13 replies to this topic

[camoguy]

This thread was started to address the issue of losing bluetooth connectivity to peripherals when switching between OS X and Windows 7 because each OS has a different link key, therefore forcing you to renegotiate for a new link key to start a secure session. It also can be applied if you have to share one mouse across multiple machines. Further testing necessary, this is a work in progress.

I got tired of my wireless mouse not working after I paired with Windows, only to have to re-pair when I booted OS X. It's an aggrevating little annoyance. Now I can pick up my mouse and walk from desktop to laptop and not have to stop and pair because I did this procedure on both. I still need to change the laptop's OS X link key, that gets done with a hex editor.

One more thing, the registry keys referred to in this tut, point to where the standard Microsoft bluetooth driver records the link keys. If you see anything in device manager in Bluetooth radio, you should try changing to the generic bluetooth driver. If you have broadcom drivers installed or others, they write their keys to different parts of the registry and I don't support them.

Converting OS X link key to Windows registry format tutorial

Here's an example of what a portion of a link key might read in OS X : ABCDEF12
Of course it will be longer but I want to keep this as simple as possible at first.
Here's how you convert it to Windows registry format.
You start at the right with 12, and work your way left, grouping up in pairs, so the next is EF, CD, AB.
This is what it should read after you're done: 12 EF CD AB
All we're doing is taking the furthest two right digits off and putting them in the beggining. Reordering

Now lets apply this to a hypothetical link key.

98542ff9 88e19449 475250e1 3943255b

Start with the furthest right group

5b 25 43 39

then the second from the right

e1 50 52 47

third from the right

49 94 e1 88

and the furthest from the right

f9 2f 54 98

Putting them back together in Windows registry format:

5b 25 43 39 e1 50 52 47 49 94 e1 88 f9 2f 54 98

Understanding how to decode the OS X link key is the difficult part. Converting from little endian to big endian, or vise versa.

Accquire your link key, convert, install to Windows registry

1.Pair the device in Windows first. So the entry and services are all created in the registry.


2. Find your device id aka unique identifier. (Open bluetooth devices icon in system tray, right click on device (mouse etc), go to properties, bluetooth.) Make a note of it

3. Boot OS X and pair the device.

4. Copy/Write down the link key from OS X into a text document or email to yourself so you have access to it when you go back in Windows.

sudo defaults read /private/var/root/Library/Preferences/blued.plist

Link key will be 16 bytes long, it looks like 4 groups of 8 characters in hex.

such as: 98542ff9 88e19449 475250e1 3943255b

To find the one you want, if there are more than one, you would need to find you device unique identifier. Refer to step 2 or you can do it in OS X. Bluetooth preferences, show more info.

5. Convert the 16 byte long string to Windows registry format. Refered to as little endian to big endian. (Refer to mini tutorial above)

5a. Boot to windows

6. Get a free utility from technet psexec (google) copy to desktop.

7. Start > type cmd > hit control+ shift+ enter to create a command prompt with Administrator privledges.

8.

cd Desktop

psexec -s -i regedit

9. Find the key in registry HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\BTHPORT\Parameters\Keys\(Unique ID of your network adapter not your device)

10. Your device unique id for your mouse should be visible on the right pane, right click and "Modify binary data".

11. We want to erase Value data, and replace our own. Open that scratch pad where you've been taking notes and hopefully have converted the OS X link key to registry format without any typos, you need to enter it in here, one digit at a time, as it doesn't support copy paste from notepad.

 valuedata.jpg   24.33K   71 downloads

12. Hit OK, close registry, now you have the same link key in OS X and Windows 7. Changes take effect upon pressing OK. No need to reboot to see results.

If you try to pair that device to something else now, you'll need to repeat this process because the link key will have changed on the device. I paired my mouse to the laptop then my desktop (Windows first for the sake of this guide, I still need to test my reverse theory to change OS X's link key values, but first I need rest.) Bootcampers automatically have this done. This procedure is just an outline of what it takes, having a streamlined process like Apple would be the goal here.

-Camoguy

[verleihnix]

Hi  camoguy,
That sounds very interesting.
I am looking for a solution for years.

Do you know how to read the keys in SnowLeopard?

Regards
verleihnix

[camoguy]

verleihnix, on Sep 28 2011, 10:37 AM, said:

Hi  camoguy,
That sounds very interesting.
I am looking for a solution for years.

Do you know how to read the keys in SnowLeopard?

Regards
verleihnix

I think I did it on my SL, but it's the same if I remember.

sudo -s

defaults read /private/var/root/Library/Preferences/blued.plist

I don't have any SL around, are the keys encrypted or something?

[verleihnix]

I tried it, but it didn't work.
The file exits as you can see.

bash-3.2# defaults read /private/var/root/Library/Preferences/blued.plist
2011-09-29 08:16:07.659 defaults[696:903]
Domain /private/var/root/Library/Preferences/blued.plist does not exist
bash-3.2#
bash-3.2#
bash-3.2#
bash-3.2# ls -la /private/var/root/Library/Preferences/blued.plist
-rw-------  1 root  wheel  392 29 Sep 08:10 /private/var/root/Library/Preferences/blued.plist

Edit:
In Snow it works with:

defaults read /private/var/root/Library/Preferences/blued

Did you ever tried to port the keys to another mac?

[camoguy]

verleihnix, on Sep 29 2011, 12:18 AM, said:

Did you ever tried to port the keys to another mac?

I port the keys around between macs and windows. The keys are pretty much the same for both platforms except, windows it's big endian and mac it's little endian.

[verleihnix]

How to inject the keys - defaults write?
Do you know the syntax?

[camoguy]

verleihnix, on Sep 29 2011, 05:06 AM, said:

How to inject the keys - defaults write?
Do you know the syntax?

I haven't got that defaults write working yet, so for now I copy blued to my desktop, change ownership and modify the values with plistedit pro.

[verleihnix]

Yeh, it s working fine now.
I am able to boot either and having bluetooth connected without pairing.
  
Thanks a lot for pointing that out.

Did you tried to transfair the keys to a Windows which has never seen the mouse and keyboard before?

[ugokind]

the KEYS child in windows regedit (under vista/7) is not authorized to view
no way to change permissions!

[camoguy]

ugokind, on Sep 30 2011, 01:21 PM, said:

the KEYS child in windows regedit (under vista/7) is not authorized to view
no way to change permissions!

Run regedit as "system" with the command:

psexec -s -i regedit

[ugokind]

great
thanks mister

[camoguy]

There is also another technique to this. First have the mouse/keyboard paired in OS X. Then switch to Windows and open bluetooth dialog. Add device, then press the power button on the keyboard. Sometimes it won't pair at first, so what I do is hold the power key on the keyboard for a few then let go, then gently press it once. Once windows sees the device and it's in the list, you right click it, properies, then the HID services will have an empty tick box, click that, hit ok, then press cancel on the dialog and windows will install the drivers and should be working in HID mode, less secure but easier.

[X-TRiAL]

Hi, I know this is old but I have wanted to know how to do this. I have done all the techniques but I have one issue.
When I boot into Windows I have to open Device Settings > Bluetooth Devices > Right click mouse/keyboard > Click 'Connect'. After that it seems to work, but is there a way to eliminate this process so that they join automatically like it does in OS X.

Regards

[xiqs00k]

Hi camoguy, I was searching the whole internet for this solution I couldn't find anywhere else!!!
Thank you very much to share this with us!

It works!