There are some files called 'lightssl_...'. But these files are not finished and it seems they are there only to support the AES communication to the Particle Cloud. On my opinion Particle will not release SSL support, they want to sell their cloud products which kinda replace SSL.
For our application we do need SSL and we can't solve it with Particle webhooks.
Is Redbear planning to work on this?
If not I'm afraid the Duo will be difficult to use in our application. We'll have to design a custom CC3200 board cause the CC3200 does support SSL natively.