Cracking an electronic safe using brute force

/*
 * Brute force safe cracker for a Sentry Fire Safe.  It took me 5 days
 * to open my safe with this.  YMMV.  Have fun!
 */

// map of keypad key number to arduino pin controlling the corresponding relay

unsigned char key2pin[10] = {
   9, // kp0
   2, // kp1
   6, // kp2
   10,// kp3
   3, // kp4
   7, // kp5
   11,// kp6
   4, // kp7
   8, // kp8
   12 // kp9
};

// arduino pin mapped to power cycling relay

unsigned char powerpin = 5;

int verbose = true;

// arduino pins mapped to photocells on green and red LEDs

int grnPin = 0;
int redPin = 1;

void setup()
{
   Serial.begin(9600);

   // Initialize key relays and power relay to open (high is open)
   int i;
   for(i = 0; i <= 9; i++)
   {
      digitalWrite(key2pin[i],HIGH);
      pinMode(key2pin[i],OUTPUT);
   }
   digitalWrite(powerpin, HIGH);
   pinMode(powerpin, OUTPUT);
}

// Read the status LEDs.  Return either the number of red blinks (the
// usual case), or that we got a green LED, which indicates a cracked
// safe.

int readStatus(double time, int& redBlink)
{
   // These values should be independently calibrated
   int redThresh = 200;
   int grnThresh = 200;

   int nsamples = 1000*time;

   redBlink = 0;
   int grnBlink = 0;

   // Count blinks via a moving avg and threshold cross

   int len = 10; // moving average length

   double avgRed = 0.0;
   double avgGrn = 0.0;
   double avgRed_last = 0.0;
   double avgGrn_last = 0.0;

   double redVals[len];
   for (int n = 0; n < len; n++) { 
      redVals[n] = 0.0; 
   }

   double grnVals[len];
   for (int n = 0; n < len; n++) { 
      grnVals[n] = 0.0; 
   }

   for (int n = 0; n < nsamples; n++) {

      // shift values to free up position 0
      for (int k = 9; k >= 1; k--) {
         redVals[k] = redVals[k-1];
         grnVals[k] = grnVals[k-1];
      }
      redVals[0] = analogRead(redPin);
      grnVals[0] = analogRead(grnPin);


      double sumRed = 0;
      for (int k = 0; k < len; k++) {
         sumRed += redVals[k];
      }
      double avgRed = sumRed / len;

      double sumGrn = 0.0;
      for (int k = 0; k < 10; k++) {
         sumGrn += grnVals[k];
      }
      double avgGrn = sumGrn / len;

      if (avgRed > redThresh && avgRed_last < redThresh) {
         redBlink++;
      }
      avgRed_last = avgRed;

      if (avgGrn > grnThresh && avgGrn_last < grnThresh) {
         grnBlink++;
      }
      avgGrn_last = avgGrn;

      delay(time/nsamples*1e3);
   }

   return grnBlink;
}

void turn_on()
{
   if (verbose) Serial.println("turning on");
   digitalWrite(powerpin,LOW);
}

void long_power_cycle()
{
   if (verbose) Serial.println("long power cycle");
   digitalWrite(powerpin, HIGH);
   delay(5000);
   digitalWrite(powerpin, LOW);
   delay(400);
}

void power_cycle()
{
   if (verbose) Serial.print("power cycle... ");
   digitalWrite(powerpin,HIGH);
   delay(3250);
   digitalWrite(powerpin,LOW);
   delay(400);
   if (verbose) Serial.println(" done.");
}

void press(int key)
{
   digitalWrite(key2pin[key], LOW);  // CLOSE
   delay(100);
   digitalWrite(key2pin[key], HIGH); // OPEN
   delay(250);
}

// try all combinations of buttons we can press

void loop()
{
   int lo = 0;
   int hi = 9;

   int attempt_count = 0;

   int cracked = 0;

   turn_on();
   delay(500);

   for (int digit1 = lo; digit1 <= hi; digit1++) {
      for (int digit2 = lo; digit2 <= hi; digit2++) {
         for (int digit3 = lo; digit3 <= hi; digit3++) {
            for (int digit4 = lo; digit4 <= hi; digit4++) {
               for (int digit5 = lo; digit5 <= hi; digit5++) { 

                  attempt_count++;

                  int redBlinks = 0;

                  if (verbose) Serial.print("Trying ");
                  Serial.print(digit1);
                  Serial.print(digit2);
                  Serial.print(digit3);
                  Serial.print(digit4);
                  Serial.print(digit5);
                  if (verbose) Serial.println();

                  press(digit1);
                  press(digit2);
                  press(digit3);
                  press(digit4);
                  press(digit5);

                  cracked = readStatus(2.0, redBlinks);

                  // 3 red blinks is a wrong combination.  5 red
                  // blinks is some mysterious error code.  When we
                  // get one of those, do a long power cycle to try to
                  // get things back to normal.
                  
                  if (redBlinks > 3) long_power_cycle();
            
                  Serial.print(redBlinks);
                  if (verbose) Serial.println(" red blinks");

                  Serial.print(cracked);
                  if (verbose) Serial.println(" green blinks");
            
                  if (cracked) {
                     Serial.print("Cracked!  Code is ");
                     Serial.print(digit1);
                     Serial.print(digit2);
                     Serial.print(digit3);
                     Serial.print(digit4);
                     Serial.print(digit5);
                     while (1) {
                     }
                  }

                  // We need to power cycle after 3 failed attempts to get
                  // out of lockout mode

                  if (attempt_count == 3) {
                     power_cycle();
                     attempt_count = 0;
                  }


               }
            }
         }
      }
   }
}