Pairing bluetooth devices in dual boot with Linux Ubuntu and Windows 10/11

pair-dual-boot-bluetooth.md

Pairing Bluetooth Devices in Dual Boot with Linux Ubuntu and Windows 10/11

Introduction

This guide provides updated instructions for pairing Bluetooth devices (such as keyboards or mice) in a dual-boot environment with Linux Ubuntu and Windows 10/11, incorporating community feedback and suggestions.

Instructions

1. Pair in Linux First

• Pair your Bluetooth device in Linux. This is crucial to ensure the LinkKey remains consistent.
• Note: Do not re-pair the device in Linux after completing the pairing in Windows.

2. Pair in Windows

• Pair the Bluetooth device in Windows. Note the MAC address of the device for later steps.

3. Install chntpw in Linux

• Install the chntpw package to read Windows registry keys:

  sudo apt-get install chntpw

4. Access Windows System Drive in Linux

• Mount your Windows system drive and navigate to the System32 config folder:

  cd /[MountedDrive]/Windows/System32/config

5. Use chntpw to Access Registry

• Execute the following command in the config folder:

  chntpw -e SYSTEM

6. Navigate to Bluetooth Registry Keys

• In the chntpw console, navigate to the Bluetooth registry keys:

  cd \ControlSet001\Services\BTHPORT\Parameters\Keys

7. Find and Copy the Pairing Key

• Use ls to list unique IDs and find your device's MAC address.
• Retrieve the pairing key (hex code) associated with your device.

8. Edit Linux Bluetooth File

• Edit the corresponding file in your Linux drive:

  sudo nano /var/lib/bluetooth/[Unique ID]/[Mac Address]/info

• Replace the Key value in the [LinkKey] section with the pairing key from Windows.
• If the [LinkKey] section is missing, add it manually.

9. Restart Bluetooth Service in Linux

• Save the changes and restart the Bluetooth service:

  sudo service bluetooth restart

Additional Methods and Tips

• Simplification with reged: Use reged to export Bluetooth pairing keys directly into a file for easier identification and copying.
• Bluetooth LE Devices: For Bluetooth LE devices, the data storage might differ. Users should research specific steps for these devices.
• Windows 11 Compatibility: This method is also compatible with Windows 11.
• Multiple Bluetooth Receivers: If you have multiple Bluetooth receivers, ensure you identify and use the correct pairing key.
• Changing Bluetooth MAC Address in Linux: If necessary, you can change the Bluetooth MAC address in Linux using the following commands:

  sudo hciconfig hci0 down
  sudo bluemoon -A
  sudo hciconfig hci0 up
  sudo systemctl restart bluetooth.service

• Adding Missing [LinkKey] Section: If the [LinkKey] section is missing in the info file, you should add it manually.

Acknowledgements

Special thanks to the community members who provided valuable insights and suggestions, including nnnnicholas, kna0085, lguangyu, KeyofBlueS, bjoern-vh, Nielius, IgorRodriguez, princeofguilty, and others.

I just successfully paired the keyboard this morning, then a sleep mode occurred when I returned from work and the keyboard wont pair with Ubuntu anymore, although I double checked the linking key harmonization is correct with Windows. Any idea why this might have happened?

@ForestEco Sleep mode usually have trouble with some bluetooth-wifi. Check your bluetooth model. If your notebook not fully support, check for experimental drivers or replace the wifi-bluetooth module with some other compatible like Intel AX

It worked, thank you!
In case someone runs into the same issues as me:

Note the MAC address of the device for later steps.

I couldn't find a tutorial for Windows 11.
You can find the mac address under:
device manager -> bluetooth -> right click the desired device -> properties -> details -> in the list scroll to "bluetooth device address"

Use chntpw to Access Registry

If chntpw SYSTEM is supposed to open a new console then it didn't happen for me. But the command shared by @KeyofBlueS works (remove the commas!)

Am I the only one for whom this doesn't work.
PS : Followed all the steps.

Am I out of luck if my Windows partition is encrypted?

@akaihola if you can mount it on Linux, it's fine, otherwise bad luck

The guide also shows how to change the bluetooth mac address on Linux if necessary. Is this something that would solve the need to re-pair my headset whenever booting to the other OS?

Windows 11 / Ubuntu 24.04

Mouse with Bluetooth 5.0 LE

I end up doing the reverse of this method to get it to work.
I tried copying the Long Term Key values from Windows to Linux, but that didn't work
but doing the reverse worked!

Here’s how you can do it:

First, Remove the current pairing of your mouse in Linux and pair it again.
Then, Note down the new MAC address and Long Term Key values, which you can find in \var\lib\bluetooth\...\{mac-address}\info

Now, reboot into Windows.

To modify the Bluetooth registry keys in Windows, you'll first need permission. Follow these steps:
1. Open the Registry Editor and navigate to ...\ControlSet001\Services\BTHPORT\Parameters\Keys
2. Right-click on the Keys folder, select 'Permissions', and add your Windows user. Grant it 'Full Control' permissions.
3. Relaunch Registry Editor

Next, rename the MAC address key of your mouse to match the one used in Linux (\var\lib\bluetooth\...\{mac-address})

(Keep the formatting as it is in Windows)
...\ControlSet001\Services\BTHPORT\Parameters\Keys\...\{mac-address}
...\ControlSet001\Services\BTHPORT\Parameters\Devices\{mac-address}

Then, navigate to ...\Keys\...\{mac-address}
and modify the LTK, ERand, and EDIV key values to match the corresponding Long Term Key values

After making these changes, restart your computer.

That’s it! Your setup should now be complete.

This method may not work with all devices, I'm having an issue with a Bluetooth 5.2 HeadPhone
When I pair it with Windows I can't find any key for the HeadPhone in ...\Parameters\Keys\...\
even with permission.

7. Find and Copy the Pairing Key
   ...
   Retrieve the pairing key (hex code) associated with your device.

Note that you need some additional steps here to retrieve the correct key.

here is what you need to do:

ls
Node has 1 subkeys and 0 values
key name
<keyid>

cd <keyid>

ls
Node has 0 subkeys and 1 values
size type value name [value if type DWORD]
16 3 REG_BINARY <regid>

hex <regid>
Value <regid> of type REG_BINARY (3), data length 16 [0x10]
:00000 XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX.......aU..'..

copy paste 17 hex number
remove spaces

key is in format
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX (34 letters)

add this to [LinkKey] section