Discretix OMA DRM Client
The OMA DRM standard is considered today as the leading DRM standard among mobile operators as it includes flexible business models like super distribution (allowing viral distribution of content among users) and subscription. Unlike proprietary standards the OMA DRM standard is an open standard which is actively promoted by leading mobile operators. The Development of OMA DRM Standard.
The Open Mobile Alliance (OMA) published the first draft of the OMA DRM V1.0 scheme in 2002, followed by the final specifications in early 2004. This scheme offered limited content distribution control and limited security. The second version of the OMA DRM scheme, published later in 2004, offered a much better content distribution control mechanism, based on symmetric and asymmetric cryptography and offered a wider range of business models through an expression language based on XML. In 2008 the OMA DRM group finalized the OMA DRM V2.1 specifications.
Discretix Multi-Scheme DRM Client fully supports OMA DRM V1.0 (link to OMA DRM V1.0), OMA DRM V2.0 (link to OMA DRM V2.0) and OMA DRM v2.1(link to OMA DRM V2.1):
OMA DRM V1.0
Discretix Multi-Scheme DRM Client fully supports OMA DRM V1.0 specifications, including the following content distribution methods:
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Forward Lock (FL) – Discretix Multi-Scheme DRM Client ensures that content delivered to the phone cannot be consumed on any other device. Forward Locked content items arrive unencrypted to the device using regular DL-OTA protocol or HTTP connection. The client encrypts these content items with a device unique secret key. In addition, encrypting FL content items ensures that items can be backed up to a removable flash device, but cannot be consumed on other devices.
Combined Delivery (CD) – Discretix Multi-Scheme DRM Client supports content items that are delivered bundled with their Rights Object (RO). ROs define the specific sets of authorizations in regards to content item consumption, including content renting and subscription. Content arrives unprotected to the device using regular DL-OTA protocol or HTTP connection just like FL content item. The content items are being protected by the same mechanism described in the previous paragraph. Note: FL and CD content-distribution methods represent a relatively low content protection level, as items arrive unencrypted to the phone.
Separate Delivery (SD) – Discretix Multi-Scheme DRM Client supports the Separate Delivery distribution method. In this distribution method content items are sent encrypted to the device. Content objects can be sent using various methods including DL-OTA, HTTP, MMS or any near field communication protocol. Content is being decrypted according to constrains and permissions that are embedded in the content’s Rights Object. The Rights Object includes also the content’s decryption key and is sent separately from the content objects (hence the method name Separate Delivery). In addition to the business models that were enabled by the Combined Delivery method, Separate Delivery also supports Super Distribution.
OMA DRM V2.0
OMA DRM V2.0 provides backward compatibility to OMA DRM V1.0. All the OMA DRM V1.0 functionality is available when implementing OMA DRM V2.0.
Discretix Multi-Scheme DRM client supports the enhanced set of constraints and permissions offered by OMA DRM V2.0. The supported constrains are:
- Count – Number of times the content item can be consumed (available in both versions of OMA DRM).
- Date Time – A timeframe in which the content can be consumed (available in both versions of OMA DRM). Example: Between August 1, 05 and August 31, 05.
- Interval – An interval in which the content can be consumed (available in both versions of OMA DRM). Example: A week from first use of the content.
- Timed Count – As like the count constraint, it enumerates the number of times the content can be consumed. However it also specifies how many seconds will pass before the counter will be decreased (available only in OMA DRM V2.0).
- Accumulated – A constraint that defines the maximum period of metered usage time during which the content can be consumed (available only in OMA DRM V2.0).
Discretix Multi-Scheme DRM Client supports Domains as defined in OMA DRM V2.0 specifications. According to the OMA specifications, a Domain is a set of devices that share a common key (called a Domain Key). This key enables the devices to share Rights Objects and content items between themselves. The OMA DRM Domain concept is network centric. The Rights Issuer defines the Domains, manages the Domain Keys, and controls which devices are included and excluded from the Domain. Users may request to add devices to a Domain before acquiring Domain-bound content, or may make these requests after receiving Domain-bound content. In addition the DRM client supports the Hash Chains methods for Domain-Key generation. Domain keys are changed from time to time. Usually when a device is added or removed from a domain (in OMA DRM V2.0 terminology this event is called Domain Generation change). Hash chains method provides an efficient method to easily determine what is the current Domain key used without storing the entire domain keys history list for the specific domain. Transaction Tracking Discretix Multi-Scheme DRM Client updates the transaction tracking field in DCF files. This field enables the Rights Issuer to collect tracking data on content items. This enables content owners to track super-distribution routes of content items.
OMA DRM V2.0 specifications support two types of content containers (file formats), both are supported by Discretix Multi-Scheme DRM Client:
- DRM Content Format (DCF) – DCF files may be used for discrete content items. Note: The DCF file may contain more than one content item.
- Packetized DRM Content Format (PDCF) – PDCF files may be used as a container to stream content. The PDCF headers are added on top of the regular streaming information.
Subscription Business Model
Discretix Multi-Scheme DRM Client supports the enhanced subscription business model defined under OMA DRM V2.0 specifications. OMA DRM V2.0 specifications offer an easier way to renew time-based rights objects compared to the OMA DRM V1.0 specifications. Rights objects can be used in a hierarchical way, in which Rights objects inherit attributes from other Rights Objects. Using this model, a user who needs to renew his subscription period must inherit only the “parent” Rights object.
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OMA DRM V2.1
Discretix Multi-Scheme DRM Client fully supports OMA DRM V2.1 specifications.
OMA DRM V2.1 presents a set of new business models, including:
- Metering – Getting information about the actual use of the content object by the user.
- Backup licenses (ROs) on the server – OMA DRM V2.1 offers a method to upload ROs to the server. These ROs can later be used by the user by downloading them again to the same or to a different device. In case of statefull RO, the current state of the license is being uploaded.
- Improved PDCF formatting – OMA DRM V2.1 includes improved definition for OMA DRM Packateized DRM Content Formatting (PDCF) files. The improved formatting matches requirements made by the OMA BCAST group.
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Comparison between OMA DRM V1.0 and V2.0 specifications
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