If you want to protect files on your Mac, on an external drive, or even in the cloud, it’s a good idea to encrypt them. You don’t need any special software to do this; your Mac already contains the app you need. Apple’s Disk Utility lets you create an encrypted disk image that you can use to store sensitive files that no one, not even the NSA, can get at.
We recently discussed how to use Disk Utility to manage disks and volumes. One of this app’s powerful features is the ability to make disk images, with or without encryption. To do this, start by opening Disk Utility — you’ll find this app in the Utilities folder in your Applications folder (go to Finder > Applications > Utilities).
You have two options for creating encrypted disk images: you can either create a new, empty disk image, or you can have Disk Utility make a disk image of a folder, such as one containing files that you want to archive. In this article, you will learn both ways how to encrypt disk images to protect files with Disk Utility.
Read the rest of the article on The Mac Security Blog.