Problem with cryptsetup

Hi,

As some of you may know from my other posts, I am trying to find a way to encrypt my data. The data has to be decrypted on-the-fly by the Readynas (Ultra 2). The clients are not encryption aware.

I thought I might try cryptsetup using loopback. That way I could get the Readynas to locally mount the encrypted file (manually, using ssh after reboot). Perhaps I could even write a Frontview addon for entering the passphrase and mounting the disk!

#### this is a 4.2.19 Readynas Ultra 2 after factory default

#### FIRST INSTALL apt-utils

nas-C1-5D-C4:/lib# apt-get -f install apt-utils
Reading package lists... Done
Building dependency tree... Done
The following NEW packages will be installed:
  apt-utils
0 upgraded, 1 newly installed, 0 to remove and 30 not upgraded.
Need to get 198kB of archives.
After unpacking 496kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  apt-utils
Install these packages without verification [y/N]? y
Get:1 http://archive.debian.org etch/main apt-utils 0.6.46.4-0.1+etch1 [198kB]
Fetched 198kB in 3s (51.6kB/s)
debconf: delaying package configuration, since apt-utils is not installed
Selecting previously deselected package apt-utils.
(Reading database ... 14737 files and directories currently installed.)
Unpacking apt-utils (from .../apt-utils_0.6.46.4-0.1+etch1_i386.deb) ...
Setting up apt-utils (0.6.46.4-0.1+etch1) ...

nas-C1-5D-C4:/lib#

#### THEN INSTALL cryptsetup

nas-C1-5D-C4:/lib# apt-get -f install cryptsetup
Reading package lists... Done
Building dependency tree... Done
The following extra packages will be installed:
  dmsetup
Suggested packages:
  initramfs-tools linux-initramfs-tool
The following NEW packages will be installed:
  cryptsetup dmsetup
0 upgraded, 2 newly installed, 0 to remove and 30 not upgraded.
Need to get 0B/300kB of archives.
After unpacking 823kB of additional disk space will be used.
Do you want to continue [Y/n]? y
WARNING: The following packages cannot be authenticated!
  dmsetup cryptsetup
Install these packages without verification [y/N]? y
Selecting previously deselected package dmsetup.
(Reading database ... 14753 files and directories currently installed.)
Unpacking dmsetup (from .../dmsetup_2%3a1.02.08-1_i386.deb) ...
Selecting previously deselected package cryptsetup.
Unpacking cryptsetup (from .../cryptsetup_2%3a1.0.4+svn26-1_i386.deb) ...
Setting up dmsetup (1.02.08-1) ...
Setting up cryptsetup (1.0.4+svn26-1) ...

nas-C1-5D-C4:/lib#
#### Note than the reason it did not need to download the packages was that I had installed them, got a warning I needed apt-utils, 
#### removed them again and then started as shown at the top.

#### THEN INSTALL cryptmount

nas-C1-5D-C4:/lib# apt-get -f install cryptmount
Reading package lists... Done
Building dependency tree... Done
The following NEW packages will be installed:
  cryptmount
0 upgraded, 1 newly installed, 0 to remove and 30 not upgraded.
Need to get 46.5kB of archives.
After unpacking 205kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  cryptmount
Install these packages without verification [y/N]? y
Get:1 http://archive.debian.org etch/main cryptmount 1.2-1 [46.5kB]
Fetched 46.5kB in 3s (11.8kB/s)
Selecting previously deselected package cryptmount.
(Reading database ... 14806 files and directories currently installed.)
Unpacking cryptmount (from .../cryptmount_1.2-1_i386.deb) ...
Setting up cryptmount (1.2-1) ...
 Adding system startup for /etc/init.d/cryptmount ...
   /etc/rc0.d/S48cryptmount -> ../init.d/cryptmount
   /etc/rc6.d/S48cryptmount -> ../init.d/cryptmount
   /etc/rcS.d/S28cryptmount -> ../init.d/cryptmount

nas-C1-5D-C4:/lib#

#### CREATE a 50.000.000 byte file and make it available thorugh /dev/loop0
#### (I know, dd is faster, but this was only a test on a small file)

nas-C1-5D-C4:/lib# head -c 50000000 /dev/zero >/c/_testf
nas-C1-5D-C4:/lib# losetup /dev/loop0 /c/_testf

#### encrypt 
nas-C1-5D-C4:/c# cryptsetup luksFormat /dev/loop0

WARNING!
========
This will overwrite data on /dev/loop0 irrevocably.

Are you sure? (Type uppercase yes): YES
Enter LUKS passphrase:
Verify passphrase:
Failed to setup dm-crypt key mapping.
Check kernel for support for the aes-cbc-essiv:sha256 cipher spec and verify that /dev/loop0 contains at least 133 sectors.
Failed to write to key storage.
Command failed.
nas-C1-5D-C4:/c#

As you can see, I have run into problems. It seems the encryption kernel modules are not installed (factory reset 4.2.19).

I have tried installing kernel modules before (while trying to install truecrypt) but have not had success.
Can anyone walk me through the procedure to install the required modules?

Thanks.