Bluetooth LE OOB Pairing

[Portilha]

Hello everyone, 

I am developing a project where I need to perform bluetooth OOB pairing using an NFC reader. I have a couple questions about this.

The first is, what options do I need to enable in proj.conf to enbale LE Secure Connections OOB pairing? I know for this method, according to Bluetooth Spec and NDEF forum the mandatory fields should be: Role, Address, Confirmation and Random values (16-byte). I have checked some options like: "BT_SMP_SC_ONLY", "BT_SMP_SC_PAIR_ONLY" and  "BT_OOB_DATA_FIXED", but I am confused about which should I set.

Then, I am getting the Address, Random and Confirm values from this function:

 bt_le_oob oob_data;
 rc = bt_le_oob_get_local(0, &oob_data);

Where, the oob_data structure has a structure with the address and type, as well as a bt_le_oob_sc_data structure with the 2 16-byte arrays (R and C). Is this correct or should I use some elyptic curve function to generate these values?

Finnaly, I have set the board to advertise and have set these connection and pairing callbacks:

 conn_callbacks = { 
        .connected = BluetoothConnected, 
        .disconnected = BluetoothDisconnected, 
        .security_changed = SecurityChanged 
    };

    bt_conn_auth_info = { 
        .pairing_complete = BluetoothPairingCompleted, 
        .pairing_failed = BluetoothPairingFailed 
    };

    auth_cb_display = {
        .passkey_display = AuthPasskeyDisplay,
        .passkey_confirm = AuthPasskeyConfirm,
        .cancel = AuthCancel
    };

Is this correct or do I need anything else?

Best regards.

[Amanda Hsieh]

Hi, 

Check out this Bluetooth: NFC pairing sample. 

Regards,
Amanda H.

[Portilha]

Hello, 

I have already checked that sample. However, in my case I cannot trigger the '

auth_oob_data_request' callback. Do you have any idea why that might be happening?

 

BR

[Amanda Hsieh]

Did you test with Bluetooth: NFC pairing sample? Do you get the same issue?

What NCS version are you using?

[Portilha]

Hello,

I did not use that sample because I am using a dedicated NFC reader with card emulation capabilities. The process I am using is very similar to the one of the demo. I encode the bluetooth NDEF record into the shield, set the OOB Data request callback and start the advertise.

When I don´t set the oob_data flag, and I touch the shield with the smartphone, the pairing procedure starts but then it changes to numeric comparison to finish the pairing.

If I set the oob_data flag the pairing fails with the code 0x03 (BT_SECURITY_ERR_OOB_NOT_AVAILABLE). Additionally, the oob_data callback is not triggered. Can you tell me if there is any configuration needed? Or how I can trigger the callback?

BR.

[Amanda Hsieh]

Do you add the .oob_data_request callback in the conn_auth_callbacks structure to handle such events as this line?

Do you enable CONFIG_NFC_NDEF_LE_OOB_REC=y and CONFIG_NFC_NDEF_LE_OOB_REC_PARSER=y in your prj.conf?

You can take a look at this post which also got pairing fails with the code 0x03 (BT_SECURITY_ERR_OOB_NOT_AVAILABLE). Not sure it can help or not, but it's worth checking it.