Abstract:
The invention relates to a method, system and re-encryption module for handling protected content in a data communications network comprising a content server providing digital rights management protected content to a distributor. The method comprises re-encrypting digital rights management protected content provided by the content server with a distributor-specific key.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to digital rights management. Particularly, the invention relates to handling protected content in a data communications network.  
         [0003]     2. Description of the Related Art  
         [0004]     Since the introduction of digital storage technologies more effective copyright enforcement has become an issue. Especially, the emergence of the Internet as an illicit distribution channel for copyright protected content has created a strong demand for new technologies in copyright protection. One such technology is the Digital Rights Management (DRM). The DRM is a common term for standards and proprietary systems where a given content item is augmented with information that specifies user rights associated with it. The content item may, for example, be an audio recording, video, picture, computer program or simply a document. The user rights may comprise various rules pertaining to the use of the content item. For example, a user may be given a time limit during which the content item can be presented, in other words, rendered to the user. Allowed number of listening times, allowed device identities and partial viewing rights are other examples of rules pertaining to the use of a content item. The DRM requires that the presentation device and the presentation software in it are not hostile, that is, they participate in the enforcement of digital rights. In the presentation device there is usually a DRM agent, or in other words, a DRM engine, which enforces the DRM rights and protects the content items from illicit copying. In order to avoid making a DRM protected content item available for copying, the content item may be encrypted while it is in transit from the network to the presentation device and while it is stored in the presentation device outside of the DRM engine, for example, on a hard disk.  
         [0005]     One standard for the DRM is the one based on Open Mobile Alliance (OMA) DRM specifications. The aim of the OMA DRM is to enable controlled consumption of digital media objects by allowing content providers to express content rights. The media objects are content items such as audio clips, video clips, pictures, Java applications and documents. Content items governed by rights are referred to as assets. In the OMA DRM content rights are expressed as document objects, that is, documents written using a Rights Expression Language (REL). In order to specify the rights pertaining to an asset it is associated with a REL object. The association between a REL object and an asset may be specified explicitly by mentioning the asset&#39;s identifier in the REL object or implicitly by providing the REL object in a same message together with the asset.  
         [0006]     OMA specification OMA-DRM-ARCHH-V2 — 0-20040715-C discloses a method to deliver content more freely between individual users. The method is referred to as “Super Distribution”. In Super Distribution a given client who has downloaded content from a Content Issuer can in turn distribute this DRM Content to other devices using various networked links as well as removable media. This DRM Content is encrypted and is not usable by the receiving device/user until the associated rights are acquired for the content from a Rights Issuer. The device that receives this super-distributed content will discover the Rights Issuer URL within the DRM Content headers and use this information to connect to the Rights Issuer portal to acquire the rights.  
         [0007]      FIG. 1  discloses a basic situation using the Super Distribution of OMA Specifications.  FIG. 1  comprises a content provider  10 , a distributor  12 , a receiving device  14  and a rights manager  16 . The distributor receives ( 100 ) some DRM Content from the content provider  10  and stores it locally. The distributor  12  wants to share this DRM Content with the receiving device  14 , and as a result, transfers ( 102 ) this to the receiving device  14  using local connectivity or removable media. The receiving device  14 , on reception of this DRM Content, discovers the Rights Issuer URL from the DRM Content headers and initiates a Rights Object Acquisition Protocol session with the Rights Manager  16  ( 104 ). On completion of this protocol and appropriate payment arrangements, the receiving device  14  obtains ( 106 ) the Rights Object associated with the requested DRM Content. Now, the user of the receiving device  14  is able to use this content.  
         [0008]     In some situations it might be desirable to convey to the Rights Issuer also a piece of information identifying the party that delivered the protected content e.g. to a friend. The Super Distribution disclosed in the OMA specifications does not provide an answer to this need.  
         [0009]     An obvious solution to this problem is to transfer a tag relating to the delivering party of the content from the friend to the Rights Issuer. Reference publication EP 1089241 discloses such a solution. A problem with this solution is that it is easy to change the tag and thus the delivered tag would refer to a wrong person. Furthermore, if the content is encrypted again with a seller identifier (tag), the existing digital rights management system needs to be changed quite a lot. If the digital rights management does not utilize the normal central digital rights management system, the content owner may have doubts on the reliability.  
       SUMMARY OF THE INVENTION  
       [0010]     According to one aspect of the invention there is provided a method of handling protected content in a data communications network comprising a content server providing digital rights management protected content to a distributor. The method comprises re-encrypting digital rights management protected content provided by the content server with a distributor-specific key.  
         [0011]     In one embodiment of the invention, the method further comprises providing the content server with the distributor-specific key, re-encrypting the digital rights management protected content provided by the content server with the distributor-specific key in the content server, and sending the re-encrypted digital rights management protected content to the distributor. In one embodiment of the invention, the method further comprises delivering the re-encrypted digital rights management protected content to a receiving device, sending, from the receiving device, verification information to the distributor, and sending, from the distributor, in response to receiving the verification information from the receiving device a decryption key to decrypt the reencryption of the digital rights management protected content to the receiving device.  
         [0012]     In one embodiment of the invention, the method further comprises providing, from the content server, digital rights management protected content to the distributor, and re-encrypting the digital rights management protected content provided by the content server with the distributor-specific key by the distributor. In one embodiment of the invention, the method further comprises delivering the re-encrypted digital rights management protected content to a receiving device, sending, from the receiving device, verification information to the distributor, and sending, from the distributor, in response to receiving the verification information from the receiving device a decryption key to decrypt the re-encryption of the digital rights management protected content to the receiving device.  
         [0013]     According to another aspect of the invention there is provided a system of handling protected content in a data communications network. The system comprises a content server providing digital rights management protected content to a distributor, a distributor-specific key, and a re-encryption module configured to re-encrypt digital management rights protected content with the distributor-specific key.  
         [0014]     In one embodiment of the invention, the distributor is configured to provide the content server with the distributor-specific key, the content server comprises the re-encryption module configured to re-encrypt the digital rights management protected content with the distributor-specific key, and the content server is configured to send the re-encrypted digital rights management protected content to the distributor. In one embodiment of the invention, the distributor is configured to deliver the re-encrypted digital rights management protected content to a receiving device, the receiving device is configured to send verification information to the distributor, and the distributor is configured to send in response to receiving the verification information from the receiving device a decryption key to decrypt the re-encryption of the digital rights management protected content to the receiving device.  
         [0015]     In one embodiment of the invention, the content server is configured to provide digital rights management protected content to the distributor, and the distributor comprises the re-encryption module configured to re-encrypt the digital rights management protected content provided by the content server with the distributor-specific key. In one embodiment of the invention, the distributor is configured to deliver the re-encrypted digital rights management protected content to a receiving device, the receiving device is configured to send verification information to the distributor, and the distributor is configured to send in response to receiving the verification information from the receiving device a decryption key to decrypt the re-encryption of the digital rights management protected content to the receiving device.  
         [0016]     According to another embodiment of the invention there is provided a re-encryption module in a data communications network. The re-encryption module comprises a distributor-specific key, and a re-encryption unit configured to re-encrypt digital management rights protected content with the distributor-specific key.  
         [0017]     According to another embodiment of the invention there is provided a computer program embodied on a computer-readable medium to handle protected content, said program configured to perform the following steps when executed on a data-processing device: re-encrypting digital rights management protected content provided with a distributor-specific key.  
         [0018]     An advantage of the invention compared to the existing DRM system is that the invention allows, for example, a network marketing business model. Transferring a tag only is simple, but it is easy to change the tag and therefore give the commission to a wrong account. If the content is encrypted again with a seller identifier, the existing DRM system needs to be changed quite a lot. However, if the seller can give the decrypting key for the exchange of the verification information from a receiving device, the digital rights management system may remain untouched. In other words, the invention can be used together with the existing DRM systems. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:  
         [0020]      FIG. 1  is a flow diagram illustrating super distribution of digital rights management protected content in prior art;  
         [0021]      FIG. 2   a  is a flow diagram illustrating a solution for re-encrypting digital rights management content according to one embodiment of the invention;  
         [0022]      FIG. 2   b  is a flow diagram illustrating a solution for re-encrypting digital rights management content according to another embodiment of the invention;  
         [0023]      FIG. 3   a  is a block diagram of a system according to one embodiment of the invention; and  
         [0024]      FIG. 3   b  is a block diagram of a system according to another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0025]     Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0026]      FIG. 2   a  discloses a solution for re-encrypting digital rights management content according to one embodiment of the invention.  FIG. 2   a  comprises a content provider  20 , a distributor  22 , a receiving device  24  and a rights manager  26 . The distributor  22  and receiving device  24  may refer to any applicable device, e.g. a computer, a personal digital assistant, a mobile terminal etc. In this example, digital rights management protected content is re-encrypted ( 200 ) in the content server  20 . For the re-encryption process, the content server  20  comprises a distributor-specific key. In one embodiment, the distributor  22  provides the content server  20  with the distributor-specific key prior the re-encryption process. After the re-encryption process the content server  20  sends ( 202 ) the re-encrypted digital rights management protected content to the distributor  22 .  
         [0027]     The distributor  22  is free to deliver the re-encrypted digital rights management protected content to anyone wishing to receive it. For example, the distributor  22  may be an ordinary user that has earlier registered him/herself as a network-marketing distributor. He accesses the web interface of network marketing distributor account server. Furthermore, he selects a bunch of content, for example images and audio files. He downloads the content (which has already been re-encrypted in this example) to his mobile device and turns the network marketing software on before meeting his friends. The content he had downloaded from the web is visible to other network marketing users e.g. over the Bluetooth interface.  
         [0028]     The re-encrypted digital rights management protected content is sent ( 204 ) to the receiving device  24 . To be able to decrypt the re-encryption, the receiving device  24  needs a decryption key from the distributor  22 . The receiving device  24  sends ( 206 ) verification information, e.g. a device certificate, to the distributor  22 . In response to receiving the device certificate, the distributor  22  sends ( 208 ) a voucher (a decryption key) to the receiving device  24 . Now the receiving device  24  is able to decrypt the re-encryption.  
         [0029]     The receiving device  24 , on reception of the DRM Content, discovers the rights manager URL from the DRM Content headers and initiates ( 212 ) a Rights Object Acquisition Protocol session with the rights manager  26 . On completion of this protocol and appropriate payment arrangements, the receiving device  24  obtains ( 214 ) the Rights Object associated with DRM Content. Now, the user of the receiving device  24  is able to use this content.  
         [0030]     Each time somebody downloads content from distributor, he may be provided with a commission from the network marketing service provider. After receiving the device certificate from the receiving device  24 , the distributor  22  sends ( 210 ) accounting information to an accounting entity  26 . The accounting information defines, for example, who has downloaded content from the distributor and what was the downloaded content. Based on the accounting information the accounting entity  26  compares ( 216 ) the accounting information from the distributor  22  to the DRM transactions of the receiving device  24 , and if they match, the accounting entity  26  gives a commission to the distributor  22 .  
         [0031]      FIG. 2   b  discloses a solution for re-encrypting digital rights management content according to another embodiment of the invention. The solution disclosed in  FIG. 2   b  is almost the same as the one in  FIG. 2   a . The difference between  FIGS. 2   a  and  2   b  is that in  FIG. 2   b  the distributor  22  performs the re-encryption process ( 222 ) of digital rights management protected content. Therefore, the content server  20  provides ( 220 ) the distributor  22  with digital right management protected content in a normal way.  
         [0032]      FIG. 3   a  discloses a block diagram of a system according to one embodiment of the invention. The system comprises a distributor  32  connected to a content server  34 . The content server  34  provides digital rights management protected content to devices requesting the content. The distributor  32  is also connected to a receiving device  36  and to an accounting entity  30 . The receiving device  38  is connected to a rights manager  38  that provides rights objects for digital rights management protected content. The accounting entity  30  is also connected to the rights manager  38 . In this embodiment, the content server  34  comprises a re-encrypting module  300  that re-encrypts digital rights management protected content with a distributor-specific key  302 . Functional operation of elements of  FIG. 3   a  is disclosed in  FIG. 2   a.    
         [0033]      FIG. 3   b  discloses a block diagram of a system according to one embodiment of the invention. The system comprises a distributor  42  connected to a content server  44 . The content server  44  provides digital rights management protected content to devices requesting the content. The distributor  42  is also connected to a receiving device  46  and to an accounting entity  40 . The receiving device  48  is connected to a rights manager  48  that provides rights objects for digital rights management protected content. The accounting entity  40  is also connected to the rights manager  48 . In this embodiment, the distributor  42  comprises a re-encrypting module  400  that re-encrypts digital rights management protected content with a distributor-specific key  402 . Functional operation of elements of  FIG. 3   b  is disclosed in  FIG. 2   b.    
         [0034]     The re-encrypting module  300 ,  400  refers e.g. to a processing unit or to a combination of a processing unit and a memory. The memory may also include a computer program (or portion thereof), which when executed on the processing unit performs at least some of the steps of the invention. The processing unit may also include memory or a memory may be associated therewith which may include the computer program (or portion thereof) which when executed on the processing unit performs at least some of the steps of the invention.  
         [0035]     Furthermore, in  FIGS. 3   a  and  3   b  each of the receiving device, distributor and content server comprises means for processing information, means for sending information to other devices and means for receiving information from other devices. The aforementioned means may refer to at least one of the hardware units (e.g. to a processor, memory etc.) or software stored on a memory.  
         [0036]     It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims.