[Bug 174738] Re: ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key length (256 bits) not supported by kernel

[Thespian]

There has been no activity on this bug for a year, but it is still a
problem in Hardy 8.04.  I've got a work-around (described below) but
"loop-AES" needs to be rebuilt and copied into the kernel dir after
*each* kernel update for my work-around.  Could we please get the
Sourceforge loop-aes sources pulled into the standard Ubuntu packages so
we have AES support by default, out of the box?

Work-around:
----------------------------------------------------------------
On Ubuntu 8.04, by default, the AES encryption isn't enabled in the kernal
for loopback mounting via "losetup".  That has to be fixed before you
can easily mount and unmount AES-encrypted file systems.

Via apt-get or the Synaptic package manager, make sure you have the
following installed:

   loop-aes-utils
   linux-headers-generic

sudo apt-get install loop-aes-utils
sudo apt-get install linux-headers-generic

 - get http://loop-aes.sourceforge.net/loop-AES-latest.tar.bz2, extract and
open a root shell in the extracted directory
 - cd into the directory you downloaded into and...
 
bunzip2 loop-AES-latest.tar.bz2
tar xf loop-AES-latest.tar
cd loop-AES-v3.2e  (or whatever the directory version is named)

*******
NOTE!!
*******
You will have to re-run the following steps (make, copy, and modprobe)
after a kernal upgrade until and unless the various package maintainers
fix the original problem.  You'll know if you need to do this if, the
next time you try to mount your secure file system after a kernal upgrade,
you get the error:

   ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key length
(256 bits) not supported by kernel

If so, just re-make against the new headers and re-copy the loop.ko file
into place, and all should be well again.
*******
NOTE!!
*******

sudo rmmod loop
sudo make clean
sudo make

(assuming the 'make" completed without errors)

sudo  mv /lib/modules/`uname -r`/kernel/drivers/block/loop.ko
/lib/modules/`uname -r`/kernel/drivers/block/loop.ko-ORIG

sudo cp tmp-d-kbuild/loop.ko /lib/modules/`uname
-r`/kernel/drivers/block/loop.ko

sudo modprobe loop
sudo  make tests

(all tests should pass)

After this, the following should work:
losetup -e aes256 /dev/loop0 aes-file-to-mount

-- 
ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key length (256 bits) not supported by kernel
https://bugs.launchpad.net/bugs/174738
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