iTwin is calling this new feature SecureBox. It works by generating a unique key that’s stored on both dongles. After deciding which files to encrypt, they’ll be protected and uploaded to your Dropbox account. Here’s the magic: both halves of the USB dongle can be separated and act independently, so you can leave one on your home computer and still bring your encryption with you when you go elsewhere. Sure, you could encrypt the files yourself and then upload them to the cloud, but having a physical key feels more secure (even if it isn’t) and you won’t worry about forgetting your encryption keys.
The iTwin is available now for $99.