Mac OS X 10.6: About FileVault
You can prevent others from seeing or copying your files by using FileVault to encrypt the files in your home folder. FileVault creates a separate volume for your home folder and encrypts the contents of it. The data in your home folder is encoded and your information is secure if your computer is lost or stolen. FileVault uses the latest government-approved encryption standard, the Advanced Encryption Standard with 128-bit keys (AES-128).
When you turn on FileVault, you also set a master password for the computer that you or an administrator can use if you forget your regular login password.
Warning:Don’t forget your master password. If you turn on FileVault and then forget both your login password and your master password, you won’t be able to log in to your account, and your files and settings will be lost forever.
If you store sensitive information on your computer, you should consider using FileVault. For example, if you carry all your company’s financial data on your portable computer, losing it could allow someone to access sensitive data that might hurt your business. If you are logged out of your account when your computer is lost and FileVault is turned on, your information is safe.
Because your home folder is encrypted, some tasks that normally access your home folder may be prevented. If you’re not logged in to your computer, other users won’t have access to shared folders in your home folder. Also, some automations or scripts that require data stored in your home folder may not run.
For example, backup utilities may see your home folder as always changing, and this could slow down your backup.