This article proposes a scientific contribution to strengthen the security of the MQTT protocol in
an IoT environment. MQTT is natively a communication protocol that does not embed any security. Messages are
transmitted in clear text over the network. Being an IoT protocol, MQTT evolves in an environment with limited
resources, where energy remains an important factor in the implementation of security solutions. It is important
to increase security without affecting the autonomy of IoT. This is what we propose by using the "Syracuse
conjuncture" (or the Collatz sequence) as a pseudo-random key generation mechanism to strengthen security and
authentication in MQTT

Collatz conjecture, Collatz sequence, dynamic authentication, Internet of Things (IoT), lightweight encryption, MQTT, Security