Encrypting Files
Encryption uses a key to transform plain text information so that it is unreadable to anyone without the decryption key. Encryption can protect both information on disk and information in transit over a network.
Using FileVault
Mac OS X Server includes FileVault, which can encrypt your home folder and all the files contained within it. You [...]

Encrypting Disk Images
Encrypted disk images are a perfect way to transport data on external media, save files to removable media, and protect files on shared systems. FileVault does not protect files transmitted over the network or saved to removable media. However, Mac OS X Server includes utilities for encrypting disk images. Using a serverbased encrypted [...]