Boot from fully encrypted disk which looks like unused

[User000]

Using luks is the standard way of boot from an encrypted disk. However luks header is not encrypted and it may cause a security shortcoming when it is necessary to hide the fact of encryption.

Standard section of grub.conf when root file system is placed on an unencrypted disk has the form:

title Fedora 12
root (hd0,0)
kernel /boot/vmlinuz-2.6.31.12-174.2.3.fc12.i686.PAE ro root=/dev/sda1 LANG=ru_RU.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb quiet
initrd /boot/initramfs-2.6.31.12-174.2.3.fc12.i686.PAE.img

Boot works.

After this I rsync this file system as a whole to a filesystem on an encrypted virtual disk /dev/mapper/hdd2 corresponding to another physical disk, for example /dev/sdb. Then I created an additional section in grub.conf so as to make it possible to boot from /dev/sdb. It looks the same as above, but with some distinctions. Location of bootloader and kernel image is unchanged (1st sector and /boot directory), only root filesystem is transferred onto an encrypted new device.

title Fedora 12 NEW
root (hd0,0)
kernel /boot/vmlinuz-2.6.31.12-174.2.3.fc12.i686.PAE ro root=/dev/mapper/hdd2 LANG=ru_RU.UTF-8 SYSFONT=latarcyrheb-sun16 KEYBOARDTYPE=pc KEYTABLE=us rhgb quiet
initrd /boot/initramfs-NEW.img

Two modifications of the initial section have been done:
1. root=/dev/sda1 ---> root=/dev/mapper/hdd2
2. initramfs-2.6.31.12-174.2.3.fc12.i686.PAE.img ---> initramfs-NEW.img

The second modification is needed to prepare /dev/mapper/hdd2 before mounting it as a root filesystem. So changing initramfs is necessary. I did it in the following way.

1. At the beginning of /mount/mount-root.sh, before 'mount' command, I put the string:

cryptsetup -d /etc/key -c aes-cbc-essiv:sha256 -s 256 create hdd2 /dev/sdb

2. key file is added to /etc

After this I reboot and select the second item in grub menu. During the boot the messages appear:

WARNING: Deprecated config file /etc/modprobe.conf, all config files belong into /etc/modprobe.d/.
(... the same string repeats a number of times ...)
No root device found
Boot has failed, sleeping forever

Please, give me a suggestion what should I do to cope with this issue.