MQTT vs. SMQTT in IoT: Key Differences Explained

This article compares MQTT and SMQTT, highlighting their differences in the context of IoT applications.

MQTT Protocol

Broker based MQTT protocol

Figure 1 illustrates the typical MQTT protocol architecture. Let’s delve into its key features:

  • MQTT stands for Message Queue Telemetry Transport.
  • It’s built upon three core components: publishers, broker, and subscribers.
  • MQTT follows a publish/subscribe architecture.
  • Publishers, often sensors or IoT devices, transmit data or updates to the broker, categorized by topic.
  • Subscribers are applications that register with the broker to receive updates related to specific topics or sensor data.

SMQTT Protocol

SMQTT builds upon the foundation of MQTT, adding a layer of security. Here’s a breakdown of its features:

  • It’s an extension of the standard MQTT protocol.
  • SMQTT stands for Secure Message Queue Telemetry Transport.
  • It employs lightweight attribute-based encryption.
  • SMQTT operates at the session layer.
  • It incorporates broadcast encryption, allowing a single encrypted message to be delivered to multiple nodes efficiently.
  • The algorithm is structured into four phases: setup, encryption, publish, and decryption.
  • Like MQTT, SMQTT utilizes a broker-based publish/subscribe architecture.
  • During the setup phase, publishers and subscribers register with the broker and obtain a master secret key.
  • Before publishing, data undergoes encryption.
  • The broker publishes the encrypted data, which is then received by the subscribers.
  • Subscribers perform decryption to decode the data using the shared master key.
  • The key generation algorithm is not standardized and is left to the developers’ discretion. Similarly, the choice of encryption algorithms also rests with the developers.