#include <Arduino.h>
#include <DHT.h>

#define DHT_PIN 4
#define DHT_TYPE DHT22

DHT dht(DHT_PIN, DHT_TYPE);

const uint8_t SECRET_KEY[] = {0x2B, 0x7E, 0x15, 0x16, 0x28, 0xAE, 0xD2, 0xA6};
const int KEY_LEN = 8;

void xorEncrypt(uint8_t* data, int len) {
  for (int i = 0; i < len; i++)
    data[i] ^= SECRET_KEY[i % KEY_LEN];
}

void printHex(uint8_t* data, int len) {
  for (int i = 0; i < len; i++) {
    if (data[i] < 0x10) Serial.print("0");
    Serial.print(data[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
}

void setup() {
  Serial.begin(115200);
  delay(1000);
  dht.begin();
  Serial.println("=== ESP32 Sensor Encryption Simulation ===");
}

void loop() {
  delay(3000);

  float temp = dht.readTemperature();
  float hum  = dht.readHumidity();

  if (isnan(temp) || isnan(hum)) {
    Serial.println("DHT22 Error: Failed to read!");
    return;
  }

  Serial.println("\n-------------------------------");
  Serial.println("Raw Sensor Data:");
  Serial.print("  Temperature : "); Serial.print(temp); Serial.println(" C");
  Serial.print("  Humidity    : "); Serial.print(hum);  Serial.println(" %");

  uint8_t payload[8];
  memcpy(&payload[0], &temp, 4);
  memcpy(&payload[4], &hum,  4);

  Serial.print("Plaintext  (hex): ");
  printHex(payload, 8);

  xorEncrypt(payload, 8);
  Serial.print("Encrypted  (hex): ");
  printHex(payload, 8);

  Serial.println("Transmitting encrypted payload...");

  xorEncrypt(payload, 8);
  float recv_temp, recv_hum;
  memcpy(&recv_temp, &payload[0], 4);
  memcpy(&recv_hum,  &payload[4], 4);

  Serial.print("Decrypted  (hex): ");
  printHex(payload, 8);
  Serial.println("Recovered Data:");
  Serial.print("  Temperature : "); Serial.print(recv_temp); Serial.println(" C");
  Serial.print("  Humidity    : "); Serial.print(recv_hum);  Serial.println(" %");
}