Quaintous // Removing DRM from E-Books on Linux

tl;dr

We’re going to install an ancient version of “Adobe Digital Editions” in wine and use some helper scripts from the DeDRM tools repository to remove DRM from E-Books.

Introduction

Do you remember the time when you used to buy something and then own it? Well I do. That’s exactly why the idea of putting DRM on digital products that I have bought and own (in contrast to DRM on for example a rented movie) is most annoying to me. I don’t pirate any kind of art, I buy it if I can and when I buy it I want to do whatever I want to do with, so the first thing I do is to remove DRMs. I used to do it using a Calibre plugin on MacOS. The trick was to use an ancient version of Adobe Digital Edictions (ADE) (v 2.0.1). As I migrated back to Linux, I wanted to have the same convenience. But I had two problems: i) I didn’t want to pollute my local machine with wine, and ii) it turned out that proper configuration of Calibre to use ADE keys (running under wine) is not working out of the box. My first intuition was to install wine in a virtual machine (VM) and use it only for DeDRM purposes. I started with Gnome Boxes to create and manage QEMU VMS. It also turned out to be a pain: spice sharing didn’t work properly and I didn’t find a quick way to conserve Gnome VM boxes (for backup/migration purposes) without having to copy different files from different directories etc. So I ended up with doing everything from the scratch!

Prepare qemu image

We start with creating a QEMU image to install Ubuntu, run ADE inside wine, and finally DeDRM our E-Books:

qemu-img create -f qcow2 ade.qcow2 10G

We move on to boot from an Ubuntu image and install the system:

 qemu-system-x86_64 -boot d -cdrom ~/Downloads/ubuntu-20.04-desktop-amd64.iso \
    -m 2048 -smp 8 -cpu host -enable-kvm -hda ade.qcow2

Note that I use a x86_64 system instead of a 32 bit version which would theoretically suffice for Wine and ADE: DON’T EVEN THINK ABOUT 32 BIT. I went down that road and it was all pain! Here I use Ubuntu 20.04 LTD beause it just works! I tried other distributions and older version and the result was a mess (maybe I missed something!). After Ubuntu is successfully installed, shut down the VM.

Preparing Ubuntu

Let’s run the freshly installed Ubuntu instance:

qemu-system-x86_64 -m 2048 -hda ade2.qcow2 -smp 8 -cpu host -enable-kvm \
    -fsdev local,id=shared_dev,path=$(pwd)/share,security_model=none \
    -device virtio-9p-pci,fsdev=shared_dev,mount_tag=shared_mount

The second and third lines are required for sharing files between host and guest machines. We’ll get back to this later. First, we need to install wine. Don’t use the version from Ubuntu repository, but use the latest version from WineHQ repo:

sudo dpkg --add-architecture i386
wget -nc https://dl.winehq.org/wine-builds/winehq.key
sudo apt-key add winehq.key
sudo apt update
sudo apt install --install-recommends winehq-stable

Verify that everything went well:

wine --version

I have wine-5.0.3 and I can assure you that it everything works on this version. Next we will create a dedicated wine prefix only for the ADE:

export WINEPREFIX=~/.ade
export WINEARCH=win32
winecfg

When wine config dialog opens, make sure that you have selected Windows XP. You can leave the rest as is. Now we need to download MS .NET 3.5 SP 1 and ADE 2.0.1. I assume that you have both files under ~/Downloads. We’ll go ahead and install both in our wine prefix:

wine start ~/Downloads/dotnetfx25.exe
wine start ~/Downloads/ADE_2.0_Installer.exe

Now you must be able to run ADE. Try to login (Authorize Computer) and see if it works. In my case, everytime I navigated to the password field ADE crashed. Interestingly enough, it turned out some of fonts are missing under wine:

sudo apt install winetricksWebKitGTK+
winetricks -q corefonts

This should solve the crashes.

Removing DRM from file

The basic idea here is to extract the private key that ADE uses to decrypt DRM and remove the DRM permanently. We need pyhthon for that, but we need it under wine and not Ubuntu:

winetricks -q python27

An additional package, pyCrypto is also required for cryptographic operations which can be downloaded here. NOTE: this is the only version of pyCrypto that worked for me; in general it’s a very bad idea to download a package used for cryptographic purposes from some random source on the Internet, but since we have everything sandboxed in QEMU I didn’t really care, but you might do!

wine start ~/Downloads/pycrypto-2.6.wine32-py2.7.exe

Now that we have python and pyCrypto on our windows machine, we can get starting with hacking ADE. I have prepared two scripts to make that easier for you. Download all three init.sh, dedrm.sh and sources.txt and run init.sh which fetches necessary python scripts and extracts the private ADE key. This step is run inside the wine machine:

After running this script, two new directories are added lib and conf:

* `lib`: contains downloaded helper scripts.
* `conf`: contains extracted ADE key.

Now open any DRM-protected book in ADE. It will save the file under ~/Documents/My Digital Editions/. You can now remove the DRM using the dedrm.sh script:

./dedrm.sh ~/Documents/My\ Digital\ Editions/${BOOK}

replace ${BOOK} with the proper file name.

Moving files between guest and host

Remember those lines that we ignored when starting the QEMU VM? Those lines “create a virtual filesystem (virtio-9p-device)” that we can use as a shared point of entry. The only thing needed to do is to run the following on the guest machine:

mkdir ~/shared
sudo mount -t 9p -o trans=virtio shared_mount ~/shared/ -oversion=9p2000.L,posixacl,msize=104857600,cache=loose

Now every file that you put inside ~/shared directory on the guest machine is going to be available on the host machine under $(pwd)/share (see path argument as part of the -fsdev flag we used earlier to start the VM).