Encrypt Folders with Password Protection in Mac OS X the Easy Way
Encrypting folders and requiring passwords for access is an excellent way to store and protect private data on a Mac. Now, there is a new means of password protecting folders and sensitive files introduced in Mac OS X that lets you create a new encrypted disk image directly from a specified folder.
Though you can still create a blank disk image and fill it as you see fit by using the older trick, this new option in Disk Utility is easier to use and extremely quick, making it the preferred method to add a very strong layer of encryption to a folder, securing itself along with all of its contents.