Digital Rights Management (DRM)

The use of mobile and portable devices to download and use content raises the
issues of rights management. The originator of the content, whether music, images,
movies or games, will have spent a lot of time and money developing that content
and will want to exert some control over the future use of that content. This is
where DRM systems can be applied to limit the use, and therefore prevent misuse
of content.

There are a large number of proprietary DRM systems at present, which reflects
the growing availability of digital content over the Internet and other networks,
and is indicative of the lack of standards in this area. The Open Mobile Alliance
(OMA) has worked on enablers for DRM systems aimed at mobile handsets and
other portable devices, and many handset manufacturers now support OMA DRM
but may also support proprietary techniques as the market dictates. DRM systems
are built around a trusted entity known as a DRM agent (or client), which in the
case of a mobile network resides in the handset.

The DRM client is able to download content and the rights to use that content.
The content and rights can be kept separate or can be delivered in a combined format.
Rights are a mixture of permissions and constraints that indicate what can
be done with the associated content.

For example, content may be valid for 30 days, or until the end of the month;
the number of plays may be limited; etc. It is the responsibility of the DRM agent
to apply the rights to the content and to track its usage, so that if, for example, it
is a song that can only be played 30 times, then the content cannot be used unless
new rights are obtained.

OMA release 1 DRM included a number of basic features, which were forward
lock (preventing content forwarding), combined delivery, and separate delivery.
Separate delivery, where the content and rights are kept separate, supports something
known as super-distribution, whereby users are able to distribute content at
will, but not the rights for that content. This can be very useful where the content
has some sort of preview mode that can be used to encourage recipients to acquire
their own rights to that content.