How to open a door from your smartphone

1#include "thingProperties.h"
2#include <TOTP.h>
3#include <NTPClient.h>
4#include  <WiFiUdp.h>
5
6// OTP configuration
7uint8_t hmacKey[] = {0x2, 0x63};
8constexpr  int keySize = 2;
9
10TOTP totp = TOTP(hmacKey, keySize);
11WiFiUDP ntpUDP;
12NTPClient  timeClient(ntpUDP, "time.ien.it");
13
14constexpr int SHELLY_RELAY = 4;
15
16void  setup() {
17  // Connect to Arduino IoT Cloud
18  initProperties();
19  ArduinoCloud.begin(ArduinoIoTPreferredConnection);
20  
21  // Initialize variables and pins
22  access_code = "";
23  pinMode(SHELLY_RELAY,  OUTPUT);
24  digitalWrite(SHELLY_RELAY, LOW);
25}
26
27void loop() {
28  ArduinoCloud.update();
29}
30
31//  Handle incoming messages
32void onAccessCodeChange()  {
33  if (access_code ==  "") return;
34  
35  timeClient.update();
36  unsigned long now = timeClient.getEpochTime();
37  String correct_code = totp.getCode(now);
38
39  if (access_code == correct_code)  {
40    digitalWrite(SHELLY_RELAY, HIGH);
41    delay(700);
42    digitalWrite(SHELLY_RELAY,  LOW);
43    access_code = "Door open!";
44  } else {
45    access_code = "Invalid  code";
46  }
47}
48
49