If you carry around a USB memory stick with personal or confidential files saved on it, you should take these simple steps to password protect it.

  1. The following process will DELETE everything on your USB stick, so the first step is to copy all of the contents of your USB stick to your computer’s hard drive.
  2. Open the Disk Utility application on your Mac.  Look in the Applications Folder, then in the Utilities Folder, then you will see Disk Utility.
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  3. Make sure that the USB memory stick is plugged into your computer and you should see the memory stick’s entry in the list of disks on the left side of the Disk Utility window.
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  4. Select the USB Stick name (or whatever you named it), but make sure that you select the disk itself and not the partition(s), which will be listed below and indented slightly.
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  5. 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. Finally, click the Erase button on the bottom of the window.
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  6. A window will appear prompting you 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.
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  7. When you are done, click the Erase button in the dialog box. 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.
  8. Close Disk Utility.

You can use the encrypted memory stick just like any other memory stick, you just need to type in the password when you first plug it into your computer. As always, before physically unplugging it, be sure to eject it by clicking the Eject button next to the disk’s entry within Finder.

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.