OS X has long let you encrypt external drives, and even your Mac HD. Mountain Lion has actually made it even easier to encrypt external disks with just a few clicks. It's sometimes a good idea to do so on items such as backup disks. This way, if they ever fall into the wrong hands, no one should be able to access your data without the password you have set to decrypt it.
If you aren't sure how to encrypt your data, follow along and we'll show you how.
- RIght click on the external disk on your desktop that you'd like to encrypt.
- Now click on Encrypt 'disk name'.
- You'll now be asked to choose a password that you'll need to gain access to encrypted content. Do not lose this password! If you do, you will not have access to the files on the disk. We suggest writing it down and storing it in a safe place or using an app like 1Password to keep it safe for you. We also recommend generating a password that is over 10 characters long (minimum).
- Once you've chosen your password and password hint, now click on Encrypt Disk.
That's all there is to it. Your Mac will now start encrypting the disk that you've chosen. This process could take quite some time depending on how much data you've got stored on it. Right clicking will show you if the disk is still encrypting.
As a side note, anytime you connect this external drive, you'll be asked for the password you set up unless you save it in your Mac keychain. Just be careful not to save this password to any Macs that you don't want to always have access to the drive when connected.