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 still have issue with my Microsoft Bluetooth Ergonomic Mouse. This one is really tricky. Yes it can pair with up to 3 device, but if I pair it on both OS on my dual boot (Windows 11, LMDE 6), the mouse with always delete the older pairing because it's the same MAC address. So everytime I boot the other OS, I have to pair the device again and lose all preferences.

First, it's one of them changing MAC Address between each pairing because why not. That I can manage. On Linux, I got 3 keys: [LongTermKey], [PeripheralLongTermKey]and [SlavelLongTermKey]. The two last ones are identical but the first one differs. On Windows, only one key stamped as LTK. I got also ERand and EDiv but no IRK or CRK, even though there is a CEntralIRKStatus with a value of 1.

I never got a working combination. The best issue I got was to remove [LongTermKey] entirely and leave the two last ones with values I copied from Windows. After that, I got a stable connection on Linux (whereas all other tries resulted in connecting/disconnecting because key seemed wrong) but the mouse is blinking saying there is no connection.

Any ideas how to do on this one?

I was finally able to get my Microsoft Explorer Mouse and Designer Compact Keyboard working, by some better guidance in this post
https://unix.stackexchange.com/a/413831. I had a similar experience to you, where mouse would connect then disconnect in a loop.

Important

1. MAC changes on device repairing, and it's easy to miss if you're only visually looking at the begin and end of a MAC entry. So make sure you rename the directory
2. With my Win11 and Microsoft devices, IRK is set in registry root folder level of Parameters\Keys\{Bluetooth-Controller-ID}' called CentralIRK. I used this value for setting any [IdentityResolvingKey] that's used for all the devices using this same Bluetooth Controller. Not sure if this was necessary, but I also added a [LocalSignatureKey] with this same value.
3. Especially for my MS mouse, the only other section I needed was [LongTermKey], and it was extremely important to get the Rand and EDiv values byte-aligned as mentioned in the post. MS Designer Compact Keyboard did not care about these values.
4. I deleted the other key sections, I can't say whether they are necessary in the longer term, but for now this is working for me

That's what was missing! I was missing the CentralIRK in the root folder level. I also got another key in that folder with an hex name but idk what it is for.
I had to add the [IdentityResolvingKey] section in info and delete the other useless one.

Now it works as well. Thanks!