Password Protect an External Drive in Mac OS X with Encrypted Partitions

We recently showed you how to password protect files and folders using encrypted Disk Images in Mac OS X, but if you have an external drive you can go a step further. By using encrypted disk partitions, any drive, be it a USB key, flash drive, hard disk, or whatever else, can be set to require a password before the drive can be mounted and the files accessed.
Require a Password to Access External Drives with an Encrypted Partition
Doing this will format the external drive and erase all of it’s contents, back up the contents before proceeding, and do not lose the set password.
- Launch “Disk Utility” from /Applications/Utilities/
- Connect the drive you want password protected
- Select the drive in Disk Utility, and click on the “Erase” tab
- Pull down the “Format” menu and choose “Mac OS Extended (Journaled, Encrypted)”
- Click on “Erase”
- At the next screen, set a password – do not lose this password or you will lose access to the drives data
- Set a hint that isn’t obvious and then click on “Erase”
- Let Disk Utility run, when finished the drives partition will show up on the desktop, the drive will be accessible for now without a password allowing files to be transferred over. Eject the disk when finished to require a password upon further mounting and usage.


Once the drive has been ejected, connecting it again will require a password before it is even mounted. That screen will look like this:

Clicking on “Remember password in keychain” will allow the drive to be mounted on the Mac without entering the password on that Mac, but it will still require a password to be used on another Mac. For maximum security, it’s best to leave that option unchecked.
For system-wide security measures, don’t forget to password protect a Mac with both login and screen saver passwords, and if you don’t mind the trade offs, to use FileVault to encrypt the entire hard drive and its contents.

I’m sorry but in my disk utility it simply doesn’t appear te be there…
I have lion so I don’t know if is a recent update op not but I really want to do this…
Okay forget about my first post, I clicked an existing partition instead of the harddrive itself SORRY
I’ve done this, but the problem that I see is that if I eject the partition, it doesn’t ask me the password again until either the drive itself is unmounted, or the computer is rebooted (which of course unmounts the disk). Is there any way to just CMD-E eject the partition and still have it ask for the password?
Good topic. Can you educate us further how I can use this encrypted drive when I am reading or writing to a windows machine?
Any way to do this without erasing the partitions of a drive?
How long should this process take?
I tried encrypting an external 320GB EIDE drive, after erasing the drive. It took only a couple of minutes for DU to finish but then the drive would not mount. I waited about 10 minutes and finally rebooted the system. Did I not wait long enough?
Upon reboot, the password entry box came up, I entered my password and got an error that the drive was unreadable. I clicked on the “Initialize” option that I was presented with and DU opened but it was unable to re-initialize the drive.
It took booting into my BootCamp partition and using the Windows XP Disk Management system to perform a low-level format on the drive. I created a Windows partition on the drive and when I booted back into Lion, the drive mounted. I opened DU and was able to re-partition the drive with a GUID and format it unencrypted. It now works fine again.
What did I do wrong?
[...] Via | OSXDaily [...]
I don’t have the “Encrypted” option alongside the “Mac OSX Extended (Journaled)” option. In total I have 6 options, but none of which have the ability to encrypt. I tried making a new image on the drive since at least THAT one has the option (I chose 128 bit), but then it says “invalid argument” and doesn’t make a new image.
I really just want a basic password on my external HD so that the average joe won’t be able to accidently plug it in and sift though it.
I’m running 10.6.8 btw. What am I missing?
It’s only available in Lion 10.7+. You’ll have to upgrade.
Since you need Lion 10.7+ for that option, will machines running older versions of osx be able to interact with the encrypted drives?
i passworded my external hard drive using this method. the problem now is i did a clean installation after i upgraded to mac osx lion. now the computer does not detect the hard drive. what do i do?
Guys, try Lockngo. No need to prepare drive or reformat it. Very fast disk locking. It works for both Mac and PC.
Not free though.
[...] they are USB drives, Firewire, or even SD cards. While you can still use the traditional route to encrypt disks through Disk Utility, from OS X Mountain Lion onward the process is streamlined directly into the Finder and [...]
i used this but now my mac doesnt prompt for password anymore and i cant format it using disk utility.
what do?
I searched for a few hours online to find out how to add a password with encrypted partitions and every other source didn’t help much. I followed your steps and it works great! Thanks so much for the screenshots as well. It helped a bunch!
I DID AS ITS SAID ON THE TEXT NOW I LOST ALL MY DATA ON THE EXTERNAL HARD DRIVE ICANT SEE ANYTHING ??? HELP PLZ ?
“Doing this will format the external drive and erase all of it’s contents, back up the contents before proceeding, and do not lose the set password.”