decryption device 100b.

  The license generation device 100a includes a function for generating a decryption license based on a user-specific contract from the user ID, license ID, and business ID transmitted from the user terminal 300, and contract information corresponding to the user ID and the license ID. A function for retaining license information, a function for retaining license information corresponding to the license ID, and a function for retaining fragment content corresponding to the license ID.

  Specifically, it includes a transmission / reception unit 11, a search / determination unit 12, a search / acquisition unit 13, a generation unit 14, a contract DB 15, a license information DB 16, and a fragment content DB 17.

  The transmission / reception unit 11 has a function of acquiring fragment content transmitted from the digital content generation device 100d via the IP network 500, a function of receiving a license acquisition request transmitted from the user terminal 300 via the IP network 500, As a response to the license acquisition request, it has a function of transmitting the decryption license and the restored fragment content to the user terminal 300. In addition, the data encryption / decryption device 100b has a function of transmitting and receiving data.

  The search / determination unit 12 has a function of searching the contract DB 15 using the user ID and license ID as keys and determining whether or not a corresponding record exists.

  The search / acquisition unit 13 has a function of searching the license information DB 16 and the fragment content DB 17 using the license ID as a key, and acquiring the license information and the fragment content corresponding to the license ID.

  The generation unit 14 combines the user ID and the license information to generate a license A, and combines the user ID with the license B generated by the data encryption / decryption device 100b to generate a decryption license. And a function for generating a message indicating that the decryption license cannot be issued.

  The contract DB 15 has a function of holding user IDs and license IDs in a one-to-many manner. If there is a record in the contract DB 15, it means that a contract exists.

  The license information DB 16 has a function of holding the license ID and the license information on a one-to-one basis, and a function of holding identification information for identifying whether the digital content corresponding to the license ID has fragment content. Yes. Note that the license information is right information that defines use conditions for using digital contents.

  The fragment content DB 17 has a function of holding the digital content license ID and the fragment content on a one-to-one basis when the digital content has fragment content. If there is no fragment content, a record corresponding to the corresponding license ID is not generated.

  Next, the data encryption / decryption device 100b will be described.

  The data encryption / decryption device 100b is communicably connected to the license generation device 100a and has a function of performing encryption / decryption using the license A, fragment content, user ID, and license ID transmitted from the license generation device 100a. And a function for holding a user key corresponding to a user ID, and a function for holding a license ID and a content key associated with each other in a DB for each company ID.

  Specifically, it includes a transmission / reception unit 31, a search / acquisition unit 32, a decryption / determination unit 33, an encryption / generation unit 34, a user key DB 35, and a content key DB 36. The content key DB 36 is composed of a content key DB (1) 36a associated with one business operator ID and a content key DB (2) 36b associated with a second business operator ID.

  The relationship between the provider ID, the license ID, and the content key is previously presented by the service provider to the encryption / decryption provider. The user key is an encryption key unique to the user terminal, and the content key is an encryption key for digital content for decrypting the digital content.

  The transmission / reception unit 31 has a function of transmitting / receiving data to / from the license generation apparatus 100a.

  The search / acquisition unit 32 searches the user key DB 35 using the user ID as a key, acquires a user key corresponding to the user ID, and searches the content key DB 36 corresponding to the business operator ID using the license ID as a key. And a function of acquiring a content key corresponding to the license ID.

  The decryption / determination unit 33 decrypts the encryption unit included in the license acquisition request with the user key, extracts the user ID and the license ID, and determines whether they are the same as compared with the user ID and the license ID of the plaintext part. It has a function to do.

  The encryption / generation unit 34 combines the content key with the license A generated by the license generation device 100a continuously after the decryption, encrypts it using the user key, and generates the license B, And a function of encrypting fragment content using a user key.

  The user key DB 35 has a function of holding a user ID and a user key on a one-to-one basis.

  The content key DB (1) 36a and the content key DB (2) 36b have a function of holding the license ID and the content key on a one-to-one basis.

  Next, operations of the license generation device 100a and the data encryption / decryption device 100b will be described. FIG. 5 is a diagram illustrating a processing flow of the license generation device 100a and the data encryption / decryption device 100b.

  First, the transmission / reception unit 11 of the license generation apparatus 100a receives a license acquisition request transmitted from the user terminal 300 via the IP network 500 (S301).

  This license acquisition request is composed of a plaintext part (user ID, license ID, business ID) and an encryption part (user ID, license ID) encrypted with the user key of the user terminal 300. In addition, when there is one content key DB 36 of the data encryption / decryption device 100b, the provider ID may not be included.

  Next, the search / determination unit 12 searches the contract DB 15 using the user ID and license ID of the plaintext part as keys, and determines whether or not a corresponding record exists (S302). As a result of searching the contract DB 15, if there is no corresponding record, the process proceeds to S317-3.

  Next, if there is a corresponding record as a result of the determination in S302 by the search / acquisition unit 13, the license information DB 16 is searched using the license ID of the plaintext portion received in S301 as a key, and the corresponding license ID is obtained. License information is acquired (S303). As a result of searching the license information DB 16, if there is no license information, the process proceeds to S317-3.

  Next, the license A is generated by combining the license information acquired in S303 and the plaintext user ID received in S301 by the generating unit 14 (S304).

  Next, the search / determination unit 12 determines, based on the identification information acquired together with the license information in S303, whether the digital content corresponding to the license ID has fragment content (S305).

  Next, as a result of the determination in S305, when it is determined that the fragment content is included, the search / acquisition unit 13 acquires the fragment content corresponding to the license ID from the fragment content DB 17, and the transmission / reception unit 11 performs the process in S304. The generated license A, the plaintext part and the encryption part received in S301, and the obtained fragment content are transmitted to the data encryption / decryption device 100b (S306-1).

  On the other hand, if it is determined as a result of the determination in S305 that there is no fragment content, the fragment content is not acquired, and the license A generated in S304 and the plaintext portion received in S301 The encryption unit is transmitted to the data encryption / decryption device 100b (S306-2).

  Next, the transmission / reception unit 31 of the data encryption / decryption device 100b receives the license A, the plaintext unit, the encryption unit, and the fragment content transmitted from the license generation device 100a (S307-1). Alternatively, the license A, the plaintext part, and the encryption part are received (S307-2).

  Next, the search / acquisition unit 32 searches the user key DB 35 using the user ID of the plaintext part received in S307-1 or S307-2 as a key, and acquires the user key of the user terminal 300 (S308). If the user key does not exist as a result of searching the user key DB 35, the process proceeds to S317-3.

  Next, the decryption / determination unit 33 uses the user key acquired in S308 to decrypt the encryption unit received in S707-1 or S707-2 to extract the user ID and license ID, and the plaintext user It is determined whether or not the ID and the license ID are the same (match or not) (S309). If the user ID and the license ID are not the same, the validity of the license acquisition request is denied, and the process proceeds to S317-3.

  Next, when the user ID and the license ID are the same as a result of the determination in S309, the search / acquisition unit 32 confirms the business operator ID received in S307-1 or S307-2 (S310). If the business ID is 1, the process proceeds to S311-1. If the business ID is 2, the process proceeds to S311-2.

  Next, if the operator ID is 1 as a result of the confirmation in S310, the search / acquisition unit 32 searches the content key DB (1) 36a using the license ID as a key immediately after the decryption in S309, and the license The content key A corresponding to the ID is acquired (S311-1). As a result of searching the content key DB (1) 36a, if there is no content key, the process proceeds to S317-3.

  On the other hand, if the operator ID is 2 as a result of the confirmation in S310, the content key DB (2) 36b is searched using the license ID as a key immediately after decryption in S309, and the content key B corresponding to the license ID is searched. Is acquired (S311-2). As a result of searching the content key DB (2) 36b, if the content key does not exist, the process proceeds to S317-3.

  Next, immediately after the acquisition of S311-1 or S311-2, the content key A acquired in S311-1 or the content key B acquired in S311-2 is combined with the license A by the encryption / generation unit 34, and in S308 The license B is generated by encrypting using the acquired user key (S312).

  Next, the decryption / determination unit 33 determines whether or not the fragment content is included in the data group transmitted from the license generation device 100a (S313).

  Next, if it is determined as a result of the determination in S313 that the fragment content is included, the encryption / generation unit 34 encrypts the fragment content with the user key acquired in S308 (S314-1). The transmission / reception unit 31 transmits the license B generated in S312 to the license generation apparatus 100a (S315-1).

Next, the transmission / reception unit 11 of the license generation device 100a receives the fragment content encrypted with the license B and the user key transmitted from the data encryption / decryption device 100b (S316-1).
Next, the generation unit 14 combines the user ID and the license ID with the license B and the fragment content received in S316-1, thereby generating a decryption license and a restoration fragment content (S317-). 1).

  Finally, the transmission / reception unit 11 transmits the decryption license and the restored fragment content to the user terminal 300 as a response to the license acquisition request in S301 (S318-1).

  On the other hand, as a result of the determination in S313, when it is determined that the fragment content is not included, only the license B generated in S312 is transmitted to the license generation apparatus 100a by the transmission / reception unit 31 (S315-2). Thereafter, the license is received by the transmission / reception unit 11 of the license generation device 100a (S316-2), and the generation unit 14 combines the user ID and the license ID with the received license B to generate a decryption license ( In S317-2), only the decryption license is transmitted to the user terminal 300 by the transmission / reception unit 11 (S318-2).

  If there is no corresponding record in S302, no license information exists in S303, no user key exists in S308, if the user ID and license ID are not the same (does not match) in S309, S311-1 or If the content key does not exist in S311-2, the generation unit 14 of the license generation apparatus 100a generates a message indicating that the decryption license cannot be issued using the plaintext part user ID and license ID ( S317-3), and is transmitted to the user terminal 300 by the transceiver 11 (S318-3).

  According to the conventional method, as shown in FIG. 6, the user terminal 300 receives the digital content encrypted with the content key from the digital content generation device 100c via the broadcasting facility 200, and receives the license generation device 100a and the data. Decryption was performed using the content key received from the encryption / decryption device 100b. However, if the content key is leaked, it is easily viewed by receiving digital content, which causes great damage to service providers.

  On the other hand, according to the present embodiment, as shown in FIG. 7, the encrypted digital content is divided into a plurality of fragments to generate a fragment content and a fragment-missing content. Since it is transmitted to the user terminal 300 via the facility 200 and the fragment content is stored in the license generation device 100a, the fragment content is acquired in addition to the content key stored in the data encryption / decryption device 100b. Otherwise, the original digital content cannot be restored / decrypted, so that viewing by an unauthorized user can be surely prevented and the security of digital content protection can be improved.

  As described above, according to the present embodiment, the digital content generation device 100d encrypts the digital content with the content key, divides the encrypted digital content into a plurality of fragments, and extracts some fragments from the plurality of fragments. Fragment missing content combined with the rest is generated and distributed to the user terminal 300 via the broadcasting facility 200. In order to restore / decrypt the original digital content, a part of the fragment is required in addition to the content key. Therefore, even if the content key is leaked, it cannot be restored to the original digital content, and the security of digital content protection can be improved.

  Further, according to the present embodiment, the license generation apparatus 100a stores the fragment content generated by the digital content generation apparatus 100d, and the data encryption / decryption apparatus stores the content key. Since the fragment content and the content key required for restoring / decrypting the original digital content are distributed and stored in different devices, security against leakage of information necessary for restoring the digital content can be improved.

  Also, according to the present embodiment, compared to the conventional method described in the background art, the processing added by the data encryption / decryption device 100b is a fragment content with a smaller capacity than the original digital content. Therefore, the encryption / decryption processing load is not greatly increased even when compared to a method in which multiple keys are applied to the entire content and each key is managed separately. , Security of digital content protection can be improved.

  In the above description, it is assumed that the digital content is transmitted from the broadcasting facility 200 to the user terminal 300 using a digital broadcast wave. However, the present invention can be similarly applied to the case where the digital content is transmitted via the IP network 500. .

DESCRIPTION OF SYMBOLS 100c, 100d ... Digital content production | generation apparatus 101d ... Encryption part 102d ... Fragmentation / generation part 103d ... Transmission / reception part 100a ... License generation apparatus 11 ... Transmission / reception part 12 ... Search / determination part 13 ... Search / acquisition part 14 ... Generation part 15 ... Contract DB
16 ... License information DB
17 Fragment content DB
DESCRIPTION OF SYMBOLS 100b ... Data encryption / decryption apparatus 31 ... Transmission / reception part 32 ... Search / acquisition part 33 ... Decryption / determination part 34 ... Encryption / generation part 35 ... User key DB
36a ... Content key DB (1)
36b ... Content key DB (2)
DESCRIPTION OF SYMBOLS 300 ... User terminal 51 ... Transmission / reception part 52 ... Restoration part 53 ... Decoding part 54 ... Display part 200 ... Broadcasting equipment 300 ... User terminal 500 ... IP network S101-S107, S201-S207, S301-S318, S501-S515 ... Step

Claims (3)

A digital content generation apparatus, a license generation apparatus, and a data encryption / decryption apparatus, which are communicably connected via a communication network, and are used for a user terminal and a digital content / license generation for generating the license In the system,
The digital content generation device includes:
Encryption means for encrypting the digital content with a content key;
Fragmentation means for dividing the encrypted digital content into a plurality of fragments;
Generating means for generating fragment content by combining partial fragments and adding restoration information to the digital content, and generating fragment missing content by combining the rest of the plurality of fragments excluding the partial fragments;
Transmitting the fragment content to the license generation device and transmitting the fragment missing content to a device that distributes the content to the user terminal, and
The license generation device includes:
First storage means for storing a license ID for identifying a license of the digital content and license information that defines a use condition of the license in association with each other;
Second storage means for receiving the fragment content from the digital content generation device and storing the fragment content in association with the license ID;
Receiving means for receiving from the user terminal a license acquisition request including at least a plain text user ID and license ID and a user ID and license ID encrypted with the user key of the user terminal;
The license information and the fragment content corresponding to the plaintext license ID are acquired from the first storage unit and the second storage unit, respectively, and the license information, the fragment content, the plaintext user ID and the license are acquired. Transmitting means for transmitting the ID and the encrypted user ID and license ID to the data encryption / decryption device;
The content key and license information encrypted with the user key and the fragment content are received from the data encryption / decryption device, and the encrypted digital content is decrypted using the content key and the license information. Generating means for generating a decryption license to be generated, and generating a fragment content for restoration to restore the digital content before fragmentation using the fragment content;
Transmitting means for transmitting the decryption license and the restoration fragment content to the user terminal,
The data encryption / decryption device comprises:
Third storage means for storing a user ID for identifying the user terminal and a user key of the user terminal in association with each other;
Fourth storage means for storing the license ID and the content key in association with each other;
Receiving means for receiving the license information, the fragment content, the plaintext user ID and license ID, and the encrypted user ID and license ID from the license generating device;
Decryption means for obtaining a user key corresponding to the plaintext user ID from the third storage means and decrypting the encrypted user ID and license ID;
When the decrypted user ID and license ID match the plain text user ID and license ID, a content key corresponding to the license ID is obtained from the fourth storage means and combined with the license information. Encryption means for encrypting with the user key and encrypting the fragment content with the user key;
Transmitting means for transmitting the content key and the license information encrypted with the user key and the fragment content to the license generating device;
A digital content license generation system comprising: A digital content generation apparatus, a license generation apparatus, and a data encryption / decryption apparatus, which are communicably connected via a communication network, and are used for a user terminal and a digital content / license generation for generating the license In the method
By the digital content generation device,
An encryption step of encrypting the digital content with a content key;
A fragmentation step of dividing the encrypted digital content into a plurality of fragments;
Generating a fragment content by combining partial fragments and adding restoration information to the digital content, and generating a fragment missing content by combining the rest excluding the partial fragments from the plurality of fragments;
Transmitting the fragment content to the license generating device and transmitting the fragment missing content to a device that distributes the content to the user terminal, and
By the license generation device,
A storage step of associating the license ID for identifying the license of the digital content with the license information defining the license usage condition in the first storage unit;
A storage step of receiving the fragment content from the digital content generation device and storing the fragment content in association with the license ID in a second storage unit;
Receiving from the user terminal a license acquisition request including at least a plain text user ID and license ID and a user ID and license ID encrypted with the user key of the user terminal;
The license information and the fragment content corresponding to the plaintext license ID are acquired from the first storage unit and the second storage unit, respectively, and the license information, the fragment content, the plaintext user ID and the license are acquired. A transmission step of transmitting an ID and the encrypted user ID and license ID to the data encryption / decryption device;
By the data encryption / decryption device,
A storage step of associating a user ID for identifying the user terminal with a user key of the user terminal in a third storage unit;
A storage step of storing the license ID and the content key in association with each other in a fourth storage unit;
Receiving the license information, the fragment content, the plaintext user ID and license ID, and the encrypted user ID and license ID from the license generating device;
Obtaining a user key corresponding to the plaintext user ID from the third storage means, and decrypting the encrypted user ID and license ID;
When the decrypted user ID and license ID match the plain text user ID and license ID, a content key corresponding to the license ID is obtained from the fourth storage means and combined with the license information. Encrypting with the user key and encrypting the fragment content with the user key;
Transmitting a content key and license information encrypted with the user key, and fragment content to the license generation device,
By the license generation device,
The content key and license information encrypted with the user key and the fragment content are received from the data encryption / decryption device, and the encrypted digital content is decrypted using the content key and the license information. Generating a decryption license to be generated, and generating a fragment content for restoration to restore the digital content before fragmentation using the fragment content;
A transmission step of transmitting the decryption license and the restoration fragment content to the user terminal;
A digital content license generation method characterized by comprising:   A digital content license generation program causing a computer to execute the digital content license generation method according to claim 2.

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