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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 a IP network, to a PC or device.
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
How it works
An analysis of an earlier version of the DRM scheme in Windows Media Audio revealed that it was using a combination of elliptic curve cryptography key exchange, DES block cipher, a custom block cipher, 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.
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. Rather than break the encryption itself, which is practically uncomputable, 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.
See also
External links
"Windows Media DRM"