AES loopback filesystem encryption

[Michael S. Peek]

Hello all,

I'm trying to create an encrypted loopback filesystem, but it bombs when 
I run the command:

# losetup -e aes256 /dev/loop0 `pwd`/file.bin
ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key length 
(256 bits) not supported by kernel.

I also tried aes (without the 256) with the same results:
ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key length 
(128 bits) not supported by kernel.

I am running the 2.6.20-16-generic kernel, I have loop-aes-utils 
installed, and I have both the loop and aes modules loaded.

When I type 'cat /proc/crypto', I get for aes:
min keysize : 16
max keysize : 32

I did a search but it turned up nothing useful -- everything I found 
simply said to install the loop-aes-utils package, which I already have.

Can anyone tell me what I have wrong?