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

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.