BLE connection with pin code

[Roei]

Hi,

I'm using NRF52840 in order to connect to a mobile device, with PIN code.

Connection to Android is ok. The issue is with IOS.

IOS can't send the PIN code to my device, I understand that NRF device should transmit it's services so IOS will read it before sending the PIN code. Am I right?

Thanks!

[run_ar]

iOS will wait with pairing until you try to read/write to a characteristic that requires a higher security level. Did you try to enable notification for one of the characteristics? If that does not trigger pairing it means you need to increase the security level for your characteristics.

[Roei]

Hi,

Thanks for your response!

Who should try to read/write to a characteristic with higher security level? The mobile?

Where should I enable notification or increase security level? On NRF device side or mobile side?

Can you please give me an example?

Thanks!

[run_ar]

Hi,

If you look at the heart rate example in the sdk. this will send and incufficient authentication error to the phone once the iPhone tries to write to the cccd of the heart rate characteristic. this causes the iphone to start the pairing process.

So the phone will need to try to write to a characteristic in one of the peripherals services. So configure security on the peripheral. For details on how to configure the characteristics please take a look at our tutorial section here: https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy

[Roei]

Hi,

Thanks for your help!

Right now, I'm using sd_ble_gatts_characteristic_add(), in order to add RX, TX and device information service. Read and write permissions are BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM.

Is that good enough? Do I need to add more characteristics with another security level, in order to make the IOS trying to read and initiate pairing process?

Thanks!

[Roei]

In addition - I couldn't find any insufficient authentication error in heart rate example. Can you please help me?

[Roei]

Hi,

Any news? I'm still having those issues.

Thanks!

[run_ar]

Hi,

The "insufficient authentication" error will be sent automatically by the Softdevice if the peer tries to read/write a characteristic that is configured to require a higher security level. So you need to configure the security level for the characteristic you want to " protect" by requiring pairing and entering a pin.

From the heart rate example:

    // Here the sec level for the Heart Rate Service can be changed/increased.
    hrs_init.hrm_cccd_wr_sec = SEC_JUST_WORKS;
    hrs_init.bsl_rd_sec      = SEC_JUST_WORKS;

    err_code = ble_hrs_init(&m_hrs, &hrs_init);
    APP_ERROR_CHECK(err_code);

Notice that the required security level is just works in this case. You should probably require SEC_MITM since you are using a PIN.

[Roei]

Hi,

I've already done that with Rx and Tx characteristics - still doesn't work. I'm using  BLE_GAP_CONN_SEC_MODE_SET_LESC_ENC_WITH_MITM to protect write and read permissions.

Any other ideas?

Thanks

[run_ar]

Can you capture a sniffer trace of the on air traffic, to see if pairing is triggered?

[Roei]

I will try.

What do I expect to see with the sniffer?

Thanks

[Roei]

In addition - should I add any special service to my application, in order to make it work? I'm using only device information service and NUS service. Is that enough?

Thanks

[Roei]

Hi,

I've tried to change to SEC_MITM and added pin code to the example by using sd_ble_opt_set(BLE_GAP_OPT_PASSKEY, ...). Still doesn't initiate secured connection with passkey, only regular connection (via NRF connect).

Can you please help me?

Thanks