Commercial Issues, Digital Rights Management, and Licensing - A Practical Guide to Video and Audio Compression - page 328

standards-based DRM system. There is a long way to go yet but some progress is begin-
ning to be made. The encryption mechanism is a 128-bit NIST/AES standard, which is free
of any patent liabilities.
This is not a solution in itself but it is a move toward an interoperable system.

18.18.3 Windows Media DRM

Windows Media DRM protection is somewhat different from the Fair Play system. The
Windows Media solution depends on a message going back to an authentication service
to request permission to play. This worries some people, and with good cause. The control
over whether I can watch a program that I own, in my own home, on my own system is
not something I relish handing over to a third party. Asking someone else for permission
to watch a program that I have recorded or purchased is something that I find very intru-
sive. I would much rather it either be allowed without intervention or that I would be
denied the original recording process.
As with all proprietary systems, there are limits to the scope of formats that this
mechanism will protect. WM9 DRM supports these formats:

Windows Media Audio

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Windows Media Video

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Microsoft MPEG-4 Video

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Windows Media Screen

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ISO-MPEG-4 version 1

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18.18.4 Macrovision

Macrovision has a variety of copy-protection technologies that they have developed over
the years. The CDS-300 scheme is designed to apply copy protection to CDs and this
remains intact on the audio all the way to its destination in an iPod. This is interesting
because to do this, the scheme must work collaboratively with iTunes and the Apple Fair
Play system.
This level of interoperability is vital to the success of any DRM system. All DRM
products must exchange information about rights and permission with each other. It is
only then that users will enjoy the rights to easily move their content around between the
various repositories they are licensed to use.
At present, the favored approach is to implement one single DRM mechanism in all
systems. No single system has proven to be robust or portable enough. Interoperability is
the key and if DRM systems utilize the MPEG-21 mechanisms, there may be an opportu-
nity to do this.

http://www.microsoft.com/windows/windowsmedia/drm/default.aspx
Windows Media Series 10 DRM:
Macrovision: http://www.macrovision.com/