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

Jan 25, 2012 - 38 Comments

Drive Password in Mac OS X

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 your data and all contents before proceeding, and do not lose the set password.

  1. Launch “Disk Utility” from /Applications/Utilities/
  2. Connect the drive you want password protected
  3. Select the drive in Disk Utility, and click on the “Erase” tab
  4. Pull down the “Format” menu and choose “Mac OS Extended (Journaled, Encrypted)”
  5. Format as Encrypted Disk to require a password before mounting

  6. Click on “Erase”
  7. At the next screen, set a password – do not lose this password or you will lose access to the drives data
  8. Set a hint that isn’t obvious and then click on “Erase”
  9. Set a disk password

  10. 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:

Enter password to mount disk

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.


Related articles:

Posted by: AJ in Mac OS, Tips & Tricks


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  1. raymon says:

    but I can’t used this hard disk with windows
    how it is working with both Mac and Windows

  2. Farras Handoko says:

    I forgot my external drive password. what can i do??

    how to format disk to recover the password?? Please help me!!

  3. Wilfred Olschewski says:

    Sadly, OSX 10.13.6 – High Sierra no longer has an encryption option for SD Cards. (Option still available for USB and Hard drives)

  4. Pranav says:

    Guys will this encrypted pen drive work on windows also? i mean will it ask a password in windows too? coz my mac has less internal storage and m using an external hard drive want it to be protected on any computer plz reply me

  5. cpc says:

    HEEELP…I did everything and when prompted for password on my encrypted Drobo drive, I hit cancel and now no matter what I do in regards to unplugging and checking disk utility makes it appear again. i have 2TB drive split into 2 – 1tb drives, the non encrypted is visible and the “cancelled” at password prompt is gone….*******Photos and business files dated back 15 years, very important please please please help…its almost hidden or something
    Your responses are greatly appreciated thank you so much

    • pau says:

      Open “Disk Utility” and find the partition or drive in there and mount it manually and enter the password, the Disk Utility app is in /Applications/Utilities/ folder

      That should work fine, the drive is still there it just needs to be authenticated again.

      • cpc says:

        I disk utility in external drop down only shows “TRUSTED Mass Storage with other partition drive but no missing partition. There is also another “TRUSTED Mass Storage with nothing inside it stated “unformatted”. Also no option to mount any idea? I can see it in my drobo dashboard…

        Your response is greatly appreciated thanks again

        • pau says:

          You should be able to select the drive in Disk Utility, then go to the ‘File” menu and choose “Unlock” on the encrypted partition.

          If it’s not showing up, you could try the next step, it dumps some system caches and does a precursory disk check in the process:

          – Disconnect the drive from the Mac

          – Rebooting the Mac into Safe Mode (hold down Shift key on boot)

          – Reboot again normally this time

          – Connect the USB drive to the Mac again once the computer starts up, see if it mounts with the dialog again – if not, return to Disk Utility again and try to mount the partition, then File menu > Mount > Unlock

          Another option would be to manually mount the drive through the command line, which is quite a bit more advanced:

          First you identify the drive UUID (it’s a long hexadecimal string) for the encrypted partition:

          diskutil cs list

          Then you would mount it, you’d want to use something like:

          diskutil coreStorage unlockVolume UUID

          Starting to get into the weeds with that one, but it would work as well. Try to use Disk Utility if possible, it’s much easier.

  6. Amma says:

    this may sound dumb but i thought this method will only put a password on my external hard drive. but i think i deleted all my files on my external hard drive :”( I was just trying to put a password on it. is there anyway i can get my files back?

    please please please do help. i’m crying

  7. Steve says:

    Is it possible to partition an external hard drive and then password protect only one of the created partitions?

  8. Paige says:

    Hello, i have tried to do this but when i go onto Disk Utility there is no option to encrypt? help please!

  9. LR says:

    Ok, so it’s set… can it be changed? I recently purchased a new external to use with a Mac (that’s on loan). I set up the external with that Mac and put all of my information on it. It’s pw protected which I wanted, but now I want to change the pw now.

    And also I can’t use it on any other type of computer but a Mac. Someone was helping me set it up, so something must have been done to cause this, but I wouldn’t know what. Still actually learning how to even use a Mac. I love my external and of course need it to work with my Mac and need it pw protected, but need it to work with any computer I hook it up to. What do I do? Thank you.

  10. Geo says:

    You jave to reformat it without the encryption

  11. Axel says:

    Great, but how do I remove the password protection from a drive I don’t want to be encrypted?

  12. Sujit says:

    Hi, Is it possible to set different passwords for different partitions. I’m talking about network drive.

  13. Sujit says:

    Thanks for your detailed explanation. I was wondering if I can encrypt/password protect only some of my partitions.
    Or protect each partition with a different password. My drive(Seagate 2TB) is attached to the router WD Mynet N900.

  14. SAM says:


  15. Be says:

    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!

  16. chris says:

    i used this but now my mac doesnt prompt for password anymore and i cant format it using disk utility.
    what do?

  17. […] 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 […]

  18. Alex says:

    Guys, try Lockngo. No need to prepare drive or reformat it. Very fast disk locking. It works for both Mac and PC.

  19. olubukola says:

    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?

  20. David says:

    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?

    • Seiji says:

      It’s only available in Lion 10.7+. You’ll have to upgrade.

      • chris says:

        Since you need Lion 10.7+ for that option, will machines running older versions of osx be able to interact with the encrypted drives?

    • Phil says:

      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.


  21. Storm608 says:

    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?

  22. Brendan says:

    Any way to do this without erasing the partitions of a drive?

  23. Kalyan says:

    Good topic. Can you educate us further how I can use this encrypted drive when I am reading or writing to a windows machine?

  24. Jonathan says:

    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?

  25. RB says:

    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…

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