d4v3y0rk/howto.md

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    Encrypted Volumes in WSL2

Description

This is a quick guide on how to setup dm_crypt under WSL2 for working with encrypted volumes. I use an encrypted volume to store things like password recovery codes and 2nd factor backup codes etc. I recently switched over to using WSL2 and wanted to figure out how to enable this functionality there. This is the distilled howto for getting it to work.
Guide

First thing you have to do is create a custom WSL2 kernel. Inside your already installed and running WSL2 (ubuntu) installation:

Install some required packages.

$ sudo apt install build-essential flex bison libssl-dev libelf-dev libncurses5-dev git


Clone the WSL2 kernel

$ git clone https://github.com/microsoft/WSL2-Linux-Kernel.git
$ cd WSL2-Linux-Kernel


Export the current (running) kernel configuration

$ cat /proc/config.gz | gunzip > .config


Edit the .config file replacing...

#CONFIG_DM_CRYPT is not set

with 

CONFIG_DM_CRYPT=y


Compile the kernel

$ sudo make
$ sudo make modules_install


Copy the resulting kernel image out to your Windows Drive

$ cp ./arch/x86_64/boot/bzImage /mnt/c/Users/<your username>


Create a .wslconfig

$ vim /mnt/c/Users/<your user name>/.wslconfig

[wsl2]
   kernel=C:\\Users\\<your user name>\\bzImage
   swap=0
   localhostForwarding=true


Exit and Restart WSL2 (In powershell)

PS C:\Users\<your user name>\wsl --shutdown

Using the New Feature

Now you should be able to create open and close encrypted disks

Create an encrypted disk image file

$ fallocate -l 1024M mysecrets.img
$ sudo cryptsetup -y luksFormat mysecrets.img


Open the newly created disk image

 $ sudo cryptsetup open mysecrets.img mysecrets


give the new disk a filesystem (you only have to do this once)

 $ sudo mkfs.ext4 /dev/mapper/mysecrets


Mount the new disk image

  $ mkdir -p ~/mysecrets
  $ sudo mount -t ext4 /dev/mapper/mysecrets ~/mysecrets


When you are done using the encrypted disk

$ sudo umount ~/mysecrets
$ sudo cryptsetup close mysecrets

When you want to use it again just open and mount it again.