Encrypted file systems?
 

I have been reading the military uses a 256-bit encrypted file system on their laptops. I am curious if anybody has setup an encrypted filesystem and how well it works. Any recommendations on what to do would be helpful.

The FBI run something called Gaurd Dog (or something like that). That program uses symmetric encryption and I assume that the military is similar. I have used PgP to encrypt directories on my hard drive and besides entering a complex password to get to the files it's not tough.

I belive there is an Encrypted FIle System available for linux called loopback-encryption.

Not sure exactly how it works but Im assuming it works with the loop device some how.

I was using loopback-encryptions (as You called it); When You compile Your kerenl with it it works like this:

losetup -e aes encrypted-fs-in-file.iso /dev/loop0
(enter passphrase and bits number)
mount /dev/loop0 directory

It is simple, fast, it is possible to create rootfs like this... its ok. Compiling is hard.

but how do you set the key size ?
what is the default key size for AES ?