Mac OS X Password Protect a Folder

Posted on 15 August 2009 • AppleBlogTechnology

In Mac OS X Leopard (version 10.5) there is no simply way to password protect a folder, but there is a clever little workaround. You can create password protected Disk Image using Apple’s Disk Utility application, and then securely store your files there.

1. Launch the application Disk Utility, located your Applications/Utilities folder.

Apple Disk Utility

2. Click on the New Image button, or use the top menu and select File> New> Blank Disk Image.

3. In the New Blank Image dialog first enter a file name into the Save As box. This will be used for the Disk Image (filename.dmg) file, and we’ll call ours My Secure Files.

4. Now enter a Volume Name, which will be the name of the disk when you mount it. Again we’ll call ours My Secure Files.

5. Set the Volume Size, ensuring it is large enough for all the files you want to store now and in the future, but not so large that it takes forever to mount. 100MB should suffice for us.

6. Leave the Volume Format on the standard Mac OS Extended (Journaled), though you can use one of the others if you prefer.

7. Set the Encryption, which is the level of protection for your password. We’re going to use 128-bit AES encryption as speed is more important than added security. If you’re a security nut, then 256-bit AES encryption might be the best choice.

8. The Partitions format determines the way the disk will appear when you mount it. We’re going to use Hard Disk so our Disk Image will mount just like an external hard drive or file server.

9. We’re going to leave the Image Format to the default read/write disk image so that we can use it just like any other disk.

10. Once you’ve checked all your settings are correct, click the Create button.

11. You should now enter and verify your Password into the dialogue box:

Hint: Use the Password Assistant to help create a super-secure password!
prot-folder-12-assist prot-folder-11-assist
Note:Remember to make a note of your password, as if you forget it then you’ll never be able to open your Disk Image again!

12. Once you’ve entered your password, it is important to Untick the Remember password in my keychain option, otherwise anyone using your computer will be able to open the archive without having to type in the password!

13. The Disk Utility Progress bar will now appear while your computer is creating the Disk Image.

14. Your Disk Image has been saved to your hard drive, so you can quit Disk Utility.

15. In the Mac OS  Finder, locate the Disk Image you just created, My Secure Files.dmg.

15. Double-click the Disk Image, and when prompted enter your Password — don’t tick the Remember password in my keychain option!

16. The volume My Secure Files can now be used like any other disk. When you’re done just eject it.

That’s it. You now have a password protected Disk Image where you can store your files.

This tutorial is for Mac OS X 10.5 Leopard. For help with other OS X versions see Apple’s support document How to create a password-protected (encrypted) disk image in Mac OS X 10.3 or later.