How to encrypt an external hard drive in OS X Mountain Lion

USB thumb drives and portable hard drives may well be outdated to some, thanks to the likes of iCloud and Dropbox, but to others they’re the perfect tool for transporting files from location to location. If you’re the sort of person who uses them regularly, you’ll no doubt have loaded information on to one of these devices that you wouldn’t want anyone else to see or use should it fall into the wrong hands. Now, with Mountain Lion, you can ensure that’s never the case by encrypting a hard drive or USB thumb drive so the data on it can’t be accessed without a password.

It’s a fairly easy process to complete and, as long as you remember your password, it proves incredibly effective. To encrypt a hard drive you’ll need to ensure it’s formatted as a Mac OS Journaled volume so be sure to back up your data and reformat if necessary. Once you’ve done that you’re ready to get started on the straightforward encryption process. Whatever you do, make sure you don’t ever forget that all-important password!

Step 1: All in context

With the drive you want to use mounted to your desktop, right-click on your drive with already encrypted, you’ll see Decrypt “Drive Name” instead.

Step 2: What’s the password?

In the dialog that appears on screen, enter the password you’d like to its icon and choose Encrypt “Drive Name” from the context menu. If it’s secure, repeat it to confirm and enter a password hint. Hit Encrypt Disk then wait for Finder to do all of the legwork.

Step 3: Test it out

You may have to leave your drive plugged in for a while to encrypt (big drives will need at least half an hour). Once it’s done you can eject it and remount it to test. You’ll see a warning if you eject the drive too early.

Step 4: Undo it

If you want to stop password protection on your drive, right-click on its icon and click Decrypt “Drive Name” from the context menu. Again, this may take some time so be patient and don’t eject it until it’s done.

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