Turning on FileVault 2
FileVault 2 is available from the Security & Privacy pane of System Preferences. Click the FileVault tab in the Security & Privacy pane to enable or disable FileVault.
If you migrated a home directory that was encrypted by an earlier version of FileVault (Legacy Filevault), you need to turn this off first. See the "Migrating a FileVault-protected Home from an earlier version of Mac OS X" section below for more information.
When you select "Turn On FileVault", you're asked to identify the user accounts that are allowed to unlock the encrypted drive if there is more than one account present. You'll need to enter the password (or have users enter their passwords) for each account you want to have the ability to unlock FileVault 2.
Users not enabled for FileVault unlock are only able to log into the computer after an unlock-enabled user has started or unlocked the drive. Once unlocked, the drive remains unlocked and available to all users, until the computer is restarted.
After selecting which users can unlock the disk, you're shown your recovery key.
This key is a backup unlock method provided to you in case the unlock-enabled user password is forgotten. You can highlight and copy this key to print it out, email it, or otherwise copy it. Remember that maintaining a copy of this key on your computer does not help you if you forget your login password. Your drive will remain encrypted and inaccessible along with the rest of your data. Make an external copy of this key, or write it down and store it in a secure but retrievable location.
You can also store your recovery key with Apple. See the "Storing your recovery key with Apple" section below for more information.
After you've completed the process of turning on FileVault, you're prompted to restart your Mac. After restarting, a login screen appears. Select your account name and enter your password to continue.This unlocks the disk. Next, an Apple logo with a spinning gear underneath it appears, and the computer continues starting up.
The user account that unlocked the drive is automatically logged in after start up completes. The first time you log in after turning on FileVault, the initial encryption of your entire hard disk begins. It should complete within a few hours. This happens in the background, and doesn't interrupt normal usage of your computer. In addition to using your computer while encryption is happening, you can sleep, log out and even turn off your computer during this time. Encryption continues when your computer is powered on again.
Choose a topic below to learn more about additional features of FileVault 2.
Storing your recovery key with Apple
After you are shown your recovery key, you are also given the opportunity to store your recovery key with Apple.
If you choose to store your key with Apple, you're presented with three "Choose a question" menus with three corresponding answer fields.
The key you store with Apple is encrypted, along with the answers you provide. Carefully choose questions and answers that you can easily remember exactly as you typed them. This is important if you later need to retrieve your recovery key from Apple. Click Continue to send your key to Apple. Your computer restarts after this step, to begin FileVault disk encryption.
Retrieving your recovery key from Apple
If you forget your login password for a FileVault-encrypted drive, but you stored your recovery key with Apple, you can contact AppleCare and request retrieval of your recovery key.
Typing in the wrong login password three times prompts you if you have the ability to retrieve your key from Apple. Click the triangle-button next to the prompt that appears to reveal a Recovery Key text field (which replaces the password text field) and AppleCare contact information, along with your computer's Serial Number and a Record Number. You need to provide these pieces of information in order for AppleCare to retrieve your recovery key.
Upon successful retrieval and entry of your recovery key, you are prompted to change your login password. After changing your login password, it's also recommended that you change your FileVault recovery key and upload the new one to Apple.
Changing your recovery key
In the Security & Privacy system preference, under the FileVault tab, click "Turn Off FileVault" to disable FileVault. After FileVault is off, FileVault will begin to decrypt your drive. Once decryption is complete, you can click the "Turn On FileVault" button. Doing this allows you to enable unlock-capable users. You're also provided with a new recovery key and have the option of sending this new key to Apple. The old key sent to Apple will not be able to unlock your newly-encrypted disk. If you need to retrieve your recovery key from Apple, only the new one will be retrieved based on the Serial Number and Record Number displayed in the login window.
Letting other users unlock the drive
If you want to make the Mac available to a user that doesn't currently have unlock capabilities, log in as a user that can unlock the disk. When you see your own desktop, choose "Log Out (user name)" from the Apple () menu. Also, you can unlock the disk, then switch to another user from Fast User Switch menu in the menu bar.
If you want to grant existing users the ability to unlock the drive on their own, open the Security & Privacy pane of System Preferences. Select the FileVault tab and click the lock icon in the lower left corner of the window. Enter your admin privileges when prompted. Click the "Enable Users..." button to add existing users to the list of accounts that can unlock the disk.
Your password and Recovery Key are critical
The encryption used in FileVault 2 prevents accessing data on your encrypted drive without a permitted user account's password, or the recovery key. When you choose to turn on FileVault, you can no longer log in automatically. Take great care in choosing an account password that you feel is both secure and easy for you to remember. When enabling FileVault, carefully write down your recovery key somewhere, and be certain to make a copy of exactly what is shown. Store this copy of your key outside of your encrypted disk. If you choose to store your recovery key with Apple, take great care in choosing your related security questions and providing answers you can, if needed, clearly convey to an AppleCare phone support advisor.
Not all languages or regions are serviced by AppleCare. Check the Apple Support website to see if you can retrieve your recovery key, should you need to. Not all AppleCare-supported regions provide support in every language. If you choose your preferred language, enable FileVault 2, and choose to store your key with Apple, your answers may be in languages and/or characters not supported by AppleCare.
Storing your recovery key with Apple provides a secure alternative to your own best efforts to remember and securely document your own password and recovery key. There is no guarantee that Apple will be able to provide your recovery key back to you.
What is FileVault 2?:
With FileVault 2, your data is safe and secure — even if your Mac falls into the wrong hands. FileVault 2 encrypts the entire drive on your Mac, protecting your data with XTS-AES 128 encryption. Initial encryption is fast and unobtrusive. It can also encrypt any removable drive, helping you secure Time Machine backups or other external drives with ease. Want to start fresh or give your Mac to someone else? FileVault 2 makes it easy to clean data off your Mac. Instant wipe removes the encryption keys from your Mac — making the data completely inaccessible — then proceeds with a thorough wipe of all data from the disk.
Apple Support - OS X: About FileVault 2