Android Client Required input Passkey Before connect with ESP32/pairing with EPS32

Below Sketch working fine for android client to ESP32 server. Here when connect with eps32 then no required any passkey. After connected when i send write request then require passkey for pairing first time. I want passkey required method before connected with esp32. How can i do this please give me instruction.

#include <NimBLEDevice.h>

BLEServer *pServer = NULL;
BLECharacteristic * pTxCharacteristic;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint8_t txValue = 0;

#define SERVICE_UUID           "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART service UUID
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"

class MyServerCallbacks: public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
      deviceConnected = true;
      BLEDevice::startAdvertising();//adding this line allows for multiple simultaneous BLE connections
    };

    void onDisconnect(BLEServer* pServer) {
      deviceConnected = false;
    }
};

class MyCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      std::string rxValue = pCharacteristic->getValue();

      if (rxValue.length() > 0) {
        Serial.print("Received Value: ");
        for (int i = 0; i < rxValue.length(); i++)
          Serial.print(rxValue[i]);
          Serial.println();

        if(rxValue.find("F") != -1)
          Serial.println("do stuff");
        }
    }
};

void setup() {
  Serial.begin(115200);

  // Create the BLE Device
  NimBLEDevice::init("NimBLE");
  NimBLEDevice::setPower(ESP_PWR_LVL_P9); /** +9db */

  NimBLEDevice::setSecurityAuth(true, true, true); 
  NimBLEDevice::setSecurityPasskey(123456);
  NimBLEDevice::setSecurityIOCap(BLE_HS_IO_DISPLAY_ONLY);

  // Create the BLE Server
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  // Create the BLE Service
  BLEService *pService = pServer->createService(SERVICE_UUID);

  // Create a BLE Characteristic
  pTxCharacteristic = pService->createCharacteristic(
                                        CHARACTERISTIC_UUID_TX,
                                    /******* Enum Type NIMBLE_PROPERTY now *******      
                                        BLECharacteristic::PROPERTY_NOTIFY
                                        );
                                    **********************************************/  
                                        NIMBLE_PROPERTY::NOTIFY
                                       );

  BLECharacteristic * pRxCharacteristic = pService->createCharacteristic(
                                            CHARACTERISTIC_UUID_RX,
                                    /******* Enum Type NIMBLE_PROPERTY now *******       
                                            BLECharacteristic::PROPERTY_WRITE
                                            );
                                    *********************************************/  
                                        NIMBLE_PROPERTY::READ |
                                        NIMBLE_PROPERTY::WRITE |
                                        NIMBLE_PROPERTY::WRITE_AUTHEN
                                       );

  pRxCharacteristic->setCallbacks(new MyCallbacks());

  // Start the service
  pService->start();

  // Start advertising
  pServer->getAdvertising()->start();
  Serial.println("Waiting for a client...");
}

void loop() {

    // disconnecting
    if (!deviceConnected && oldDeviceConnected) {
        delay(500); // give the bluetooth stack the chance to get things ready
        pServer->startAdvertising(); // restart advertising
        Serial.println("start advertising");
        oldDeviceConnected = deviceConnected;
    }
    // connecting
    if (deviceConnected && !oldDeviceConnected) {
        // do stuff here on connecting
        oldDeviceConnected = deviceConnected;
    }
}

h2zero / NimBLE-Arduino

Android Client Required input Passkey Before connect with ESP32/pairing with EPS32 #517