File Types

Content downloaded using the OMA Separate Delivery format has been converted from plaintext format into DRM content format (DCF). This conversion includes symmetric encryption of the content making the DRM protected content object useless to parties not having access to the Content Encryption Key (CEK). The CEK is contained within a rights object which is delivered independently of the DCF(containing the media). The DCF file can be distributed as much as desired, yet it will remain protected as the rights object shall be forward-locked. This is the basis for the superdistribution model. Typically, the DCF object is downloaded using the browser, after which the rights object is separately delivered to the device using WAP push. Handsets that support Separate Delivery MUST support OMA combined delivery as well as OMA forward locking.

DRM solutions apply to all file formats. The OMA DRM solution is content agnostic and can be used for any type of content that the handset supports. Individual files are handled in the same manner as a DRM file would be handled. Files downloaded using OMA Combined Delivery will be downloaded within a DRM message and will consist of a media object and a rights object. The download manager will recognize the DRM message MIME type and the MIME type ‘application/vnd.oma.drm.rights+xml’ as a valid file type. A single media object in the body of the DRM message that is encoded in the following identity transfer encoding ‘7bit’, ‘8 bit’, and ‘binary’ will be accepted by the download manager.

RFC 2045 [RFC2045] defines the Content-Transfer-Encoding, which specifies how a specific body part is encoded for transfer by some transfer protocol. Content-Transfer- Encoding MUST only be used with body parts of DRM message, not with the whole body of the DRM message. The device MUST support the identity transfer encoding “binary”. Other nonidentity Content-Transfer-Encodings like “base64” MAY also be supported

A Content-Transfer-Encoding header, as defined in RFC 2045 [RFC2045], MUST be present in the body part of the DRM message.