KR100725918B1 - License Issuance System and Method for Protecting Multi-Level Digital Contents - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a license issuing system and method for the protection of multi-level digital content.

2. The technical problem to be solved by the invention

The present invention provides a license issuing system and method for protecting digital content distributed in multiple stages by supporting multi-level packaging and multi-level licensing of contents, thereby enabling multi-level distribution while protecting digital contents at each distribution stage. For that purpose.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided a license issuance system for multi-level distribution of digital content, comprising: content packaging means for packaging content to include encrypted content, corresponding metadata, and an unencrypted electronic signature for the content to be distributed; Distribution means for requesting a license issuance to a license issuing means in accordance with a purchaser's or other distributor's request for content purchase, and for delivering the packaged content generated in the content packaging means to the buyer or the other distributor; And upon request of the distribution means, newly generate a license key necessary to decrypt the distribution target content, and generate the license key, the usage right information on the distribution target content, and the electronic signature. And said license issuance means for issuing a containing license.

4. Important uses of the invention

The present invention is used for digital content protection and the like.

License, Packaging, Content, DRM, Encryption, License Key, Base License

Description

LICENSING SYSTEM AND METHOD FOR PROTECTING MULTIPLE DISTRIBUTION OF DIGITAL CONTENT {SYSTEM AND METHOD OF ISSUING LICENSES TO PROTECT THE MULTI-LEVEL DISTRIBUTED DIGITAL CONTENT}             

1 is a configuration diagram of an embodiment of a license issuing system for protecting digital content in a multi-step distribution according to the present invention;

2 is a structural diagram of an embodiment of a secure container according to the present invention;

3 is a configuration diagram of an embodiment of the content packager of FIG. 1 according to the present invention;

4 is a configuration diagram of an embodiment of a license issuing server of FIG. 1 according to the present invention;

5 is a flow chart of an embodiment of a license issuing method for protecting multi-level digital content in accordance with the present invention;

6 is a flowchart illustrating a method for generating a license key by a content packager according to the present invention;

7 is a flowchart illustrating a method for transmitting a content license base license and license key information to a license issuing server by a content packager according to the present invention;

8 is a flowchart illustrating a method for requesting a purchaser from a distribution server according to the present invention;

9 is a flowchart illustrating a method for requesting a license issuance to a license issuing server by a distribution server according to the present invention;

10 is a flowchart illustrating a method for checking a validity of a license issuance request by a license issuing server according to the present invention;

11 is a flowchart illustrating a method for generating a license by a license issuing server according to the present invention.

* Explanation of symbols for the main parts of the drawings

10: Content Creator 11, 21, 31: Content Packager

12, 22, 32: license issuing server 13, 23, 33: distribution server

14, 24, 34: Database on license issuing server

15, 25, 35: Database of distribution servers 20, 30: Content distributor

40: Buyer

The present invention relates to a license issuing system and method for the protection of digital content that is distributed in multiple stages, and more particularly, by supporting multi-level packaging and multi-level licensing of the content, the digital content is protected at each distribution stage and multi-level distribution. The present invention relates to a license issuing system and method for protecting digital content distributed in multiple stages.

A license is a document in the form of XML (eXtensible Markup Language) that contains the information necessary for a user to view protected content. This information includes the decryption key and encryption options required to decrypt the protected content, and an electronic signature using the issuer's certificate is added to prevent forgery in the transmission process.

Today's digitalized multimedia contents production method has been introduced and various production tools have been spread to make contents production easy and fast. As the high-speed Internet is popularized, great changes have been made in the consumption structure of contents. In addition, with the spread of PDAs and mobile phones, the expansion of high-speed wireless communication networks is being made, and this change is expected to accelerate further.

In order for the digital economy to be suitable for the digital content era, technical devices necessary for the delivery, consumption, and distribution of content using the Internet, wireless communication networks, and digital TV must be provided. Means should be provided to effectively address compatibility issues, copyright protection and management issues, and the establishment of the right distribution system.

Digital Rights Management (DRM) is a technology for copyright protection of digital content, and it encrypts and protects the content and issues a license to a legitimate user that uses the decryption key to decrypt the content. .

Content Packaging is a term that refers to an operation of generating content protected by DRM, and the protected content generated by the packaging is called a secure container. The secure container consists of encrypted content, metadata related to the content, business rules, and the like.

In the currently provided DRM-based content distribution method, content encryption, metadata, content packaging, and license issuance are all performed considering only a 1: 1 relationship between a distributor and a consumer. Since there is no way to protect contents from the content producer to the content consumer, the contents protection at each distribution stage is dependent on conscience and law.

Therefore, if the protection of the contents is provided systematically, different distributors can supply contents of different fields with each other or even the same contents under different conditions to meet consumer demand and contribute to market activation.

One of the biggest reasons why existing DRM cannot be applied to digital contents distributed through multiple stages is that the encryption key system included in the license of the existing DRM cannot be applied to multiple stage distribution. In other words, if the existing DRM is applied to the multi-level distribution, it is necessary to go through a packaging process of decrypting the encrypted content in each distribution step and encrypting it again with the encryption key generated by the user. In this case, there is a risk that the original content is leaked due to decryption, and there is a possibility that the information of the previous distributor may be deleted or forged in the process of repackaging.

Therefore, in order to protect contents in each distribution stage, the content encryption key should be securely distributed and managed to verify the forgery of the packaged content and license.

The present invention has been proposed to solve the above problems, by supporting multi-level packaging and multi-level licensing of the content, to enable the multi-level distribution while protecting the digital content in each distribution stage, for the protection of digital content that is distributed in multiple stages The purpose is to provide a license issuing system and method thereof.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The present invention for achieving the above object, in the license issuance system for the multi-level distribution of digital content, the content packaging to include the encrypted content, the corresponding metadata and the unencrypted electronic signature for the content to be distributed Content packaging means for; Distribution means for requesting a license issuance to a license issuing means in accordance with a purchaser's or other distributor's request for content purchase, and for delivering the packaged content generated in the content packaging means to the buyer or the other distributor; And upon request of the distribution means, newly generate a license key necessary to decrypt the distribution target content, and generate the license key, the usage right information on the distribution target content, and the electronic signature. And the license issuing means for issuing a license to be included.

On the other hand, the present invention, in the license issuing method for digital content protection, a license key generation step of generating a license key for the content that the content packager (Packager) to be distributed; A license delivery step of transmitting, by the content packager, a base license issued from the outside and the generated license key information to a license issuing server; A license issuing step of receiving, by a distribution server, a content purchase request from a buyer, and issuing a license to the license issuing server; And a new license key and content generated based on the base license and the license key information received in the license delivery step after the license issuing server checks the validity of the license issuance request according to the license issuance request of the distribution server. And generating a new license including usage right information and an electronic signature, and encrypting the generated license with the public key of the buyer and transmitting the license to the buyer.

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The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a license issuing system for protecting digital content in a multi-step distribution according to the present invention.

The present invention relates to a license issuing apparatus in multi-level content distribution based on DRM (Digital Rights Management).

The license issuing system for protecting digital contents in multi-level distribution is a content packager (11, 21, 31) for generating an encryption key, and a license for issuing a license containing information on usage rights, conditions, and decryption key for the content. Issuance server 12, 22, 32, distribution server 13, 23, 33 for processing the purchase request of the buyer, and database (14, 24, 34).

First, the meaning of terms used to describe the multi-stage content packaging processing system according to the present invention will be described.

Distributor means a person who sells packaged content for sale as a product to a consumer or another distributor under certain conditions of use, and the buyer distributes the content for use according to the original purpose for which the content was produced. Means the person who purchases and uses the content from the vendor.

Multi-level distribution means distribution for content transactions between content distributors, and resale means selling packaged content purchased by one distributor from another distributor to the buyer.

Secure Container refers to protected content generated by packaging, and Secure Container is composed of encrypted content, metadata related to the content, business rules, and the like.

License refers to authorization information including usage rules and decryption keys for using packaged content.

Multi-packaged content refers to a secure container that is repeatedly packaged at each distribution stage to enable multi-level distribution between distributors.

Multi-license means a Proof of Entitlement to use multi-packaged content to enable multi-level distribution, sale, and use between distributors, and Base License means Refers to a multilevel license purchased from a previous distributor that is needed to create multilevel packaged content.

The content key refers to a symmetric key used to encrypt the original content, and the license key refers to a symmetric key used to encrypt the content key.

The present invention supports multi-level packaging and multi-level licensing of content to enable multi-level distribution, so that when the content creator 10 first packages and issues a license, the next distributor 20 is responsible for the content. License, repackage, and distribute the repackaged content to another distributor (30) or end-user (buyer) (40) while issuing, repackaging, and distributing licenses for its own distribution purposes within its own rights; To sell directly to

Hereinafter, with reference to FIG. 1, it demonstrates in detail as follows.

When the content producer 10 first packages the original content, the original content (c) and the use authority (R ₁ ) are input as the input of the packager (100).

The content packager 11 generates three key seeds s _k , s ₁₁ , and s ₁₂ for generating an encryption key. And to generate a symmetric key, the symmetric key K L ₁₂ for content encryption from s _k, a symmetric key from L ₁₁ s _11, s ₁₂ from. The original content (c) is encrypted using the symmetric key K. The symmetric key K is encrypted using the symmetric key L ₁₁ , and the encrypted value is again encrypted using the symmetric key L ₁₂ as shown in Equation 1 below. This value is called N ₁ .

)(101). 그리고, 콘텐츠 패키저에 의해 생성된 시큐어 콘테이너(C₁), 키씨드 s₁₂, 사용권한정보(R₁)을 유통서버의 데이터베이스(15)에 저장한다(101). 라이센스 발급 서버(12)는 전달받은 정보를 라이센스 발급 서버의 데이 터베이스(14)에 저장한다(101).The content packager 11 transmits s ₁₁ , N ₁ , and R ₁ to the license issuing server 12. Encrypt each data with the public key of the license issuing server for secure data transmission.

(101). The secure container C ₁ , the key s ₁₂ , and the usage right information R ₁ generated by the content packager are stored in the database 15 of the distribution server (101). The license issuing server 12 stores the received information in the database 14 of the license issuing server (101).

When the distributor CD ₁ connects to the content producer's distribution server 13 and requests the purchase of content, the distribution server 13 receives the distributor's certificate public key (P _CD1 ) from the packager 21 of the distributor CD ₁ . (102). The purchaser (here distributor CD ₁ ) receives the secure container C ₁ from the distribution server 13 (102).

) 라이센스 발급을 요청한다(103).On the other hand, the distribution server 13 takes the key seed s ₁₂ from the database 15, encrypts it with the distributor's public key, issues a license together with the distributor certificate public key (P _CD1 ) and the authority information (r ₁ ) selected by the buyer. To server 12 and (

Request a license issuance (103).

Upon receiving the license issuance request, the license issuing server 12 retrieves the stored information s ₁₁ , N ₁ , R ₁ from the database 14 (104). The license L ₁ is generated using this information and the information received from the distribution server 13. The license has encryption key seed information (s ₁₁ , s ₁₂ ), encrypted content encryption key information (N ₁ ) and authorization information (r ₁ ), and the buyer's public key (P _CD1 ) as shown in Equation 2 below. Encrypted together.

The generated license is then transmitted 104 to the purchaser CD ₁ .

On the other hand, when packaging again using the packaged content, the content packager 21 generates two encryption key seeds s ₂₁ and s ₂₂ . Generate license keys L ₂₁ and L ₂₂ from each seed. The content packager 21 extracts s ₁₁ , s ₁₂ , and N ₁ from the license L ₁ , and decodes N ₁ to s ₁₂ . The decrypted value is sequentially encrypted using L ₂₁ and L ₂₂ to generate N ₂ (see Equation 3).

The content packager 21 transmits s ₂₁ , N ₂ , and L ₁ to the license issuing server 22. For secure data transmission, each data is encrypted using the public key of the license issuing server 22 as shown in Equation 4 below (111).

Then, the repackaged secure container C ₂ , encryption key seed s ₂₂ , and base license L ₁ are stored in the database 25 of the distribution server (111). The license issuing server 22 stores the received information in the database 24 of the license issuing server 22 (111).

The purchase process is the same as the previous purchase process.

When the next distributor CD ₂ connects to the distribution server of the distributor CD ₁ and requests content purchase, the distribution server receives the distributor's certificate public key P _CD2 from the packager of the distributor CD ₂ . The buyer receives the secure container C ₂ from the distribution server.

), 라이센스 발급을 요청한다The distribution server takes the key seed s ₂₂ from the database, encrypts it with the distributor's public key, sends it to the license issuing server together with the distributor certificate public key (P _CD2 ) and the buyer's selected authorization information (r ₂ ) (

), Request a license issuance

Upon receiving the license issuance request, the license issuing server retrieves the stored information S ₂ , N ₂ , and L ₁ from the database. The license L ₂ is generated using this information and the information received from the distribution server. The license has encryption key seed information (S ₂ , s ₂₂ ), encrypted content encryption key information (N ₂ ) and authorization information (r ₂ ), and is encrypted with the buyer's public key (P _CD2 ) (Equation 5). Reference). The generated license is then transmitted to the purchaser CD ₂ .

On the other hand, by generalizing the above process in the n-stage distributor is expressed as follows.

The method of generating symmetric keys L _i1 , L _{i2 and} generating N _i values using the keys s _i1 , s _i2 generated in the package of the n-stage distributor is represented by Equation 6 below.

Data transmitted from the content packager to the license issuing server is shown in Equation 7 below (121).

Data stored in the distribution server database in the content packager are repackaged content C _n , key seed s _n2 , and base license L _n-1 (121).

When the n + 1 stage distributor makes a purchase request, the distribution server brings the buyer's public key P _{CDn + 1} (122). The buyer receives the secure container C _n from the distribution server (122).

), 라이센스 발급을 요청한다(123).The distribution server obtains the key seed s _n2 from the database and encrypts it with the public key of the distributor CD _{n + 1} , and distributes the license certificate server together with the distributor certificate public key (P _{CDn + 1} ) and the authority information selected by the buyer (r _n ). To (

), The license issuance request (123).

Upon receiving the license issuance request, the license issuing server fetches the stored information (S _n , N _n , L _n-1 ) from the database (124). The license L _n is generated using this information and the information received from the distribution server. The license has encryption key seed information (S _n , s _n2 ), encrypted content encryption key information (N _n ) and authorization information (r _n ), and is encrypted with the buyer's public key (P _{CDn + 1} ) 8].

The generated license is then transmitted to the buyer CD ₂ (124).

FIG. 2 is a structure diagram of a secure container according to an embodiment of the present invention. As shown in the drawing, the secure container includes a content 201 encrypted with a symmetric key K, metadata 202, and an electronic signature 203. .

3 is a block diagram of an embodiment of the content packager of FIG. 1 in accordance with the present invention.

First, the content packager 310 for generating the protected content on the second distributor side in FIG. 3 will be described as follows.

The content packager 310 may include a multi-level packaging analysis unit 311 which extracts information (metadata, encrypted content, and digital signature) about the packaged content 301 and metadata that interprets metadata included in the packaged content. An analysis unit 312, a multi-level packaging analysis unit 311, and a multi-level packaging unit 313 for packaging content again using the analysis results of the metadata analysis unit 312.

In addition, the content packager 310 interprets the license 302 and performs a license engine unit 314 that performs inspection of authority information, an encryption key generation unit 315 that generates an encryption key, and encrypts content or main information. An encryption processing unit 316 to perform, and an external system communication unit 317 for communication with the license issuing server and distribution server.

The content packager 320 of the distributor of the third and fourth stages performs the same function with the same configuration as the content packager 310.

Distributor A who has already purchased Packaged Content and Licenses may establish terms of sale for the Content within the scope of the rights set forth in his license, and Distributor B who has purchased this Content may only purchase Content within the scope set by Distributor A. It becomes available for sale.

4 is a configuration diagram of an embodiment of a license issuing server of FIG. 1 according to the present invention.

The license issuing server (12, 22, 32) for issuing a multi-level license analyzes the key management unit 404 for securely storing the license key information, the base license management unit 402 for securely storing the base license, and the base license. It includes a license engine unit 403 for checking the validity of the issuance request, a license generation unit 405 for generating a license, and an external system communication unit 401 for communication with an external system.

FIG. 5 is a flowchart illustrating a license issuing method for protecting digital content in a multi-step distribution according to the present invention, which is performed by the license issuing servers 12, 22, and 32.

The content packager generates a license key (500), and transmits a base license and license key information to a license issuing server (502).

Then, when the buyer requests the purchase to the distribution server (504), the distribution server requests a license issuance to the license issuing server accordingly.

The license issuing server checks the validity of the license issuing request (506), and if it is valid, the license issuing server generates a license (508), and transmits the generated license to the purchaser (510). Transmit (512).

FIG. 6 is a flowchart illustrating an example of a method of generating a license key by a content packager according to the present invention, and shows a detailed process of “500” of FIG. 5.

The content packager generates an encryption key seed (600) and generates an encryption key from the seed (602). After extracting the license key and the encrypted content key from the base license (604), decrypting the encrypted content key using the extracted license key (606), and using the encryption key generated at "602". Encrypt the content key.

The above process can be divided into a case of packaging the original content and a process of repackaging the packaged content, as described in FIG. 1.

FIG. 7 is a flowchart illustrating a method of transmitting, by a content packager, a base license and license key information to a license issuing server according to the present invention, and shows a detailed process of "502" in FIG.

Obtain a license of the license issuing server certificate from the license issuing server (700), encrypt the license key with the public key of the license issuing server certificate (702), and then use the content issuance, content title, and encrypted license key information to issue the license issuing server. A message to be sent is generated (704). Then, after digitally signing the generated message (706), the base license and the message electronically signed at "706" are transmitted to the license issuing server.

8 is a flowchart illustrating a method for requesting a purchaser to make a purchase request to a distribution server according to the present invention, and shows a detailed process of “504” of FIG. 5.

When the buyer logs in to the distribution server (800) and the buyer selects the rights and conditions of the content to purchase from the distribution server (802), the buyer's certificate is transmitted to the distribution server (804).

9 is a flowchart illustrating a method for requesting a license issuance to a license issuing server by a distribution server according to the present invention.

When the distribution server requests the license issuance to the license issuing server, the license key is retrieved from the database managing the license key (902), and the obtained license key is encrypted with the buyer's certificate public key (902).

A message is generated 904 including the rights and conditions selected by the buyer, the encrypted license key generated at " 902 ", and the buyer's certificate. The generated message is electronically signed with the certificate secret key of the distribution server (906), and the generated electronic signature message is transmitted to the license issuing server (908).

FIG. 10 is a flowchart illustrating a method for checking a validity of a license issuance request by a license issuing server according to the present invention, and shows a detailed process of "506" of FIG.

Upon receiving a license issuance request from the distribution server (1002), the base license is retrieved from the base license management unit (1004), and a license engine is used to check whether the rights and conditions received from the distribution server meet the rights and conditions of the base license. (1006).

FIG. 11 is a flowchart illustrating a method for generating a license by a license issuing server according to the present invention, and shows a detailed process of "508" of FIG.

Obtain the license key information from the key management unit (1100), extract the license key information included in the base license (1102), and the information related to the key in the "1100" and "1102" process using the buyer's certificate public key Encrypt (1104).

Then, after generating the authority and condition information of the license using the authority and condition information received from the distribution server (1106), using the information in the "1104" and "1106" process generates a license XML (1108), The digital signature of the license issuing server is added to the license XML (1110).

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, the present invention supports multi-level packaging and multi-level licensing of content so that when one distributor first packages and issues a license, the next distributor may own the content. In the content distribution market, it is possible to repackage and distribute the content by setting rights and conditions suitable for the purpose of distribution, and to re-package or resell the repackaged content to another distributor or directly to the end consumer. Multi-level distribution can be applied, and as a result, efficient contents can be sold, and the same content can be applied to the conditions of use of various distributors involved in the distribution. It is effective to protect.

In addition, when the multi-level distribution is applied in the content distribution market according to the present invention, the distributor who does not have the content that the consumer wants to purchase can obtain the content from other distributors through distribution relay or resale and sell it to the desired consumer. For consumers, the burden of finding the desired content and searching for other distributors repeatedly is reduced. On the other hand, the distributor directly requests the content from the content provider, purchases the packaged content, and repackages the content ( Instead of opening the packaging, creating, and repackaging sales metadata, you can get content already available for sale from other distributors, making it more efficient to trade content. have.

In addition, the present invention, when a distributor participating in the distribution process for the same content is issued a multi-level license, it is possible to add its own rules of use, thereby enabling a multi-rule business, while preventing the violation of the rights of the predecessor. There is an effect that can be prevented in advance.

In addition, the present invention has the effect of preventing the leakage of the encryption key by managing the distribution key of the content distributed to the distribution agents instead of centralized management by one distributor.

In addition, the present invention has the effect of controlling the authority of the distributor for the content by using a license having the authority information of each distributor. This means that distributor A who has already purchased the packaged content and license can set the terms of sale for the content within the scope of the rights specified in his license, and distributor B who purchased this content can only purchase the content within the rights set by distributor A. This is because it makes available for sale.

Claims (14)

In the license issuance system for multi-level distribution of digital content, Content packaging means for packaging content such that encrypted content, corresponding metadata, and an unencrypted electronic signature are included for the content to be distributed; Distribution means for requesting a license issuance to a license issuing means in accordance with a purchaser's or other distributor's request for content purchase, and for delivering the packaged content generated in the content packaging means to the buyer or the other distributor; And Upon request of the distribution means, a new license key for decrypting the distribution target content is newly generated, and the generated license key, usage right information on the distribution target content, and an electronic signature are generated. Said license issuance means for issuing a license comprising; License issuance system for the protection of digital content being distributed in multiple stages. The method of claim 1, The content packaging means, In the case where the content to be distributed has already been distributed by a content producer, the packaged content distributed and delivered from the outside is interpreted, the content is repackaged according to the distribution request of another distributor, and the license issued from the outside is decrypted. The license issuance system for protecting multi-level distributed digital content, characterized in that the license key is encrypted and delivered to the license issuing means in accordance with a content sale request from another distributor. The method of claim 2, Repackaging in the content packaging means, Issuance of license for protection of multi-level distributed digital contents, which includes repackaging to include 'encrypted contents' included in 'packaged contents' distributed from outside, newly changed metadata, and new electronic signatures system. The method of claim 2, The content packaging means, Multi-step packaging analysis means for analyzing the packaged content received from the outside and extracting metadata, encrypted content, and electronic signature included in the packaged content; Metadata analysis means for interpreting the extracted metadata; Multi-step packaging means for generating newly packaged content including the encrypted content, modified metadata, and a new digital signature; License engine means for interpreting licenses issued and transmitted from the outside and checking usage right information; Encryption key generating means for generating an encryption key; Encryption processing means for decrypting the license key interpreted by the license engine means, or for encrypting the license key using the encryption key and transmitting the license key to the license issuing means when a license issuance request is received from the outside; And External system communication means for communication with external license issuance means or distribution means License issuance system for the protection of digital content being distributed in multiple stages. The method of claim 1, The content packaging means, Multi-level digital distribution, characterized in that the content is distributed for the first time by the content creator, and the content is packaged, including metadata having information about the content, and electronic signatures to prevent forgery and forgery. Licensing system for the protection of content. The method according to any one of claims 1 to 5, The license issuance means, External system communication means for communicating with an external system to receive a license from an external system through the packaging means or to transmit the issued license to the external system; Key management means for storing license key information included in the license; Base license management means for storing a base license issued from the external system; A license engine means for analyzing a base license issued from the external system, validating a request for issuance from the outside, and if necessary, transferring the base license to a license generation means and requesting for a new license issuance; And The license generating means for generating a new license based on the transferred base license License issuance system for the protection of digital content being distributed in multiple stages. The method of claim 6, The electronic signature included in the license is License issuance system for the protection of multi-level distributed digital content, characterized in that the digital signature is not encrypted. In the license issuance method for protecting digital content, A license key generation step of generating, by a content packager, a license key for content to be distributed; A license delivery step of transmitting, by the content packager, a base license issued from the outside and the generated license key information to a license issuing server; A license issuing step of receiving, by a distribution server, a content purchase request from a buyer, and issuing a license to the license issuing server; And After the license issuing server checks the validity of the license issuance request according to the license issuance request of the distribution server, a new license key and content use right generated based on the base license and the license key information received in the license delivery step. The license issuing step of generating a new license including the information and the digital signature, encrypting the generated license with the public key of the buyer, and transmitting it to the buyer. License issuance method for the protection of multi-level distributed digital content comprising a. The method of claim 8, The license key generation step, A key seed generation step of generating an encryption key seed; An encryption key generation step of generating an encryption key from the encryption key seed; A base license analyzing step of extracting a license key and an encrypted content key from the base license; A content key decryption step of decrypting an encrypted content key using the extracted license key; And A content key encryption step of encrypting the content key again using the encryption key License issuance method for the protection of multi-level distributed digital content comprising a. In paragraph 8 The license delivery step, A certificate request step of obtaining a certificate of a license issuing server from the license issuing server; A license key encryption step of encrypting the license key with a public key of a license issuing server certificate; A transmission message generation step of generating a message to be transmitted to the license issuing server using a content ID, a content title, and encrypted license key information; An electronic signature step of digitally signing the transmission message; A transmission step of transmitting the base license and the digitally signed transmission message to the license issuing server License issuance method for the protection of multi-level distributed digital content comprising a. The method of claim 8, The purchase request process in the license issue request step, A login step of the purchaser logging into the distribution server; A permission / condition selection step of the buyer selecting the rights and conditions of the content to be purchased from the distribution server; And Certificate transmission step of transmitting the certificate of the buyer to the distribution server License issuance method for the protection of multi-level distributed digital content comprising a. The method of claim 8, Issuance request process in the license issuance request step, A license key obtaining step of obtaining a license key from a database managing a license key; Encrypting the license key with a certificate public key of a purchaser; A request message generation step of generating a license issuance request message including a permission and condition selected by the buyer, an encrypted license key, and a certificate of the buyer; An electronic signature step of digitally signing the license issuance request message with a certificate secret key of the distribution server; And Request message transmission step of transmitting the electronically signed message to the license issuing server License issuance method for the protection of multi-level distributed digital content comprising a. The method according to any one of claims 8 to 12, Issuance request validation process in the license issuance step, An issuing request receiving step of receiving a license issuing request from the distribution server; A base license import step of bringing the base license from the base license manager; And Rights / conditions checking step that checks whether the rights and conditions received from the distribution server meet the rights and conditions of the base license using the license engine. License issuance method for the protection of multi-level distributed digital content comprising a. The method of claim 13, The license generation process in the license issuance step, Importing key information for obtaining license key information from a key management unit; A key information extracting step of extracting license key information included in the base license; A key encryption step of encrypting the information related to the key of the key information importing step and the key information extracting step by using a certificate public key of a purchaser; An authority / condition step of generating authority and condition information of a license by using authority and condition information received from the distribution server; A license XML generation step of generating a license XML using the information of the key encryption step and the authority / condition step; And Digital signature step of adding the digital signature to the license XML License issuance method for the protection of multi-level distributed digital content comprising a.

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