In “Tutorial: Secure TLS Communication with MQTT using mbedTLS on top of lwip” I already used TLS for a secure communication, but I had not enabled server certificate verification. This article is about closing that gap.
Secure MQTT running on NXP FRDM-K64F with lwip and mbed TLS
I love to commute by train, and I use three different Swiss train companies for my daily work commute to the Lucerne University of Applied Sciences in Horw, near Lucerne. Returning this evening, I enjoyed a beautiful view to the snow-covered mountains from my home destination. I’m lucky, and this is yet another reason why I love my commute:
View from Train Station
One of the most important aspects of the ‘IoT’ world is having a secure communication. Running MQTT on lwip (see “MQTT with lwip and NXP FRDM-K64F Board“) is no exception. Despite of the popularity of MQTT and lwip, I have not been able to find an example using a secure TLS connection over raw/native lwip TCP :-(. Could it be that such an example exists, and I have not found it? Or that someone implemented it, but has not published it? Only what I have found on the internet are many others asking for the same kind of thing “running MQTT on lwip with TLS”, but there was no answer? So I have to answer my question, which seems to be a good thing anyway: I can learn new things the hard way :-).
Block diagram MQTT Application with TLS using lwip
MQTT is a lightweight and broadly used internet protocol (see “MQTT with lwip and NXP FRDM-K64F Board“). And probably the majority of IoT applications today are using Mosquitto as server (or ‘broker’ in MQTT language). By default, Mosquitto is using a protocol without encryption. In “Introduction to Security and TLS (Transport Layer Security)” I have covered the basics and needs for encryption. This article is about how to enable Mosquitto and clients to use the TLS protocol.
TLS Handshaking with certificates and keys
IoT (Internet of Things) is all about connecting to the internet. And even more it is about security. Without security and without encrypted communication, everyone possibly can see what I send or receive. And this is especially bad if passwords or user names are sent in an unencrypted way. So encryption and secure communication is key. The solution to that is to use a connection which uses the TLS (Transport Layer Security) protocol.
I want to use TLS for my MQTT communication (see “MQTT with lwip and NXP FRDM-K64F Board“). I’m still learning MQTT, and I’m even more learning about the fundamentals of security and security protocols. So this article is about what I have learned recently, and what I can use to make my data communication secure: Network stack architecture, symmetric and asymmetric encryption and certificates.
Certificate Based Key Exchange
In the area of IoT (Internet of Things), one obvious need is to have a way to send and receive data with an internet protocol. MQTT (or Message Queue Telemetry Transport) is exactly like that: a light-weight Machine-to-Machine communication protocol. With the MQTT protocol a microcontroller (or ‘client’) can send data and/or subscribe to data. For example to the Adafruit.IO:
Adafruit MQTT IO Feed
In “MCUXpresso IDE: Importing Kinetis Design Studio Projects” I explained how Kinetis Design Studio projects can be imported and used inside the MCUXpresso IDE. Processor Expert projects can be used, but no new components added, modified or new Processor Expert projects created. To fully use Processor Expert, two plugins need to installed, and this is what this article is about.
Processor Expert in MCUXpresso IDE
Amazing to see what a few sunny and warm days can do in nature:
Spring Awakening
Happy Springing 🙂
The Eclipse CDT build system automatically scans the files in my project folders and adds them to the list of files to be built. That works great if files are added through Eclipse and its plugins: That way Eclipse is notified and aware, and has the files added. But what if I have added files externally (outside of Eclipse)? how can I make Eclipse aware of it?
File added but not shown in Eclipse Project View
MCU on Eclipse 