DRM refers to the fact that you can't view Amazon Kindle books on other devices (including your computer), or on other Kindles - i.e. no sharing, the purpose of DRM.
We've known for some time already that Amazon's AZW files are actually Mobi files, but Amazon didn't share Kindle's Mobi PID which would allow one to buy encrypted Mobi books for Kindle.
There are converters available from Amazon and/or Mobi for pdf and doc files.
Hack let you convert encrypted Mobipocket files that were intended for another reader so that that work on Kindle.
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