RFID Lock System with MFRC522

#include <SPI.h>
#include <MFRC522.h>
#include <Servo.h>


#define SS_PIN 53
#define RST_PIN 5
#define O 8

MFRC522 mfrc522(SS_PIN, RST_PIN);
MFRC522::MIFARE_Key key;

Servo Ser;

int blockNum = 2;
byte blockData [10];

byte bufferLen = 18;   //Set buffer length for reading, it has to be 2 more than block size : 16 + 2
byte readBlockData[18];   //Array to store data from card
byte Registry[18];   //Array to store key

String UID, RUID = "f6255c11";   //UID of the card you are going to use, use MFRC522 Library to find UID of your Card or simply use your phone
bool Access;

MFRC522::StatusCode status;
long R;
void setup() {
  Serial.begin(115200);   //You can connect Serial output for debugging
  Ser.attach(7);
  Ser.write(130);
  SPI.begin();
  mfrc522.PCD_Init();   //Initiate tranciever module
  
  long R = 1234567899;   //Default key for which this code would be looking for, change it if you like and then write the same key on RFID card for first time use
  for(int i = 9;i >= 0;i--) {
    int D = R % 10;
    R = R / 10;
    Registry[i] = D;
  }
  Serial.print("Default Key : ");
  for (int j = 0 ; j < 10 ; j++) {
    Serial.print(Registry[j]);
  } 
  Serial.println();
  Serial.print("RUID : " + RUID);
  Serial.println("\n");
  Serial.println("Place Key");
}

void loop() {
  for (byte i = 0; i < 6; i++) {
    key.keyByte[i] = 0xFF;
  }
  if(!mfrc522.PICC_IsNewCardPresent()) {   //Detect if new card is present
    return; 
  }
  if (!mfrc522.PICC_ReadCardSerial()) {
    return;
  }
  Serial.println("Card Detected");
  R = random(1000000000, 9999999999);   //New random key generation
  
  Serial.print(F("PICC type: "));
  MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
  
  if (piccType != MFRC522::PICC_TYPE_MIFARE_1K) {   //Check whether the card is of supported type otherwise communication drops
    Serial.println(F("Your tag is not of supported type"));
    return;
  }
  String Type = mfrc522.PICC_GetTypeName(piccType);
  Serial.println(Type);

  Serial.print("UID : ");
  UID = "";

  for(byte i = 0;i < mfrc522.uid.size;i++) {
    UID = UID + String(mfrc522.uid.uidByte[i], HEX);
  }
  Serial.println(UID);

  if(UID == RUID) {   //Checks whether Card UID are Stored UID are equal
    Serial.println("UID Verification Successful");
  }
  else {
    Serial.println("UID Verification Failed");
  }
  
  Serial.print("Stored Key : ");
  
  mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, blockNum, &key, &(mfrc522.uid));   //Authenticate the sector and the block for reading memory
  mfrc522.MIFARE_Read(blockNum, readBlockData, &bufferLen);   //Store read value in readBlockData

  for (int j = 0 ; j < 10 ; j++) {
    Serial.print(readBlockData[j]);
  } 
  Serial.println();

  Serial.print("Current Registered Key Match : ");
  for (int j = 0 ; j < 10 ; j++) {
    Serial.print(Registry[j]);
  }
  Serial.println();
 
  if(Check(readBlockData, Registry)) {   //Calls function to check whether the arrays containing Card Key and Stored key are equal
    Serial.println("Key Match Successful");
    Serial.println("Access Granted");
    Access = 1;
  }
  else {
    Serial.println("Key Match Failed");
    Serial.println("Access Denied");
    Ring(0);
    Serial.println();
    mfrc522.PICC_HaltA();   //Communication broken, this makes the module ready to scan card again
    mfrc522.PCD_StopCrypto1();
    return;   //nothing else will execute, the loop starts over
  }

  Serial.print("New Key : ");
  Serial.println(R);
  for(int i = 9;i >= 0;i--) {
    int D = R % 10;
    R = R / 10;
    blockData[i] = D;
    Registry[i] = D;   //Storing new key in memory
  }
  
  mfrc522.MIFARE_Write(blockNum, blockData, 16);   //write the new random key in block 2 of sector 0
  Serial.println("New Key Written Successfully");
  Serial.println();

  if(Access) {
    Ring(1);   //buzzer plays welcome tone
  }
  Ser.write(130);   //door opens
    
  mfrc522.PICC_HaltA();   //communication broken
  mfrc522.PCD_StopCrypto1();
}

void Ring(bool I) {
  if(I) {
    tone(O, 330, 200);   //welcome tone
    delay(200);
    tone(O, 494, 250);
    Ser.write(0);
    delay(5000);
  }
  else {
    tone(O, 75, 150);   //access denied tone
    delay(200);
    tone(O, 75, 150);
    Ser.write(130);
  }
}
bool Check(byte A[], byte B[]) {
  for(int i = 0;i < 10;i++) {
    if(A[i] == B[i]) {
      continue;
    }
    else {
      return 0;
    }
  }
  return 1;
}