I need a free file encryption software

TrueCrypt is a simple, easy-to-use, on-the-fly encryption program. It works on Windows 2000/XP/2003 and Linux.

Some features include:

  1. Ability to encrypt entire hard disk partition or a storage device
  2. Creation of a virtual encrypted disk within a file that mounts as a real disk.
  3. Encryption using AES-256, Blowfish (448-bit key), CAST5, Serpeant, Triple DES, and Twofish.

For a more information, please visit:
TrueCrypt

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UCLA offers PGP WDE (whole disk encryption) free to all departments. It is cross platform, has central key management (for recovery!), and there are staff to assist implementation:

Crashed PGP encrypted disks can be recovered by DriveSavers: