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scanning and decryption of data

I had two nRF52832 where one broadcasts with encrypted data of advertising beacon info and another nRF52832 should only scan without connecting and should decrypt the data of beacon which is broadcasting.

for that what should i do?

please give me any sample code if available

Parents
  • Hi @Simon

    ok with the decryption part but now my problem is mainly about the Scanning part

    I need to scan the beacon's MAC address,UUID,Major,Minor,battery level etc the scanner should only scan beacons it should not get connected after detecting. 

    Thank you

  • the advertising packets is redirected to the function nrf_ble_scan_on_adv_report(..) where the contents of the packets is located at the address in p_adv_report.data.p_data. Here you can check the content of the advertising packets, like UUID, Major, Minor, RSSI and so on..

    can please give me that code which displays all these fields with MAC address also 

  • Hi @Simon

           case BLE_GAP_EVT_ADV_REPORT:
    			
                            {
    				NRF_LOG_INFO("Advertise received");
    				scan_start();
                                    
    
    				
    				memmove(uuid, p_gap_evt->params.adv_report.data.p_data, p_gap_evt->params.adv_report.data.len);
    				
    				NRF_LOG_INFO("UUID: %02x%02x%02x%02x%02x%02x", uuid[0], uuid[1], uuid[2], uuid[3], uuid[4], uuid[5]);
    				
    				NRF_LOG_INFO("TX_POWER: %02x", p_gap_evt->params.adv_report.tx_power);
    				
    				NRF_LOG_INFO("RSSI: %02x", p_gap_evt->params.adv_report.rssi);
                           
    				
    			} break;

    i wrote this code for UUID,RSSI but what i do get MAC Address and MAJOR,MINOR Values?

  • Take a look at the m_beacon_info array in the beacon example:

    static uint8_t m_beacon_info[APP_BEACON_INFO_LENGTH] =                    /**< Information advertised by the Beacon. */
    {
        APP_DEVICE_TYPE,     // Manufacturer specific information. Specifies the device type in this
                             // implementation.
        APP_ADV_DATA_LENGTH, // Manufacturer specific information. Specifies the length of the
                             // manufacturer specific data in this implementation.
        APP_BEACON_UUID,     // 128 bit UUID value.
        APP_MAJOR_VALUE,     // Major arbitrary value that can be used to distinguish between Beacons.
        APP_MINOR_VALUE,     // Minor arbitrary value that can be used to distinguish between Beacons.
        APP_MEASURED_RSSI    // Manufacturer specific information. The Beacon's measured TX power in
                             // this implementation.
    };

    Here you can see in which order the different field is put into the advertising packet.

    Next you can see that this array is sent as «Manufacturer Specific Data»:

    manuf_specific_data.data.p_data = (uint8_t *) m_beacon_info;
    manuf_specific_data.data.size   = APP_BEACON_INFO_LENGTH;

    When you receive the advertising packet, you simply look for the AD type 0xFF (which is the type for Manufacturer Specific Data) and fetch the fields you are interested in, by using the offsets you see in the m_beacon_info array. Here  and here are some useful links that explains how the a BLE advertising packet is structured.

    The address can be found inside p_gap_evt->params.adv_report.peer_addr.addr.

    Best regards,

    Simon

  • Hi @Simon

    Can you give me the code to scan  UUID,RSSI,MAC Address and MAJOR,MINOR Values

    i wrote code to scan the mac address but there is no value displaying

           case BLE_GAP_EVT_ADV_REPORT:
    			
                            {
    				NRF_LOG_INFO("Advertise received");
    				scan_start();
                                    
    
    				
    				memmove(uuid, p_gap_evt->params.adv_report.data.p_data, p_gap_evt->params.adv_report.data.len);
    				
    				NRF_LOG_INFO("UUID: %02x%02x%02x%02x%02x%02x", uuid[0], uuid[1], uuid[2], uuid[3], uuid[4], uuid[5]);
    				
    				NRF_LOG_INFO("TX_POWER: %02x", p_gap_evt->params.adv_report.tx_power);
    				
    				NRF_LOG_INFO("RSSI: %02x", p_gap_evt->params.adv_report.rssi);
                           
                                     ble_gap_addr_t  addr;
    
                                       printf(" Connected to %02x:%02x:%02x:%02x:%02x:%02x", 
                                         addr.addr[5],addr.addr[4],addr.addr[3],
                                         addr.addr[2],addr.addr[1],addr.addr[0],
                                         p_gap_evt->params.adv_report.peer_addr.addr);
    
                                        
    				
    			} break;

    Please help me to solve this problem.

    Thank you

  • Before you read my explanation I would recommend you to read through the links below. The first link explains how the advertising packet is structured. In short, the advertising  packet consist of a set of advertising data elements (AD types):

    Let me explain in more details and go through how the advertising data is set up and decoded on respectively the advertising and scanner side.

    On the peripheral/advertiser side:

    If you open the ble_app_beacon peripheral example and take a look inside the function advertising_init() you can see how the advertising beacon data is set.

    The example uses the ble_advdata library to configure the advertising packet and if you look inside the data structure ble_advdata_t you can see the data types needed to set up the advertising data. 

    In this example, the advertising data is set to contain two data types, specifically a flag and manufacturer specific data. If you look at link 2 you will see that their data types are respectively 0x01 and 0xFF. The flag included is BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED, which equals a value of 0x04 and. The manufacturer specific data includes a company identifier and the user specific data. The company identifier is set to 0x0059 and the actual data is filled with the data in the m_beacon_info array.

    As explained in link 1, the advertising packet is structured in this manner:   

    | Length | AD Type | AD Data | Length | AD Type | AD Data...........

    The beacon advertising packet should then look like this:

    | 0x02 (Length of flag) | 0x01 (flags) | 0x04 (BR_EDR_NOT_SUPPORTED) | 0x1A (Length of manuf. spec. data) | 0xFF (manuf. spec. data) | m_beacon_info[]

    On the central/scanner side:

    I modified the ble_app_uart central example, since it already implement scanning functionality.  Specifically inside the nrf_ble_scan.c library i added the code shown below to the nrf_ble_scan_on_ble_evt() function:

    void nrf_ble_scan_on_ble_evt()
    .
    .
     case BLE_GAP_EVT_ADV_REPORT:
            {
            if(p_adv_report->rssi > -35){
                    uint8_t adv_data[50] = {0};
                    memmove(adv_data, p_adv_report->data.p_data, p_adv_report->data.len);
                    uint8_t count = 0;
                    NRF_LOG_INFO("-----------------------------------------------------");
                    while(count < p_adv_report->data.len + 6){
                        NRF_LOG_INFO("values: %02x | %02x | %02x | %02x | %02x | %02x", adv_data[0+count], adv_data[1+count],   adv_data[2+count],  adv_data[3+count],  adv_data[4+count],  adv_data[5+count]);                 
                        count = count + 6;
                    }
                    NRF_LOG_INFO("-----------------------------------------------------");
                }
            .
            .
            .

    The output I got was the following:

    <info> ble_scan: values: 02 | 01 | 04 | 1A | FF | 59
    <info> ble_scan: values: 00 | 02 | 15 | 01 | 12 | 23
    <info> ble_scan: values: 34 | 45 | 56 | 67 | 78 | 89
    <info> ble_scan: values: 9A | AB | BC | CD | DE | EF
    <info> ble_scan: values: F0 | 01 | 02 | 03 | 04 | C3
    <info> ble_scan: values: 00 | 00 | 00 | 00 | 00 | 00

    Which matches the assumptions made above.

    The beacon UUID and the MINOR and MAJOR values are located inside the manufacturer specific data, and if you look inside the m_beacon_info array inside the ble_app_beacon example you can see that the UUID is on position 3 while the MAJOR and MINOR values are located on position 4 and 5 respectively.

    In order to get the UUID and the MINOR and MAJOR values , you first need to look for the field 0xFF inside the advertising data, then you need to know what offset/position the different values are located. In the code snippet I provided I also showed how to get the RSSI and the address is, as mentioned, inside the field p_gap_evt->params.adv_report.peer_addr.addr.

    Best regards,

    Simon

Reply
  • Before you read my explanation I would recommend you to read through the links below. The first link explains how the advertising packet is structured. In short, the advertising  packet consist of a set of advertising data elements (AD types):

    Let me explain in more details and go through how the advertising data is set up and decoded on respectively the advertising and scanner side.

    On the peripheral/advertiser side:

    If you open the ble_app_beacon peripheral example and take a look inside the function advertising_init() you can see how the advertising beacon data is set.

    The example uses the ble_advdata library to configure the advertising packet and if you look inside the data structure ble_advdata_t you can see the data types needed to set up the advertising data. 

    In this example, the advertising data is set to contain two data types, specifically a flag and manufacturer specific data. If you look at link 2 you will see that their data types are respectively 0x01 and 0xFF. The flag included is BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED, which equals a value of 0x04 and. The manufacturer specific data includes a company identifier and the user specific data. The company identifier is set to 0x0059 and the actual data is filled with the data in the m_beacon_info array.

    As explained in link 1, the advertising packet is structured in this manner:   

    | Length | AD Type | AD Data | Length | AD Type | AD Data...........

    The beacon advertising packet should then look like this:

    | 0x02 (Length of flag) | 0x01 (flags) | 0x04 (BR_EDR_NOT_SUPPORTED) | 0x1A (Length of manuf. spec. data) | 0xFF (manuf. spec. data) | m_beacon_info[]

    On the central/scanner side:

    I modified the ble_app_uart central example, since it already implement scanning functionality.  Specifically inside the nrf_ble_scan.c library i added the code shown below to the nrf_ble_scan_on_ble_evt() function:

    void nrf_ble_scan_on_ble_evt()
    .
    .
     case BLE_GAP_EVT_ADV_REPORT:
            {
            if(p_adv_report->rssi > -35){
                    uint8_t adv_data[50] = {0};
                    memmove(adv_data, p_adv_report->data.p_data, p_adv_report->data.len);
                    uint8_t count = 0;
                    NRF_LOG_INFO("-----------------------------------------------------");
                    while(count < p_adv_report->data.len + 6){
                        NRF_LOG_INFO("values: %02x | %02x | %02x | %02x | %02x | %02x", adv_data[0+count], adv_data[1+count],   adv_data[2+count],  adv_data[3+count],  adv_data[4+count],  adv_data[5+count]);                 
                        count = count + 6;
                    }
                    NRF_LOG_INFO("-----------------------------------------------------");
                }
            .
            .
            .

    The output I got was the following:

    <info> ble_scan: values: 02 | 01 | 04 | 1A | FF | 59
    <info> ble_scan: values: 00 | 02 | 15 | 01 | 12 | 23
    <info> ble_scan: values: 34 | 45 | 56 | 67 | 78 | 89
    <info> ble_scan: values: 9A | AB | BC | CD | DE | EF
    <info> ble_scan: values: F0 | 01 | 02 | 03 | 04 | C3
    <info> ble_scan: values: 00 | 00 | 00 | 00 | 00 | 00

    Which matches the assumptions made above.

    The beacon UUID and the MINOR and MAJOR values are located inside the manufacturer specific data, and if you look inside the m_beacon_info array inside the ble_app_beacon example you can see that the UUID is on position 3 while the MAJOR and MINOR values are located on position 4 and 5 respectively.

    In order to get the UUID and the MINOR and MAJOR values , you first need to look for the field 0xFF inside the advertising data, then you need to know what offset/position the different values are located. In the code snippet I provided I also showed how to get the RSSI and the address is, as mentioned, inside the field p_gap_evt->params.adv_report.peer_addr.addr.

    Best regards,

    Simon

Children
  • Hi Simon

    How should i decrypt the m_beacon_info in the scanning part using ble_app_uart_c example

    if any code is available please give me 

  • Open the ble_app_uart_c (central) example, and take a look at the function ble_advdata_parse() in the ble_advdata.h file, which enables you to get the data for a specific AD type. 

    Best regards,

    Simon

  • Hi Simon,

    I had done the encryption part as given in this link 

    Encryption code:

    #include <stdint.h>
    #include <string.h>
    #include "ble_advertising.h"
    #include "nordic_common.h"
    #include "nrf.h"
    #include "nrf_soc.h"
    #include "nrf_drv_saadc.h"
    #include "nrf_sdm.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_tps.h"
    #include "ble_ias.h"
    #include "ble_lls.h"
    #include "ble_bas.h"
    #include "ble_conn_params.h"
    #include "ble_conn_state.h"
    #include "sensorsim.h"
    #include "nrf_sdh.h"
    #include "nrf_sdh_soc.h"
    #include "nrf_sdh_ble.h"
    #include "nrf_delay.h"
    #include "app_timer.h"
    #include "app_error.h"
    #include "ble_ias_c.h"
    #include "app_util.h"
    #include "bsp_btn_ble.h"
    #include "ble_db_discovery.h"
    #include "peer_manager.h"
    #include "peer_manager_handler.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_ble_scan.h"
    #include "nrf_pwr_mgmt.h"
    #include "nrf_fstorage.h"
    #include "nrf_log.h"
    #include "nrf_log_ctrl.h"
    #include "nrf_log_default_backends.h"
    
    
    #define DEVICE_NAME                     "NORDIC"                           
    
    #define APP_BLE_OBSERVER_PRIO           3                                       
    #define APP_BLE_CONN_CFG_TAG            1                                       
    
    #define BATTERY_LEVEL_MEAS_INTERVAL     APP_TIMER_TICKS(120000)                 
    
    #define MIN_CONN_INTERVAL               MSEC_TO_UNITS(500, UNIT_1_25_MS)        
    #define MAX_CONN_INTERVAL               MSEC_TO_UNITS(1000, UNIT_1_25_MS)       
    #define SLAVE_LATENCY                   0                                       
    #define CONN_SUP_TIMEOUT                MSEC_TO_UNITS(4000, UNIT_10_MS)         
    
    #define APP_ADV_INTERVAL                40 
    #define APP_ADV_TIMEOUT_IN_SECONDS      80                                      
    #define NON_CONNECTABLE_ADV_INTERVAL    MSEC_TO_UNITS(100, UNIT_0_625_MS)  
    
    #define APP_ADV_DURATION                18000                                    
    #define BLE_ADV_DIRECTED_ENABLED        true
    #define BLE_ADV_DIRECTED_DISABLED       false
    #define BLE_ADV_DIRECTED_SLOW_ENABLED   true
    #define BLE_ADV_DIRECTED_SLOW_DISABLED  false
    #define BLE_ADV_FAST_ENABLED            true
    #define BLE_ADV_FAST_DISABLED           false
    #define BLE_ADV_SLOW_ENABLED            true
    #define BLE_ADV_SLOW_DISABLED           false
    #define BLE_ADV_WHITELIST_ENABLED       true
    #define BLE_ADV_WHITELIST_DISABLED      false
    
    #define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000)                   
    #define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(30000)                  
    #define MAX_CONN_PARAMS_UPDATE_COUNT    3                                       
    
    #define SEC_PARAM_BOND                  1                                       
    #define SEC_PARAM_MITM                  0                                       
    #define SEC_PARAM_LESC                  0                                       
    #define SEC_PARAM_KEYPRESS              0                                       
    #define SEC_PARAM_IO_CAPABILITIES       BLE_GAP_IO_CAPS_NONE                    
    #define SEC_PARAM_OOB                   0                                       
    #define SEC_PARAM_MIN_KEY_SIZE          7                                       
    #define SEC_PARAM_MAX_KEY_SIZE          16
    #define BLE_GAP_ADV_TYPE_ADV_IND          0x00
    #define BLE_GAP_ADV_TYPE_ADV_DIRECT_IND   0x01
    #define BLE_GAP_ADV_TYPE_ADV_SCAN_IND     0x02
    #define BLE_GAP_ADV_TYPE_ADV_NONCONN_IND  0x03 
    #define BLE_GAP_ADDR_TYPE_PUBLIC                        0x00
    #define BLE_GAP_ADDR_TYPE_RANDOM_STATIC                 0x01
    #define BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE     0x02
    #define BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_NON_RESOLVABLE 0x03                                     
    
    #define INITIAL_LLS_ALERT_LEVEL         BLE_CHAR_ALERT_LEVEL_NO_ALERT           
    #define TX_POWER_LEVEL                  (-8)                                    
    
    #define ADC_REF_VOLTAGE_IN_MILLIVOLTS   600                                     
    #define ADC_PRE_SCALING_COMPENSATION    6                                       
    #define DIODE_FWD_VOLT_DROP_MILLIVOLTS  270                                     
    #define ADC_RES_10BIT                   1024                                    
    
    #define DEAD_BEEF                       0xDEADBEEF  
    #define ECB_KEY_LEN            (16UL)
    #define COUNTER_BYTE_LEN       (4UL)
    #define NONCE_RAND_BYTE_LEN    (12UL)
    
    static uint8_t m_ecb_key[16] = {0x6E,0x88,0x90,0x8D,0x75,0xBB,0x95,0xEA,0x2C,0x65,0x93,0x01,0x43,0xF8,0x1B,0x5F};
    static uint8_t m_counter_byte[4] = {0x6F,0x88,0x99,0x84};
    
    // The RNG wait values are typical and not guaranteed. See Product Specifications for more info.
    #ifdef NRF51
    #define RNG_BYTE_WAIT_US       (677UL)
    #elif defined NRF52
    #define RNG_BYTE_WAIT_US       (124UL)
    #else
    #error "Either NRF51 or NRF52 must be defined."
    #endif                            
    
    #define APP_BEACON_INFO_LENGTH          0x17                               
    #define APP_ADV_DATA_LENGTH             0x15                               
    #define APP_DEVICE_TYPE                 0x02                               
    #define APP_MEASURED_RSSI               0xC5                               
    #define APP_COMPANY_IDENTIFIER          0x0059                             
    #define APP_MAJOR_VALUE                 0x00, 0x02                         
    #define APP_MINOR_VALUE                 0x00, 0x02                         
    #define APP_BEACON_UUID                 0x01, 0x12, 0x23, 0x34, \
                                            0x45, 0x56, 0x67, 0x78, \
                                            0x89, 0x9a, 0xab, 0xbc, \
                                            0xcd, 0xde, 0xef, 0xf0            
    
    #if defined(USE_UICR_FOR_MAJ_MIN_VALUES)
    #define MAJ_VAL_OFFSET_IN_BEACON_INFO   18                                
    #define UICR_ADDRESS                    0x10001080                         
    #endif
    
    
    #define ADC_RESULT_IN_MILLI_VOLTS(ADC_VALUE)\
            ((((ADC_VALUE) * ADC_REF_VOLTAGE_IN_MILLIVOLTS) / ADC_RES_10BIT) * ADC_PRE_SCALING_COMPENSATION)
    
    
    APP_TIMER_DEF(m_battery_timer_id);                      
    BLE_TPS_DEF(m_tps);                                     
    BLE_IAS_DEF(m_ias, NRF_SDH_BLE_TOTAL_LINK_COUNT);       
    BLE_LLS_DEF(m_lls);                                     
    BLE_BAS_DEF(m_bas);                                     
    BLE_IAS_C_DEF(m_ias_c);                                 
    NRF_BLE_GATT_DEF(m_gatt);                               
    NRF_BLE_QWR_DEF(m_qwr);                                 
    BLE_ADVERTISING_DEF(m_advertising);                     
    BLE_DB_DISCOVERY_DEF(m_ble_db_discovery);               
    
    static volatile bool m_is_high_alert_signalled;         
    static volatile bool m_is_ias_present = false;          
    
    static nrf_saadc_value_t adc_buf[2];
    
    static ble_uuid_t m_adv_uuids[] =                       
    {
        {BLE_UUID_IMMEDIATE_ALERT_SERVICE, BLE_UUID_TYPE_BLE},
        {BLE_UUID_BATTERY_SERVICE, BLE_UUID_TYPE_BLE},
        {BLE_UUID_TX_POWER_SERVICE, BLE_UUID_TYPE_BLE},
        {BLE_UUID_LINK_LOSS_SERVICE, BLE_UUID_TYPE_BLE}
    };
    
    static ble_gap_adv_params_t m_adv_params;                                  
    static uint8_t              m_adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET; 
    static uint8_t              m_enc_advdata[BLE_GAP_ADV_SET_DATA_SIZE_MAX];  
    static uint8_t              m_enc_scandata[BLE_GAP_ADV_SET_DATA_SIZE_MAX];  
    
    
    static ble_gap_adv_data_t m_adv_data =
    {
        .adv_data =
        {
            .p_data = m_enc_advdata,
            .len    = BLE_GAP_ADV_SET_DATA_SIZE_MAX
        },
        .scan_rsp_data =
        {
            .p_data = m_enc_scandata,
            .len    = BLE_GAP_ADV_SET_DATA_SIZE_MAX
    
        }
    };
    
    
    
    
    static uint8_t m_beacon_info[APP_BEACON_INFO_LENGTH] =                    
    {
        APP_DEVICE_TYPE,     
                             
        APP_ADV_DATA_LENGTH, 
                             
        APP_BEACON_UUID,     
        APP_MAJOR_VALUE,     
        APP_MINOR_VALUE,     
        APP_MEASURED_RSSI    
                             
    };
    
    
    static void on_ias_evt(ble_ias_t * p_ias, ble_ias_evt_t * p_evt);
    static void on_lls_evt(ble_lls_t * p_lls, ble_lls_evt_t * p_evt);
    static void on_ias_c_evt(ble_ias_c_t * p_lls, ble_ias_c_evt_t * p_evt);
    static void on_bas_evt(ble_bas_t * p_bas, ble_bas_evt_t * p_evt);
    static void advertising_init(void);
    static void advertising_start(bool erase_bonds);
    
    
    
    void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
    {
        app_error_handler(DEAD_BEEF, line_num, p_file_name);
    }
    
    
    
    static void service_error_handler(uint32_t nrf_error)
    {
        APP_ERROR_HANDLER(nrf_error);
    }
    
    
    
    static void pm_evt_handler(pm_evt_t const * p_evt)
    {
        pm_handler_on_pm_evt(p_evt);
        pm_handler_flash_clean(p_evt);
    
        switch (p_evt->evt_id)
        {
            case PM_EVT_PEERS_DELETE_SUCCEEDED:
                advertising_start(false);
                break;
    
            default:
                break;
        }
    }
    
    
    
    void saadc_event_handler(nrf_drv_saadc_evt_t const * p_event)
    {
        if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
        {
            nrf_saadc_value_t adc_result;
            uint16_t          batt_lvl_in_milli_volts;
            uint8_t           percentage_batt_lvl;
            uint32_t          err_code;
    
            adc_result = p_event->data.done.p_buffer[0];
    
            err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, 1);
            APP_ERROR_CHECK(err_code);
    
            batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_result) +
                                      DIODE_FWD_VOLT_DROP_MILLIVOLTS;
            percentage_batt_lvl = battery_level_in_percent(batt_lvl_in_milli_volts);
    
            err_code = ble_bas_battery_level_update(&m_bas, percentage_batt_lvl, 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);
            }
        }
    }
    
    
    
    static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
    {
        ble_ias_c_on_db_disc_evt(&m_ias_c, p_evt);
    }
    
    
    
    static void adc_configure(void)
    {
        ret_code_t err_code = nrf_drv_saadc_init(NULL, saadc_event_handler);
        APP_ERROR_CHECK(err_code);
    
        nrf_saadc_channel_config_t config =
            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD);
        err_code = nrf_drv_saadc_channel_init(0, &config);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_buffer_convert(&adc_buf[0], 1);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_drv_saadc_buffer_convert(&adc_buf[1], 1);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void battery_level_meas_timeout_handler(void * p_context)
    {
        UNUSED_PARAMETER(p_context);
    
        ret_code_t err_code;
        err_code = nrf_drv_saadc_sample();
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void timers_init(void)
    {
        ret_code_t err_code;
    
        
        err_code = app_timer_init();
        APP_ERROR_CHECK(err_code);
    
        
        err_code = app_timer_create(&m_battery_timer_id,
                                    APP_TIMER_MODE_REPEATED,
                                    battery_level_meas_timeout_handler);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    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_KEYRING);
        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);
    }
    
    
    
    static void gatt_init(void)
    {
        ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void sleep_mode_enter(void)
    {
        ret_code_t err_code;
    
        err_code = bsp_indication_set(BSP_INDICATE_IDLE);
        APP_ERROR_CHECK(err_code);
    
        
        err_code = bsp_btn_ble_sleep_mode_prepare();
        APP_ERROR_CHECK(err_code);
    
        
        err_code = sd_power_system_off();
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    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;
        }
    }
    
    
    
    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);
    }
    
    
    static void advertising_init(void)
    {
        uint32_t      err_code;
        ble_advdata_t advdata;
        ble_advdata_t scandata;
        uint8_t       flags = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED;
    
        ble_advdata_manuf_data_t manuf_specific_data;
    
        manuf_specific_data.company_identifier = APP_COMPANY_IDENTIFIER;
    
    #if defined(USE_UICR_FOR_MAJ_MIN_VALUES)
    
        uint16_t major_value = ((*(uint32_t *)UICR_ADDRESS) & 0xFFFF0000) >> 16;
        uint16_t minor_value = ((*(uint32_t *)UICR_ADDRESS) & 0x0000FFFF);
    
        uint8_t index = MAJ_VAL_OFFSET_IN_BEACON_INFO;
    
        m_beacon_info[index++] = MSB_16(major_value);
        m_beacon_info[index++] = LSB_16(major_value);
    
        m_beacon_info[index++] = MSB_16(minor_value);
        m_beacon_info[index++] = LSB_16(minor_value);
    #endif
    
        manuf_specific_data.data.p_data = (uint8_t *) m_beacon_info;
        manuf_specific_data.data.size   = APP_BEACON_INFO_LENGTH;
    
    
        memset(&advdata, 0, sizeof(advdata));
    
        advdata.name_type             = BLE_ADVDATA_NO_NAME;
        advdata.flags                 = flags;
        advdata.p_manuf_specific_data = &manuf_specific_data;
    
    
        memset(&m_adv_params, 0, sizeof(m_adv_params));
    
        m_adv_params.properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED;
        m_adv_params.p_peer_addr     = NULL;    
        m_adv_params.filter_policy   = BLE_GAP_ADV_FP_ANY;
        m_adv_params.interval        = NON_CONNECTABLE_ADV_INTERVAL;
        m_adv_params.duration        = 0;       
    
        err_code = ble_advdata_encode(&advdata, m_adv_data.adv_data.p_data, &m_adv_data.adv_data.len);
        APP_ERROR_CHECK(err_code);
    
    
        memset(&scandata, 0, sizeof(scandata));
    
        scandata.name_type             = BLE_ADVDATA_FULL_NAME;
        scandata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
        scandata.uuids_complete.p_uuids  = m_adv_uuids;
    
        ble_gap_addr_t gap_address;
        gap_address.addr_type = BLE_GAP_ADDR_TYPE_PUBLIC;
        memcpy(&gap_address.addr, "\xee\xdd\xcc\xbb\xaa\xAC", sizeof(gap_address.addr));
        err_code = sd_ble_gap_addr_set(&gap_address);
        APP_ERROR_CHECK(err_code);
    
        err_code = ble_advdata_encode(&scandata, m_adv_data.scan_rsp_data.p_data, &m_adv_data.scan_rsp_data.len);
        APP_ERROR_CHECK(err_code);
    
        err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &m_adv_params);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void advertising_start(bool erase_bonds)
    {
        ret_code_t err_code;
        if (erase_bonds == true){
            delete_bonds();
            
        }
        else
        {
            err_code = sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
            APP_ERROR_CHECK(err_code);
    
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
        }
        
        
    }
    
    
    void nonce_generate(uint8_t * p_buf)
    {
        uint8_t i         = COUNTER_BYTE_LEN;
        uint8_t remaining = NONCE_RAND_BYTE_LEN;
    
    
        while(0 != remaining)
        {
            uint32_t err_code;
            uint8_t  available = 0;
    
            err_code = sd_rand_application_bytes_available_get(&available);
            APP_ERROR_CHECK(err_code);
    
            available = ((available > remaining) ? remaining : available);
            if (0 != available)
            {
    	        err_code = sd_rand_application_vector_get((p_buf + i), available);
    	        APP_ERROR_CHECK(err_code);
    
    	        i         += available;
    	        remaining -= available;
    	    }
    
    	    if (0 != remaining)
    	    {
    	        nrf_delay_us(RNG_BYTE_WAIT_US * remaining);
    	    }
        }
    }
    
    static bool m_initialized = false;
    
    
    static nrf_ecb_hal_data_t m_ecb_data;
    
    
    void ctr_init(const uint8_t * p_nonce, const uint8_t * p_ecb_key)
    {
        m_initialized = true;
    
        // Save the key.
        memcpy(&m_ecb_data.key[0], p_ecb_key, ECB_KEY_LEN);
    
        // Copy the nonce.
        memcpy(&m_ecb_data.cleartext[COUNTER_BYTE_LEN],
    	          &p_nonce[COUNTER_BYTE_LEN],
    	          NONCE_RAND_BYTE_LEN);
    
        // Zero the counter value.
        memset(&m_ecb_data.cleartext[0], 0x00, COUNTER_BYTE_LEN);
    }
    
    static uint32_t crypt(uint8_t * buf)
    {
        uint8_t  i;
        uint32_t err_code;
    
        if (!m_initialized)
        {
    	    return NRF_ERROR_INVALID_STATE;
        }
    
        err_code = sd_ecb_block_encrypt(&m_ecb_data);
        if (NRF_SUCCESS != err_code)
        {
    	    return err_code;
        }
    
        for (i=0; i < ECB_KEY_LEN; i++)
        {
    	    buf[i] ^= m_ecb_data.ciphertext[i];
        }
    
        // Increment the counter.
        (*((uint32_t*) m_ecb_data.cleartext))++;
    
        return NRF_SUCCESS;
    }
    
    
    uint32_t ctr_encrypt(uint8_t * p_clear_text)
    {
        return crypt(p_clear_text);
    }
    
    
    uint32_t ctr_decrypt(uint8_t * p_cipher_text)
    {
        return crypt(p_cipher_text);
    }
    
    
    ///**@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)
    //{
    //    ret_code_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);
    //}
    
    
    
    static void nrf_qwr_error_handler(uint32_t nrf_error)
    {
        APP_ERROR_HANDLER(nrf_error);
    }
    
    
    
    static void qwr_init(void)
    {
        ret_code_t         err_code;
        nrf_ble_qwr_init_t qwr_init_obj = {0};
    
     
        qwr_init_obj.error_handler = nrf_qwr_error_handler;
    
        err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void tps_init(void)
    {
        ret_code_t     err_code;
        ble_tps_init_t tps_init_obj;
    
        memset(&tps_init_obj, 0, sizeof(tps_init_obj));
        tps_init_obj.initial_tx_power_level = TX_POWER_LEVEL;
    
        tps_init_obj.tpl_rd_sec = SEC_JUST_WORKS;
    
        err_code = ble_tps_init(&m_tps, &tps_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void ias_init(void)
    {
        ret_code_t     err_code;
        ble_ias_init_t ias_init_obj;
    
        memset(&ias_init_obj, 0, sizeof(ias_init_obj));
        ias_init_obj.evt_handler  = on_ias_evt;
    
        ias_init_obj.alert_wr_sec = SEC_JUST_WORKS;
    
        err_code = ble_ias_init(&m_ias, &ias_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void lls_init(void)
    {
        ret_code_t     err_code;
        ble_lls_init_t lls_init_obj;
    
        // Initialize Link Loss Service
        memset(&lls_init_obj, 0, sizeof(lls_init_obj));
    
        lls_init_obj.evt_handler         = on_lls_evt;
        lls_init_obj.error_handler       = service_error_handler;
        lls_init_obj.initial_alert_level = INITIAL_LLS_ALERT_LEVEL;
    
        lls_init_obj.alert_level_rd_sec = SEC_JUST_WORKS;
        lls_init_obj.alert_level_wr_sec = SEC_JUST_WORKS;
    
        err_code = ble_lls_init(&m_lls, &lls_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void bas_init(void)
    {
        ret_code_t     err_code;
        ble_bas_init_t bas_init_obj;
    
        memset(&bas_init_obj, 0, sizeof(bas_init_obj));
    
        bas_init_obj.evt_handler          = on_bas_evt;
        bas_init_obj.support_notification = true;
        bas_init_obj.p_report_ref         = NULL;
        bas_init_obj.initial_batt_level   = 100;
    
        bas_init_obj.bl_rd_sec        = SEC_OPEN;
        bas_init_obj.bl_cccd_wr_sec   = SEC_OPEN;
        bas_init_obj.bl_report_rd_sec = SEC_OPEN;
    
        err_code = ble_bas_init(&m_bas, &bas_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void ias_client_init(void)
    {
        ret_code_t       err_code;
        ble_ias_c_init_t ias_c_init_obj;
    
        memset(&ias_c_init_obj, 0, sizeof(ias_c_init_obj));
    
        m_is_high_alert_signalled = false;
    
        ias_c_init_obj.evt_handler   = on_ias_c_evt;
        ias_c_init_obj.error_handler = service_error_handler;
    
        err_code = ble_ias_c_init(&m_ias_c, &ias_c_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void services_init(void)
    {
        qwr_init();
        tps_init();
        ias_init();
        lls_init();
        bas_init();
        ias_client_init();
    }
    
    
    
    static void db_discovery_init(void)
    {
        ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
        APP_ERROR_CHECK(err_code);
    }
    
    
    static void conn_params_error_handler(uint32_t nrf_error)
    {
        APP_ERROR_HANDLER(nrf_error);
    }
    
    
    
    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_PARAMS_UPDATE_COUNT;
        cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
        cp_init.disconnect_on_fail             = true;
        cp_init.evt_handler                    = NULL;
        cp_init.error_handler                  = conn_params_error_handler;
    
        err_code = ble_conn_params_init(&cp_init);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void alert_signal(uint8_t alert_level)
    {
        ret_code_t err_code;
    
        switch (alert_level)
        {
            case BLE_CHAR_ALERT_LEVEL_NO_ALERT:
                NRF_LOG_INFO("No Alert.");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
                APP_ERROR_CHECK(err_code);
                break; // BLE_CHAR_ALERT_LEVEL_NO_ALERT
    
            case BLE_CHAR_ALERT_LEVEL_MILD_ALERT:
                NRF_LOG_INFO("Mild Alert.");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_0);
                APP_ERROR_CHECK(err_code);
                break; // BLE_CHAR_ALERT_LEVEL_MILD_ALERT
    
            case BLE_CHAR_ALERT_LEVEL_HIGH_ALERT:
                NRF_LOG_INFO("HIGH Alert.");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_3);
                APP_ERROR_CHECK(err_code);
                break; // BLE_CHAR_ALERT_LEVEL_HIGH_ALERT
    
            default:
    
                break;
        }
    }
    
    
    
    static void on_ias_evt(ble_ias_t * p_ias, ble_ias_evt_t * p_evt)
    {
        switch (p_evt->evt_type)
        {
            case BLE_IAS_EVT_ALERT_LEVEL_UPDATED:
                if (p_evt->p_link_ctx != NULL)
                {
                    alert_signal(p_evt->p_link_ctx->alert_level);
                }
                break; // BLE_IAS_EVT_ALERT_LEVEL_UPDATED
    
            default:
                // No implementation needed.
                break;
        }
    }
    
    
    
    static void on_lls_evt(ble_lls_t * p_lls, ble_lls_evt_t * p_evt)
    {
        switch (p_evt->evt_type)
        {
            case BLE_LLS_EVT_LINK_LOSS_ALERT:
                alert_signal(p_evt->params.alert_level);
                break; // BLE_LLS_EVT_LINK_LOSS_ALERT
    
            default:
                // No implementation needed.
                break;
        }
    }
    
    
    
    
    static void on_ias_c_evt(ble_ias_c_t * p_ias_c, ble_ias_c_evt_t * p_evt)
    {
        ret_code_t err_code;
    
        switch (p_evt->evt_type)
        {
            case BLE_IAS_C_EVT_DISCOVERY_COMPLETE:
                // IAS is found on peer. The Find Me Locator functionality of this app will work.
                err_code = ble_ias_c_handles_assign(&m_ias_c,
                                                    p_evt->conn_handle,
                                                    p_evt->alert_level.handle_value);
                APP_ERROR_CHECK(err_code);
    
                m_is_ias_present = true;
                break; // BLE_IAS_C_EVT_DISCOVERY_COMPLETE
    
            case BLE_IAS_C_EVT_DISCOVERY_FAILED:
                // IAS is not found on peer. The Find Me Locator functionality of this app will NOT work.
                break; // BLE_IAS_C_EVT_DISCOVERY_FAILED
    
            case BLE_IAS_C_EVT_DISCONN_COMPLETE:
                // Disable alert buttons
                m_is_ias_present = false;
                break; // BLE_IAS_C_EVT_DISCONN_COMPLETE
    
            default:
                break;
        }
    }
    
    
    
    static void on_bas_evt(ble_bas_t * p_bas, ble_bas_evt_t * p_evt)
    {
        ret_code_t err_code;
    
        switch (p_evt->evt_type)
        {
            case BLE_BAS_EVT_NOTIFICATION_ENABLED:
                // Start battery timer
                err_code = app_timer_start(m_battery_timer_id, BATTERY_LEVEL_MEAS_INTERVAL, NULL);
                APP_ERROR_CHECK(err_code);
                break; // BLE_BAS_EVT_NOTIFICATION_ENABLED
    
            case BLE_BAS_EVT_NOTIFICATION_DISABLED:
                err_code = app_timer_stop(m_battery_timer_id);
                APP_ERROR_CHECK(err_code);
                break; // BLE_BAS_EVT_NOTIFICATION_DISABLED
    
            default:
                // No implementation needed.
                break;
        }
    }
    
    
    
    static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
    {
        ret_code_t err_code = NRF_SUCCESS;
    
        switch (p_ble_evt->header.evt_id)
        {
            case BLE_GAP_EVT_DISCONNECTED:
                NRF_LOG_INFO("Disconnected.");
                // LED indication will be changed when advertising starts.
                break;
    
            case BLE_GAP_EVT_CONNECTED:
            {
                NRF_LOG_INFO("Connected.");
                err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
                APP_ERROR_CHECK(err_code);
    
                // Assign connection handle to the Queued Write module.
                err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, p_ble_evt->evt.gap_evt.conn_handle);
                APP_ERROR_CHECK(err_code);
    
                // Discover peer's services.
                err_code = ble_db_discovery_start(&m_ble_db_discovery,
                                                  p_ble_evt->evt.gap_evt.conn_handle);
                APP_ERROR_CHECK(err_code);
            } 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;
    
            default:
                // No implementation needed.
                break;
        }
    }
    
    
    
    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);
    }
    
    
    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);
    }
    
    
    
    static void bsp_event_handler(bsp_event_t event)
    {
        ret_code_t err_code;
    
        switch (event)
        {
            case BSP_EVENT_SLEEP:
                sleep_mode_enter();
                break;
    
            case BSP_EVENT_DISCONNECT:
                err_code = sd_ble_gap_disconnect(m_ias_c.conn_handle,
                                                 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
                break;
    
            case BSP_EVENT_KEY_0:
            {
                if (m_is_ias_present)
                {
                    if (!m_is_high_alert_signalled)
                    {
                        err_code =
                            ble_ias_c_send_alert_level(&m_ias_c, BLE_CHAR_ALERT_LEVEL_HIGH_ALERT);
                    }
                    else
                    {
                        err_code = ble_ias_c_send_alert_level(&m_ias_c, BLE_CHAR_ALERT_LEVEL_NO_ALERT);
                    }
    
                    if (err_code == NRF_SUCCESS)
                    {
                        m_is_high_alert_signalled = !m_is_high_alert_signalled;
                    }
                    else if (
                        (err_code != NRF_ERROR_RESOURCES)
                        &&
                        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
                        &&
                        (err_code != NRF_ERROR_NOT_FOUND)
                            )
                    {
                        APP_ERROR_HANDLER(err_code);
                    }
                }
            } break;
    
            case BSP_EVENT_KEY_1:
                NRF_LOG_INFO("Alert Off.");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
                APP_ERROR_CHECK(err_code);
                break;
    
            default:
                break;
        }
    }
    
    
    
    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);
    }
    
    
    
    static void log_init(void)
    {
        ret_code_t err_code = NRF_LOG_INIT(NULL);
        APP_ERROR_CHECK(err_code);
    
        NRF_LOG_DEFAULT_BACKENDS_INIT();
    }
    
    
    
    static void power_management_init(void)
    {
        ret_code_t err_code;
        err_code = nrf_pwr_mgmt_init();
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void idle_state_handle(void)
    {
        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_SUCEEDED event.
    //    }
    //    else
    //    {
    //        uint32_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
    //
    //        APP_ERROR_CHECK(err_code);
    //    }
    //}
    
    
    
    static void tx_power_set(void)
    {
        ret_code_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle, TX_POWER_LEVEL);
        APP_ERROR_CHECK(err_code);
    }
    
    
    int main(void)
    
    {
        bool erase_bonds;
    
        uint8_t nonce[16] = {0};
    
        // Initialize.
        log_init();
        timers_init();
        buttons_leds_init(&erase_bonds);
        power_management_init();
        ble_stack_init();
        adc_configure();
        gap_params_init();
        gatt_init();
    
        NRF_LOG_INFO("Unencrypted info:");
    
       NRF_LOG_HEXDUMP_INFO(m_beacon_info, sizeof(m_beacon_info));
    
        nonce_generate(nonce);
        ctr_init(nonce,m_ecb_key);
    
    
        ctr_encrypt(m_beacon_info);
        ctr_encrypt(&m_beacon_info[16]);
         NRF_LOG_INFO("Encrypted info:");
        NRF_LOG_HEXDUMP_INFO(m_beacon_info, sizeof(m_beacon_info));
    
        m_ecb_data.cleartext[0] = 0x00;
        m_ecb_data.cleartext[1] = 0x00;
        m_ecb_data.cleartext[2] = 0x00;
        m_ecb_data.cleartext[3] = 0x00;
    
    
            // Decrypt the ciphertext with the same counter value, i.e. 0x00,0x00,0x00,0x00, that was used for encrypting. 
        ctr_decrypt(m_beacon_info);
        ctr_decrypt(&m_beacon_info[16]);
            
        NRF_LOG_INFO("Decrypted info:");
        NRF_LOG_HEXDUMP_INFO(m_beacon_info, sizeof(m_beacon_info));
       
        advertising_init();
        db_discovery_init();
        services_init();
        conn_params_init();
        peer_manager_init();
    
        // Start execution.
        NRF_LOG_INFO("Proximity example started.");
    
        advertising_start(erase_bonds);
        tx_power_set();
    
        // Enter main loop.
        for (;;)
        {
            idle_state_handle();
        }
    }

    and same i wrote for the decryption part for central i am not receiving the values that are encrypted in the peripheral

    Decryption code: 

    #include <stdio.h>
    #include <stdint.h>
    #include <stdbool.h>
    #include "nordic_common.h"
    #include "app_error.h"
    #include "app_uart.h"
    #include "ble_db_discovery.h"
    #include "app_timer.h"
    #include "app_util.h"
    #include "bsp_btn_ble.h"
    #include "ble.h"
    #include "ble_gap.h"
    #include "ble_hci.h"
    #include "nrf_sdh.h"
    #include "nrf_sdh_ble.h"
    #include "nrf_sdh_soc.h"
    #include "ble_nus_c.h"
    #include "nrf_ble_gatt.h"
    #include "nrf_pwr_mgmt.h"
    #include "nrf_ble_scan.h"
    
    #include "nrf_log.h"
    #include "nrf_log_ctrl.h"
    #include "nrf_log_default_backends.h"
    
    
    #define APP_BLE_CONN_CFG_TAG    1                                       /**< Tag that refers to the BLE stack configuration set with @ref sd_ble_cfg_set. The default tag is @ref BLE_CONN_CFG_TAG_DEFAULT. */
    #define APP_BLE_OBSERVER_PRIO   3                                       /**< BLE observer priority of the application. There is no need to modify this value. */
    
    #define UART_TX_BUF_SIZE        256                                     /**< UART TX buffer size. */
    #define UART_RX_BUF_SIZE        256                                     /**< UART RX buffer size. */
    
    #define NUS_SERVICE_UUID_TYPE   BLE_UUID_TYPE_VENDOR_BEGIN              /**< UUID type for the Nordic UART Service (vendor specific). */
    
    #define ECHOBACK_BLE_UART_DATA  1                                       /**< Echo the UART data that is received over the Nordic UART Service (NUS) back to the sender. */
    #define ECB_KEY_LEN            (16UL)
    #define COUNTER_BYTE_LEN       (4UL)
    #define NONCE_RAND_BYTE_LEN    (12UL)
    
    static uint8_t m_ecb_key[16] = {0x6E,0x88,0x90,0x8D,0x75,0xBB,0x95,0xEA,0x2C,0x65,0x93,0x01,0x43,0xF8,0x1B,0x5F};
    
    // The RNG wait values are typical and not guaranteed. See Product Specifications for more info.
    #ifdef NRF51
    #define RNG_BYTE_WAIT_US       (677UL)
    #elif defined NRF52
    #define RNG_BYTE_WAIT_US       (124UL)
    #else
    #error "Either NRF51 or NRF52 must be defined."
    #endif     
    
    BLE_NUS_C_DEF(m_ble_nus_c);                                             /**< BLE Nordic UART Service (NUS) client instance. */
    NRF_BLE_GATT_DEF(m_gatt);                                               /**< GATT module instance. */
    BLE_DB_DISCOVERY_DEF(m_db_disc);                                        /**< Database discovery module instance. */
    NRF_BLE_SCAN_DEF(m_scan);                                               /**< Scanning Module instance. */
    
    static uint16_t m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - OPCODE_LENGTH - HANDLE_LENGTH; /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */
    
    /**@brief NUS UUID. */
    static ble_uuid_t const m_nus_uuid =
    {
        .uuid = BLE_UUID_NUS_SERVICE,
        .type = NUS_SERVICE_UUID_TYPE
    };
    
    
    void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
    {
        app_error_handler(0xDEADBEEF, line_num, p_file_name);
    }
    
    
    /**@brief Function for starting scanning. */
    static void scan_start(void)
    {
        ret_code_t ret;
    
        ret = nrf_ble_scan_start(&m_scan);
        APP_ERROR_CHECK(ret);
    
        ret = bsp_indication_set(BSP_INDICATE_SCANNING);
        APP_ERROR_CHECK(ret);
    }
    
    
    /**@brief Function for handling Scanning Module events.
     */
    static void scan_evt_handler(scan_evt_t const * p_scan_evt)
    {
        ret_code_t err_code;
    
        switch(p_scan_evt->scan_evt_id)
        {
             case NRF_BLE_SCAN_EVT_CONNECTING_ERROR:
             {
                  err_code = p_scan_evt->params.connecting_err.err_code;
                  APP_ERROR_CHECK(err_code);
             } break;
    
             case NRF_BLE_SCAN_EVT_CONNECTED:
             {
                  ble_gap_evt_connected_t const * p_connected =
                                   p_scan_evt->params.connected.p_connected;
                 // Scan is automatically stopped by the connection.
                 NRF_LOG_INFO("Connecting to target %02x%02x%02x%02x%02x%02x",
                          p_connected->peer_addr.addr[0],
                          p_connected->peer_addr.addr[1],
                          p_connected->peer_addr.addr[2],
                          p_connected->peer_addr.addr[3],
                          p_connected->peer_addr.addr[4],
                          p_connected->peer_addr.addr[5]
                          );
             } break;
    
             case NRF_BLE_SCAN_EVT_SCAN_TIMEOUT:
             {
                 NRF_LOG_INFO("Scan timed out.");
                 scan_start();
             } break;
    
             default:
                 break;
        }
    }
    
    
    /**@brief Function for initializing the scanning and setting the filters.
     */
    static void scan_init(void)
    {
        ret_code_t          err_code;
        nrf_ble_scan_init_t init_scan;
    
        memset(&init_scan, 0, sizeof(init_scan));
    
        init_scan.connect_if_match = true;
        init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;
    
        err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_UUID_FILTER, &m_nus_uuid);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_UUID_FILTER, false);
        APP_ERROR_CHECK(err_code);
    }
    
    
    
    static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
    {
        ble_nus_c_on_db_disc_evt(&m_ble_nus_c, p_evt);
    }
    
    
    
    static void ble_nus_chars_received_uart_print(uint8_t * p_data, uint16_t data_len)
    {
        ret_code_t ret_val;
    
        NRF_LOG_DEBUG("Receiving data.");
        NRF_LOG_HEXDUMP_DEBUG(p_data, data_len);
    
        for (uint32_t i = 0; i < data_len; i++)
        {
            do
            {
                ret_val = app_uart_put(p_data[i]);
                if ((ret_val != NRF_SUCCESS) && (ret_val != NRF_ERROR_BUSY))
                {
                    NRF_LOG_ERROR("app_uart_put failed for index 0x%04x.", i);
                    APP_ERROR_CHECK(ret_val);
                }
            } while (ret_val == NRF_ERROR_BUSY);
        }
        if (p_data[data_len-1] == '\r')
        {
            while (app_uart_put('\n') == NRF_ERROR_BUSY);
        }
        if (ECHOBACK_BLE_UART_DATA)
        {
            // Send data back to the peripheral.
            do
            {
                ret_val = ble_nus_c_string_send(&m_ble_nus_c, p_data, data_len);
                if ((ret_val != NRF_SUCCESS) && (ret_val != NRF_ERROR_BUSY))
                {
                    NRF_LOG_ERROR("Failed sending NUS message. Error 0x%x. ", ret_val);
                    APP_ERROR_CHECK(ret_val);
                }
            } while (ret_val == NRF_ERROR_BUSY);
        }
    }
    
    
    
    void uart_event_handle(app_uart_evt_t * p_event)
    {
        static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
        static uint16_t index = 0;
        uint32_t ret_val;
    
        switch (p_event->evt_type)
        {
            /**@snippet [Handling data from UART] */
            case APP_UART_DATA_READY:
                UNUSED_VARIABLE(app_uart_get(&data_array[index]));
                index++;
    
                if ((data_array[index - 1] == '\n') || (index >= (m_ble_nus_max_data_len)))
                {
                    NRF_LOG_DEBUG("Ready to send data over BLE NUS");
                    NRF_LOG_HEXDUMP_DEBUG(data_array, index);
    
                    do
                    {
                        ret_val = ble_nus_c_string_send(&m_ble_nus_c, data_array, index);
                        if ( (ret_val != NRF_ERROR_INVALID_STATE) && (ret_val != NRF_ERROR_RESOURCES) )
                        {
                            APP_ERROR_CHECK(ret_val);
                        }
                    } while (ret_val == NRF_ERROR_RESOURCES);
    
                    index = 0;
                }
                break;
    
            /**@snippet [Handling data from UART] */
            case APP_UART_COMMUNICATION_ERROR:
                NRF_LOG_ERROR("Communication error occurred while handling UART.");
                APP_ERROR_HANDLER(p_event->data.error_communication);
                break;
    
            case APP_UART_FIFO_ERROR:
                NRF_LOG_ERROR("Error occurred in FIFO module used by UART.");
                APP_ERROR_HANDLER(p_event->data.error_code);
                break;
    
            default:
                break;
        }
    }
    
    
    
    
    /**@snippet [Handling events from the ble_nus_c module] */
    static void ble_nus_c_evt_handler(ble_nus_c_t * p_ble_nus_c, ble_nus_c_evt_t const * p_ble_nus_evt)
    {
        ret_code_t err_code;
    
        switch (p_ble_nus_evt->evt_type)
        {
            case BLE_NUS_C_EVT_DISCOVERY_COMPLETE:
                NRF_LOG_INFO("Discovery complete.");
                err_code = ble_nus_c_handles_assign(p_ble_nus_c, p_ble_nus_evt->conn_handle, &p_ble_nus_evt->handles);
                APP_ERROR_CHECK(err_code);
    
                err_code = ble_nus_c_tx_notif_enable(p_ble_nus_c);
                APP_ERROR_CHECK(err_code);
                NRF_LOG_INFO("Connected to device with Nordic UART Service.");
                break;
    
            case BLE_NUS_C_EVT_NUS_TX_EVT:
                ble_nus_chars_received_uart_print(p_ble_nus_evt->p_data, p_ble_nus_evt->data_len);
                break;
    
            case BLE_NUS_C_EVT_DISCONNECTED:
                NRF_LOG_INFO("Disconnected.");
                scan_start();
                break;
        }
    }
    /**@snippet [Handling events from the ble_nus_c module] */
    
    
    /**
     * @brief Function for handling shutdown events.
     *
     * @param[in]   event       Shutdown type.
     */
    static bool shutdown_handler(nrf_pwr_mgmt_evt_t event)
    {
        ret_code_t err_code;
    
        err_code = bsp_indication_set(BSP_INDICATE_IDLE);
        APP_ERROR_CHECK(err_code);
    
        switch (event)
        {
            case NRF_PWR_MGMT_EVT_PREPARE_WAKEUP:
                // Prepare wakeup buttons.
                err_code = bsp_btn_ble_sleep_mode_prepare();
                APP_ERROR_CHECK(err_code);
                break;
    
            default:
                break;
        }
    
        return true;
    }
    
    NRF_PWR_MGMT_HANDLER_REGISTER(shutdown_handler, APP_SHUTDOWN_HANDLER_PRIORITY);
    
    
    /**@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;
        ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt;
        uint8_t uuid[26];
    
        switch (p_ble_evt->header.evt_id)
        {
            case BLE_GAP_EVT_CONNECTED:
                err_code = ble_nus_c_handles_assign(&m_ble_nus_c, p_ble_evt->evt.gap_evt.conn_handle, NULL);
                APP_ERROR_CHECK(err_code);
    
                err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
                APP_ERROR_CHECK(err_code);
    
                // start discovery of services. The NUS Client waits for a discovery result
                err_code = ble_db_discovery_start(&m_db_disc, p_ble_evt->evt.gap_evt.conn_handle);
                APP_ERROR_CHECK(err_code);
                break;
    
            case BLE_GAP_EVT_DISCONNECTED:
    
                NRF_LOG_INFO("Disconnected. conn_handle: 0x%x, reason: 0x%x",
                             p_gap_evt->conn_handle,
                             p_gap_evt->params.disconnected.reason);
                break;
    
            case BLE_GAP_EVT_TIMEOUT:
                if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
                {
                    NRF_LOG_INFO("Connection Request timed out.");
                }
                break;
    
            case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
                // Pairing not supported.
                err_code = sd_ble_gap_sec_params_reply(p_ble_evt->evt.gap_evt.conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
                APP_ERROR_CHECK(err_code);
                break;
    
            case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
                // Accepting parameters requested by peer.
                err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle,
                                                        &p_gap_evt->params.conn_param_update_request.conn_params);
                APP_ERROR_CHECK(err_code);
                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_ADV_REPORT:
    			
                            {
    				NRF_LOG_INFO("Advertise received");
    				scan_start();
                                    
    	//			nrf_gpio_pin_toggle(LED1_PIN);
    				
    				memmove(uuid, p_gap_evt->params.adv_report.data.p_data, p_gap_evt->params.adv_report.data.len);
    				
    				NRF_LOG_INFO("UUID: %02x%02x%02x%02x%02x%02x", uuid[9], uuid[10], uuid[11], uuid[12], uuid[13], uuid[14]);
    				
    				NRF_LOG_INFO("TX_POWER: %02x", p_gap_evt->params.adv_report.tx_power);
    				
    				NRF_LOG_INFO("RSSI: %02x", p_gap_evt->params.adv_report.rssi);
                           
                                     ble_gap_addr_t  addr;
                                     memcpy(addr.addr, p_gap_evt->params.adv_report.peer_addr.addr, 6);
                                     NRF_LOG_INFO("Beacon address: %02x:%02x:%02x:%02x:%02x:%02x",
                                     p_gap_evt->params.adv_report.peer_addr.addr[5],
                                     p_gap_evt->params.adv_report.peer_addr.addr[4],
                                     p_gap_evt->params.adv_report.peer_addr.addr[3],
                                     p_gap_evt->params.adv_report.peer_addr.addr[2],
                                     p_gap_evt->params.adv_report.peer_addr.addr[1],
                                     p_gap_evt->params.adv_report.peer_addr.addr[0]);
      //                               uint8_t           batt_lvl;
     //                               NRF_LOG_INFO("battery level: %02x", p_gap_evt->params.adv_report.batt_lvl);
    
    
    		        } break;
    
                default:
                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 GATT library. */
    void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
    {
        if (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED)
        {
            NRF_LOG_INFO("ATT MTU exchange completed.");
    
            m_ble_nus_max_data_len = p_evt->params.att_mtu_effective - OPCODE_LENGTH - HANDLE_LENGTH;
            NRF_LOG_INFO("Ble NUS max data length set to 0x%X(%d)", m_ble_nus_max_data_len, m_ble_nus_max_data_len);
        }
    }
    
    
    /**@brief Function for initializing the GATT library. */
    void gatt_init(void)
    {
        ret_code_t err_code;
    
        err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
        APP_ERROR_CHECK(err_code);
    
        err_code = nrf_ble_gatt_att_mtu_central_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
        APP_ERROR_CHECK(err_code);
    }
    
    
    /**@brief Function for handling events from the BSP module.
     *
     * @param[in] event  Event generated by button press.
     */
    void bsp_event_handler(bsp_event_t event)
    {
        ret_code_t err_code;
    
        switch (event)
        {
            case BSP_EVENT_SLEEP:
                nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF);
                break;
    
            case BSP_EVENT_DISCONNECT:
                err_code = sd_ble_gap_disconnect(m_ble_nus_c.conn_handle,
                                                 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
                break;
    
            default:
                break;
        }
    }
    
    /**@brief Function for initializing the UART. */
    static void uart_init(void)
    {
        ret_code_t err_code;
    
        app_uart_comm_params_t const comm_params =
        {
            .rx_pin_no    = RX_PIN_NUMBER,
            .tx_pin_no    = TX_PIN_NUMBER,
            .rts_pin_no   = RTS_PIN_NUMBER,
            .cts_pin_no   = CTS_PIN_NUMBER,
            .flow_control = APP_UART_FLOW_CONTROL_DISABLED,
            .use_parity   = false,
            .baud_rate    = UART_BAUDRATE_BAUDRATE_Baud115200
        };
    
        APP_UART_FIFO_INIT(&comm_params,
                           UART_RX_BUF_SIZE,
                           UART_TX_BUF_SIZE,
                           uart_event_handle,
                           APP_IRQ_PRIORITY_LOWEST,
                           err_code);
    
        APP_ERROR_CHECK(err_code);
    }
    
    /**@brief Function for initializing the Nordic UART Service (NUS) client. */
    static void nus_c_init(void)
    {
        ret_code_t       err_code;
        ble_nus_c_init_t init;
    
        init.evt_handler = ble_nus_c_evt_handler;
    
        err_code = ble_nus_c_init(&m_ble_nus_c, &init);
        APP_ERROR_CHECK(err_code);
    }
    
    
    /**@brief Function for initializing buttons and leds. */
    static void buttons_leds_init(void)
    {
        ret_code_t err_code;
        bsp_event_t startup_event;
    
        err_code = bsp_init(BSP_INIT_LEDS, bsp_event_handler);
        APP_ERROR_CHECK(err_code);
    
        err_code = bsp_btn_ble_init(NULL, &startup_event);
        APP_ERROR_CHECK(err_code);
    }
    
    
    /**@brief Function for initializing the timer. */
    static void timer_init(void)
    {
        ret_code_t err_code = app_timer_init();
        APP_ERROR_CHECK(err_code);
    }
    
    
    /**@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 initializing the database discovery module. */
    static void db_discovery_init(void)
    {
        ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
        APP_ERROR_CHECK(err_code);
    }
    
    
    /**@brief Function for handling the idle state (main loop).
     *
     * @details Handles any pending log operations, then sleeps until the next event occurs.
     */
    static void idle_state_handle(void)
    {
        if (NRF_LOG_PROCESS() == false)
        {
            nrf_pwr_mgmt_run();
        }
    }
    
    void nonce_generate(uint8_t * p_buf)
    {
        uint8_t i         = COUNTER_BYTE_LEN;
        uint8_t remaining = NONCE_RAND_BYTE_LEN;
    
    
        while(0 != remaining)
        {
            uint32_t err_code;
            uint8_t  available = 0;
    
            err_code = sd_rand_application_bytes_available_get(&available);
            APP_ERROR_CHECK(err_code);
    
            available = ((available > remaining) ? remaining : available);
            if (0 != available)
            {
    	        err_code = sd_rand_application_vector_get((p_buf + i), available);
    	        APP_ERROR_CHECK(err_code);
    
    	        i         += available;
    	        remaining -= available;
    	    }
    
    	    if (0 != remaining)
    	    {
    	        nrf_delay_us(RNG_BYTE_WAIT_US * remaining);
    	    }
        }
    }
    
    static bool m_initialized = false;
    
    
    static nrf_ecb_hal_data_t m_ecb_data;
    
    
    void ctr_init(const uint8_t * p_nonce, const uint8_t * p_ecb_key)
    {
        m_initialized = true;
    
        // Save the key.
        memcpy(&m_ecb_data.key[0], p_ecb_key, ECB_KEY_LEN);
    
        // Copy the nonce.
        memcpy(&m_ecb_data.ciphertext[COUNTER_BYTE_LEN],
    	          &p_nonce[COUNTER_BYTE_LEN],
    	          NONCE_RAND_BYTE_LEN);
    
        // Zero the counter value.
        memset(&m_ecb_data.cleartext[0], 0x00, COUNTER_BYTE_LEN);
    }
    
    static uint32_t crypt(uint8_t * buf)
    {
        uint8_t  i;
        uint32_t err_code;
    
        if (!m_initialized)
        {
    	    return NRF_ERROR_INVALID_STATE;
        }
    
        err_code = sd_ecb_block_encrypt(&m_ecb_data);
        if (NRF_SUCCESS != err_code)
        {
    	    return err_code;
        }
    
        for (i=0; i < ECB_KEY_LEN; i++)
        {
    	    buf[i] ^= m_ecb_data.ciphertext[i];
        }
    
        // Increment the counter.
        (*((uint32_t*) m_ecb_data.cleartext))++;
    
        return NRF_SUCCESS;
    }
    
    
    uint32_t ctr_encrypt(uint8_t * p_clear_text)
    {
        return crypt(p_clear_text);
    }
    
    
    uint32_t ctr_decrypt(uint8_t * p_cipher_text)
    {
        return crypt(p_cipher_text);
    }
    
    
    int main(void)
    {
        // Initialize.
        log_init();
        timer_init();
        uart_init();
        buttons_leds_init();
        db_discovery_init();
        power_management_init();
        ble_stack_init();
        gatt_init();
        nus_c_init();
        scan_init();
        printf("BLE UART central example started.\r\n");
        NRF_LOG_INFO("BLE UART central example started.");
        scan_start();
    
        uint8_t nonce[16] = {0};
      //  uint8_t m_beacon_info[32];
    
        ctr_init(nonce,m_ecb_key);
        NRF_LOG_INFO("Encrypted info:");
        NRF_LOG_HEXDUMP_INFO(m_ecb_data.ciphertext, sizeof(m_ecb_data.ciphertext));
    
        
        m_ecb_data.cleartext[0] = 0x00;
        m_ecb_data.cleartext[1] = 0x00;
        m_ecb_data.cleartext[2] = 0x00;
        m_ecb_data.cleartext[3] = 0x00;
    
        // Decrypt the ciphertext with the same counter value, i.e. 0x00,0x00,0x00,0x00, that was used for encrypting. 
        ctr_decrypt(m_ecb_data.ciphertext);
        ctr_decrypt(&m_ecb_data.ciphertext[16]);
            
        NRF_LOG_INFO("Decrypted info:");
        NRF_LOG_HEXDUMP_INFO(m_ecb_data.ciphertext, sizeof(m_ecb_data.ciphertext));
        // Start execution.
    
        // Enter main loop.
        for (;;)
        {
            idle_state_handle();
        }
    }

    please say if any changes that i need to change in this decryption code or please give me if any code if available for decryption of the info that i had encrypted in peripheral 

  • Does it work? If not, could you specify which part of the encryption code that fails.

    Best regards,

    Simon

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