Flash drives are getting better, harder, faster, stronger--and smaller. As storage becomes more portable, so does the need to secure your data. Read on and we'll show you how easy it can be to create a secure disk image on your thumb drive to store all your top secret files.
A disk image is similar to a .zip file in that it has its own individual folder structure, but it's virtual. This Disk Image can also be encrypted to enable secure storage of files.
>> USB Flash Drive
>> Mac OS X and a user account with admin privileges
Plug in your drive and open Disk Utility (located in /Applications/Utilities).
To create the disk image, head to File > New > Blank Disk Image. Disk Utility will then open a new dialog window, where you'll need to make a few changes. Tackle them in order:
1. Type in a name in the Save As text field.
2. From the Where drop-down menu, select the flash drive as it appears in the Finder.
3. In the Name field, type what you'd like the alias to be when you launch it in the Finder window.
4. In the Size drop-down menu, select the size you want your disk image to be. If you're using a blank flash drive, you may want to consider making it the entire capacity. This will give you the maximum amount of space to store files securely. If you have files on your drive already, though, you can select a size that’s appropriate for the free space left on your flash drive.
Selecting the Custom option in this drop-down will allow you to specify a custom size.
5. In the Format drop-down menu, select “Mac OS Extended (Journaled)” if you will be using the Flash drive specifically on a Mac. Use MS-DOS (FAT) if you need the the device to work with Windows, as well.
6. In the Encryption drop-down box, select 256-bit AES encryption if you want your security to be extra tight. Otherwise, select the recommended setting of 128-bit AES.
7. Ensure that the Partitions drop-down menu remains Single partition (the default).
8. In the Image Format drop-down menu, ensure that read/write disk image is selected (the default).
Click the Create button when you're finished.
Disk Utility will then request that you type a password to secure the disk image. Write it down and remember it.
After you type the password, Disk Utility will create the disk image.
After Disk Utility finishes creating your disk image, you will find a new DMG file on your flash drive with the name you gave it earlier.
To access it, all you have to do is double-click on this file. Finder will then request the password you specified earlier.
After you type in your password, you will see the disk image in the Finder, allowing you to access, add, or delete files securely.
Whenever you want to unplug your flash drive, simply eject the secure disk image volume, followed by the actual flash drive volume.
Follow this article’s author, Cory Bohon on Twitter.
dhuff
February 09, 2011 at 9:07am
"Use MS-DOS (FAT) if you need the the device to work with Windows, as well."
OK, but is there a way to mount that image later on Windows ?
corybohon
February 09, 2011 at 12:34pm
Yes, you can mount DMG files in Windows using a program called MacDrive. There are also a few other programs. Windows even recommends one when trying to associate the file extension. Unfortunately, the stock version of Windows does not support DMG files.
