Bluetooth Pairing – Stop Having to Pair Devices on Dual Boot of Windows & Linux Mint/Ubuntu

bluetoothdual-bootlinux-mintwindows

When dual booting Windows 7/10 and Linux Mint/Ubuntu, you may find yourself having to re-pair your Bluetooth devices again and again. This will happen every time you switch OS.

Now, how do you prevent this?

I'm answering my own question with the following guide, which has been tested on Ubuntu 14.4 and Linux Mint 17.2, 17.3 and now Linux Mint 18.x.

Best Answer

Why does this happen?

Basically, when you pair your device, your Bluetooth service generates a unique set of pairing keys. First, your computer stores the Bluetooth device's MAC address and pairing key. Second, your Bluetooth device stores your computer's MAC address and the matching key. This usually works fine, but the MAC address for your Bluetooth port will be the same on both Linux and Windows (it is set on the hardware level). Thus, when you re-pair the device in Windows or Linux and it generates a new key, that key overwrites the previously stored key on the Bluetooth device. Windows overwrites the Linux key and vice versa.

Bluetooth LE Devices: These may pair differently. I haven't investigated myself, but this may help Dual Boot Bluetooth LE (low energy) device pairing

How to fix

Using the instructions below, we'll first pair your Bluetooth devices with Ubuntu/Linux Mint, and then we'll pair Windows. Then we'll go back into our Linux system and copy the Windows-generated pairing key(s) into our Linux system.

Pair all devices w/ Mint/Ubuntu
Pair all devices w/ Windows
Copy your Windows pairing keys in one of two ways:
- Use psexec -s -i regedit.exe from Windows (harder)
  1. Go to "Device & Printers" in Control Panel and go to your Bluetooth device's properties. Then, in the Bluetooth section, you can find the unique identifier. Copy that (you will need it later).
  2. Download PsExec from http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx.
  3. Unzip the zip you downloaded and open a cmd window with elevated privileges. (Click the Start menu, search for cmd, then right-click the CMD and click "Run as Administrator".)
  4. cd into the folder where you unzipped your download.
  5. Run psexec -s -i regedit.exe
  6. Navigate to find the keys at HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\BTHPORT\Parameters\Keys. If there is no CurrentControlSet, try ControlSet001.
  7. You should see a few keys labels with the MAC addresses - write down the MAC address associated with the unique identifier you copied before.
- Use chntpw from your Linux distro (easier). Start in a terminal then:
  1. sudo apt-get install chntpw
  2. Mount your Windows system drive
  3. cd /[WindowsSystemDrive]/Windows/System32/config
  4. chntpw -e SYSTEM opens a console
  5. Run these commands in that console:
```
> cd CurrentControlSet\Services\BTHPORT\Parameters\Keys
> # if there is no CurrentControlSet, then try ControlSet001
> # on Windows 7, "services" above is lowercased.
> ls
# shows you your Bluetooth port's MAC address
Node has 1 subkeys and 0 values
  key name
  <aa1122334455>
> cd aa1122334455  # cd into the folder
> ls  
# lists the existing devices' MAC addresses
Node has 0 subkeys and 1 values
  size     type            value name             [value if type DWORD]
    16  REG_BINARY        <001f20eb4c9a>
> hex 001f20eb4c9a
=> :00000 XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX ...ignore..chars..
# ^ the XXs are the pairing key
```
  6. Make a note of which Bluetooth device MAC address matches which pairing key. The Mint/Ubuntu one won't need the spaces in-between. Ignore the :00000.
Go back to Linux (if not in Linux) and add our Windows key to our Linux config entries. Just note that the Bluetooth port's MAC address is formatted differently when moving from Windows to Linux - referenced as aa1122334455 in Windows in my example above. The Linux version will be in all caps and punctuated by ':' after every two characters - for example AA:11:22:33:44:55. Based on your version of Linux, you can do one of these:
- Before Mint 18/16.04 you could do this:
  1. sudo edit /var/lib/bluetooth/[MAC address of Bluetooth]/linkkeys - [the MAC address of Bluetooth] should be the only folder in that Bluetooth folder.
  2. This file should look something like this:
```
[Bluetooth MAC]   [Pairing key]                 [digits in pin]  [0]
AA:11:22:33:44:55 XXXXXXXXxxXXxXxXXXXXXxxXXXXXxXxX 5 0
00:1D:D8:3A:33:83 XXXXXXXXxxXXxXxXXXXXXxxXXXXXxXxX 4 0
```
  3. Change the Linux pairing key to the Windows one, minus the spaces.
- In Mint 18 (and Ubuntu 16.04) you may have to do this:
  1. Switch to root: su -
  2. cd to your Bluetooth config location /var/lib/bluetooth/[bth port MAC addresses]
  3. Here you'll find folders for each device you've paired with. The folder names being the Bluetooth devices' MAC addresses and contain a single file info. In these files, you'll see the link key you need to replace with your Windows ones, like so:
```
[LinkKey]
Key=B99999999FFFFFFFFF999999999FFFFF
```
Once updated, restart your Bluetooth service in one of the following ways, and then it works!
- Ubuntu, Mint, Arch:
```
sudo systemctl restart Bluetooth 
```
- Alternatively, reboot your machine into Linux.
Reboot into Windows - it works!

Related Solutions

Linux – How to have triple boot Linux Mint 17 Cinnamon/Ubuntu 14.04/Windows 8

Just install normally. You can boot from your USB and follow the steps of the installer. You can either create a partition manually before installing or use the tools provided by the Mint installer to partition during the installation process.

The only thing you really have to worry about is when the installer asks you whether to install a boot loader (GRUB). Then, you have 2 choices. Since you already have a GRUB installed by Ubuntu, you can either choose to not install a new one from mint and use Ubuntu's or you can install Mint's and overwrite Ubuntu's.

Use the existing GRUB.

When the installer asks you whether to install a boot loader, say no. Once the installation has finished, reboot and load Ubuntu (Mint will not appear in the list of available OSs). From Ubuntu, refresh GRUB so it will detect your new Mint installation:
```
sudo update-grub
```
Use Mint's GRUB.

When the installer asks you whether to install a boot loader, say yes. Make sure you install it in the same location where your Ubuntu's GRUB was installed. This will probably be the master boot record (MBR) of your primary hard drive. Reboot and you should now have Mint's GRUB installed and will be able to choose Mint, Ubuntu or Windows.

Linux – Simpler method of pairing Bluetooth Devices for both Windows & Linux

Pair your bluetooth device(s) in Linux.
Reboot into Windows, and pair your same bluetooth device(s) in Windows.
Run regedt32.exe. Navigate to "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BTHPORT\Parameters\Keys"
Right-click on the "Keys" folder in the lefthand pane of the path above, and select "Export." In the pop-up dialog, change "Save as type" to "Text files," be sure that the "Export range" radio button "Selected branch" is selected, and save the file to your choice of name and location. For this purpose it's convenient if you've already configured a drive partition that's shared between your two OS, but it's not absolutely necessary, as you can use a thumb drive to transfer the file as well. If you have trouble exporting the folder, right click on it, select Permissions, and add Users to the groups that can read and edit the folder.
Now reboot into Linux.
Open a command prompt in Linux type sudo caja (if you're not running Linux with MATE, you may have a different file manager; substitute as necessary) and enter your password at the prompt. This will open a file manager with SU rights, so handle with care ... I'm not responsible if you brick your system!
Navigate to /var/lib/bluetooth. Inside of this folder you will see one or both of two things -- either a single folder named with a single MAC address (of your computer's bluetooth adapter) or multiple folders, each with its own MAC address, for each paired bluetooth device (the MAC address will be in the format XX:XX:XX:XX:XX:XX). If you find only the single folder, folders with those individual MAC addresses will be inside the first adapter folder.
Open the folder containing the MAC address of the device you wish to pair in dual-boot mode. Inside that folder will be one or two files ... the one you care about is the "info" file. Double-click on it and it will open in a text editor with SU rights -- that is, you'll be able to edit it and save it. (by the way, if you're not sure which device you're looking for, the "info" file contains the plain-English device name, so just open each one in turn till you find the right one).
Open a separate (non-SU) instance of your file manager, and use it to open the text file you saved from Windows in another pane. When you double-click on that file, Linux may ask if you want to execute or edit it ... choose to edit.
The Windows registry export will contain multiple stanzas (one for each device) that look like this (don't worry, I've changed to a bogus MAC and key):

Value 1  
  Name:            0008e024d45e  
  Type:            REG_BINARY  
  Data:              
00000000   31 c0 08 fa 4f 7b d2 4c - 6f e1 7d ba 32 29 a9 a7  1À.ïO{ÒLoá}ºQ)©§

Find the stanza containing the value on the "Name:" line which corresponds the MAC address of the file you have open in the first (SU) pane. Note that in the Windows files, the format of the MAC address uses lower-case letters instead of upper-case, and there are no colons.
Your Bluetooth pairing key is the string in the line that begins "00000000" and ends with a bunch of gibberish. Don't copy either the zeros or the gibberish, just the string in-between containing the 16 hex codes with the dash in the middle.
Insert that key into the "Key=" line in your "info" file. You can copy and paste if you want (I did), but you need to change lower-case letters to upper-case, and delete all spaces and dashes. In the example above, the resulting line will look like this:

Key=31C008FA4F7BD24C6FE17DBA3229A9A7

Now save the file, repeat for any additional devices. Reboot into Windows, your device should now work. Reboot into Linux, it should also work.

One final note: I did this with an old Lenovo diNovo setup that includes a mouse, a keyboard, and a separate keypad. The set comes with a Bluetooth dongle, but I could not get them to work with that dongle because Windows sees the dongle as a single device (meaning only one pairing key in the registry), while Linux sees through the device and pairs each individual piece. To solve this problem, I paired each device individually through the Bluetooth adapter on the laptop itself. The downside of this is that the Bluetooth keyboard does not work in Grub or BIOS, only within the OS. But it's the only way I succeeded with this setup.