How to: Dualboot Windows +Bitlocker and Ubuntu +LUKS

Preparation

Tested with

Tested with: Win 11 Pro 23H2, Ubuntu 23.10
Last Update: 2024-02-07

Environment

UEFI Notebook
Secure Boot enabled (should also work without)
NVMe disk /dev/nvme0n1

Steps

1. Create partitions

Boot Ubuntu live session from a pendrive.
Open gparted via “sudo gparted”
- create new GPT partition table
- create partition: 550MiB FAT32 labelled EFI
- create partition: 550MiB EXT4
- create partition: 103264 MiB NTFS (102500 + 764)
  My windows will be using 100 GB here. If you activate Bitlocker later on, 764 MB will be taken from this partition. If you need 200 GB for instance, you can take 205664 (204900 + 764).
- apply changes
- right click on EFI partition, manage flags, set BOOT and ESP

2. Install Windows

Boot Windows from pendrive and install into your NTFS partition above.
(Keep in mind that only the Pro versions and above are supporting Bitlocker.)
Do not set up Bitlocker yet.

3. Install Ubuntu

Boot Ubuntu live session
Open gparted
- create partition for your Linux: 204800 MiB ext4 (/dev/nvme0n1p5)
  you can take as much as you need
- apply and close
Open “Ubuntu Legacy Installer” on the desktop
If you have Secure Boot enabled, you will be asked to set a password for the Secure Boot MOK key. Choose anything you want. You will have to type it on your next reboot once.
When the installer asks for partitioning choose “something else”.
Doubleclick on /dev/nvme0n1p5, choose physical volume for encryption and a reasonable password
Doubleclick on /dev/mapper/nvme0n1p5_crypt at the top, use EXT4 or BTRFS, format, mount point: /
You can choose any filesystem you like. I’ve made good experience with BTRFS.
Doubleclick on /dev/nvme0n1p2, use EXT4, format, moint point: /boot
Device for boot loader installation is: /dev/nvme0n1
Reboot system after installation and if you will be asked to perform MOK management, then choose to enroll MOK, continue, yes, provide your chosen password.

Both systems can boot up properly now. You will be asked by GRUB which operating system to boot now: Ubuntu or Windows Boot Manager.

4. Activate Windows Bitlocker

Boot into Windows and look for Bitlocker in the settings. Go through the guided steps as you normally do, to achieve Bitlocker encryption.

Good to know

If you are not living in a region with timezone UTC, you will notice the system time differs between Windows and Ubuntu. To fix that simply issue “sudo timedatectl set-local-rtc 1” in the Ubuntu terminal. Once you set up your time correctly within Windows, your system time will not jump around any more.