Thorium Reader EPUB Extractor

[Martin Krpan]

Thorium Book Extractor

Thorium Book Extractor is a small utility that automates the process of extracting EPUB books exported from the Thorium Reader. It follows the manual process described in the shkspr.mobi article and performs the required steps automatically.

The tool takes an EPUB file exported from Thorium Reader and generates a usable version of the book.

Requirements
Before using this tool, make sure the following requirements are met:

• Thorium Reader version: 3.1.0
• The book must be exported as EPUB from Thorium Reader first
• Thorium Reader must be closed before running the extractor

Download Thorium Reader 3.1.0 here:
https://github.com/edrlab/thorium-re...etup.3.1.0.exe

How It Works
The extractor automates the manual extraction process described in the article linked above. After exporting a book from Thorium Reader, the tool processes the file and generates a new EPUB file.

The output file will have the same name as the original file with _decrypted appended.
original_book.epub -> original_book_decrypted.epub

Step 1 – Export the Book from Thorium Reader

1. Open the .lcpl file in Thorium Reader.
2. Export the book as EPUB.
3. Close Thorium Reader completely.

The extractor will not work correctly if Thorium Reader is running.

Step 2 – Run Thorium Book Extractor
Option 1: Process a Single Book
Run the tool from the terminal:

ThoriumBookExtractor.exe path_to_the_book.epub

Option 2: Process Multiple Books
You can also extract multiple EPUB files automatically.

1. Place ThoriumBookExtractor.exe in the folder containing your EPUB files.
2. Double-click the executable.

The application will:

• Scan the folder for .epub files
• Process each file
• Generate a decrypted version for each one

ThoriumBookExtractor opens and closes the Thorium Reader automatically.
This is necessary for the extraction process.
Do not close automatically opened Thorium Reader while the app is running.


Source code and the executable file can be found here:
https://gitflic.ru/project/xna83444/...book-extractor

[Martinoptic]

Does this work with latest Thorium 3.3?

[DeLitCommonPotoo]

Originally Posted by Martinoptic

Does this work with latest Thorium 3.3?

Probably not. As after edent's blog post highlighting the extraction techniques this tool uses Readium added code to try to block connecting a debugger - which this tool relies on.

This Docker-based tool does work with Thorium 3.3, because instead of trying to connect directly to Thorium, it wraps Thorium with an Electron app script (Electron version needs to match exactly what is used to build Thorium).

OP might be able to patch their Windows tool to use the same approach, (if you wrap Thorium will an Electron app you can have the debugger connect and remove the command line args before handing over executionto Thorium) but I'm not sure how practical that is. It might not be easy to automatically download and execute Electron on Windows, and also might not be worthwhile requiring the user to install Electron on their own for the tool to work.

[batonebo]

Thorium is unnecessary, you can simply decrypt the epub/pdf/etc directly.

This (local) browser-based file (download and open in browser) does the whole decryption alone. Source code at rad:z41uCZqyBUSRQoBCQq4Bpq8ZSCHKr (radicle repository)

[DeLitCommonPotoo]

Originally Posted by batonebo

Thorium is unnecessary, you can simply decrypt the epub/pdf/etc directly.

This (local) browser-based file (download and open in browser) does the whole decryption alone. Source code at rad:z41uCZqyBUSRQoBCQq4Bpq8ZSCHKr (radicle repository)

Oooh, extremely nice!

Hard to argue that a standalone (Thorium-less) Rust-based CLI (or WASM single-page web interface) is anything other than a much nicer user experience!!!

Curious though, am I reading it correctly that the extent to which spoofing goes when fetching the encrypted epub is to set the User-Agent to "ThoriumReader/windows-mac-linux/1.1"?

I guess one reason I opted for the "remoting Thorium approach" (other than the obvious of not having the cryptographic know-how to implement what's in that radicle repo), is that I perceived doing so (perhaps naively?) as being a little bit safer in terms of potential risk of being e.g. blacklisted by stores or license providers...

Do you know if Thorium itself uses that User-Agent internally? Or whether this simple spoofing approach has otherwise been used widely in the past without issue?

[batonebo]

Originally Posted by DeLitCommonPotoo

Oooh, extremely nice!

Hard to argue that a standalone (Thorium-less) Rust-based CLI (or WASM single-page web interface) is anything other than a much nicer user experience!!!

Curious though, am I reading it correctly that the extent to which spoofing goes when fetching the encrypted epub is to set the User-Agent to "ThoriumReader/windows-mac-linux/1.1"?

I guess one reason I opted for the "remoting Thorium approach" (other than the obvious of not having the cryptographic know-how to implement what's in that radicle repo), is that I perceived doing so (perhaps naively?) as being a little bit safer in terms of potential risk of being e.g. blacklisted by stores or license providers...

Do you know if Thorium itself uses that User-Agent internally? Or whether this simple spoofing approach has otherwise been used widely in the past without issue?

Sorry for replying so late. This is somewhat the extent of the "spoofing", but spoofing is wholly unneeded. This is indeed the user agent used in thorium (according to the github repo). When you receive an encrypted book, what you actually get is a license file which contains the decryption key to the book (encrypted via your user key so that your license is personal), and a link to the actual encrypted epub. The actual encrypted epub is shared between all users of a given vendor, which means that no matter how unusual your request may look, the server doesn't know what user is requesting the file. I'll add that in my experience such files are hosted on CDNs which absolutely do not care about user agent.

If you *really* don't want to take a chance, thorium will actually download the encrypted epub to somewhere in /tmp, so you can grab that instead and work from there.

The whole schtick about LCP is that it can work completely offline (every telemetry/tracking feature is, as per the spec, completely optional by design). Stores have actually no idea if/when you're decrypting books and if/when it's for legitimate reasons. The only information they get is "Someone fetched this encrypted resource" (don't know who, they only know what the http request contains, which I suspect they give no F about). Use a VPN if you're paranoid!

[Marko]

Thorium 3.1.0 has been removed from GitHub but luckily it can be downloaded from the WAPT Store and extracted from the wapt archive. Would be great to mirror it elsewhere, though.

[Real_Bookworm]

Originally Posted by Marko

Thorium 3.1.0 has been removed from GitHub but luckily it can be downloaded from the WAPT Store and extracted from the wapt archive. Would be great to mirror it elsewhere, though.

Newer versions won't work? The author says that there were important security fixes, and versions before 3.2.1 were deleted from the repository.

[JSWolf]

There are other ways to remove LCP DRM that work much easier.. Read the following thread.

https://www.mobileread.com/forums/sh...d.php?t=366846