Patent Publication Number: US-2005138400-A1

Title: Digital content protection method

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a digital content protection method, which is applied in the technical field of a digital rights management (DRM) mechanism.  
      2. Description of the Related Art  
      Currently, due to the increasing popularity of networking technology, information transmission speeds have increased substantially, resulting in the more vigorous and convenient circulation of information. However, enormous amounts of information can be spread about. The ease of content reproduction is seen in the downloading of MP3 music files, valuable articles and pictures. All of this content can be sent to other end users, and the unrestricted spread and reproduction of this information devalues the information. Therefore, digital rights management (DRM) mechanisms are provided, which encrypt digital content and right authorizations, to safely exchange digital media content through the Internet, or via other media, to protect the content provider&#39;s rights and interests.  
      However, in the prior art digital rights management mechanism standard, there exists no specific content access protection. The standard simply roughly defines if the digital rights management mechanism can control access contents and access rights. As there is no clear specification description, valuable content may be illegally used, reproduced and transmitted, which defeats content protection for the provider&#39;s rights and security. For example, a prior art structure is frequently embedded within a mobile phone or in a user agent (UA) managed by a user; however, the validity of such a structure may have been queried for a long time. Furthermore, it is not easy to control valid access rights for the digital content, since the prior art structure can be moved and executed in other devices, which can entail security problems.  
      Therefore, it is desirable to provide a digital content protection method to mitigate and/or obviate the aforementioned problems.  
     SUMMARY OF THE INVENTION  
      A main objective of the present invention is to provide a digital content protection method; the digital content comprises a verification program to implement an identification certification process to ensure that every usage is valid. Since the verification program is provided by the content provider, the content provider&#39;s rights and interests are protected completely.  
      Another objective of the present invention is to provide a digital content protection method, which verifies the validity of the user agent and the player to ensure the valuable content cannot be illegally reproduced or spread.  
      According to the present invention, a digital content protection method applied in a digital rights management (DRM) system is provided, the digital rights management system includes a software provider, a software identification certification authority, a content provider, and an end user. The software provider provides at least one player for executing or rendering digital content, and a user agent for controlling a usage authority for the player and management of a public key and a secret key. The software identification certification authority issues an identification certification for the player and the user agent and confirming the identity of the player and the user agent. The content provider provides at least one piece of digital content for the end user to download, and the digital content containing a verification program for examining a validity of the player and the user agent.  
      The method of the present invention comprises: (A) issuing a software download request for downloading the user agent and its corresponding identification certification; (B) receiving the user agent, its corresponding identification certification and a public key corresponding to the user agent, wherein the user agent is embedded with a corresponding secret key; (C) sending a digital content request with a user identity of the user and the public key corresponding to the user agent; (D) receiving a digital content package comprising an encrypted package, an verification program and a user identification code of the end user, the encrypted package being digital content encrypted according to a public key of the user agent; and (E) examining the validity of the identification certification of the user agent according to the verification program and the validity identification certification of the player by the user agent, then using the secret key of the user agent to decrypt the encrypted package to combine the digital content with a right permission for regulating a use limitation of the digital content and to be played by the player.  
      Furthermore, the present invention includes a unit for issuing right permissions, which can be provided by an independent right issuer or by the content provider. In addition, depending upon different definitions of the practical environment, the present invention can issue the software download request to the software provider or to the software identification certification authority. The digital content can be valuable digital content or unvalued digital content.  
      Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic drawing of a practical environment of a first embodiment according to the present invention;  
       FIG. 2  is a flowchart of the first embodiment according to the present invention;  
       FIG. 3  is a schematic drawing of a verification process of the first embodiment according the present invention;  
       FIG. 4  is schematic drawing of a practical environment of a second embodiment according to the present invention; and  
       FIG. 5  is a schematic drawing of a practical environment of a third embodiment according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Please refer to  FIG. 1 .  FIG. 1  is a schematic drawing of a practical environment of a first embodiment according to the present invention. In this embodiment, a digital rights management (DRM) system comprises a software provider  1 , a software certification authority (CA) unit  2 , a content provider  3 , a right issuer  4  and an end user  5 . The software provider  1  provides a player  11  for executing or rendering digital content and a user agent (UA)  12  for controlling usage authority of the player  11 , such as an MPEG4 player, an MP3 player or a JPEG2000 browser. The user agent  12  can manage a public key and a secret key. The software certification authority unit  2  is a valid and authentic third party, which issues identification certifications, performs certifications, and certifies tasks for the player  11  and the user agent  12  in a networking environment. The content provider  3  provides at least one piece of valued or unvalued digital content  31  for the user to download, such as MP3 music files, articles, images or pictures, and digital content  31  is embedded with a verification program  32  for verifying the validity of the player  11  and the user agent  12  used by the end user  5 . The right issuer  4  issues a corresponding right permission for the digital content  31  to control the usage authority of the digital content  31 . In order to ensure information transmission security among every network element in the networking environment, this embodiment transmits information through the wireless transport layer security (WTLS) in the digital rights management system.  
      Please refer to  FIG. 2 .  FIG. 2  is a flowchart of the first embodiment according to the present invention. The end user  5  needs first to be provided with the player  11  and the user agent  12 , and can then use the digital content  31  provided by the content provider  3 . Therefore, the end user  5  issues a software download request  51  to the software certification authority unit  2  to download the player  11  and the user agent  12  (step  201 ). Since the player  11  and the user agent  12  are both verified and issued with an identification certification by the software certification authority unit  2 , the software certification authority unit  2  sends the player  11 , the user agent  12  and their corresponding identification certifications  111 ,  121 , and a user agent public key  122 , to the end user  5  (step  202 ). If the end user  5  already has a valid user agent  12 , the end user  5  only needs to download the player  11  and its corresponding identification certification  111 . One thing to be noted is that a UA public key, UA pk    122 , is provided for the content provider  3  to encrypt the digital content  31 ; a UA secret key, UA sk , is embedded in the user agent  12  and provided for later decrypting the encrypted digital content  31 .  
      Next, the end user  5  sends a digital content download request  52  with a user identification code  501  and the UA public key UA pk    122  to the content provider  3  (step  203 ). The content provider  3  sends back a digital content package  33  to the end user  5  according to the end user  5  (step  204 ). The user identification code  501  can be a subscriber identity module (SIM) number stored in a terminating machine of the end user  5 , or a unique number for the end user  5  that represents the end user  5 . The digital content package  33  comprises an encrypted package, a verification program  32  and the user identification code  501 . The encrypted package is the digital content  31  encrypted by the UA public key UA pk    122 .  
      Since the digital rights management system defining the digital content can only be executed with corresponding right permissions, the end user  5  needs to send a right download request  53  to the right issuer  4  (step  205 ); afterwards, the right issuer  4  sends a right permission  41  with its identification certification  42  to the end user  5  (step  206 ). When the end user  5  receives the right permission  41  with its identification certification  42 , the end user  5  can use a right issuer public key RI pk  provided by the software certification authority unit  2  to verify the validity of the right issuer  4  (step  207 ).  
      Now, when the end user  5  wants to play or use the digital content  31 , the verification program  32  embedded in the digital content  31  is started to perform the identification verification process (step  208 ). Please refer to  FIG. 3 .  FIG. 3  is a schematic drawing of a verification process of the first embodiment according the present invention. The verification program  32  checks the identification certification  121  of the user agent  12  to verify the validity of the user agent  12 . Furthermore, the user agent  12  will also verify the identification certification  111  of the player  11  to ensure the validity of the player  11 . The user agent  12  also reads the subscriber identity module (SIM) number stored in the terminating machine of the end user  5  to compare the SIM number with the identification code  501  in the digital content package  33 ; if they match with each other, the player  11  can execute the digital content  31 , otherwise the end user  5  is not qualified to use the digital content  31 .  
      When the above mentioned verification processes are completed, the user agent  12  can use its secret key to decrypt the encrypted package to obtain the digital content  31  (step  209 ) and limitations (such as playing time, playing frequency, etc.) of the end user  5  according to the right permission content. Finally, the player  11  can play the digital content  31  through the user agent  12  (step  210 ).  
      In addition, please refer to  FIG. 4 .  FIG. 4  is a schematic drawing of a practical environment of a second embodiment according to the present invention. In this embodiment, the corresponding flowchart is similar to the first embodiment. In the first embodiment, the end user  5  issues the software download request  51  to the software certification authority unit  2 . In this embodiment, however, the end user  5  issues the software download request  51  to the software provider  1 . In the other words, in this embodiment, the software certification authority unit  2  sends the player  11 , the user agent  12  and their corresponding identification certifications  111 ,  121 , and the user agent public key  122  back to the software provider  1  for storage.  
      In addition, please refer to  FIG. 5 .  FIG. 5  is a schematic drawing of a practical environment of a third embodiment according to the present invention. In the above-mentioned embodiments, the content provider  3  and the right issuer  4  are two different means; however, in this embodiment, the content provider  3  is also the right issuer  4 , so that when the end user  5  sends a digital content download request  52  to the content provider  3 , the content provider  3  sends back a digital content package comprising an encrypted package with right permission information, which means the encrypted package is formed by using the UA public key UA pk    122  to encrypt the digital content  31  and the right permission. Therefore, this embodiment can skip steps  205  to step  207  shown in  FIG. 2  to simplify the process.  
      According to the above descriptions, the present invention needs to qualify the identification certification of the player  11 , the user agent  12  and the end user  5 , and then the user agent  12  in the end user  5  can control the player  11  according to the right permission  41  to play the digital content  31 . In this manner, the content provider&#39;s rights and interests are protected. Therefore, the end user  5  can only use a valid user agent  12  to present the digital content  31 , since the verification program  32  embedded in the digital content  31  will verify the validity of the user agent  12 . Since the player  11  is verified, the end user  5  cannot illegally reproduce or spread the digital content  31  after being decrypted because other end users don&#39;t have the valid player to play the digital content  31 . Furthermore, the digital content  31  is encrypted by the valid user agent public key, so it must be decrypted by the corresponding secret key to obtain correct digital data for the player  11  to play. Moreover, the user agent  12  compares the user identification code  501  in the digital content  31  with that stored with the end user  5 ; if the digital content gets sent to another user, the identification code  501  will not match, and so the digital content  31  will not be played. Therefore, the digital content protection method provided by the present invention is very strict and safe, which ensures that the digital content  31  provided by the content provider  3  is protected effectively and completely.  
      Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.