How do I secure/encrypt SD card data transparent to apps? Are there any off-the-shelf options for securing the contents of an SD card so that files written by apps writing to SD are encrypted?  If so, what is the best option?

I'm looking for something for all apps. I would strongly prefer to do it without rooting.
For anyone who stumbles upon this topic. Motorola seems to offer a solution for full storage encryption of internal and sd card.

Link: https://motorola-enterprise.custhelp.com/app/answers/detail/a_id/57094