I recommend talking to Sales about this.
but with the ability to store the information in PostGres, you can put encryption on that store.
Not sure about Cassandra, imagine it is available.
You could even go as far as storing it with hardware encryption? Not sure about this, not an expert in this area.
Cryptosoft recently launched our official ThingWorx extension, to integrate our encryption platform directly into the ThingWorx platform. You can use the solution for strong encryption during transit, and even at rest in the ThingWorx database.
You can see it here ThingWorx IoT Marketplace » Cryptosoft Extension
I'd be happy to help you anyway that I can.