Encryption and Password Protection under Mac OS X
Everyone’s got something to hide. Here’s a great way to encrypt and password protect your sensitive material natively under Macintosh OS X. This guide assumes you have the latest OS 10.6.3, however the encryption feature is nothing new.
Launch Disk Utility either by navigating to /Applications/Utilities with Finder or by using Spotlight.
Select the New Image icon at the top of the main window.
Select a location to save your disk image, then type the name of the disk image in the “Save As:” text field above. Another text field and several drop-down menus appear at the bottom of the window. Name the disk image as you see fit and select a file size appropriate to your needs. This size cannot be changed later, however you can always create additional disk images or create a larger disk image and migrate your data.
I suggest leaving the “Format:” field the default “Mac OS Extended (Journaled), unless you plan on accessing the information from other operating systems, in which case I suggest selecting “MS-DOS FAT.”
Encryption is what makes your data secure, however stronger encryption means more time required to decrypt and re-encrypt data when reading and writing to disk. Under “Encryption:”, Select “128-bit AES encryption (recommended)” if you expect to read and write from the disk image often, or select “256-bit AES encryption (more secure, but slower)” if you’re goal is complete security. You can never be too careful.
Leave “Partitions:” as the default “Single Partition – Apple Partition Map” as well, unless you’re using multiple Operating Systems, in which case you should select “Hard disk”.
Leave “Image Format:” as the default “read/write disk image”.
Selecting the “Create” button at the bottom right will bring up a password window. There’s little point to strong encryption without a decent password, so choose your password carefully. Refer here for tips on creating strong passwords. Deselect “Remember password in my keychain”, otherwise the operating system will store your password and defeat everything we hoped to accomplish here.
What you have effectively done is to create a separate, portable file system on your hard disk which is mobile enough to place on a flash drive or migrate too and from disks. Think of it as a secure folder, but without the expensive and taxing elements of a third-party solution.