Turn Any USB Memory Stick Into An Ultra-Secure, Password Protected Filestore [OS X Tips]

Turn Any USB Memory Stick Into An Ultra-Secure, Password Protected Filestore [OS X Tips]

It’s time for me to sign off my tipster post here at Cult of Mac. For my final tip, here’s one of my absolute favorites from my book. It describes how to turn any USB memory stick or storage device into an ultra-secure filestore. When inserted into any Mac, a password prompt will appear, just like with expensive ‘government grade secure’ memory sticks, and the contents will be as equally inaccessible to anybody else.

Here’s another tip from Mac Kung Fu, which contains over 300 tips, tricks, hints and hacks for OS X. It’s Amazon ($2.46) as well as other bookstores, and also as an eBook for all eReaders.

OS X Lion lets you format a USB memory stick so that its contents are encrypted. You’ll need to enter a password whenever it’s inserted.

Essentially this turns any USB stick into a ultrasecure portable file storage device, of the type often sold at a premium. However, bear in mind that the memory stick will only work on Macs also running OS X Lion and not on Macs running earlier versions of OS X or on PCs running Windows or Linux. To those operating systems, the memory stick will appear to be unformatted or corrupted.

For this tip to work, you’ll need a memory stick of any size. Be aware that files already on the stick will be deleted during the formatting process, so you should temporarily copy them to a safe location and then copy them back once the following procedure is finished.

  1. Start by opening Disk Utility (Finder->Applications->Utilities->Disk Utility) and then insert the USB memory stick you intend to use.
  2. Look for the memory stick’s entry in the list of disks on the left side of the Disk Utility window. It will probably be identified by its size. Select the entry, but make sure that you select the disk itself and not the partition(s), which will be listed below and indented slightly.
  3. Click the Erase tab in the Disk Utility window. In the dropdown menu alongside the Format heading, select Mac OS Extended (Journaled, Encrypted). In the Name field, type whatever you wish to call the memory stick. This name will appear in Finder’s sidebar whenever you insert the stick in future.
  4. Click the Erase button. You’ll be prompted to enter a password and verify it by typing it again immediately below. It’s important that you don’t forget this password! If you do there is absolutely no way of recovering the contents of the memory stick—they’re lost forever. However, you will be able to reformat the memory stick so you can keep using it although the contents will obviously be lost. Because of the risk, it’s a good idea to type something in the Hint field that might provide a clue to what the password is—the hint will appear in future should you get stuck when entering the password.
  5. When you are done, click the Erase button in the dialog box that should have appeared. Erasing, partitioning, and encrypting will take a minute or two depending on the size of the memory stick. Once you’re done, the new memory stick will be ready for use. You can copy files to it by selecting its entry in the sidebar of Finder. You can also close Disk Utility.

From now on you can use the encrypted memory stick just like any other memory stick. Before physically unplugging it, be sure to eject it by clicking the Eject button next to the disk’s entry within Finder.

When you insert the memory stick, you’ll be prompted for the password. If when prompted for the password, you put a check in the box next to Remember the Password in My Keychain, you’ll never be prompted for the password again on that computer. However, if it’s inserted into another Mac, the password prompt will appear. Therefore, you’ll have a USB memory stick that—essentially—works seamlessly on your computer but whose data is inaccessible to anyone else.

Note that the steps outlined in this tip are not limited to USB memory sticks. You could encrypt an entire portable USB, Firewire, or Thunderbolt hard disk in this way, making it so that the contents will only be accessible upon entry of a password. Bear in mind that accessing an encrypted drive might be a tiny bit slower. However, this effect is only likely if you regularly save large files such as movies there.

Related
  • ninjalabstudios

    It’s sort of useful and then becomes shit because it won’t work other/older OS’s

  • KeirThomas

    What about this part of the article: “You’ll have a USB memory stick that—essentially—works seamlessly on your computer but whose data is inaccessible to anyone else.”

    Isn’t that useful? Essentially you can give the memory stick to anybody because it’ll be useless to them. It won’t matter if you lose it.

  • Ahmed Alassafi

    And how to reverse this process?

  • ninjalabstudios

    I suppose but i just wish it work with my other macs which do not have Lion.
    Still pretty sweet tho :P

  • KeirThomas

    One day that will be true — just one or two years until Lion becomes the dominant OS X, and it’s only die-hards who even remember Snow Leopard! 

  • KeirThomas

    Copy the files off the stick, then reformat it as usual as FAT32 memory stick in Disk Utility. 

  • ninjalabstudios

    lol i still use Snow Leopard from time to time. 

  • Millard Fillmore

    Not while most of the U.S. federal government is still using Office 2003, it won’t.  With all the complaints that later versions of Office on either platform aren’t *quite* compatible with 2003, and the flat dictat by some administrators that Office 2003 Will Be Used No Matter What, Office 2004 on the Mac isn’t going away for quite a while … and it, of course, requires Rosetta which, of course, requires a pre-Lion OS.  Mine will be a Snow Leopard machine for quite some time to come, which is fine with me, since there’s a bunch of old, small utilities and things that I use frequently, and they don’t play with the Lion too well.

  • Aaron

    …or better yet, HFS+ Journaled, NON-encrypted. That way you’re not limited to FAT32′s 4GB maximum file size and easy corruptibility. 

  • KeirThomas

    Te FAT32 provided in Lion is the extended version that supports much larger partitions than 4GB. So it’s still better to use that than HFS because it’ll mean the stick can be used on Windows/Linux. 

  • KeirThomas

    Haven’t some Rosetta-supported apps just died in the latest Snow Leopard update?

    So we’re looking at mandate vs practical reality…

  • Sebastian_S

    Let’s say you did this and then installed Lion on said stick as a portable OS you could take with you – would you be able to boot off of it and will it still ask your password during boot up?

  • bobab

    it will install but won’t boot. You can instead encrypt your user folder by turning on Filevault available since OSX 10.3 Panther. In 10.7 Lion, Filevault2 encrypts the entire drive.

  • Sebastian_S

    Ah, that makes perfect sense. Install Lion on the stick and then turn Filevault on. Thanks, Bobab!

About the author

Keir ThomasKeir Thomas (http://keirthomas.com) is the author of Mac Kung Fu, which contains over 300 tips, tricks, hints and hacks for Mac OS X Lion. He's also the author of over 10 other computing titles.

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