[2] According to the specification, the client software obtains a 7 byte plain-text content key Kcontent from the license server.
As an anti-spoofing measure, additional fields such as playback rights and a random number are encrypted with three more predefined ECC key pairs either by the client or server software: 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.
Tools have been created to strip files of Windows Media DRM, enabling them to be played on non-Janus platforms.
Microsoft has been more successful in squashing the development and distribution of the tools capable of key finding than those that decrypt encoding, as is apparent by the continual existence of the SourceForge project FreeMe2.
[4] It was claimed that one particular tool, FairUse4WM (released on August 19, 2006)[5] written by Viodentia, had the ability to strip DRM from files protected with WMDRM.
[11] By October 16, 2006, distributors using the Windows Media DRM protection, such as Sky Anytime, were using a patched codec.
On September 6, 2007, Microsoft updated IBX to version 11.0.6000.7000, in an attempt to thwart circumvention efforts by variants of the original program.
[12] DRMDBG is a key-finder, it extracts the keys by hooking an instance of Windows Media Player that it launches.