Patent Publication Number: US-2006014521-A1

Title: Data protection method and system using the same

Description:
BACKGROUND  
      The invention relates to wireless communication techniques, and in particular to a data protection method for protecting media data.  
      Presently, certain mobile phones are capable of downloading media data through wireless communication from the Internet using Hypertext Transmission Protocol (HTTP) and Wireless Application Protocol (WAP). The downloaded media data is typically plain text. When no protection mechanism is provided, mobile phone users can transfer the downloaded media data to other users via the mobile phone. Occasionally, media data comprising high value content may be copied arbitrarily.  
      Some media designers establish their own media data formats which are different from standard media formats. To decode and play special format media data, a mobile phone must support the special format. Under this condition, compatibility of shared media data is reduced, reversing the media data format and mobile phone standardization trend.  
      Hence, a need exists for a data protection method capable of ameliorating the above-described disadvantages of conventional techniques.  
     SUMMARY  
      Accordingly, an object of the invention is to provide a data protection method implemented in a server and a mobile communication device capable of wireless communication with the server. The mobile communication device transmits a media download request to the server for downloading a set of media data. The server receives the media download request and then generates a description file, a protected media file and a license file in response to the media download request. The description file comprises download information of the protected media file and the license file. The protected media file comprises a set of encrypted data generated from encrypting the set of media data. The license file comprises a decryption key for decrypting the encrypted data into media data. The server transmits the description file to the mobile communication device. The mobile communication device receives the description file from the server.  
      Additionally, the invention provides a data protection method implemented in a server capable of wireless communication with a mobile communication device. The server receives a media download request from the mobile communication device, wherein the media download request requests transmission of media data to the mobile communication device. The server generates a description file, a protected media file and a license file corresponding to the requested. The description file comprises download information of the protected media file and the license file. The protected media file comprises encrypted data generated from the media data. The license file comprises a decryption key for decrypting the encrypted data into unencrypted media data. The server transmits the description file to the mobile communication device.  
      Additionally, an embodiment of the invention provides a data protection method implemented in a mobile communication device capable of wireless communication with a server. The mobile communication device transmits a media download request to the server for downloading media data. The mobile communication device receives a description file from the server, wherein the description file comprises download information of a protected media file and a license file. The protected media file comprises a set of encrypted data generated by the server encrypting the set of the media data. The license file comprises a decryption key for decrypting the encrypted data into decrypted media data. The mobile communication device transmits a protected media file download request to the server for downloading the protected media file based on the download information of the protected media file. The mobile communication device receives the protected media file from the server. The mobile communication device transmits a license file download request to the server for downloading the license file based on the download information of the license file. The mobile communication device receives the license file from the server.  
      Additionally, the invention provides a data protection system comprising a mobile communication device and a server. The server is capable of wireless communication with the mobile communication device. The server receives a media download request from the mobile communication device, wherein the media download request is used for requesting transmission of media data to the mobile communication device. The server generates a description file, a protected media file and a license file of the set of media data in response to the media download request. The description file comprises download information of the protected media file and the license file. The protected media file comprises encrypted data generated from encrypting the media data. The license file comprises a decryption key for decrypting the encrypted data into the decrypted media data, and the server transmits the description file to the mobile communication device. 
    
    
     DESCRIPTION OF THE DRAWINGS  
      Embodiments of the invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
       FIG. 1  is a block diagram of the configuration of a data protection system of an embodiment of the invention;  
       FIG. 2  is a flowchart of the data protection method of an embodiment of the invention;  
       FIG. 3  is a schematic diagram of a description file of an embodiment of the invention;  
       FIG. 4  is a schematic diagram of a protected media file of an embodiment of the invention; and  
       FIG. 5  is a schematic diagram of a license file of an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION  
      An embodiment of the invention provides a data protection method implemented in a data protection system comprising a server and a mobile communication device.  
       FIG. 1  is a block diagram of the configuration of a data protection system of the invention. The data protection system comprises a mobile communication device  10 , WAP gateway  15 , and a server  20 . Mobile communication device  10  is capable of wireless communication comprising but not limited to decoding and playing media data. Mobile communication device  10  may comprise various mobile communication devices, such as a mobile phone or a person digital assistant (PDA).  
      Mobile communication device  10  comprises memory  4 , a media drive  11  responsible for reading, decoding and playing media data. WAP gateway  15  is a conventional Wireless Application Protocol (WAP) gateway connecting mobile communication device  10  and server  20  is capable of end-user authentication. Server  20  comprises an encryption key  135  and a database  21  storing a plurality of media data comprising media data  100 .  
      Media data  100  may comprise various kinds of media data, such as video game programs, still images, video clips, audio clips, or text. Media data in the description conform to Multipurpose Internet Mail Extensions (MIME) formats. It is noted that the media data is not limited to the mentioned format.  
      WAP gateway  15  connects to server  20  through the Internet. Mobile communication device  10  may connect to WAP gateway  15  through a wireless telecommunication network.  
      The data protection method of an embodiment of the invention can be implemented in server  20  and mobile communication device  10 . Mobile communication device  10  communicates with server  20  through WAP gateway  15 . In other words, all transmission data between mobile communication device  10  and server  20  will be transferred by WAP gateway  15 . Thus, a detailed description of the data transfer via WAP gateway  15  is omitted in following. Mobile communication device  10  communicates with server  20  using Wireless Application Protocol (WAP). It is noted that this arrangement is not intended to limit the invention.  
       FIG. 2  is a flowchart of the data protection method of the invention.  
      Mobile communication device  10  transmits a media download request to the server  20  (step S 2 ), wherein the media download request is used for downloading media data  100  from the server  20  to mobile communication device  10 .  
      Server  20  receives the media download request from the mobile communication device (step S 4 ). Server  20  generates a description file  110 , a protected media file  120  and a license file  130  based on media data  100  (step S 6 ) in response to the media download request. In an embodiment of the invention, Server  20  generates description file  110 , protected media file  120  and license file  130  after receiving the media download request. The arrangement ameliorates heavy workload caused by translating each of media data in database  21  into three kinds of corresponding files in advance as described above. In addition, production license file content may be controlled individually. In other words, the license file content for individual media data may be different. Thus, translating media data in database  21  into three corresponding files in advance generates a heavy work load on the server.  
       FIG. 3  is a schematic diagram of a description file of an embodiment of the invention. Description file  110  comprises download information  111  for protected media file  120 , download information  112  for license file  130  and introduction information  113  of media data  100 . Description file  110  may further comprise other information. Download information  111  comprises the address of protected media file  120 . Download information  112  comprises the address of license file  130 . For example, if server  20  generates and stores protected media file  120  and license file  130  therein, download information  111  and  112  comprises the address of server  20  and further comprises paths of protected media file  120  and license file  130  respectively. It is noted that this arrangement is not intended to limit the invention. Server  20  may couple to other servers, for example, a first server and a second server. If server  20  generates and stores protected media file  120  and license file  130  in the first server and the second server respectively, download information  111  and  112  comprises the addresses of the first and second server respectively rather than the address of server  20 .  
      Introduction information  113  comprises introductory information or description of media data  100 . A user of mobile communication device  10  may read the introduction information  113  to determine whether to download protected media file  120  and license file  130 .  
       FIG. 4  is a schematic diagram of a protected media file of the invention. Protected media file  120  comprises a MIME type length field  121 , a MIME type field  122 , an encrypted data length field  123  and encrypted data  124 . All protected media files conform to the same MIME type format regardless of the MIME type of the original media data. The server may encode media data  100  using any encoding method, such as binary encoding or UU-encoding.  
      MIME type length field  121  records MIME type length. MIME type field  122  records MIME type. Encrypted data length field  123  records the length of the encrypted data  124 . Encrypted data  124  is generated from encrypting media data  100  using an encryption key  135  on server  20 , i.e. encrypted data  124  comprises encrypted media data  100 . It is noted that protected media file  120  may comprise other information.  
       FIG. 5  is a schematic diagram of a license file of the invention. License file  130  comprises a decryption key  131  and license information  132 . Decryption key  131  is used for decrypting the encrypted data  124  into decrypted media data  100 . License information  132  comprises time-limit information limiting usage of media data  100 . License information  132  may comprise other information, such as copyright regulation.  
      After generating protected media file  120  and license file  130 , server  20  stores protected media file  120  and license file  130  in a memory of server  20 .  
      Server  20  transmits description file  110  to mobile communication device  10  (step S 8 ).  
      Mobile communication device  10  receives description file  110  from server  20  (step S 10 ). Description file  110  may be represented as a web page, conforming to Extensible Markup Language (XML) or Wireless Markup Language (WML) for example. Mobile communication device  10  can use media drive  11  to decode description file  110  and display the web page thereof which can then be viewed by the user of mobile communication device  10  to determine whether to download protected media file  120  and license file  130 .  
      If the user decides to download protected media file  120 , mobile communication device  10  transmits a protected media file download request to server  20  based on the download information  111  of protected media file  120  (step S 12 ). Protected media file  120  is downloaded to mobile communication device  10  in response to the download request. After receiving the protected media file download request (step S 14 ), server  20  transmits protected media file  120  from server  20  to mobile communication device  10  (step S 16 ).  
      Mobile communication device  10  receives protected media file  120  from server  20  (step S 18 ) and stores protected media file  120  in memory  4 .  
      If the user decides to download license file  130 , mobile communication device  10  transmits a license file download request to server  20  based on the download information  112  of license file  130  (step S 20 ). The license file  130  is downloaded from server  20  to mobile communication device  10  in response to the download request. After receiving the license file download request (step S 22 ), server  20  transmits license file  130  to mobile communication device  10  (step S 24 ).  
      Mobile communication device  10  receives license file  130  from server  20  (step S 26 ) and stores license file  130  in memory  4 .  
      Mobile communication device  10  decodes and decrypts protected media file  120  to acquire the media data  100  using license file  130  (step S 28 ). Specifically, mobile communication device  10  decrypts encrypted data  124  to acquire the media data  100  using decryption key  131 . Mobile communication device  10  then opens and displays or plays media data  100  using the media drive  11 .  
      License information  132  sets an expiration date or limits the usage period for media data  100 . When decrypting protected media file  120  using license file  130 , mobile communication device  10  limits the usage period or expiration date of media data  100  according to license information  132 . For example, the limitation of the usage period or the expiration date is recorded in the data structure of media data  100 . When playing media data  100 , mobile communication device  10  must determine whether the usage period or expiration date is expired and limit the usage of media data accordingly. Under the condition, no usage time limitation of the license file  130  is provided. License file  130  is used only once when decrypting protected media file  120 . Mobile communication device  10  enforces the usage period or the expiration date recorded in the data structure to limit the usage of media data  100 .  
      For example, mobile communication device  10  is prevented from storing decrypted media data  100 . When opening media data  100 , mobile communication device  10  must use the license file  130  to decrypt protected media file  120  and generate media data  100 . Usage of license file  130  or protected media file  120  is limited by license information  132 . After expiration, mobile communication device  10  no longer outputs license file  130 . Thus, media data  100  cannot be copied.  
      License information  132  may further comprise a usage time limit for limiting the usage of media data  100  to a predetermined number of times.  
      The data protection method of the invention may further include a fee mechanism. For example, a fee gateway may be located at WAP gateway  15  or server  20 , whereby users downloading media data  100  are charged a fee.  
      Hence, the data protection method of the invention can ameliorate the disadvantages of conventional techniques.  
      While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.