ESP32 MQTT secure TLS v1.2

[mitja123]

Hello all,

I am working on a project where I want to connect ESP32 to a MQTT server, which uses TLS v1.2 protocol. After quite some researching I am still not sure if this is possible - If I get it right, ESP32 in general supports mbedTLS, which should cover all the SSL and TLS protocols...? But in the MQTT section of the espressif documentation I only see the SSL with mbedTLS (this means that only SSL protocols are covered right?). Has anyone been working on this or has any useful info?

Thanks in advance,

Mitja

[ESP_Sprite]

Can't give you an absolute answer, but I do know esp-mqtt uses esp-tls under the hood, which (as the name implies) supports TLS connections, so I'd think it supports it.

[mitja123]

Thank you for your reply and sorry for my late response.. I've been trying to solve this issue but without success. Here are some parts of my code:

static const char DSTroot_CA[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
XXXXXXXXX
-----END CERTIFICATE-----
)EOF";

mqtt_cfg.port = MQTT_PORT;
mqtt_cfg.uri = MQTT_ADDR;
mqtt_cfg.username = MQTT_USER;
mqtt_cfg.password = MQTT_PASSWD;
mqtt_cfg.keepalive = 15;
// mqtt_cfg.transport = MQTT_TRANSPORT_OVER_SSL;
mqtt_cfg.event_handle = mqtt_event_handler;
mqtt_cfg.cert_pem = (const char*)DSTroot_CA;


// esp_err_t err = esp_tls_set_global_ca_store (DSTroot_CA, sizeof (DSTroot_CA));
client = esp_mqtt_client_init(&mqtt_cfg);
esp_mqtt_client_start (client);

When I try to connect to the mqtt server I get this:

E (20009090) esp-tls: mbedtls_ssl_handshake returned -0x2700
E (20009092) esp-tls: Failed to open new connection
E (20009092) TRANS_SSL: Failed to open a new connection
E (20009094) MQTT_CLIENT: Error transport connect

I've been searching for 0x2700 error and it seems to be verification fail.
Anyone knows how to propperly include the pem certificate in esp_mqtt_client_init?
I'm not sure I'm doing it the right way...