I’ve always wanted to have a fully encrypted memory stick which when plugged in, OS X would automatically ask me for a password before mounting it. As far as I know (and from what tests I carried out), it’s not possible to create an encrypted disk image and overwrite the entire device with it.
My solution involves placing a hidden encrypted disk image on a device, hiding the volume itself so it doesn’t show up in the desktop, and applying a Folder Action to the /Volumes folder which takes care of mounting the encrypted image when the device is plugged in, and unmounting the device when the encrypted image is ejected.
No Terminal access necessary: an AppleScript droplet for preparing the device, the Folder Action AppleScript, and an AppleScript for restoring the device are provided here.
The scripts are tested in 10.5.1, but they really should work in …
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