encrypted-walkie-talkie/code/code.ino

//TODO: Learn how to use radio module, transmit data with it
//TODO: Learn how to use mic. in arduino, transmit plain sound among two arduinos and play it
//TODO: Implement encryption and decryption using AES128, test it with text, then use to encrypt sound

#include <LiquidCrystal_I2C.h>
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#include <AESLib.h>
#include <EEPROM.h>

//Components
LiquidCrystal_I2C lcd(0x27, 16, 2);
RF24 radio(7,8);

//Settings
byte unsigned address = 1;
unsigned short key = 0;
byte unsigned screen = 0;
const String seed = "1305b5cfa1a59e9789de"; // "random" seed ;)
String password;
bool mode = 0; // 0 = transmit, 1 = recieve, bool is 2 bytes less than byte :)
bool encryption = 1; // will the trafic be encrypted?

//Switch screen button
const byte switchScreenButton = 2;
byte switchScreenLast;

//IncreaseButton
const byte increaseButton = 3;
byte increaseButtonLast;

//DecreaseButton
const byte decreaseButton = 4;
byte decreaseButtonLast;

void switchMode();
void printOutput();
void updatePassword();

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

  //Setting up buttons
  pinMode(switchScreenButton, INPUT_PULLUP);
  pinMode(increaseButton, INPUT_PULLUP);
  pinMode(decreaseButton, INPUT_PULLUP);
  
  //Setting up a radio module
  radio.begin();
  radio.setPALevel(RF24_PA_MIN);
  switchMode(); //default is recieving
  
  //Setting up a LCD
  lcd.init();
  lcd.backlight();

  updatePassword();
}

void loop() {
//  switchMode();
  byte switchButtonValue = digitalRead(switchScreenButton);
  byte increaseValue = digitalRead(increaseButton);
  byte decreaseValue = digitalRead(decreaseButton);
  
  
  if (switchButtonValue == 0 && switchScreenLast == 1) {
    screen = screen < 3? screen + 1 : 0; 
  }

  if ((decreaseValue == 0 && decreaseButtonLast == 1) || increaseValue == 0 && increaseButtonLast == 1) {
    switch (screen) {
      case 0:
        mode = !mode;
      break;
      case 1:
        if (decreaseValue == 0 && decreaseButtonLast == 1)
          address = address > 0? address - 1 : 127;
        else
          address = address < 127? address + 1 : 0;
      break;
      case 2:
        if (decreaseValue == 0 && decreaseButtonLast == 1)
          key --;
        else
          key ++;
      break;
      case 3:
        encryption = !encryption;
      break;
    }
  }
  
  switchScreenLast = switchButtonValue;
  increaseButtonLast = increaseValue;
  decreaseButtonLast = decreaseValue;
  
  printOutput();
  delay(100);
}

void switchMode () {
  if (mode) {    // transmit -> recieve
    radio.openReadingPipe(0, address);
    radio.startListening();
  } else {        // recieve -> transmit
    radio.openWritingPipe(address);
    radio.stopListening();
  }
  
  mode = !mode;
}

void printOutput () {
   lcd.clear();
   switch (screen) {
    case 0:
      lcd.print("Mode: ");
      lcd.print(mode? "rec." : "tra.");
    break;
    case 1:
      lcd.print("Addr.: ");
      lcd.print(address);
    break;
    case 2:
      lcd.print("Password: ");
      lcd.print(key);
    break;
    case 3:
      lcd.print("Enc.: ");
      lcd.print(encryption? "yes" : "no");
   }

   
//   for (int i = 0; i < 5; i ++) lcd.print(address[i] - '0');
   //lcd.print(mode);
}

void updatePassword() {
  password = seed + key;
}