OS X Yosemite: The Missing Manual

The Keychain

The information explosion of the computer age may translate into bargains, power, and efficiency, but as noted above, it carries with it a colossal annoyance: the proliferation of passwords we have to memorize. Shared folders on the network, Web sites, FTP sites—each requires another password.

POWER USERS’ CLINIC: Virtual Memory, Security, and You

Virtual memory is a trick that computers use to keep a lot of programs open at once—more, in fact, than they technically have enough memory (RAM) for. How do they manage to keep so many software balls in the air? Easy: They set some of them down on the hard drive.

When you bring Photoshop to the front, OS X frees up the necessary memory for it by storing some of the background programs’ code on the hard drive. When you switch back to, say, Safari, OS X swaps Photoshop for the Safari code it needs from the hard drive, so that the frontmost program always has full command of your actual memory.

Sophisticated software snoopers could, in theory, sneak up to the Mac while you’re logged in but away from your desk. Using a built-in Unix command called strings, the no-goodniks could actually read what’s stored on the hard drive in that virtual-memory swap file—in particular, your passwords.

When you turned on the old FileVault, your virtual memory swap files were also encrypted.

But in Yosemite, your virtual memory swap files are encrypted all the time, automatically and invisibly, so nobody can read them.

Apple has done the world a mighty ...