I'm writing a series Of articles on how to use free and open source software to work with e-books. I established an absolutely arbitrary distinction, which is to consider e-books only those formats that allow a high level of interactivity, because in my opinion, this is where this format takes a great advantage over paper books.
Amazon and its formats. A real headache
For better or for worse, Amazon is an inescapable benchmark in the e-book market. In an ideal world, my recommendation would be to avoid buying from them since their distribution model imposes serious restrictions on user rights.s. But, there are books that are only available on Amazon. As a technical curiosity (I would never influence readers to violate the law) I mentioned that there are three methods to bypass copy protection technology:
- Use Caliber with a plugin.
- Use shareware with Wine.
- Use a sequential screenshot script.
The first method took me almost the entire previous article And it only works properly using older versions of the Kindle app or program. that only work with the .azw format. However, later I discovered that there is a plugin that under certain conditions allows converting .kfx to other formats.
The complement KFX input allows you to import books in Amazon KFX format and convert them to other e-book formats, such as EPUB, for archiving and reading on alternative devices. The plugin can convert from various versions of KFX: monolithic KFX, KFX-ZIP or KPF.
When we download a book in .kfx format from Amazon pages, we get a package of files made up of an encrypted main container, a metadata container, auxiliary containers (zero or more) and the DRM data. Each of them contains only a part of the content of the book and cannot be converted one by one. In addition to the ".kfx" extension, we can see them in other programs with the extensions (".azw", ".azw8" and ".azw9").
Limitations
This plugin has a very limited field of action. The method will only work with Kindle PC / Mac versions 1.19 to 1.26 and Kindle E-ink device firmware versions 5.6.5 to 5.12.1. You will not achieve anything with books downloaded with other versions of that software or obtained with the Kindle applications for iOS or Android.
Please note that all books downloaded with new versions of Amazon hardware and software have DRM protection, At most, the only thing the publisher can decide is to remove the limit of devices on which the user can install them.
The plugin installation method is exactly the same as we saw in the previous article, only we shouldn't extract the folder previously.
Methods of importing .kfx files
If we are using version 1.19 or higher of Kindle for Windows or Mac we will have to go to the My Kindle Content folder. In it we will find a subfolder for each book, named with the ten character ASIN of the book followed by "_EBOK". Inside it we will find the main file of the book will have an extension ".azw", On Kindle electronic ink devices connected via USB, the main file of each book is in the folder "documents" or, perhaps, in a subfolder called "Downloads" within the previous one. The files are identified by both the book title and the ASIN. Books in KFX format will have a ".kfx" extension.
Once we find the book, we can press the Add books button and go to the directory or simply drag and drop it into the application window. Under no circumstances should the import be made from a folder other than the original one. The import process may take a while and, if it is successful, we will see the file in the .kfx format listed. You are now ready for conversion to other formats.
If you are sensitive, do not read the following article. I'm not going to behave as required in an open source broadcaster. But, is that if I can not do it the good way, I will have to go the hard way.