2 Steps Verifications from Dropbox
This was like one of those James Bond or MI movie. You need to plug in a USB stick to unlock your files on the cloud.
Dropbox had introduce Universal 2nd Factor (U2F) security keys as an additional method for 2 steps verification, giving you stronger authentication protection for all the files that you save with them in Dropbox.
If you need to know more, you can find out here at dropbox blog update.
*Sources from: blogs.dropbox.com