Rendering digital content in an encrypted rights-protected form

Abstract

To render digital content determined to be in an encrypted rights-protected form, each available license corresponding to the digital content to be rendered is identified, where each such license includes a decryption key (KD) for decrypting the digital content to be rendered, and where the decryption key (KD) in the license is encrypted according to a public key (PU) (PU(KD)). One of the identified licenses is selected and (KD) is obtained from the selected license by obtaining (PU(KD)) from the selected license and decrypting (PU(KD)) according to a private key (PR) corresponding to (PU) to produce (KD). The digital content is decrypted with (KD), and the decrypted digital content is provided for actual rendering.

1 . A method for rendering digital content determined to be in an encrypted rights-protected form, the method comprising: 
 invoking, by the rendering application, a Digital Rights Management (DRM) system having a public key (PU) and a corresponding private key (PR), the DRM system having access to at least one stored digital license, each license corresponding to a piece of digital content and including a decryption key (KD) for decrypting the corresponding digital content, the decryption key (KD) in the license being encrypted according to the public key (PU) of the DRM system (PU(KD));    identifying, by the DRM system, each license corresponding to the digital content to be rendered;    selecting, by the DRM system, one of the identified licenses;    obtaining, by the DRM system, (KD) from the selected license by obtaining (PU(KD)) from the selected license and decrypting (PU(KD)) according to (PR) to produce (KD);    decrypting, by the DRM system, the digital content with (KD); and    providing, by the DRM system, the decrypted digital content to the rendering application for actual rendering.    
     
     
         2 . The method of  claim 1  further comprising, after invoking the DRM system: 
 firstly calling, by the rendering application, the DRM system; and    ceding, by the rendering application, control to the DRM system.    
     
     
         3 . The method of  claim 2  further comprising, after selecting a license and before decrypting the digital content with (KD): 
 returning, by the DRM system, control to the rendering application;    secondly calling, by the rendering application, the DRM system to decrypt the encrypted digital content; and    authenticating, by the DRM system, the rendering application.    
     
     
         4 . The method of  claim 3  wherein firstly calling the DRM system includes passing, by the rendering application, a first identification of such rendering application to the DRM system, wherein secondly calling the DRM system includes passing, by the rendering application, a second identification of such rendering application to the DRM system, and wherein authenticating the rendering application includes verifying that the first identification is the same as second identification.  
     
     
         5 . The method of  claim 1  further comprising authenticating, by the DRM system, the rendering application.  
     
     
         6 . The method of  claim 1  wherein the digital content is sought to be rendered in a particular manner, and wherein selecting one of the licenses further comprises determining whether each corresponding license provides the right to render the digital content in the manner sought.  
     
     
         7 . The method of  claim 6  further comprising passing, by the rendering application, the particular manner that the digital content is sought to be rendered to the DRM system.  
     
     
         8 . The method of  claim 1  further comprising, after invoking the DRM system, calling, by the rendering application, the DRM system to decrypt the encrypted digital content.  
     
     
         9 . The method of  claim 1  wherein identifying each license corresponding to the digital content to be rendered comprises acquiring, by the DRM system, a license corresponding to the digital content from a license source if no such license is found.  
     
     
         10 . The method of  claim 9  wherein the acquiring of the license comprises acquiring the license from a remote license server by way of a communications network.  
     
     
         11 . The method of  claim 1  wherein the digital content includes a content ID, wherein each license includes a content ID of the digital content corresponding thereto, and wherein identifying each license corresponding to the digital content comprises searching for each license having the content ID of the digital content.  
     
     
         12 . The method of  claim 1  wherein the decryption key (KD) in the license being encrypted according to the public key (PU) of the DRM system (PU(KD)) comprises the license including (PU) encrypting an intermediate value (Z) to result in (PU(Z)) and the intermediate value (Z) protecting the decryption key (KD) to result in (Z(KD)), the method comprising obtaining, by the DRM system, (KD) from the selected license by obtaining (PU(Z)) and (Z(KD)) from the selected license, decrypting (PU(Z)) according to (PR) to produce (Z), and employing (Z) to derive (KD) from (Z(KD)).  
     
     
         13 . The method of  claim 12  wherein the intermediate value (Z) protecting the decryption key (KD) to result in (Z(KD)) in the license comprises a value (DZ) encrypting (KD) to result in (DZ(KD)), the value (DZ) being derived from (Z), the method comprising obtaining, by the DRM system, (KD) from the selected license by obtaining (PU(Z)) and (DZ(KD)) from the selected license, decrypting (PU(Z)) according to (PR) to produce (Z), employing (Z) to derive (DZ), and decrypting (DZ(KD)) according to (DZ) to result in (KD).  
     
     
         14 . A method for rendering digital content determined to be in an encrypted rights-protected form, the method comprising: 
 identifying each available license corresponding to the digital content to be rendered, each such license including a decryption key (KD) for decrypting the digital content to be rendered, the decryption key (KD) in the license being encrypted according to a public key (PU) (PU(KD));    selecting one of the identified licenses;    obtaining (KD) from the selected license by obtaining (PU(KD)) from the selected license and decrypting (PU(KD)) according to a private key (PR) corresponding to (PU) to produce (KD);    decrypting the digital content with (KD); and    providing the decrypted digital content for actual rendering.    
     
     
         15 . The method of  claim 14  wherein the digital content is sought to be rendered in a particular manner, and wherein selecting one of the licenses further comprises determining whether each corresponding license provides the right to render the digital content in the manner sought.  
     
     
         16 . The method of  claim 14  wherein identifying each license corresponding to the digital content to be rendered comprises acquiring a license corresponding to the digital content from a license source if no such license is found.  
     
     
         17 . The method of  claim 16  wherein the acquiring of the license comprises acquiring the license from a remote license server by way of a communications network.  
     
     
         18 . The method of  claim 14  wherein the digital content includes a content ID, wherein each license includes a content ID of the digital content corresponding thereto, and wherein identifying each license corresponding to the digital content comprises searching for each license having the content ID of the digital content.  
     
     
         19 . The method of  claim 14  wherein the decryption key (KD) in the license being encrypted according to the public key (PU) (PU(KD)) comprises the license including (PU) encrypting an intermediate value (Z) to result in (PU(Z)) and the intermediate value (Z) protecting the decryption key (KD) to result in (Z(KD)), the method comprising obtaining (KD) from the selected license by obtaining (PU(Z)) and (Z(KD)) from the selected license, decrypting (PU(Z)) according to (PR) to produce (Z), and employing (Z) to derive (KD) from (Z(KD)).  
     
     
         20 . The method of  claim 19  wherein the intermediate value (Z) protecting the decryption key (KD) to result in (Z(KD)) in the license comprises a value (DZ) encrypting (KD) to result in (DZ(KD)), the value (DZ) being derived from (Z), the method comprising obtaining (KD) from the selected license by obtaining (PU(Z)) and (DZ(KD)) from the selected license, decrypting (PU(Z)) according to (PR) to produce (Z), employing (Z) to derive (DZ), and decrypting (DZ(KD)) according to (DZ) to result in (KD).