[nRF Connect SDK]Force to make pairing(bonding)

[Tim Hwang]

Target nRF52832(nrf52dk_nrf52832)
SDK NCS v2.0.0

I'm testing NCS 2.0 with Android 12.

Making pairing with Android, I call two API when connected.

bt_set_bondable(true);
bt_conn_set_security(conn, BT_SECURITY_L4);

It worked well so far (under Android 11)

BTW Android 12 make trouble security level 1 error.


[log]
00> HS connected
00> HS Connected 4A:B4:CA:22:85:2D (random)
00> Connection parameters updated.
00> interval: 6, latency: 0, timeout: 500
00> Conn params updated: interval 7 ms, latency 0, timeout: 5000 ms
00> Security failed: 4A:B4:CA:22:85:2D (random) level 1 err 2
00> Disconnected: 4A:B4:CA:22:85:2D (random) (reason 34)

Can I have another option to make pairing automatically?

[Kenneth]

Do the following config option impact the isse?
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/kconfig/index.html#CONFIG_BT_GATT_AUTO_SEC_REQ

I just wan to check if part of the problem here can be that zephyr will automatically start security procedures, and the application try to do this in paralell.

If there is no difference, then I think the next step would be to provide an on-air sniffer log with the same peripheral that show successful (android 11) vs unsuccessful (android 12):
https://www.nordicsemi.com/Products/Development-tools/nrf-sniffer-for-bluetooth-le 

Kenneth

[Tim Hwang]

1. CONFIG_BT_GATT_AUTO_SEC_REQ

In my test, it was not effective for me.


2. sniff log: please find attached.
I checked passkey ( 6 bytes ), and input it to wireshark. But "Encrypted packet decrypted incorrectly (bad MIC)). 

case_294898_sniff_log.7z

Here is snoop log captured yesterday.(Android 12)

BT_HCI_2022_0905_122121.7z

#10711 create connection

[Kenneth]

Just to make sure we don't misunderstand eachother, you did use CONFIG_BT_GATT_AUTO_SEC_REQ=n right?

Reason for asking is that I can see from the log that the default CONFIG_BT_GATT_AUTO_SEC_REQ=y is used.

Kenneth

[Tim Hwang]

In my test, it failed.
00> [00:00:33.518,554] <wrn> peripheral_uart: Security failed: 64:94:94:68:36:CF (random) level 1 err 1
00> [00:00:33.518,798] <inf> peripheral_uart: Pairing failed conn: 64:94:94:68:36:CF (random), reason 1
00> [00:00:36.582,489] <inf> peripheral_uart: Disconnected: 64:94:94:68:36:CF (random) (reason 19)

I'm testing with "nrf\samples\bluetooth\peripheral_uart" sample.

[Kenneth]

If you look at the link I provided:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/kconfig/index.html#CONFIG_BT_GATT_AUTO_SEC_REQ 

It says that Defaults y

So you need to set CONFIG_BT_GATT_AUTO_SEC_REQ=n

Please provide sniffer logs with this setting.

Edit: If the above is not the problem, then try to comment out bt_conn_set_security() and see if that impact the issue.

My main goal at the moment is to get a sniffer log without the security request I see in the start of the log files:

Kenneth

[Tim Hwang]

I changed it as 'n'
I'll make log and update it with peripheral_uart sample when ready.

[Tim Hwang]

Android12_pairing_failure.7z

sniff log with peripheral_uart sample

Thank you!

[Kenneth]

Hmm.. I can see that the peripheral still send the security request on connection. My main goal at the moment is to get a sniffer log without the security request I see in the start of the log files:

Can you comment out bt_conn_set_security() and see if that impact the issue?

Ideally bt_conn_set_security() should not be sent upon connection establishment, but instead sent after some seconds if the link is not been encrypted already.

Kenneth

[Tim Hwang]

1. In my test, there was no pairing without bt_conn_set_security().

2. Although CONFIG_BT_GATT_AUTO_SEC_REQ=n is set, pairing will be initiated from BLE, right?

In Korea, we will have national holiday by end of this week. I'll be back next Monday.

Thank you.