Avoid "Bluetooth pairing request" alert on iOS

RE: Avoid "Bluetooth pairing request" alert on iOS

nosignal — Sat, 18 Nov 2017 12:44:48 GMT

@shibshab: on my device when I sniffed the traffic with Wireshark, on SCAN_RSP I always get Scan Response Data: Other devices I tested have some data in this field. My device is working, but I think there is some wrong coding that causes this. Maybe because an incorrect order of my advertising data?

RE: Avoid "Bluetooth pairing request" alert on iOS

Hung Bui — Wed, 09 Sep 2015 09:34:59 GMT

@Kasper: If you pass NULL as the p_sec_keyset, then it will be only pairing with no bonding. No longterm keys will be exchanged and you will see the pairing request popup everytime. The p_sec_keyset is where you will have the keys after the bonding process is done (BLE_GAP_EVT_AUTH_STATUS event).

I would suggest you to have a look at the ble_app_template example we have in SDK v8.0. In this example we handle the bonding without device manager and could be a good example to refer. Note that in that example, we don't store LTK in flash so if you reset the chip, the LTK will go missing. You will have to erase bond on the phone to reconnect and rebond.

RE: Avoid "Bluetooth pairing request" alert on iOS

Kasper Leonhardt — Wed, 09 Sep 2015 08:47:43 GMT

Thank you shibshab, you have been very helpfully, but I believe that your last sentence is the most important: "Also note that this requires support on the iOS side..." I still get the "Bluetooth pairing request" :-( I believe that I have to give up, it is not possible.

Compared to the UART example in 8.0 I have done following changes

changes.txt

RE: Avoid "Bluetooth pairing request" alert on iOS

shibshab — Wed, 09 Sep 2015 07:16:25 GMT

Taking the UART example in 8.0 as an example. The necessary steps to enable Just Works encryption is:

Set SEC_PARAM_BOND to 0
For characteristics (read/write) set BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM

Note that RX characteristic is WriteWithoutResponse, which will not allow you to verify using a sniffer that authentication is required. Set it to write by removing the line setting write_wo_resp to 1.

Also note that this requires support on the iOS side (the nRF Toolbox app will not support this setup).

RE: Avoid "Bluetooth pairing request" alert on iOS

Kasper Leonhardt — Tue, 08 Sep 2015 13:36:05 GMT

Thanks for you help shishab, so far. And you were right the call to sd_ble_gap_sec_params_reply did return with error (16=NRF_ERROR_INVALID_ADDR). I believe that the parameter p_sec_keyset cannot be NULL in this case, as suggested on the "Message Sequence Charts" as linked to before. The comment in the header file also describes the possibility to pass a NULL. I think I need more changes. So far I have changed following (probably not compleate list) from the uart example:

BLE_GAP_CONN_SEC_MODE_SET_OPEN changed to BLE_GAP_CONN_SEC_MODE_SET_ENC_WITH_MITM
Parameters to sd_ble_gap_sec_params_reply
Upgraded from SD 7.2 to 8.0 (might need further changes) (main.c and ble_* files kept)

But then I tried to change BLE_GAP_CONN_SEC_MODE_SET_ENC_WITH_MITM to BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM, and correct in main.c. I expect that it should be more correct. But then no smp pairing request was performed. (and no call of sd_ble_gap_sec_info_reply).

Maybe I should try to start all over from a new copy of the new version of the BLE UART example.

RE: Avoid "Bluetooth pairing request" alert on iOS

Hung Bui — Tue, 08 Sep 2015 13:30:20 GMT

@Kaster: As Shibshab pointed, you need to handle the BLE_GAP_EVT_SEC_PARAMS_REQUEST event and reply with the sd_ble_gap_sec_params_reply() with correct parameters. It's shown here.

RE: Avoid "Bluetooth pairing request" alert on iOS

shibshab — Tue, 08 Sep 2015 07:31:24 GMT

I see you have one packet of type SMP (as seen in Protocol column), which is a Pairing Request (the one we are looking for). This is packet nr 213, and it comes after getting an "Insufficient Authentication" error message, indicating that the encryption requirements for the characteristic is in place.

I do not see any response to this packet, have you verified that your code handles this correctly?

RE: Avoid "Bluetooth pairing request" alert on iOS

Kasper Leonhardt — Tue, 08 Sep 2015 06:35:29 GMT

Log from Wireshark:

JustWorksPairingAttempt.pcapng

RE: Avoid "Bluetooth pairing request" alert on iOS

Kasper Leonhardt — Tue, 08 Sep 2015 06:31:11 GMT

I know. But Wireshark shows it in plain text, and the encryption flag is false. Please see next answer

RE: Avoid "Bluetooth pairing request" alert on iOS

shibshab — Tue, 08 Sep 2015 06:12:08 GMT

Remember that the sniffer will be able to decrypt just work encryptions automatically. Do you mean that there is no pairing request?

RE: Avoid "Bluetooth pairing request" alert on iOS

Kasper Leonhardt — Tue, 08 Sep 2015 06:05:31 GMT

Did not work. Verified the connection with the Nordic BLE sniffer and Wireshark. The data is not encrypted. Suggestions needed.

RE: Avoid "Bluetooth pairing request" alert on iOS

Kasper Leonhardt — Mon, 07 Sep 2015 12:21:30 GMT

Solved. I needed to upgrade to SD 8.0.0, and change the line (last parameter changed to NULL): sd_ble_gap_sec_params_reply(p_ble_evt->evt.gap_evt.conn_handle, BLE_GAP_SEC_STATUS_SUCCESS, &m_application_table[0].sec_param, NULL/&keys_exchanged/); in the file device_manager_peripheral.c

RE: Avoid "Bluetooth pairing request" alert on iOS

shibshab — Mon, 07 Sep 2015 07:51:30 GMT

This page describes what parameters needs to be set in order for the peripheral to use Just Works.

When this is used correctly you should not get a prompt from iOS regarding the pairing request.