Use FileVault to Encrypt Data
FileVault is encryption built into Mac OS and protects your data if your computer is lost or stolen. Mac OS 10.6 (Snow Leopard) and below encrypts the entire user's folder, while 10.7 (Lion) encrypts the entire disk. CUS recommends FileVault for users running Mac OS 10.7 and above.
Note: Consult with CUS before turning on FileVault. Some precautions, like having good backups, are necessary before enabling it.
The following instructions were performed on an iMac running OSX Lion (10.7.4).
Get to the FileVault settings by selecting the Apple Icon > System Preferences > Security & Privacy (the grey house with the lock, in the top row of icons).
Under the FileVault tab, select "Turn on FileVault..." to begin encrypting your data. You may have to click a "padlock" icon in the bottom left corner and provide your username/password if the button to turn on FileVault is grayed out. Additionally, your information may be asked for again if there are multiple user accounts on your computer. You will then be presented with a "recovery key" which is a safety net that can unlock the disk if you forget your password. Please make a copy of this key and store it in a safe place, and NOT on the Hard Drive itself. A good place to store this key can be on your AFS Home folder or printing it and storing it in a locked drawer. If you lose both your password and the recovery key, your data on the disk will be lost.
You may be asked to restart your computer to start the encryption process. Afterwards, it may take some time as FileVault goes through and encrypts all the data on your computer. You can use your computer normally while the encryption is underway.