Can mqtt use SSL?

[Joeviocoe]

I don't see anything in the source using paho mqtt, for using secure MQTT.

[mjmccans]

I believe paho does support ssl, but there may be another solution to your issue. While I do not have this setup anymore so my recollection could be a bit fuzzy, I recall setting up multiple "listeners" in mosquitto on different ports, with one being encrypted and one being encrypted. For the non-encrypted one I locked down the ACL to only write access and only on certain topics. While that still meant that someone could maliciously feed bad values to the mqtt server for those topics, that level of security was sufficient for my environment and considering that there was no danger if the sensor values were manipulated. Just a thought that you may want to explore.