Full disk encryption software
Mac OS X
Mac OS X includes FileVault for hard disc encryption. It was significantly improved in the Mac OS X 10.7 (Lion) release.
- FileVault 2 in Mac OS X Lion transparently encrypts the entire hard disc.
- Legacy FileVault in previous versions of Mac OS X encrypt users’ home folders only. This protects confidential information on lost laptops, but doesn’t prevent tampering with the operating system.
It’s worth upgrading to the latest Mac OS X for FileVault 2.
See your distribution’s documentation for the options available to you, for example, LUKS.
Wikipedia has a useful article on the more technical aspects of password strength.