I was looking for a way to password protect a folder on the Mac. I needed to be able to backup a large collection of files onto a USB hard drive and then send it securely through the mail for safe off-site storage. For some reason, this functionality is not integrated directly into Finder.
Finally I stumbled upon a way to do it with built-in OS X software. That is perfect because I wanted to avoid using random 3rd-party trialware for something that an operating system ought to be able to do for free.
How to Password Protect a Folder on the Mac:
- Open up the “Disk Utility” application
- File -> New -> Disk Image from Folder…
- choose a folder to protect
- choose “AES-128″ encryption and press Save
- Enter your desired new password twice (Do not forget it.)
This process creates an ordinary Macintosh disk image (.dmg) file. The disk image contains the entire contents of the folder, but cannot be opened unless the correct password is supplied. To open it, just double-click the .dmg file in Finder. A password dialog box will appear. Once you supply your correct password, Finder will automatically unencrypt your data and mount the image as a disk.