RFID - CRC parameters, how to calculate them?

Projects Networking, Protocols, and Devices
9 
int dato=1, inByte;
void setup() {
    // initialize both serial ports:
    Serial.begin(115200);
    Serial1.begin(57600);
    Serial.println("read = 1");
}
void loop() {
    if (Serial.available()) {
        dato = Serial.read();
    }
    switch(dato){
        case '1':
        dato=0;
        Serial.print("pin E= ");

        Serial1.write(0x04);
        Serial1.write(0x00);
        Serial1.write(0x01);
        Serial1.write(??); // What are the data belonging to these fields?
        Serial1.write(??); // What are the data belonging to these fields?
        
        Serial.println(" espera");

        break;
    }
}

void serialEvent1() {
    if (Serial1.available()) {
        inByte = Serial1.read();
        Serial.print(inByte,HEX);
        Serial.print(" ");
    }
}