DII
DevHeads IoT Integration Server•4w ago
Boss lady

Establish a secure MQTT connection to a broker using TLS on an ESP32

@Middleware & OS Hello everyone, I have a code that I'm trying to use to establish a secure MQTT connection to a broker using TLS on an ESP32. However, I keep getting an undefined error when calling espClient.setCACert(test_root_ca). In order to fix this error, I need to generate a CA certificate using 
openssl req -new -x509 -days 3650 -key ca.key -out ca.crt
openssl req -new -x509 -days 3650 -key ca.key -out ca.crt
and replace "YOUR_CA_CERTIFICATE_HERE" with the generated certificate. Can anyone help me with this issue? Thank you. Here's the code I'm using: 
#include <WiFi.h>
#include <WiFiClientSecure.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqtt_server = "broker.hivemq.com";

WiFiClientSecure espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  espClient.setCACert(test_root_ca);
  client.setServer(mqtt_server, 8883);
  client.setCallback(callback);
}

void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.print(topic);
  Serial.print(". Message: ");
  String messageTemp;
  for (int i = 0; i < length; i++) {
    messageTemp += (char)message[i];
  }
  Serial.println(messageTemp);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe("test/topic");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

static const char test_root_ca[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
YOUR_CA_CERTIFICATE_HERE
-----END CERTIFICATE-----
)EOF";
#include <WiFi.h>
#include <WiFiClientSecure.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqtt_server = "broker.hivemq.com";

WiFiClientSecure espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  espClient.setCACert(test_root_ca);
  client.setServer(mqtt_server, 8883);
  client.setCallback(callback);
}

void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.print(topic);
  Serial.print(". Message: ");
  String messageTemp;
  for (int i = 0; i < length; i++) {
    messageTemp += (char)message[i];
  }
  Serial.println(messageTemp);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe("test/topic");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

static const char test_root_ca[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
YOUR_CA_CERTIFICATE_HERE
-----END CERTIFICATE-----
)EOF";
Solution:
@Boss lady your code looks correct to me and should run perfectly well without any issues once all required parameters are field, just in case this is what it looked like once I tried it out ```cpp #include <WiFi.h> #include <WiFiClientSecure.h> ...
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1 Reply
Solution
Enthernet Code
Enthernet Code•4w ago
@Boss lady your code looks correct to me and should run perfectly well without any issues once all required parameters are field, just in case this is what it looked like once I tried it out 
#include <WiFi.h>
#include <WiFiClientSecure.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqtt_server = "broker.hivemq.com";

WiFiClientSecure espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  espClient.setCACert(test_root_ca);
  client.setServer(mqtt_server, 8883);
  client.setCallback(callback);
}

void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.print(topic);
  Serial.print(". Message: ");
  String messageTemp;
  for (int i = 0; i < length; i++) {
    messageTemp += (char)message[i];
  }
  Serial.println(messageTemp);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe("test/topic");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

static const char test_root_ca[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
MIIDXTCCAkWgAwIBAgIJAK5tdeuXKHVWMA0GCSqGSIb3DQEBCwUAMEUxCzAJBgNV
...
U9uHgT3UtNymf6O9Dp+u3e5VzXk=
-----END CERTIFICATE-----
)EOF";
#include <WiFi.h>
#include <WiFiClientSecure.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqtt_server = "broker.hivemq.com";

WiFiClientSecure espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  espClient.setCACert(test_root_ca);
  client.setServer(mqtt_server, 8883);
  client.setCallback(callback);
}

void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.print(topic);
  Serial.print(". Message: ");
  String messageTemp;
  for (int i = 0; i < length; i++) {
    messageTemp += (char)message[i];
  }
  Serial.println(messageTemp);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe("test/topic");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

static const char test_root_ca[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
MIIDXTCCAkWgAwIBAgIJAK5tdeuXKHVWMA0GCSqGSIb3DQEBCwUAMEUxCzAJBgNV
...
U9uHgT3UtNymf6O9Dp+u3e5VzXk=
-----END CERTIFICATE-----
)EOF";
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