Bonding after pairing for "ble_app_multirole_lesc"

[takashina hiroki]

I have a question about the sample project "ble_app_multirole_lesc (SDK V15.3.0)".

I set the following parameters to perform pairing without bonding.

////////////////////////////////////////////////////////////////////////////////////////
// Security parameters to be used for all security procedures.
sec_params.bond = 0;
sec_params.mitm = 0;
sec_params.lesc = 1;
sec_params.keypress = 0;
sec_params.io_caps = BLE_GAP_IO_CAPS_NONE;
sec_params.oob = 0;
sec_params.min_key_size = 7;
sec_params.max_key_size = 16;
sec_params.kdist_own.enc = 0;
sec_params.kdist_own.id = 0;
sec_params.kdist_peer.enc = 0;
sec_params.kdist_peer.id = 0;

err_code = pm_sec_params_set(&sec_params);
APP_ERROR_CHECK(err_code);
////////////////////////////////////////////////////////////////////////////////////////

Is it possible to manually bond after pairing is confirmed?
Also, please let me know how.

[Sigurd]

Hi,

Yes, call pm_sec_params_set() with the new security parameters, and after that call pm_conn_secure() to start the bonding procedure.

[takashina hiroki]

Hi,

When I tried it, an error occurred after the "PM_EVT_CONN_SEC_PARAMS_REQ" event occurred.
After that, the connection is disconnected and bonding is not completed.
Looks like the security procedure is starting over.

<info> peer_manager_handler: Connection security failed: role: Peripheral, conn_handle: 0x2, procedure: Encryption, error: 4102

Please tell me the cause and measures.

[Sigurd]

Could you add the whole log, from startup until the error occurs ? Could you also check the security status of the link before calling pm_conn_secure(), using pm_conn_sec_status_get() ?

[takashina hiroki]

The log is shown below.
I tried calling pm_conn_sec_status_get, but encryption seems to be established.

<info> app: LE Secure Connections example started.
<info> app: Scanning
<info> app: Advertising
<info> app: PERIPHERAL: Connected, handle 1.
<info> app: PERIPHERAL: BLE_GAP_EVT_SEC_PARAMS_REQUEST
<info> app: PERIPHERAL: BLE_GAP_EVT_LESC_DHKEY_REQUEST
<info> nrf_ble_lesc: Calling sd_ble_gap_lesc_dhkey_reply on conn_handle: 1
<info> peer_manager_handler: Connection secured: role: Peripheral, conn_handle: 1, procedure: Pairing
<info> app: PERIPHERAL: BLE_GAP_EVT_AUTH_STATUS: status = 0x0 bond = 0x0 lv4: 0 kdist_own: 0x0 kdist_peer: 0x0
<info> app: Peer param to bond
<info> app: [pm_conn_sec_status_get] connected = 1, encrypted = 1, mitm_protected = 0, bonded = 0
<info> peer_manager_handler: Connection security failed: role: Peripheral, conn_handle: 0x1, procedure: Encryption, error: 4102
<warning> peer_manager_handler: Disconnecting conn_handle 1.
<info> app: PERIPHERAL: Disconnected, handle 1, reason 0x16.

[Sigurd]

Try to delete any previous bond information you might have stored on the phone for this device. (See this post regarding error 4102).

Also, what security parameters are you using when you call pm_conn_secure() the second time ?

[takashina hiroki]

The parameters for calling pm_conn_secure () after the second time are shown below.

sec_params.bond = 1;
sec_params.mitm = 0;
sec_params.lesc = 1;
sec_params.keypress = 0;
sec_params.io_caps = BLE_GAP_IO_CAPS_NONE;
sec_params.oob = 0;
sec_params.min_key_size = 7;
sec_params.max_key_size = 16;
sec_params.kdist_own.enc = 1;
sec_params.kdist_own.id = 1;
sec_params.kdist_peer.enc = 1;
sec_params.kdist_peer.id = 1;

err_code = pm_sec_params_set (& sec_params);
APP_ERROR_CHECK (err_code);

[takashina hiroki]

An attempt to delete previous bond information that may have been stored on the phone of this device was disconnected.
I am using "nRF Connect".
After "Connect", "Delete bond information" was performed.
Is the method wrong?
The log when disconnected is shown below.

<info> app: LE Secure Connections example started.
<info> app: Erase bonds!
<info> peer_manager_handler: All peers deleted.
<info> app: Scanning
<info> app: Advertising
<info> app: PERIPHERAL: Connected, handle 1.
<info> app: PERIPHERAL: BLE_GAP_EVT_SEC_PARAMS_REQUEST
<info> app: PERIPHERAL: BLE_GAP_EVT_LESC_DHKEY_REQUEST
<info> nrf_ble_lesc: Calling sd_ble_gap_lesc_dhkey_reply on conn_handle: 1
<info> peer_manager_handler: Connection secured: role: Peripheral, conn_handle: 1, procedure: Pairing
<info> app: PERIPHERAL: BLE_GAP_EVT_AUTH_STATUS: status=0x0 bond=0x0 lv4: 0 kdist_own:0x0 kdist_peer:0x0
<info> app: PERIPHERAL: Disconnected, handle 1, reason 0x13.

[Sigurd]

takashina hiroki said:

After "Connect", "Delete bond information" was performed.

Try to delete the old bond information before you connect again.

[takashina hiroki]

The same result was obtained by following the procedure below.

1. Delete the old bond information
2. Call pm_conn_secure () to start the pairing procedure.
3. Connect by pairing
4. Call pm_conn_secure () to start the bonding procedure.

[Marjeris Romero]

Hi,

Do you delete the old bond information on the phone as well?

Best regards,

Marjeris

[takashina hiroki]

Yes, I deleted the old bond information on the phone.

[Marjeris Romero]

Hi,

Do you get the disconnected, handle 1, reason 0x13 message after trying to read or write to the heart rate characteristics?

In that case it may be because in the example this characteristics are initialize to require LESC with MITM (numeric comparison).

In line 1061, inside hrs_init():

    // Require LESC with MITM (Numeric Comparison).
    hrs_init_params.hrm_cccd_wr_sec = SEC_MITM;
    hrs_init_params.bsl_rd_sec      = SEC_MITM;

If your characteristics require MITM then you should bond with MITM and set IO capabilities. If you don't want to use MITM then you should change the requirements for the characteristics to "SEC_JUST_WORKS".

Best Regards,

Marjeris