How to use Static Passkey for a no-display-no-output peripheral

[Boaz]

I'm looking to implement the following security schema:

• The peripheral does not have a display nor input capabilities
• A smartphone will connect to the device
• The peripheral will pair (but not bond) with the smartphone
• Pairing will require the smartphone user to enter a 6-digit passkey
• Upon successful pairing, the passkey can be changed via the mobile application
• A physical button on the peripheral will enable resetting the passkey to a default

Some questions:

• Is it possible to implement this schema in nRF52840, s140, SDK15? If so, what are the required steps.
• Does this schema provide MITM protection (assuming I change the passkey often)?

I know there are a lot of security and passkey relate questions out there, but I couldn't quite find the answers I needed. Thanks!

[Sigurd]

Hi,

Is it possible to implement this schema in nRF52840, s140, SDK15? If so, what are the required steps.

Yes, but it will not provide 100% MITM protection(opens up for passive eavesdropping). See this post. A starting point would be to take a look at the Glucose Application example in the SDK, it shows you how to implement passkey. By default it will use a random passkey, printed over UART, and you will need to input the passkey on the phone.

If you want a static prepreogrammed passkey instead of generaring a randome one, you can do it like this:

#define STATIC_PASSKEY    "123455"

static void set_static_passkey()

{

    static ble_opt_t    m_static_pin_option;

    uint8_t passkey[] = STATIC_PASSKEY;

    m_static_pin_option.gap_opt.passkey.p_passkey = &passkey[0];

    uint32_t err_code =  sd_ble_opt_set(BLE_GAP_OPT_PASSKEY, &m_static_pin_option);

    APP_ERROR_CHECK(err_code);     

}

 

Call the set_static_passkey() function after you have called ble_stack_init() in main()

Snippet:

int main(void)
{
.
.
ble_stack_init();
set_static_passkey();
.
..

Then make sure that you have this:

#define SEC_PARAM_BOND                  0                                           /**< Perform bonding. */
#define SEC_PARAM_MITM                  1                                           /**< Man In The Middle protection required (applicable when display module is detected). */
#define SEC_PARAM_LESC                  0                                           /**< LE Secure Connections not enabled. */
#define SEC_PARAM_KEYPRESS              0                                           /**< Keypress notifications not enabled. */
#define SEC_PARAM_IO_CAPABILITIES       BLE_GAP_IO_CAPS_DISPLAY_ONLY                /**< Display I/O capabilities. */
#define SEC_PARAM_OOB                   0                                           /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE          7                                           /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE          16                                          /**< Maximum encryption key size. */

and that in peer_manager_init(), this is commented out:

 

sec_param.kdist_own.enc  = 1;
sec_param.kdist_own.id   = 1;
sec_param.kdist_peer.enc = 1;
sec_param.kdist_peer.id  = 1;

 

Also see this link.

 

Does this schema provide MITM protection (assuming I change the passkey often)?

The passkey method is generally considered to be secure from MITM attacks, but it's not 100% secure, and it opens up for passive eavesdropping. Please see this, this and this post.

Also read this document by Bluetooth SIG. Also this wiki-site provide some good information.

Note that what type of security you need will depend on what type of application you have.

(PS: bonding is generally recommended, so that the end-user don't have to enter the passkey every time he need to connect to the device.)

[Siddharth rana]

Hi Sigurd.

I have tried to implement the process u mentioned.but I haven't achieved static passkey method.

Please help me out 

[beemavishnu]

Hi Sigurd,

I implemented and working fine. Later I saw your post. Now I got confidence. 

Hi Rana,

I am not sure which example you are using. I am using nRF52832, SDK_15.3.0, S132 SoftDevice and Segger for flashing the image. I am using ‘ble_app_blinky’.

One more change to be done

1) In ble_evt_handler() You need to comment below case as it replies with "Pairing not supported".

     

case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
{
    // Pairing not supported
    err_code = sd_ble_gap_sec_params_reply(m_conn_handle,
                                           BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP,
                                           NULL,
                                           NULL);
    APP_ERROR_CHECK(err_code);
}
break;

Thanks & Regards

Vishnu Beema

[Campeotto]

Hi Sigurd,

thanks for your steps, they are really clear as compared to other threads but it is not working in my case (I am a beginner).

I am using the nRF52832(PCA10040), SDK 15.3 and I tried to modify the ble_app_gls_pca10040_s132 using SEGGER.

The original project works and I can see the random passkey in the UART (I use the Arduino serial monitor).

I followed your steps for making a statin passkey but when I build the code this error occurs:
"'ble_gap_opt_t' {aka 'union <anonymous>'} has no member named 'passkey'"

So, I tried to understand and find in the devzone how to fix the "has no member named" error but I did find nothing clear.

can you explain to me which is and how to fix this type of error?

Can you help me, please? I attached an image of error and the mail.c file.

Fullscreen 6712.main.c Download

/**
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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/** @file
 *
 * @defgroup ble_sdk_app_gls_main main.c
 * @{
 * @ingroup ble_sdk_app_gls
 * @brief Glucose Meter service Sample Application
 *
 * This file contains the source code for a sample application using the Glucose Meter service
 * (and also Battery and Device Information services). This application uses the
 * @ref srvlib_conn_params module.
 */

#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "app_error.h"
#include "ble.h"
#include "ble_err.h"
#include "ble_hci.h"
#include "ble_srv_common.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_dis.h"
#include "ble_bas.h"
#include "ble_gls.h"
#include "ble_racp.h"
#include "ble_conn_params.h"
#include "sensorsim.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "app_timer.h"
#include "peer_manager.h"
#include "peer_manager_handler.h"
#include "bsp_btn_ble.h"
#include "fds.h"
#include "ble_conn_state.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_lesc.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"


#define DEVICE_NAME                     "Nordic_Glucose"                            /**< Name of device. Will be included in the advertising data. */
#define MANUFACTURER_NAME               "NordicSemiconductor"                       /**< Manufacturer. Will be passed to Device Information Service. */
#define MODEL_NUMBER                    "nRF51"                                     /**< Model Number string. Will be passed to Device Information Service. */
#define MANUFACTURER_ID                 0x55AA55AA55                                /**< DUMMY Manufacturer ID. Will be passed to Device Information Service. You shall use the ID for your Company*/
#define ORG_UNIQUE_ID                   0xEEBBEE                                    /**< DUMMY Organisation Unique ID. Will be passed to Device Information Service. You shall use the Organisation Unique ID relevant for your Company */

#define APP_BLE_OBSERVER_PRIO           3                                           /**< Application's BLE observer priority. You shouldn't need to modify this value. */
#define APP_BLE_CONN_CFG_TAG            1                                           /**< A tag identifying the SoftDevice BLE configuration. */

#define APP_ADV_INTERVAL                40                                          /**< The advertising interval (in units of 0.625 ms. This value corresponds to 25 ms). */
#define APP_ADV_DURATION                18000                                       /**< The advertising duration (180 seconds) in units of 10 milliseconds. */

#define BATTERY_LEVEL_MEAS_INTERVAL     APP_TIMER_TICKS(10000)                      /**< Battery level measurement interval (ticks). */
#define MIN_BATTERY_LEVEL               81                                          /**< Minimum battery level as returned by the simulated measurement function. */
#define MAX_BATTERY_LEVEL               100                                         /**< Maximum battery level as returned by the simulated measurement function. */
#define BATTERY_LEVEL_INCREMENT         1                                           /**< Value by which the battery level is incremented/decremented for each call to the simulated measurement function. */

#define MIN_CONN_INTERVAL               MSEC_TO_UNITS(10, UNIT_1_25_MS)             /**< Minimum acceptable connection interval (10 ms). */
#define MAX_CONN_INTERVAL               MSEC_TO_UNITS(100, UNIT_1_25_MS)            /**< Maximum acceptable connection interval (100 ms) */
#define SLAVE_LATENCY                   0                                           /**< Slave latency. */
#define CONN_SUP_TIMEOUT                MSEC_TO_UNITS(4000, UNIT_10_MS)             /**< Connection supervisory timeout (4 seconds). */
#define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000)                       /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(30000)                      /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAM_UPDATE_COUNT     3                                           /**< Number of attempts before giving up the connection parameter negotiation. */

#define LESC_DEBUG_MODE                 0                                           /**< Set to 1 to use LESC debug keys, allows you to use a sniffer to inspect traffic. */

//#define SEC_PARAM_BOND                  1                                           /**< Perform bonding. */
//#define SEC_PARAM_MITM                  1                                           /**< Man In The Middle protection required (applicable when display module is detected). */
//#define SEC_PARAM_LESC                  1                                           /**< LE Secure Connections enabled. */
//#define SEC_PARAM_KEYPRESS              0                                           /**< Keypress notifications not enabled. */
//#define SEC_PARAM_IO_CAPABILITIES       BLE_GAP_IO_CAPS_DISPLAY_ONLY                /**< Display I/O capabilities. */
//#define SEC_PARAM_OOB                   0                                           /**< Out Of Band data not available. */
//#define SEC_PARAM_MIN_KEY_SIZE          7                                           /**< Minimum encryption key size. */
//#define SEC_PARAM_MAX_KEY_SIZE          16                                          /**< Maximum encryption key size. */

#define SEC_PARAM_BOND                  0                                           /**< Perform bonding. */
#define SEC_PARAM_MITM                  1                                           /**< Man In The Middle protection required (applicable when display module is detected). */
#define SEC_PARAM_LESC                  0                                           /**< LE Secure Connections not enabled. */
#define SEC_PARAM_KEYPRESS              0                                           /**< Keypress notifications not enabled. */
#define SEC_PARAM_IO_CAPABILITIES       BLE_GAP_IO_CAPS_DISPLAY_ONLY                /**< Display I/O capabilities. */
#define SEC_PARAM_OOB                   0                                           /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE          7                                           /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE          16                                          /**< Maximum encryption key size. */

#define PASSKEY_TXT                     "Passkey:"                                  /**< Message to be displayed together with the pass-key. */
#define PASSKEY_TXT_LENGTH              8                                           /**< Length of message to be displayed together with the pass-key. */
#define PASSKEY_LENGTH                  6                                           /**< Length of pass-key received by the stack for display. */

#define DEAD_BEEF                       0xDEADBEEF                                  /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

////////// STATIC PASSKEY
#define STATIC_PASSKEY    "123455"


///////////////
BLE_BAS_DEF(m_bas);                                                                 /**< Structure used to identify the battery service. */
BLE_GLS_DEF(m_gls);                                                                 /**< Structure used to identify the glucose service. */
NRF_BLE_GATT_DEF(m_gatt);                                                           /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr);                                                             /**< Context for the Queued Write module.*/
BLE_ADVERTISING_DEF(m_advertising);                                                 /**< Advertising module instance. */
APP_TIMER_DEF(m_battery_timer_id);                                                  /**< Battery timer. */

static pm_peer_id_t m_peer_to_be_deleted = PM_PEER_ID_INVALID;
static uint16_t     m_conn_handle        = BLE_CONN_HANDLE_INVALID;                 /**< Handle of the current connection. */
static ble_uuid_t   m_adv_uuids[] =                                                 /**< Universally unique service identifiers. */
{
    {BLE_UUID_GLUCOSE_SERVICE, BLE_UUID_TYPE_BLE},
    {BLE_UUID_BATTERY_SERVICE, BLE_UUID_TYPE_BLE},
    {BLE_UUID_DEVICE_INFORMATION_SERVICE, BLE_UUID_TYPE_BLE}
};
static sensorsim_cfg_t   m_battery_sim_cfg;                                         /**< Battery Level sensor simulator configuration. */
static sensorsim_state_t m_battery_sim_state;                                       /**< Battery Level sensor simulator state. */


static void advertising_start(bool erase_bonds);


/**@brief Callback function for asserts in the SoftDevice.
 *
 * @details This function will be called in case of an assert in the SoftDevice.
 *
 * @warning This handler is an example only and does not fit a final product. You need to analyze
 *          how your product is supposed to react in case of Assert.
 * @warning On assert from the SoftDevice, the system can only recover on reset.
 *
 * @param[in] line_num   Line number of the failing ASSERT call.
 * @param[in] file_name  File name of the failing ASSERT call.
 */
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
    app_error_handler(DEAD_BEEF, line_num, p_file_name);
}

/**@brief Function for handling Peer Manager events.
 *
 * @param[in] p_evt  Peer Manager event.
 */
static void pm_evt_handler(pm_evt_t const * p_evt)
{
    ret_code_t err_code;

    pm_handler_on_pm_evt(p_evt);
    pm_handler_disconnect_on_sec_failure(p_evt);
    pm_handler_flash_clean(p_evt);

    switch (p_evt->evt_id)
    {
        case PM_EVT_CONN_SEC_SUCCEEDED:
        {
            pm_conn_sec_status_t conn_sec_status;

            // Check if the link is authenticated (meaning at least MITM).
            err_code = pm_conn_sec_status_get(p_evt->conn_handle, &conn_sec_status);
            APP_ERROR_CHECK(err_code);

            if (conn_sec_status.mitm_protected)
            {
                NRF_LOG_INFO("Link secured. Role: %d. conn_handle: %d, Procedure: %d",
                             ble_conn_state_role(p_evt->conn_handle),
                             p_evt->conn_handle,
                             p_evt->params.conn_sec_succeeded.procedure);
            }
            else
            {
                // The peer did not use MITM, disconnect.
                NRF_LOG_INFO("Collector did not use MITM, disconnecting");
                err_code = pm_peer_id_get(m_conn_handle, &m_peer_to_be_deleted);
                APP_ERROR_CHECK(err_code);
                err_code = sd_ble_gap_disconnect(m_conn_handle,
                                                 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
                APP_ERROR_CHECK(err_code);
            }
        } break;

        case PM_EVT_CONN_SEC_FAILED:
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            break;

        case PM_EVT_PEERS_DELETE_SUCCEEDED:
            advertising_start(false);
            break;

        default:
            break;
    }
}


/**@brief Function for handling Service errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in] nrf_error  Error code containing information about what went wrong.
 */
static void service_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for performing battery measurement and updating the Battery Level characteristic
 *        in Battery Service.
 */
static void battery_level_update(void)
{
    ret_code_t err_code;
    uint8_t  battery_level;

    battery_level = (uint8_t)sensorsim_measure(&m_battery_sim_state, &m_battery_sim_cfg);

    err_code = ble_bas_battery_level_update(&m_bas, battery_level, BLE_CONN_HANDLE_ALL);
    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the Battery measurement timer timeout.
 *
 * @details This function will be called each time the battery level measurement timer expires.
 *
 * @param[in] p_context  Pointer used for passing some arbitrary information (context) from the
 *                       app_start_timer() call to the timeout handler.
 */
static void battery_level_meas_timeout_handler(void * p_context)
{
    UNUSED_PARAMETER(p_context);
    battery_level_update();
}


/**@brief Function for updating glucose measurement and updating glucose characteristic in Glucose.
          Service.
 */
static void read_glucose_measurement(void)
{
    ble_gls_rec_t rec;
    uint32_t      err_code;

    static int16_t s_mantissa = 550;
    static int16_t s_exponent = -3;
    static uint8_t s_secs     = 5;

    // simulate the reading of a glucose measurement.
    rec.meas.flags = BLE_GLS_MEAS_FLAG_TIME_OFFSET |
                     BLE_GLS_MEAS_FLAG_CONC_TYPE_LOC |
                     BLE_GLS_MEAS_FLAG_UNITS_MOL_L;
    rec.meas.base_time.year                 = 2012;
    rec.meas.base_time.month                = 1;
    rec.meas.base_time.day                  = 1;
    rec.meas.base_time.hours                = 12;
    rec.meas.base_time.minutes              = 30;
    rec.meas.base_time.seconds              = s_secs;
    rec.meas.glucose_concentration.exponent = s_exponent;
    rec.meas.glucose_concentration.mantissa = s_mantissa;
    rec.meas.time_offset                    = 0;
    rec.meas.type                           = BLE_GLS_MEAS_TYPE_CAP_BLOOD;
    rec.meas.sample_location                = BLE_GLS_MEAS_LOC_FINGER;
    rec.meas.sensor_status_annunciation     = 0;

    // change values for next read.
    s_mantissa += 23;
    if (s_mantissa > 939)
    {
        s_mantissa -= 434;
    }

    s_secs += 3;
    if (s_secs > 59)
    {
        s_secs = 0;
    }

    err_code = ble_gls_glucose_new_meas(&m_gls, &rec);
    if (err_code != NRF_SUCCESS)
    {
        // Do nothing.
    }
}


/**@brief Function for the Timer initialization.
 *
 * @details Initializes the timer module. This creates and starts application timers.
 */
static void timers_init(void)
{
    ret_code_t err_code;

    // Initialize timer module.
    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);

    // Create timers.
    err_code = app_timer_create(&m_battery_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                battery_level_meas_timeout_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for the GAP initialization.
 *
 * @details This function sets up all the necessary GAP (Generic Access Profile) parameters of the
 *          device including the device name, appearance, and the preferred connection parameters.
 */
static void gap_params_init(void)
{
    ret_code_t              err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *)DEVICE_NAME,
                                          strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

    err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_GENERIC_GLUCOSE_METER);
    APP_ERROR_CHECK(err_code);

    memset(&gap_conn_params, 0, sizeof(gap_conn_params));

    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;

    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the GATT module.
 */
static void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling Queued Write Module errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void nrf_qwr_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing services that will be used by the application.
 *
 * @details Initialize the Glucose, Battery and Device Information services.
 */
static void services_init(void)
{
    ret_code_t         err_code;
    ble_gls_init_t     gls_init;
    ble_dis_init_t     dis_init;
    ble_bas_init_t     bas_init;
    nrf_ble_qwr_init_t qwr_init = {0};

    // Initialize Queued Write Module.
    qwr_init.error_handler = nrf_qwr_error_handler;

    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init);
    APP_ERROR_CHECK(err_code);

    // Initialize Glucose Service - sample selection of feature bits.
    memset(&gls_init, 0, sizeof(gls_init));

    gls_init.evt_handler          = NULL;
    gls_init.error_handler        = service_error_handler;
    gls_init.feature              = 0;
    gls_init.feature             |= BLE_GLS_FEATURE_LOW_BATT;
    gls_init.feature             |= BLE_GLS_FEATURE_TEMP_HIGH_LOW;
    gls_init.feature             |= BLE_GLS_FEATURE_GENERAL_FAULT;
    gls_init.is_context_supported = false;

    // Here the sec level for the Glucose Service can be changed/increased.
    gls_init.gl_meas_cccd_wr_sec = SEC_JUST_WORKS;
    gls_init.gl_feature_rd_sec   = SEC_JUST_WORKS;
    gls_init.racp_cccd_wr_sec    = SEC_JUST_WORKS;
    gls_init.racp_wr_sec         = SEC_JUST_WORKS;

    err_code = ble_gls_init(&m_gls, &gls_init);
    APP_ERROR_CHECK(err_code);

    // Initialize Battery Service.
    memset(&bas_init, 0, sizeof(bas_init));

    // Here the sec level for the Battery Service can be changed/increased.
    bas_init.bl_rd_sec        = SEC_OPEN;
    bas_init.bl_cccd_wr_sec   = SEC_OPEN;
    bas_init.bl_report_rd_sec = SEC_OPEN;

    bas_init.evt_handler          = NULL;
    bas_init.support_notification = true;
    bas_init.p_report_ref         = NULL;
    bas_init.initial_batt_level   = 100;

    err_code = ble_bas_init(&m_bas, &bas_init);
    APP_ERROR_CHECK(err_code);

    // Initialize Device Information Service.
    memset(&dis_init, 0, sizeof(dis_init));

    ble_srv_ascii_to_utf8(&dis_init.manufact_name_str, MANUFACTURER_NAME);

    ble_srv_ascii_to_utf8(&dis_init.serial_num_str, MODEL_NUMBER);

    ble_dis_sys_id_t system_id;
    system_id.manufacturer_id            = MANUFACTURER_ID;
    system_id.organizationally_unique_id = ORG_UNIQUE_ID;
    dis_init.p_sys_id                    = &system_id;

    dis_init.dis_char_rd_sec = SEC_OPEN;

    err_code = ble_dis_init(&dis_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the sensor simulators.
 */
static void sensor_simulator_init(void)
{
    m_battery_sim_cfg.min          = MIN_BATTERY_LEVEL;
    m_battery_sim_cfg.max          = MAX_BATTERY_LEVEL;
    m_battery_sim_cfg.incr         = BATTERY_LEVEL_INCREMENT;
    m_battery_sim_cfg.start_at_max = true;

    sensorsim_init(&m_battery_sim_state, &m_battery_sim_cfg);
}


/**@brief Function for starting application timers.
 */
static void application_timers_start(void)
{
    ret_code_t err_code;

    // Start application timers.
    err_code = app_timer_start(m_battery_timer_id, BATTERY_LEVEL_MEAS_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling the Connection Parameter events.
 *
 * @details This function will be called for all events in the Connection Parameters Module which
 *          are passed to the application.
 *          @note All this function does is to disconnect. This could have been done by simply
 *                setting the disconnect_on_fail configuration parameter, but instead we use the
 *                event handler mechanism to demonstrate its use.
 *
 * @param[in] p_evt  Event received from the Connection Parameters Module.
 */
static void on_conn_params_evt(ble_conn_params_evt_t * p_evt)
{
    ret_code_t err_code;

    if (p_evt->evt_type == BLE_CONN_PARAMS_EVT_FAILED)
    {
        err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_CONN_INTERVAL_UNACCEPTABLE);
        APP_ERROR_CHECK(err_code);
    }
}


/**@brief Function for handling a Connection Parameters error.
 *
 * @param[in] nrf_error  Error code containing information about what went wrong.
 */
static void conn_params_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void)
{
    ret_code_t             err_code;
    ble_conn_params_init_t cp_init;

    memset(&cp_init, 0, sizeof(cp_init));

    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAM_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = on_conn_params_evt;
    cp_init.error_handler                  = conn_params_error_handler;

    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    ret_code_t err_code;;
    err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling advertising events.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    ret_code_t err_code;

    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_FAST:
            NRF_LOG_INFO("Fast advertising");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break; // BLE_ADV_EVT_FAST

        case BLE_ADV_EVT_IDLE:
            sleep_mode_enter();
            break; // BLE_ADV_EVT_IDLE

        default:
            break;
    }
}


/**@brief Function for handling BLE events.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    ret_code_t err_code;

    pm_handler_secure_on_connection(p_ble_evt);

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_DISCONNECTED:
        {
            NRF_LOG_INFO("Disconnected");
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            // Check if the last connected peer had not used MITM, if so, delete its bond information.
            if (m_peer_to_be_deleted != PM_PEER_ID_INVALID)
            {
                err_code = pm_peer_delete(m_peer_to_be_deleted);
                APP_ERROR_CHECK(err_code);
                NRF_LOG_DEBUG("Collector's bond deleted");
                m_peer_to_be_deleted = PM_PEER_ID_INVALID;
            }
        } break;

        case BLE_GAP_EVT_CONNECTED:
        {
            NRF_LOG_INFO("Connected");
            m_peer_to_be_deleted = PM_PEER_ID_INVALID;
            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);
            m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
            err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
            APP_ERROR_CHECK(err_code);
            // Start Security Request timer.
        } break;

        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_DEBUG("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_GATTC_EVT_TIMEOUT:
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTS_EVT_TIMEOUT:
            // Disconnect on GATT Server timeout event.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            NRF_LOG_DEBUG("BLE_GAP_EVT_SEC_PARAMS_REQUEST");
            break;

        case BLE_GAP_EVT_PASSKEY_DISPLAY:
        {
            char passkey[PASSKEY_LENGTH + 1];
            memcpy(passkey, p_ble_evt->evt.gap_evt.params.passkey_display.passkey, PASSKEY_LENGTH);
            passkey[PASSKEY_LENGTH] = 0;

            NRF_LOG_INFO("Passkey: %s", nrf_log_push(passkey));
        } break;
        
        case BLE_GAP_EVT_AUTH_KEY_REQUEST:
            NRF_LOG_INFO("BLE_GAP_EVT_AUTH_KEY_REQUEST");
            break;

        case BLE_GAP_EVT_LESC_DHKEY_REQUEST:
            NRF_LOG_INFO("BLE_GAP_EVT_LESC_DHKEY_REQUEST");
            break;

         case BLE_GAP_EVT_AUTH_STATUS:
             NRF_LOG_INFO("BLE_GAP_EVT_AUTH_STATUS: status=0x%x bond=0x%x lv4: %d kdist_own:0x%x kdist_peer:0x%x",
                          p_ble_evt->evt.gap_evt.params.auth_status.auth_status,
                          p_ble_evt->evt.gap_evt.params.auth_status.bonded,
                          p_ble_evt->evt.gap_evt.params.auth_status.sm1_levels.lv4,
                          *((uint8_t *)&p_ble_evt->evt.gap_evt.params.auth_status.kdist_own),
                          *((uint8_t *)&p_ble_evt->evt.gap_evt.params.auth_status.kdist_peer));
            break;

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for initializing the BLE stack.
 *
 * @details Initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

    // Configure the BLE stack using the default settings.
    // Fetch the start address of the application RAM.
    uint32_t ram_start = 0;
    err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
    APP_ERROR_CHECK(err_code);

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);

    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}


/**@brief Function for handling events from the BSP module.
 *
 * @param[in]   event   Event generated by button press.
 */
static void bsp_event_handler(bsp_event_t event)
{
    ret_code_t err_code;

    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break; // BSP_EVENT_SLEEP

        case BSP_EVENT_DISCONNECT:
            err_code = sd_ble_gap_disconnect(m_conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break; // BSP_EVENT_DISCONNECT

        case BSP_EVENT_WHITELIST_OFF:
            if (m_conn_handle == BLE_CONN_HANDLE_INVALID)
            {
                err_code = ble_advertising_restart_without_whitelist(&m_advertising);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
            }
            break; // BSP_EVENT_WHITELIST_OFF

        case BSP_EVENT_KEY_1:
            read_glucose_measurement();
            break; // BSP_EVENT_KEY_1

        default:
            break;
    }
}


/**@brief Function for the Peer Manager initialization.
 */
static void peer_manager_init(void)
{
    ble_gap_sec_params_t sec_param;
    ret_code_t           err_code;

    err_code = pm_init();
    APP_ERROR_CHECK(err_code);

    memset(&sec_param, 0, sizeof(ble_gap_sec_params_t));

    // Security parameters to be used for all security procedures.
    sec_param.bond           = SEC_PARAM_BOND;
    sec_param.mitm           = SEC_PARAM_MITM;
    sec_param.lesc           = SEC_PARAM_LESC;
    sec_param.keypress       = SEC_PARAM_KEYPRESS;
    sec_param.io_caps        = SEC_PARAM_IO_CAPABILITIES;
    sec_param.oob            = SEC_PARAM_OOB;
    sec_param.min_key_size   = SEC_PARAM_MIN_KEY_SIZE;
    sec_param.max_key_size   = SEC_PARAM_MAX_KEY_SIZE;
    sec_param.kdist_own.enc  = 1;
    sec_param.kdist_own.id   = 1;
    sec_param.kdist_peer.enc = 1;
    sec_param.kdist_peer.id  = 1;


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

    err_code = pm_register(pm_evt_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Clear bond information from persistent storage.
 */
static void delete_bonds(void)
{
    ret_code_t err_code;

    NRF_LOG_INFO("Erase bonds!");

    err_code = pm_peers_delete();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the Advertising functionality.
 *
 * @details Encodes the required advertising data and passes it to the stack.
 *          Also builds a structure to be passed to the stack when starting advertising.
 */
static void advertising_init(void)
{
    uint32_t               err_code;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = true;
    init.advdata.flags                   = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;
    init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.advdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_fast_enabled  = true;
    init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout  = APP_ADV_DURATION;

    init.evt_handler = on_adv_evt;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);

    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}


/**@brief Function for initializing buttons and leds.
 *
 * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
 */
static void buttons_leds_init(bool * p_erase_bonds)
{
    ret_code_t err_code;
    bsp_event_t startup_event;

    err_code = bsp_init(BSP_INIT_LEDS | BSP_INIT_BUTTONS, bsp_event_handler);
    APP_ERROR_CHECK(err_code);

    err_code = bsp_btn_ble_init(NULL, &startup_event);
    APP_ERROR_CHECK(err_code);

    *p_erase_bonds = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
}


/**@brief Function for initializing the nrf log module.
 */
static void log_init(void)
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
}


/**@brief Function for initializing power management.
 */
static void power_management_init(void)
{
    ret_code_t err_code;
    err_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    ret_code_t err_code;

    err_code = nrf_ble_lesc_request_handler();
    APP_ERROR_CHECK(err_code);

    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}


/**@brief Function for starting advertising.
 */
static void advertising_start(bool erase_bonds)
{
    if (erase_bonds == true)
    {
        delete_bonds();
        // Advertising is started by PM_EVT_PEERS_DELETE_SUCCEEDED event.
    }
    else
    {
        ret_code_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);

        APP_ERROR_CHECK(err_code);
    }
}
/////////// STATIC PASSKEY
static void set_static_passkey()

{

    static ble_opt_t    m_static_pin_option;

    uint8_t passkey[] = STATIC_PASSKEY;

    m_static_pin_option.gap_opt.passkey.p_passkey = &passkey[0];

    uint32_t err_code =  sd_ble_opt_set(BLE_GAP_OPT_PASSKEY, &m_static_pin_option);

    APP_ERROR_CHECK(err_code);     

}
///////////////

/**@brief Function for application main entry.
 */
int main(void)
{
    bool erase_bonds;

    // Initialize.
    log_init();
    timers_init();
    buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    set_static_passkey();
    gap_params_init();
    gatt_init();
    advertising_init();
    services_init();
    sensor_simulator_init();
    conn_params_init();
    peer_manager_init();

    // Start execution.
    NRF_LOG_INFO("Glucose example started.");
    application_timers_start();
    advertising_start(erase_bonds);

    // Enter main loop.
    for (;;)
    {
        idle_state_handle();
    }
}


/**
 * @}
 */

[Siddharth rana]

Hi beemavishnu

I was able to achieve paring with static passkey .

The thing is u need to build the static passkey function before connection and paring function 

As for bonding u can change its parameter to no bond or bond once