There are plenty of reasons to want to encrypt the data on a hard drive. Before OS X Mountain Lion, Apple provided tools to do this with the startup drive, via FileVault. Starting right now, however, with OS X 10.8, you can encrypt almost any external drive you like, including flash drives (also known as thumb drives in my neck of the woods). Here’s how.
I tested this on a 4 Gb generic flash drive, but you can really use any drive that has a GUID Partition Table, which OS X has supported since OS X 10.4. If you get an error when trying to encrypt the drive and it mentions GUID, simply format the drive with Apple’s build in Disk Utility as a Mac OS, Journaled volume and you’ll be good to go.
Plug the flash drive into your Mac, and find the icon in the Finder, either on the Desktop or in the left sidebar of any Finder window. Right click (or Control-click) on the drive’s icon, and then choose Encrypt “DiskName,” where DiskName is the actual name of the drive you’re trying to encrypt. In other words, if your drive is called Untitled, you’ll choose Encrypt “Untitled” from the contextual menu.
Your Mac will show you a dialog window. Type in a good password that you’ll remember into both password fields, then type in a password hint, which is required. Click on Encrypt Disk when you’re done.
After quite a bit of time, your drive will be encrypted, and only available to someone with the password. It took a good 15 minutes or so for my 4 Gb flash drive to finish up, and the only way I knew it was working was that my flash drive has a blinking red “accessing” light on it. If you’re encrypting a bigger disk than that, be prepared to wait a long time.
To undo it will take another right-click, this time choosing Decrypt “DiskName” from the pop-up menu. If you head into Disk Utility to erase as you would a non-encrypted disk, you won’t even see it. Like a Ninja.
- Via Macworld Hints