NCS 2.2.0 - Connect two nRF52840-DKs paired with level 3 security using fixed key.

[Joao Dullius]

Hello, 

I created a BLE Peripheral (ble_custom_auth) that has a custom service. I also create a BLE Central (scan_adv) that scans for that service UUID in devices, once found connects and should pair level 3 using a fixed password.

I validated both sides versus the nRF Connect for Bluetooth Low Energy Standalone v4.0.4, as follows:

1) Validating the BLE Peripheral - nRF52840-DK Peripheral - BLE Standalone Central

1.1) Run app and start advertising. Using nRF Connect BLE Standalone, scan for the device, connect and ask to pair using the fixed 123456 password:

*** Booting Zephyr OS build v3.2.99-ncs1 ***
[00:00:00.004,180] <inf> app: main: Starting Hello Bluetooth
[00:00:00.004,455] <inf> sdc_hci_driver: hci_driver_open: SoftDevice Controller build revision:
                                         6d 90 41 2a 38 e8 ad 17  29 a5 03 38 39 27 d7 85 |m.A*8... )..89'..
                                         1f 85 d8 e1                                      |....
[00:00:00.006,896] <inf> bt_hci_core: hci_vs_init: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.006,927] <inf> bt_hci_core: hci_vs_init: HW Variant: nRF52x (0x0002)
[00:00:00.006,958] <inf> bt_hci_core: hci_vs_init: Firmware: Standard Bluetooth controller (0x00) Version 109.16784 Build 2917677098
[00:00:00.007,965] <inf> bt_hci_core: bt_dev_show_info: Identity: F9:FC:08:12:08:72 (random)
[00:00:00.007,995] <inf> bt_hci_core: bt_dev_show_info: HCI: version 5.3 (0x0c) revision 0x11fa, manufacturer 0x0059
[00:00:00.008,026] <inf> bt_hci_core: bt_dev_show_info: LMP: version 5.3 (0x0c) subver 0x11fa
[00:00:00.008,056] <inf> app: main: Bluetooth initialized
[00:00:00.008,880] <inf> app: main: Advertising successfully started
[00:01:18.554,290] <inf> app: connected: Connected
[00:01:24.879,211] <inf> app: auth_passkey_display: Passkey for CD:40:25:0F:69:68 (random): 123456
[00:01:24.879,425] <inf> app: pairing_confirm: Pairing confirmed: CD:40:25:0F:69:68 (random)
[00:01:28.898,468] <inf> app: pairing_complete: Pairing completed: CD:40:25:0F:69:68 (random), bonded: 0
[00:01:28.898,681] <wrn> app: security_changed: Security changed: CD:40:25:0F:69:68 (random) level 3

Notice that it works, as I get security changed to level 3.

2) Validating the BLE Central - BLE Standalone Peripheral -  nRF52840-DK Central 

2.2 Create a SERVER SETUP in the BLE Standalone software with the same service UUID in the DK peripheral and set the same 123456 password. Advertise and let the DK central scan for it and try to connect and pair.

*** Booting Zephyr OS build v3.2.99-ncs1 ***
[00:00:00.004,241] <inf> sdc_hci_driver: hci_driver_open: SoftDevice Controller build revision:
                                         6d 90 41 2a 38 e8 ad 17  29 a5 03 38 39 27 d7 85 |m.A*8... )..89'..
                                         1f 85 d8 e1                                      |....
[00:00:00.006,652] <inf> bt_hci_core: hci_vs_init: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.006,713] <inf> bt_hci_core: hci_vs_init: HW Variant: nRF52x (0x0002)
[00:00:00.006,744] <inf> bt_hci_core: hci_vs_init: Firmware: Standard Bluetooth controller (0x00) Version 109.16784 Build 2917677098
[00:00:00.007,781] <inf> bt_hci_core: bt_dev_show_info: Identity: E9:1E:67:7E:39:E7 (random)
[00:00:00.007,812] <inf> bt_hci_core: bt_dev_show_info: HCI: version 5.3 (0x0c) revision 0x11fa, manufacturer 0x0059
[00:00:00.007,843] <inf> bt_hci_core: bt_dev_show_info: LMP: version 5.3 (0x0c) subver 0x11fa
[00:00:00.007,843] <inf> ble_scanner: main: Bluetooth initialized
[00:00:00.007,873] <inf> ble_scanner: scan_init: Scan module initialized
[00:00:00.008,483] <inf> ble_scanner: start_scan: Scanning successfully started
[00:00:06.330,047] <inf> ble_scanner: scan_filter_match: Filters matched. Address: CD:40:25:0F:69:68 (random) connectable: 1
[00:00:44.996,490] <inf> ble_scanner: connected: Connected: CD:40:25:0F:69:68 (random)
[00:00:51.097,961] <inf> ble_scanner: pairing_complete: Pairing completed: CD:40:25:0F:69:68 (random), bonded: 0
[00:00:51.098,175] <inf> ble_scanner: security_changed: Security changed: CD:40:25:0F:69:68 (random) level 3

Notice that this also pair at level 3.

3) Running both BLE Peripheral and BLE Central in the DKs:

Notice that, in this case, even running the same firmware as the tests above, there is a SMP timeout error and the boards wont pair.

BLE Peripheral:

*** Booting Zephyr OS build v3.2.99-ncs1 ***
[00:00:00.004,180] <inf> app: main: Starting Hello Bluetooth
[00:00:00.004,455] <inf> sdc_hci_driver: hci_driver_open: SoftDevice Controller build revision:
                                         6d 90 41 2a 38 e8 ad 17  29 a5 03 38 39 27 d7 85 |m.A*8... )..89'..
                                         1f 85 d8 e1                                      |....
[00:00:00.006,896] <inf> bt_hci_core: hci_vs_init: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.006,927] <inf> bt_hci_core: hci_vs_init: HW Variant: nRF52x (0x0002)
[00:00:00.006,958] <inf> bt_hci_core: hci_vs_init: Firmware: Standard Bluetooth controller (0x00) Version 109.16784 Build 2917677098
[00:00:00.007,965] <inf> bt_hci_core: bt_dev_show_info: Identity: F9:FC:08:12:08:72 (random)
[00:00:00.007,995] <inf> bt_hci_core: bt_dev_show_info: HCI: version 5.3 (0x0c) revision 0x11fa, manufacturer 0x0059
[00:00:00.008,026] <inf> bt_hci_core: bt_dev_show_info: LMP: version 5.3 (0x0c) subver 0x11fa
[00:00:00.008,056] <inf> app: main: Bluetooth initialized
[00:00:00.008,880] <inf> app: main: Advertising successfully started
[00:00:00.339,050] <inf> app: connected: Connected
[00:00:00.491,027] <inf> app: pairing_confirm: Pairing confirmed: E9:1E:67:7E:39:E7 (random)
[00:00:00.740,661] <inf> app: auth_passkey_display: Passkey for E9:1E:67:7E:39:E7 (random): 123456
[00:00:30.740,539] <err> bt_smp: smp_timeout: SMP Timeout
[00:00:30.740,753] <err> app: security_changed: Security failed: E9:1E:67:7E:39:E7 (random) level 1 err 9
[00:00:30.740,936] <inf> app: pairing_failed: Pairing failed conn: E9:1E:67:7E:39:E7 (random), reason 9

BLE Central:

*** Booting Zephyr OS build v3.2.99-ncs1 ***
[00:00:00.004,241] <inf> sdc_hci_driver: hci_driver_open: SoftDevice Controller build revision:
6d 90 41 2a 38 e8 ad 17 29 a5 03 38 39 27 d7 85 |m.A*8... )..89'..
1f 85 d8 e1 |....
[00:00:00.006,683] <inf> bt_hci_core: hci_vs_init: HW Platform: Nordic Semiconductor (0x0002)
[00:00:00.006,713] <inf> bt_hci_core: hci_vs_init: HW Variant: nRF52x (0x0002)
[00:00:00.006,744] <inf> bt_hci_core: hci_vs_init: Firmware: Standard Bluetooth controller (0x00) Version 109.16784 Build 2917677098
[00:00:00.007,781] <inf> bt_hci_core: bt_dev_show_info: Identity: E9:1E:67:7E:39:E7 (random)
[00:00:00.007,843] <inf> bt_hci_core: bt_dev_show_info: HCI: version 5.3 (0x0c) revision 0x11fa, manufacturer 0x0059
[00:00:00.007,873] <inf> bt_hci_core: bt_dev_show_info: LMP: version 5.3 (0x0c) subver 0x11fa
[00:00:00.007,873] <inf> ble_scanner: main: Bluetooth initialized
[00:00:00.007,904] <inf> ble_scanner: scan_init: Scan module initialized
[00:00:00.008,514] <inf> ble_scanner: start_scan: Scanning successfully started
[00:00:00.690,155] <inf> ble_scanner: scan_filter_match: Filters matched. Address: F9:FC:08:12:08:72 (random) connectable: 0
[00:00:00.801,269] <inf> ble_scanner: connected: Connected: F9:FC:08:12:08:72 (random)
[00:00:01.254,241] <inf> ble_scanner: passkey_entry: Passkey entry request for F9:FC:08:12:08:72 (random)
[00:00:31.002,807] <err> bt_smp: smp_timeout: SMP Timeout
[00:00:31.003,021] <wrn> ble_scanner: security_changed: Security failed: F9:FC:08:12:08:72 (random) level 1 err 9
[00:00:31.003,204] <err> ble_scanner: pairing_failed: Pairing failed conn: F9:FC:08:12:08:72 (random), reason 9

Questions:

How can I further debug this to understand why when running DK vs DK I get this SMP error? Both fixed passwords are set the same (123456), as validated on tests 1 and 2 above.

How can I check if the Peripheral DK is receiving the right password from the Central DK?

Please see codes in this file:

pair_level3_error_840dk.zip

[Joao Dullius]

I don't know if it is related, but i just realized that the Central running on the DK detects the peripheral also running on DK as non connectable:

[00:00:00.690,155] <inf> ble_scanner: scan_filter_match: Filters matched. Address: F9:FC:08:12:08:72 (random) connectable: 0

What do I need to change in my peripheral ad or advertising configurations for it o be detected as connectable?

Here is my current implementation:

static const struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	BT_DATA(BT_DATA_NAME_COMPLETE, DEVICE_NAME, DEVICE_NAME_LEN),
};

static const struct bt_data sd[] = {
    BT_DATA_BYTES(BT_DATA_UUID128_ALL, BT_UUID_CUSTOM_SERV_VAL),
};


	err = bt_le_adv_start(BT_LE_ADV_CONN, ad, ARRAY_SIZE(ad),
			      sd, ARRAY_SIZE(sd));
	if (err) {
		LOG_ERR("Advertising failed to start (err %d)", err);
		return;
	}

[Amanda Hsieh]

Hi, 

Please kindly provide a sniffer log to help investigate the issue. Thanks. 

-Amanda H.

[Joao Dullius]

Hi Amanda,

Please, see attached.

level3_pairing_failure.pcapng

[Amanda Hsieh]

Hi, 

I will be out of the office on Friday and will keep looking into this case next week. 

Merry Christmas,
Amanda H.

[Joao Dullius]

Hi Amanda,

I was able to figure it out.

I was misinterpreting how the .passkey_entry, .passkey_confirm and .passkey_display works.

As I want for both sides to simply set the same fixed password, I implementes it using .passkey_entry with success. This way "emulate" user entering a password by setting a fixed hard coded defined one.

As reference here is my working code regarding the pairing with fixed pass on L4:

nrf-examples/pairing_fixed_passkey at pair_ok · joaodullius/nrf-examples (github.com)