#include <SPI.h>
#include <SD.h>

File myFile;
int output = 8;

void setup() {
  Serial.begin(9600);
  if (!SD.begin(10)) { //make sure sd card was found
    while (true);
  }

  delay(2000);
}

void loop() {
  String password = "xyz123#";
  //String sdhc = myFile.read();
  //Serial.println(sdhc);
  myFile = SD.open("txt_file.txt"); 
  if (myFile) { 
    while (myFile.available()) { 
      if (password = myFile.read()) {
        digitalWrite(output, HIGH);
        Serial.print("\nUnlocked");
      }else{
        digitalWrite(output, LOW);
        Serial.print("\nLocked");
      }
      delay(300);
    }

    myFile.close();
  }
}