How to pair and bond with a static passkey?

[Chaoyue Ying]

I developed a project that using static passkey to pair and bond with nRF SDK17.

It be fulfilled by the follow way:

//write static passkey	
	m_static_pin_option.gap_opt.passkey.p_passkey = passkey;
	err_code =  sd_ble_opt_set(BLE_GAP_OPT_PASSKEY, &m_static_pin_option);
	APP_ERROR_CHECK(err_code);
//pair with MITM and check the passkey from phone
    #define  SEC_PARAM_BOND  1
    #define  SEC_PARAM_MITM  1
    #define  SEC_PARAM_LESC  0
    #define  SEC_PARAM_KEYPRESS  0
    #define  SEC_PARAM_IO_CAPABILITIES   BLE_GAP_IO_CAPS_DISPLAY_ONLY 
    #define  SEC_PARAM_OOB  0
    #define  SEC_PARAM_MIN_KEY_SIZE  7
    #define  SEC_PARAM_MAX_KEY_SIZE  16
    
    m_sec_param.bond           = SEC_PARAM_BOND;
    m_sec_param.mitm           = SEC_PARAM_MITM;
    m_sec_param.lesc           = SEC_PARAM_LESC;
    m_sec_param.keypress       = SEC_PARAM_KEYPRESS;
		m_sec_param.io_caps        = BLE_GAP_IO_CAPS_DISPLAY_ONLY;
    m_sec_param.oob            = SEC_PARAM_OOB;
    m_sec_param.min_key_size   = SEC_PARAM_MIN_KEY_SIZE;
    m_sec_param.max_key_size   = SEC_PARAM_MAX_KEY_SIZE;
    m_sec_param.kdist_own.enc  = 1;
    m_sec_param.kdist_own.id   = 1;
    m_sec_param.kdist_peer.enc = 1;
    m_sec_param.kdist_peer.id  = 1;
		
    err_code = pm_sec_params_set(&m_sec_param);
    APP_ERROR_CHECK(err_code);

However,when I turn to NCS,I don't know how to fulfill it.

I used the hid_mouse sample but it just push the button to confirm the bond.

How can I use the passkey to do the MITM protect?

[Chaoyue Ying]

The location of bt_passkey_set() as above.The application run normally before pairing.And I debugged to check the return value of bt_passkey_set() and the num is zero that mean set success.

I think the issue due to conn_auth_callbacks.I'm not familiar with it.So I just copy it from hid_mouse.And the passkey_confirm is high priority, so i'm failed to use passkey.

If there have some samples use passkey to pairing?

[Edvin]

We don't have any samples using a static/fixed passkey (because of the false security it gives). 

You can check out the ncs\nrf\samples\bluetooth\peripheral_cgms, which uses a non-static passkey. 

I was able to make this use a static passkey by adding CONFIG_BT_FIXED_PASSKEY=y in the prj.conf, and adding this snippet after settings_load(); (after bt_enable())

    err = bt_passkey_set(123456);
    printk("bt_passkey_set returned %d\n", err);

Best regards,

Edvin

[Chaoyue Ying]

Hi Edvin,

I checked the code of cgms.But it use the security_change to trigger the process of pairing.

I want to arrive those function that using hid service and appearance to realize the board can be connected in my phone settings->bluetooth.And find a way to realize when my board be connected,the phone need to input the passkey otherwise it will be refused and disconnected.

But the cgms sample use  security_change that mean only have data change can trigger the pairing?

It is unsuitable to my application.If there have other sample can I refer to?

[Chaoyue Ying]

1202.rar

This is the project file.It is semi-finished.

Now I seem realize the pairing and bonding with passkey successfully.But the time of this process seem a little bit long,at least longer than it in nrf SDK.If there have some methods to let it quicker?

[Edvin]

What do you mean by slow? How long does it take?

It looks like it happens almost instantly when I run it. 

What HW are you running on? The nRF52832 DK?

Best regards,

Edvin