tcplay is a free (BSD-licensed), pretty much fully featured (including
multiple keyfiles, cipher cascades, etc) and stable TrueCrypt
implementation.

This implementation supports mapping (opening) both system and normal
TrueCrypt volumes, as well as opening hidden volumes and opening an
outer volume while protecting a hidden volume. There is also support
to create volumes, including hidden volumes, etc. Since version 1.1,
there is also support for restoring from the backup header (if
present), change passphrase, keyfile and PBKDF2 PRF function.

Since tcplay uses dm-crypt (or dm_target_crypt on DragonFly) it makes
full use of any available hardware encryption/decryption support once
the volume has been mapped.
