Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

Hung Bui — Mon, 15 Aug 2022 09:12:04 GMT

Hello , this is an inactive case. Please create a new ticket for your question.

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

eblas — Fri, 29 Jul 2022 00:11:44 GMT

Hi Fabian,

I am working on a similar personal project (ultimately connecting a pi to Omron BPM, using nrf52dk to sniff and help figure it out) and was wondering if you have have references on how to properly set the security parameters on the pi to pair in order to read the BPM data? I also saw on stack overflow you were using python on the pi, which BLE library did you use and is that public or are there references to that?

Unfortunately I only have 1 nrf52dk so I am using it to sniff between the pi or phone and BPM device. Hopefully I can get another sniffer to sniff the nrf52dk.

Currently this is where I am:

Successful pair from manufacturer app:

devzone.nordicsemi.com/.../BP7450_5F00_success_5F00_pair_5F00_from_5F00_manufacture_5F00_app.pcapng

NRF app on iPhone:

- can read blood pressure data after pairing through manufacturer app. However when connecting via nrf phone app then trying to read BP measurement (which you need to be paired) it tries to pair and fails.

devzone.nordicsemi.com/.../BP7450_5F00_pair_5F00_from_5F00_nrf_5F00_phone_5F00_app.pcapng

Pi:

- using gatttool, security-level = low, cleared BPM paired data, BPM in pairing mode (hold down bluetooth button) -> can connect, read device info etc. But when I try to read BPM data it fails with "Passkey entry failed". This is what is seen sniffing the BPM:

and this is what btmon reads on the pi:

- Now same thing but with security-level= medium -> btmon shows the pi connected but then pairing failed with same reason

nrf52DK as Central trying to pair through BLE tool in nrf connect for desktop:

note: can't sniff this atm, only have one nrf device

- can connect but when trying to pair with params [No keyboard/no display, no secure connection, no MITM, no OOB, no keypress, bonding yes] I receive this error

15:35:43.967	Error when calling replySecParams: Error: Error occured when replying sec params. Errorcode: Unknown value (0x8005)
15:35:43.970	Received status with code 4 Unknown value, message: 'Error sending packet to target. Code: 0x802a'

Additionally is there reference code for the nrf52dk for connecting and pairing to a peripheral, so that I can mess with security params and don't have to start from scratch?

I believe I just need to set the security parameters properly as the models I have are supposed to be able to pair without a pin, but unsure how to do so. I believe it is Bonding, no SC, no MITM, no OOB.

Any help is much appreciated.

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

fabocode — Tue, 22 Dec 2020 19:26:11 GMT

Hi Hung and thank you for your suggestions.

I realized that I made two terrible mistakes and 1 step was also required to make this to work:

This BPM device has a button to enable a "Pairing Mode" which I thought this was something that was activated after pairing with the mobile device, after re-checking the user guide I realized about this and then I was able to pair to it successfully with my nRF52 DK board and Raspberry Pi.
The problem in the raspberry pi is that I was using bluetoothctl tool to pair and then I was trying to request indications with the gatttool, apparently working with both systems creates a conflict and leads to this kind of problems where in gatttool you may find the [quote userid="84523" url="~/f/nordic-q-a/68865/pairing-always-fail-with-nrf52-raspberry-pi-4-win10-and-an-omron-bpm/284620#284620"]Status: PIN or Key Missing (0x06[/quote]But once you try to work only with gatttool everything else is much easier

Another tip to have in consideration is that gatttool can enable pairing by setting the security level (sec-level) to "medium", if you set it to "high" it will enable MITM and there the connection was not successfull in my side becuase of "authentication failure".

Now both devices, my nRF52 DK and my Raspberry Pi 4 are able to request data to the Omron BPM easily. Thank you very much for your tips.

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

Hung Bui — Mon, 14 Dec 2020 10:23:17 GMT

Hi,

In the RPI trace you provided, what I can get is that the first connection worked and they paired properly.
However, on the second connection the RPI tried to re-encrypt with stored bond but the BPM rejected with "Pin or Key missing". This meant that the bond information on the BPM was missing or it didn't store the bond information. You may want to try erase all bond information on the BPM and test again.

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

fabocode — Fri, 11 Dec 2020 20:36:30 GMT

Hi and sorry for my lack of response.

I have some news, I realized that I was reproducing my scenario as it was no suppossed to be done.

Now I am able to pair the nRF52 board and the Pi to my BPM, I still have problems to retrieve data from the BPM to the Raspberry Pi.

With the nRF52 it was very easy to do after the pairing process was done. I am sharing you both wireshark files if you want to take alook

devzone.nordicsemi.com/.../nRF52-_2D00_-BPM.pcapng devzone.nordicsemi.com/.../Rpi_2D00_BPM.pcapng

In the Pi I have an error everytime I write to the correspondent handle to retrieve data from the BPM.

The test command:

[28:FF:B2:8A:DF:2F][LE]> connect 28:FF:B2:8A:DF:2F
Attempting to connect to 28:FF:B2:8A:DF:2F
Connection successful
[28:FF:B2:8A:DF:2F][LE]> char-desc 0x0810 0x0820
handle: 0x0810, uuid: 00002803-0000-1000-8000-00805f9b34fb
handle: 0x0811, uuid: 00002a35-0000-1000-8000-00805f9b34fb
handle: 0x0812, uuid: 00002902-0000-1000-8000-00805f9b34fb
handle: 0x0820, uuid: 00002803-0000-1000-8000-00805f9b34fb
[28:FF:B2:8A:DF:2F][LE]> char-write-req 0x0812 0200
Characteristic value was written successfully
[28:FF:B2:8A:DF:2F][LE]>
(gatttool:11667): GLib-WARNING **: 15:03:18.681: Invalid file descriptor.

And the response using btmon tool

< ACL Data TX: Handle 64 flags 0x00 dlen 9
                                                                       #489 [hci0] 697.495168
      ATT: Write Request (0x12) len 4
        Handle: 0x0812
          Data: 0200
> ACL Data RX: Handle 64 flags 0x02 dlen 5
                                                                       #490 [hci0] 697.556732
      ATT: Write Response (0x13) len 0
> ACL Data RX: Handle 64 flags 0x02 dlen 6
                                                                       #491 [hci0] 697.557374
      SMP: Security Request (0x0b) len 1
        Authentication requirement: Bonding, No MITM, Legacy, No Keypresses (0x01)
< HCI Command: LE Start Encryption (0x08|0x0019) plen 28
                                                                       #492 [hci0] 697.557456
        Handle: 64
        Random number: 0x4a0b5a95a287eb03
        Encrypted diversifier: 0xfe7b
        Long term key: 92a67452d8ae4a615340ea18b743669c
> HCI Event: Command Status (0x0f) plen 4
                                                                       #493 [hci0] 697.557975
      LE Start Encryption (0x08|0x0019) ncmd 1
        Status: Success (0x00)
> HCI Event: Encryption Change (0x08) plen 4
                                                                       #494 [hci0] 697.646939
        Status: PIN or Key Missing (0x06)
        Handle: 64
        Encryption: Disabled (0x00)
< HCI Command: Disconnect (0x01|0x0006) plen 3
                                                                       #495 [hci0] 697.647023
        Handle: 64
        Reason: Authentication Failure (0x05)
> HCI Event: Command Status (0x0f) plen 4
                                                                       #496 [hci0] 697.647413
      Disconnect (0x01|0x0006) ncmd 1
        Status: Success (0x00)
> HCI Event: Number of Completed Packets (0x13) plen 5
                                                                       #497 [hci0] 697.677408
        Num handles: 1
        Handle: 64
        Count: 1
> HCI Event: Disconnect Complete (0x05) plen 4
                                                                       #498 [hci0] 697.677506
        Status: Success (0x00)
        Handle: 64
        Reason: Connection Terminated By Local Host (0x16)
@ MGMT Event: Device Disconnected (0x000c) plen 8

So the problem that I want to solve now is to understand why I have an

> HCI Event: Encryption Change (0x08) plen 4
#494 [hci0] 697.646939
Status: PIN or Key Missing (0x06)
Handle: 64
Encryption: Disabled (0x00)

Please let me know if you are able to provide me more information about what could be the issue on this case.

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

Hung Bui — Wed, 02 Dec 2020 09:22:33 GMT

Please send us the full sniffer trace when you use the Omron Application app to pair. There could be a special command that Omron designed for their own device to accept pairing or not. (and the sniffer trace when you use the nRF52 DK)
You can also test with bonding with IRK in the Initiator Key Distribution using sd_ble_gap_privacy_set() and sd_ble_gap_device_identities_set().

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

fabocode — Wed, 02 Dec 2020 00:59:25 GMT

Hi Hung,

Thank you for such a great response, is definitely something different from what people have said to me before.

However, I capture the trace with the nRF52 (PCA10040) and the BPM with the following setup:
- Secure Connection turned off
- CT2 bit flag turned off
- Enabling/disabling the MITM Flag

With no progress 😞

This test was developed with the inbuilt software that comes when you select an nRF52 device in the Bluetooth Low Energy Application in the nRF Connect v3.6.0

Another thing is that the error looks like its happenning in the SMP Protocol according to the sniffer trace.

Response from the BPM

Following the same logic as you did, is it possible that is might be required to enable the IRK initiator/responder type key? Because it seems that the BPM supports it and is part of the request and response between devices (Android - BPM).

ANOTHER HINT THAT I FOUND TODAY:

I have another android device, an Amazon Fire HD 10 where I installed the nRF Connect for Mobile app and before anything else I tried to pair with the BPM. the Response was failed, then I decided to try with the native Omron Application to pair with the device, this pair process was successful, then I deleted the bond information from the nRF android app and tried again and this time the pairing process was a success... Weird right?

Here is the request and response from the Amazon Fire HD 10 android device:

response here

I will keep in touch with you to get more help, thank you!!

RE: Pairing always fail with nRF52/Raspberry Pi 4/Win10 and an Omron BPM.

Hung Bui — Mon, 30 Nov 2020 14:33:33 GMT

Hi Fabian,
If you look at the trace between the RPI and the BPM you can find that the Secure Connection Flag is set to True (as well as the CT2 bit in the reserved flags) when it's false in the trace with the phone.

The response from the BPM also showed that Secure Connection is not supported.
Usually if it doesn't support Secure Connection and send such response, the central device will not use Secure Connection pairing and it should be fine. But I guess in this case the BPM doesn't understand what the flag is and just refuse the bonding process.

Please try to capture a sniffer trace with the NRF52 with Secure Connection turn off (SEC_PARAM_LESC = 0).