Before you start please note that this process will format any data you have. Have a full backup of your system before you begin. Be sober while you are doing this please. I have tested the tutorial for backtrack 4 pre-final, backtrack 4 final, backtrack 5 and backtrack 5 r1.
Kindly note that my hardisk setup may be different than yours. I want to install backtrack as follows:
/dev/sda1 —– /boot partition
/dev/sda2 —– /root partition
My /root partition will be encrypted with luks such that in order for me to boot, i will have to enter a password.Boot with a live cd and proceed as follows
Kindly remember to change your partitions as necessary
Format the /root partition with luks. Enter the password you want to be using at startup.
root@bt:~# cryptsetup luksFormat /dev/sdXX
Open the partion for mounting. Enter the password you entered above
root@bt:~# cryptsetup luksOpen /dev/sdXX root
Format the container with ext3 filesystem. You can use whichever linux filesystem you are comforable with
root@bt:~# mkfs.ext3 -j -O extent /dev/mapper/root
After this is done, run the backtrack installer(install.sh) on backtrack desktop. Double clicking it should do.
Select your country.
Select the keyboard layout.
Then we now go to partition the disk . Select manual and click next
Select the partition for boot, for me thats /dev/sda1. Click “edit partition” and then set the options. In my options, i use ext3 as the file system, i choose to format the partition and the most important bit is that i set the mountpoint as /boot
Select the partition for root, for me thats /dev/mapper/root. Click “edit partition” and then set the options. In my options, i use ext3 as the file system, i choose to format the partition and the most important bit is that i set the mountpoint as /root
My final setup for the install looks as below. I know, my hardisk is rather small 
When you click next, you will get a warning about swapspace. I personally opt not to have swapspace. I have enough memory to run backtrack and a few virtual machines. Click “continue”
The next bit is important. Click “Advanced” .It is the location backtrack will install the bootloader. I usually install the bootloader to hd0 but you can install it to the linux partition. Even if you have windows, you can install the bootloader to hd0, and when it comes time to boot, you will be presented with options as to which os to boot.
You are now set for the install. Click install and wait for the backtrack install to finish. After its done, click the “continue using the live cd”
We need to make a few changes before we exit the live cd
root@bt:~# mkdir /mnt/root
root@bt:~# mount /dev/mapper/root /mnt/root/
Mount the /boot partition
root@bt:~# mount /dev/sdXX /mnt/root/boot
root@bt:~# mount -t proc proc /mnt/root/proc/
root@bt:~# mount -o bind /dev /mnt/root/dev/
root@bt:~# chroot /mnt/root/ /bin/bash
Using a text editor like vi or nano, edit the /etc/crypttab and add the /root partition here
root /dev/sdXX none luks
Using a text editor like vi or nano, edit the /etc/fstab file. Remove any other lines you will find and leave your file in the below order. Replace the XX with your partitions
/dev/mapper/root / ext3 relatime,errors=remount-ro 0 1
/dev/sdXX /boot ext3 defaults 0 0
Using a text editor like vi or nano, edit the /etc/initramfs-tools/modules file and add the following modules to the end of the file
aes-i586
sha256
dm-mod
dm-crypt
Create the new initrd image
root@bt:~# update-initramfs -k all -c
Install grub to your harddisk. Use the device name and not a partition e.g /dev/sda
root@bt:~# grub-install /dev/sdX
root@bt:~# exit
root@bt:~# reboot
Your /root partition should now be encrypted and you will be asked a password when booting to decrypt it.
Credits to esc201, who wrote a good tutorial on encrypting the disk with bt4-prefinal.
