I think the copy could provide a more self-explanatory user experience.
Create New
Self-Destructing Message → Create A New Self-Destructing Message
Submit → Encrypt Message
Self-Destructing URL
Needs some language to explain what to do next. It's not obvious to an end-user that the URL isn't automatically shared with the host.: e.g. “Share this URL via email, chat or other messaging service. It will self-destruct after being viewed once.”
I think the copy could provide a more self-explanatory user experience.
Create New
Self-Destructing URL