If that button is grayed out, it means FileVault is turned off in your system settings.
To turn it on, follow these steps:. Click on the gold-colored padlock icon in the lower left corner of the "Security and Privacy" window. You'll be asked to enter the username and password for the administrator account on the computer. Once you do so the gold padlock will switch to look unlocked instead of locked. Choose which user accounts can access the encrypted volume you're about to make.
The account from which you're making the volume will be checked by default. If you want any other accounts to have access, manually select them.
As promised, it's time for a little primer on encrypting your files. In this article, we'll focus just on what Apple has already provided you on OS X. There are many tools for encrypting files in OS X. GUI apps to do that have varying prices. Unfortunately, OS X itself doesn't have many built-in.
Make sure these accounts have passwords set before you choose them. When you're done, click "Continue. Write down your recovery key.
You should now see a window displaying a "recovery key" which acts as a backup password for your encrypted volume if you ever forget your account password. The key should be twenty-four characters long. The only way to change it is to re-encrypt the FileVault volume. Write this key down somewhere and secure it in a safe place.
Press "Continue" once you've secured your recovery key. Choose whether you want Apple to store your recovery key or not. You should now have the option to let Apple store your recovery key for you.
First, make sure you have an Internet connection, then check the box next to either "Store the recovery key with Apple" or "Do not store the recovery key with Apple. Restart the Mac. You'll be prompted to do so by a new window.
Click the "Restart" button. When you next log into your user account, the computer will begin encrypting all of the files on your hard drive. To protect your files from hackers and thieves, Macs offer excellent encryption features built-in. You can encrypt your entire hard drive, encrypt an external drive, or just create an encrypted container for your most important files.
When you enable FileVault, your files are stored on your hard drive in an encrypted, seemingly scrambled format. You can choose which user accounts have the ability to unlock your disk. Your drive will be locked again when you shut down your Mac. This allows you to regain access to the drive if you forget the username and password for the local account on your Mac. This can take days, so consider keeping your Mac awake overnight.
With macOS you can also encrypt entire external drives. The contents of the drive will be encrypted with a passphrase you choose, and no one will be able to access them without that passphrase.
To encrypt a drive, simply open the Finder and connect the drive to your Mac. The disk will be encrypted once you enter your password of choice—be sure to use a secure one!
You may have to wait several minutes for the contents of your disk to be encrypted, depending on the size of your drive and its speed. You can encrypt individual files by creating an encrypted file container, or disk image. Whenever you want to work with your encrypted files just mount the disk image and enter your password.
The files will be available to use and any files you save to the disk image will be encrypted.