I wanted to keep a backup of my private PGP key and I wanted to install it on multiple devices: a couple of Mac OS X Mavericks laptops and my Android smartphone, a Moto G 4.4.2.
Naturally this needs to be encrypted but the limitations to setting up that encryption are surprising. In the end I found that I could use EncFS on both the Macs and the smartphone.
On the Macs you need to drop to the terminal:
brew update brew install osxfuse
System Preferences > FUSE for OS X > Install FUSE for OS X
brew install encfs
Check you’ve plugged in your external USB drive then mount the encrypted folder:
encfs /Volumes/M/private.enc ~/private
The mount point will appear as OSXFUSE Volume 0 (encfs) in your home directory. You can import your key file directly from here.
Once done, before ejecting your USB drive, remember to unmount the FUSE folder: