Windows Media DRM

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Windows Media DRM is a Digital Rights Management service for the Windows Media platform. It is designed to provide secure delivery of audio and/or video content over an IP network to a PC or other playback device in such a way that the distributor can control how that content is used.

WMDRM includes the following components:

Windows Media Rights Manager (WMRM) SDK for packaging content and issuing licenses
Windows Media Format SDK (WMF SDK) for building Windows applications which support DRM and the Windows Media format
Windows Media DRM for Portable Devices (WMDRM-PD) for supporting offline playback on portable devices
Windows Media DRM for Network Devices (WMDRM-ND) for streaming protected content to devices attached to a home network

1 How it works
2 Interoperability
3 Removal
4 References
5 See also
6 External links

[edit] How it works

An analysis of version 2 of the DRM scheme in Windows Media Audio revealed that it was using a combination of elliptic curve cryptography key exchange, the DES block cipher, a custom block cipher dubbed MultiSwap (for MACs only), the RC4 stream cipher, and the SHA-1 hashing function.

Windows Media DRM is designed to be renewable, that is, it is designed on the assumption that it will be cracked and must be constantly updated by Microsoft. The result is that while the scheme has been cracked several times, it has usually not remained cracked for long.^{[citation needed]}

Version 1 was released in April 1999 and supported basic business rules such as expiration dates. Version 2 was released in January 2003 and is also known as version 7.x and 9, to keep in sync with the equivalent versions of Windows Media Player. Version 3, better known as DRM v10, was released in 2004. Earlier versions of the system have cracks available, meaning content protected with these versions can have the protections stripped. Version 10 was cracked in early 2005, but a software update was shortly pushed which sealed the relevant hole.

Generally, these sorts of cracks have all worked in the same way to a certain extent. Rather than break the encryption itself, which is infeasible, they hook or interfere with the "black box" component as it runs to dump out the content keys or the unencrypted content from memory. These sorts of techniques are brittle and easily patched by Microsoft via Windows Update^{[citation needed]}. Still, since all Software DRMs ultimately rely on obfuscation rather than true security, as crackers sharpen their tools, they will also improve the speed and quality of their attacks.

[edit] Interoperability

The content delivered with the WMDRM encryption is not universally accessible but limited to those users running Microsoft Windows, since Microsoft does not develop compatible software for any other platform.

[edit] Removal

Tools have been created to strip files of Windows Media DRM, such as FairUse4WM, a program released on August 19, 2006^[1] written by Viodentia has the ability to strip DRM from files protected with WMDRM version 10 and 11.^[2] However, on August 28, 2006 Microsoft released a new version of the individualized blackbox component (IBX) to prevent FairUse4WM from working. Within 3 days, a new version of FairUse4WM was released circumventing this fix.^[3] Microsoft informed partners that they are working to fix this issue again ^[4] and issued notices to web site owners. ^[5] They soon followed up by filing lawsuits. ^[6] As of October 16th, distributors using the Windows Media DRM protection such as Sky Anytime, are up and running using a patched codec.