"Driver Error" when trying BLE HIDS mouse example disabling SMP

[Pedro]

Hi! 

I have a working example of BLE HIDs mouse in nRF52DK. I changed the HID report and works ok in Windows 10.

My problem is I need to connect to PC without confirming connection from MCU side. I tried disabling SMP and it connects automatically, but then after a few seconds, Windows shows "driver error"

Any suggestion? Is it possible to pair with Windows without SMP? Any way to use SMP and automatically accept connection? Any way to do not see the confirmation numbers from Windows?

Thank you!

Pedro.

[Hung Bui]

Hi Pedro, 

By spec, the communication between a HID device (mouse/keyboard) and the host must be encrypted. It's not allowed to have open connection for a mouse/keyboard for security reason. So Windows expect the device to support SMP (pairing) if the device doesn't have it supported Windows will display "Driver error". 

One option I can think of is to run your own application on Windows. Then you can make your device connect to Windows via the app. It doesn't need to be HIDs hence doesn't require encryption. Your app on Windows should be incharge of converting BLE data to mouse/keyboard input to Windows. 

[Pedro]

Hi Hung Bui,

Thank you for your answer. I need to use HID so I will enable SMP and automatically accept connection from MCU.

Is there any way to do not show "Numeric Match"? 

[Turbo J]

Yes. Set the device caps to not have either display nor keyboard.

This means the bluetooth security stuff, which is separate from HID.

The number inputs are a bit more secure, you loose MITM whitout them.

[Pedro]

Sorry but how can I do that? A CONFIG_ parameter in prj.conf?

[Hung Bui]

Hi Pedro, 
If you don't define the callback for keyboard or display, JustWork will be used and Windows will not display "Nummeric Match?"

I would suggest to have a look at our new Bluetooth LE Fundamental in Nordic Academy. At chapter 5 we discussed security: https://academy.nordicsemi.com/lessons/lesson-5-bluetooth-le-security-fundamentals/

[Pedro]

Ok thank you very much! I will study in detail chapter 5.

[Pedro]

Hi Hung,

I've done it, commenting out display and keyboard callbacks, and commenting out all functions related to mitm management. And now I have two problems:

1- If I just do that, it can't be paired to Windows. 

Connected 00:1A:7D:DA:71:15 (public)
Security failed: 00:1A:7D:DA:71:15 (public) level 1 err 4
Disconnected from 00:1A:7D:DA:71:15 (public) (reason 19)

Then I have to disable CONFIG_BT_SETTINGS and CONFIG_SETTINGS in prj.conf and it can connect and be paired (But then never connects automatically).

2- Although it is connected successfully, mouse does not work.

I don't know why. I call hid_init() after bt_enable(NULL), and then in ble connected callback, I call bt_hids_connected(). 

Please I need some help.

Thank you and kind regards,

Pedro.

[Hung Bui]

Hi Pedro, 
Have you tried to test with the default peripheral_hids_mouse examle in nRF Connect SDK ? 

I did this modification: 

And it worked fine with my Windows machine. The device can be paired/bonded with Windows without the number confirmation.

 I attached here the hex file that worked for me on a nRF52832 Dev Kit. It compiled with nRF Connect SDK v2.3

0118.zephyr.hex

If it works please check what's the difference between your project and the sample in the SDK. 
Notice : CONFIG_BT_HIDS_DEFAULT_PERM_RW_ENCRYPT=y  in prj.conf. 

Note that if you disable CONFIG_BT_SETTINGS and CONFIG_SETTINGS , it will not able to re-connect as the bond information is not stored in flash.