When you buy a book for your Kindle on Amazon, it comes with a special surprise: DRM. Yes we are in 2015, every book ever published is already available everywhere to download for free, but you still get this stupid thing that basically pisses everybody and forbids to just use the stuff you paid for. Unbelievable. They will never learn.
So, what do you do when you accidentally bought a DRM e-book? First you swear you'll never do the same mistake again, and next time you'll just download the book from The Pirate Bay, it will be faster, easier and you will be able to read the book without wondering why the hell did you pay for a file that you can't read. When that is done, you will actually get rid of the DRM following this simple procedure:
$ unzip DeDRM_plugin.zip
$ python k4mobidedrm.py -s YOUR_KINDLE_SERIAL_NUMBER Stupid_encrypted_DRM_book.azw ./
That's it. A new file called Stupid_encrypted_DRM_book_nodrm.mobi will be in the directory. Delete the old one.
What was this DRM thingy for?