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+Installing Slackware on encrypted volumes
+=========================================
+
+
+Contents:
+
+* Introduction
+* Using cryptsetup during Slackware installation
+* Encrypting your '/home' partition
+* Encrypted swap
+* Encrypted root filesystem
+* Combining LUKS and LVM
+* Hibernation (suspend-to-disk)
+* Additional passphrases, keyfiles
+* A note on custom kernels
+* A mkinitrd helper script
+
+
+Introduction
+------------
+
+ Increasingly common in modern Linux distributions is the ability to
+install onto an encrypted partition (or drive, or volume). Especially for
+people with a laptop who are traveling a lot, it adds a lot to the security
+of your data if access to that data is denied to the potential thief of
+your computer.
+
+ Starting with release 12.0, Slackware has support for LVM built into the
+installer. With a little more effort, the installer offers the opportunity to
+use transparent encryption on the partitions/volumes/disks where you install
+Slackware. You can combine the use of LVM and encryption to minimize the
+number of times you need to enter an unlock passphrase. If you want to know
+more about setting up and using LVM during the installation, read the file
+'README_LVM.TXT'.
+
+ Slackware uses device-mapper and cryptsetup to achieve transparent
+encryption of your data partitions and your swap. Cryptsetup uses a
+concept called LUKS (Linux Unified Key Setup) which enables you to change
+your unlock password for the encrypted volume without having to re-encrypt
+all of your data. You can even assign multiple passphrases to an encrypted
+volume, so that other people besides you are able to unlock the encryption
+without the need to know _your_ passphrase.
+
+ When preparing a partition for transparent encryption with cryptsetup,
+the program will ask you for a password. This password is used to encrypt
+another randomly generated password and this particular password is used
+to actually encrypt the data inside the mapped volume. Cryptsetup will
+create a mapped device and make this block device available under the
+'/dev/mapper' directory. Any data read from or written to this mapped device
+will automatically be decrypted from / encrypted to the actual partition.
+
+ A big NOTE finally. When you encrypt your root filesystem, you will have
+to make sure that there will be at least one (small) partition which is
+left unencrypted. This partition must contain the kernel(s) you want to boot
+from, and the initrd image that is needed with encrypted volumes. You need
+to install LILO either to the MBR - or if that is not possible, into the
+root sector of this small unencrypted partition. You will probably guess
+why we can not use an encrypted partition for this...
+
+
+Using cryptsetup during Slackware installation
+----------------------------------------------
+
+ We are going to enable encryption on some or all of our partitions or
+volumes before installing Slackware onto them. The first section to follow
+deals with encrypting a single partition which is not the root partition.
+Typically, people have a need to encrypt their homedirectories and that is
+where that section will focus on. Next is a section on encrypting your
+swap partition in addition to your /home partition. The swap partition
+contains valuable information for a data thief, even after you power off
+your computer. By encrypting the swap partition we deny the potential thief
+access to this data. The section following that will show you how to get
+a fully encrypted system, by encrypting the root ('/') filesystem as well.
+This is a little harder to do, but probably worth the effort.
+
+ To make it more interesting, _and_ easier to use, we will devote a final
+section to using a combination of LVM and disk encryption. As an example,
+we will create a single big encrypted partition, and inside that encrypted
+'container' we create several Logical Volumes which we will use as our root
+(/), /home and swap partitions. The advantages of this approach are, that you
+will need only a single passphrase to unlock your computer, and you will not
+have to maintain an '/etc/crypttab' file containing information about encrypted
+volumes that need to be unlocked during boot-up. Additionally, we will be
+rewarded with a swap partition that we can use for suspend-to-disk and that
+will remain encrypted after shutdown (so that for instance a potential data
+thief will not be able to get to your valuable data even if you hibernated
+your laptop).
+
+ If you choose this last option to get a fully encrypted Slackware, it is
+advisable to read the 'README_LVM.TXT' file to make yourself more familiar
+with the process of creating and using Logical Volumes during installation
+of Slackware. And then, skip right through to the section of this document
+called "Combining LUKS and LVM".
+
+
+Encrypting your '/home' partition
+---------------------------------
+
+ After the computer boots up from the install CD/DVD (or USB flash disk,
+or PXE) and you find yourself at the '#' prompt, the first thing to do is
+use 'fdisk' or 'cfdisk' to create any partitions you need for your Slackware.
+Next, use 'cryptsetup' to prepare the partitions you intend to be
+encrypted. Note: this section of the README concerns itself with setting
+up encrypted *data* partitions. If you want to know how to configure an
+encrypted *swap* partition, skip to the section called "Encrypted swap".
+
+ Suppose, you want to encrypt the partition called '/dev/sdx2' and use it
+as your '/home' filesystem. (Please replace '/dev/sdx2' with the name of YOUR
+PARTITION in the next series of examples). Several of the commands shown below
+will irrevocably destroy any data that you currently have on the partition. It
+is a good idea to double check the output from 'fdisk -l' before you start.
+
+* To begin with, we are going to fill the partition with random data. This
+will make it a lot harder for any forensics expert to determine where your
+encrypted data resides on that partition after we're finished installing
+Slackware onto it. The process will take a long time - depending on the
+size of your partition it may take hours or more. if you're not _too_
+concerned with the possibility of an FBI agent confiscating your computer,
+you can skip this command:
+
+ # dd if=/dev/urandom of=/dev/sdx2
+
+* Prepare the partition for encryption. You will be asked twice to enter
+a passphrase. Note that a passphrase is not limited to a single word. The
+passphrase may contain spaces. We will use a key size of 256 bits. The
+default cipher is 'aes', with mode 'cbc-essiv:sha256' which is safe enough.
+
+ # cryptsetup -s 256 -y luksFormat /dev/sdx2
+
+You can dump information about the encrypted partition to your console by
+running the following command:
+
+ # cryptsetup luksDump /dev/sdx2
+
+* Now we will 'open' the encrypted partition and let the devicemapper create
+a mapped block device. We will use the mapped device which behaves just like
+an ordinary disk partition when we get to the TARGET selection in 'setup'. The
+mapped device nodes will be created in the directory '/dev/mapper'. The command
+will ask you for the passphrase which you entered during the "luksFormat"
+operation. The last argument that the command takes is the name of the mapped
+device. We will call our mapped device 'crypthome' (any name will do). It
+will be available for use as the block device '/dev/mapper/crypthome'.
+
+ # cryptsetup luksOpen /dev/sdx2 crypthome
+
+* We've now finished our preparations, and it is time to start the 'setup'
+program and install Slackware. This setup does not differ at all from the
+setup you have become used to. The only notable difference lies in the
+names of the devices you will select for your target partitions. Be sure
+to read until the end of the story though, because we will have to do some
+postprocessing in order to make your encrypted partitions available after
+reboot (setup can not yet do all of this automatically).
+
+* In setup, under "ADDSWAP", proceed as usual and configure a normal
+unencrypted swap partition, even if you want to have your swap encrypted.
+We will take care of swap encryption after the installation of Slackware
+finishes.
+
+* In setup, when you choose "TARGET" in the main menu, you will notice that
+the mapped device is available in the 'Linux partition' selection as
+"/dev/mapper/crypthome". Select the partition you designated for your
+root ('/') filesystem, and next select "/dev/mapper/crypthome" for your
+'/home' filesystem. Create any filesystem you like on them. My favorite
+fstype still is ext3, but you can choose xfs or jfs for stability and speed.
+
+NOTE: The underlying partition will *also* be visible in the target selection
+ menu. Be very careful NOT to select this device ('/dev/sdx2' in our
+ example) for any other filesystem you wish to create, or you will
+ destroy the data on the encrypted partition.
+
+* At the end of the Slackware installation when you select "Exit", don't
+reboot just yet! We are going to create a configuration file for
+the cryptsetup program, called '/etc/crypttab'. This file contains the
+information cryptsetup needs for unlocking your encrypted volume and mapping
+it to the correct device name. The file '/etc/crypttab' contains lines of the
+format: "mappedname devicename password options". Since we are still inside
+the installer, the root filesystem of our fresh Slackware installation is
+still mounted under '/mnt'. For our example where we encrypted '/dev/sdx2'
+and mapped the unlocked device to '/dev/mapper/crypthome', we need this
+single line in '/etc/crypttab':
+
+crypthome /dev/sdx2
+
+So, we need to run the command:
+
+ # echo "crypthome /dev/sdx2" > /mnt/etc/crypttab
+
+in order to create the file with the required content (I am assuming here
+that the file did not yet exist... the above command will overwrite the
+data in the file should it have existed). You can of course also just
+start the 'vi' editor and add the above line. When the password is not
+listed in the crypttab file (potentially very unsafe of course) cryptsetup
+will ask you for the password when your computer boots.
+
+
+Encrypted swap
+--------------
+
+ In the previous chapter we have installed Slackware using an encrypted
+/home partition, but left the swap partition unencrypted. We are going
+to take care of that 'omission' right now, because we do not want to give
+a potential data thief access to any sensitive data which landed on your
+disk because of the kernel's memory swapping process.
+
+It really is very simple and straight-forward. It is also independent of
+whether or not you are using encryption for any other (data) partition.
+Add the following line to the 'crypttab' file on your fresh installation
+of Slackware - for the sake of this example I am assuming that the swap
+partition you chose is '/dev/sdx3':
+
+cryptswap /dev/sdx3 none swap
+
+You can use the 'vi' editor to add this line to '/mnt/etc/crypttab'.
+You can also choose to run the following command which adds that line to
+the end of the file:
+
+ # echo "cryptswap /dev/sdx3 none swap" >> /mnt/etc/crypttab
+
+We need to edit the 'fstab' file of your Slackware installation so that
+the correct device will be used for the swap after your computer reboots
+(the device '/dev/sdx3' will no longer be useful, but '/dev/mapper/cryptswap
+will'). The line in '/mnt/etc/fstab' for your swap will look like this at
+first:
+
+/dev/sdx3 swap swap defaults 0 0
+
+and you will have to change it so that it becomes like this:
+
+/dev/mapper/cryptswap swap swap defaults 0 0
+
+ These two edits are sufficient. The above instructions assume that you
+edited the 'crypttab' file at the end of a Slackware installation, but in
+fact you can do this at any time. The Slackware boot-up process will
+take care of the rest. At shutdown of your Slackware, the encrypted swap
+partition will be reformatted as a normal unencrypted swap, so that any
+other OS-es you might be running in a multi-boot configuration will have
+no problems in using this swap partition as well.
+
+NOTE: the swap partition is encrypted with a new randomly generated key every
+ time your computer boots.
+ There is no need to ever enter a passphrase!
+
+NOTE: having an encrypted swap like this causes a re-format of the swap
+ partition on avery boot-up and shutdown. This is perfectly OK as long
+ as you do not change the order of your hard disks. If you add a disk,
+ or move this disk to another computer, the device name may change (for
+ instance from sda to sdb) and if you forget to modify '/etc/crypttab'
+ your system may end up formatting the wrong partition!
+ For this reason alone, it is recommended that you implement disk
+ encryption including swap using the "Combining LUKS and LVM" method
+ described in the chapter with the same name!
+
+
+Encrypted root filesystem
+-------------------------
+
+ You can go one step further than merely encrypting your '/home'
+filesystem's partition. You can choose to encrypt _all_ of your Slackware
+partitions, including the root partition. In that case you will have to
+perform some additional post-install configuration before you reboot your
+Slackware box.
+
+NOTE: the method described here will result in having several independently
+ encrypted partitions. This may require you to enter multiple
+ passphrases in order to unlock all of these partitions. If you want to
+ unlock your complete system using a single passphrase, and if you do
+ not shy back from using LVM, then the better alternative is to follow
+ the instructions in the "Combining LUKS and LVM" chapter which follows
+ next. If you think that LVM adds one layer of complexity too much,
+ then just read on and implement the solution described right here.
+
+* Be sure to create a small partition which you leave *unencrypted*. Tell
+the installer to mount it under '/boot'. The kernel and the initrd (with
+the cryptsetup and additional required kernel modules) will go there. We are
+going to assume that Slackware is the only OS on the computer so that you
+can tell lilo to install the bootloader in the MBR (which is the default
+option). Lilo is able to boot a Windows if you already had that installed on
+your computer, so even in the dual-boot situation it should be safe to use
+the MBR. With other Linux distributions already present on the computer,
+things may be a little more difficult - you will have to install lilo to
+the /boot partition then.
+
+* Perform a Slackware install just like I described above, creating
+additional encrypted partitions and mapping them to appropriate names -
+for this example I assume that you map the encrypted root partition
+'/dev/sdx1' to 'cryptroot'. When the LILO configuration pops up, tell lilo
+that your root partition is '/dev/mapper/cryptroot'. Lilo will try to
+install and fail, and will tell you so. It will however have written a
+'lilo.conf' file which we can edit in a follow-up action. Proceed with
+the installation and at the end, exit the setup program but do _not_
+reboot just yet.
+
+* After you are returned to the command prompt, perform a 'chroot' into the
+new installation. All the filesystems are still mounted, and the Slackware
+installer will already have mounted the /sys and /proc filesystems for use
+in the 'chroot'. We only need to run the following command:
+
+ # chroot /mnt
+
+* Next, now that we are in the chroot, create the initrd with LVM (if you
+used Logical Volumes) and CRYPT support - or else your Slackware computer
+will not be able to proceed past the initial stage of booting the kernel.
+The initial ramdisk (initrd) contains a small filesystem with the tools
+needed to unlock the root filesystem, so that the kernel can start the init
+program. In the example command line below which creates the 'initrd.gz'
+image I assume that the root filesystem is 'ext3', we used the mapped device
+'cryptroot' for the root filesystem on the real partition '/dev/sdx1',
+and are running the Slackware 13.0 default SMP kernel '2.6.29.6-smp'
+and we did not use Logical Volumes (more about that in the next section):
+
+ # mkinitrd -c -k 2.6.29.6-smp -m ext3 -f ext3 -r cryptroot -C /dev/sdx1
+
+* The resulting initrd image will be written to the file '/boot/initrd.gz'
+by default. We still need to tell lilo about this initrd. Open the
+configuration file '/etc/lilo.conf' in an editor such as vi or pico -
+it should already have been generated by the 'liloconfig' part of setup.
+Look for the "Linux bootable partition config" and add a line for the initrd.
+We also need to change the kernel file to a generic kernel, because lilo
+is unable to combine the 'huge' kernels in Slackware 13.0 with an initrd
+image - it will complain about "The initial RAM disk is too big to fit
+between the kernel and the 15M-16M memory hole" if you try with a 'huge'
+kernel. We can live with that, since the 'huge' kernels are not meant
+for day-to-day use anyway. They are meant to install Slackware on a wide
+range of computers and that is why they are 'huge'. The linux part of
+'/etc/lilo.conf' should end up looking somewhat like this:
+
+image = /boot/vmlinuz-generic-smp-2.6.29.6-smp
+ initrd = /boot/initrd.gz
+ root = /dev/mapper/cryptroot
+ label = linux
+ read-only
+
+If you add the above section as an extra instead of editing what's already
+present, make sure that the label you use ('linux' in the example above)
+is unique in the configuration file.
+
+* If you have another OS on your computer and can not install lilo to the
+MBR, you will have selected "Install to superblock (Root)" instead. In
+that case, we have one additional change to make, and that is almost at the
+top of the file. Look up the line that says "boot = /dev/mapper/cryptroot"
+which is the device for your root partition and which was the reason for
+lilo failing to install. Change the boot device to the name of the small
+*unencrypted* partition you've created at the beginning and which is
+mounted under '/boot'. Assuming the name of that partition is '/dev/sdx4',
+the "boot =" line must become like this:
+
+ boot = /dev/sdx4
+
+We are done. Write the changes, exit the editor and run the command 'lilo'.
+Lilo will issue a couple of warnings concerning a difference in what
+'/proc/partitions' reports and what lilo thinks are the available partitions,
+but it is safe to ignore these.
+Reboot now, and you will be presented with a "Enter passphrase: "
+prompt. After entering the passphrase which unlocks your root filesystem,
+the system will boot into Slackware. If there are other encrypted partitions,
+you will be prompted for their respective passphrases, too.
+
+
+Combining LUKS and LVM
+----------------------
+
+ Until now, we have been occupying ourselves with encrypting separate
+partitions. This is all fully functional, but there are a few drawbacks.
+One, you will need to enter a passphrase for every partition you have encrypted
+(except for the swap which Slackware encrypts with a random passphrase
+on every boot). Two, the method used for encrypting the swap partition
+prohibits the use of the swap as a hibernation partition. And since the
+initrd of Slackware 13.0 supports hibernation, it would be a shame not to be
+able to use this feature on your laptop (which, because of it's portability,
+is the primary target for full disk encryption anyway).
+
+ This section of the README_CRYPT.TXT will deal with these drawbacks and
+offer you full disk encryption (including swap) that needs only a single
+passphrase to unlock and allows for hibernation (suspend-to-disk).
+
+ We are assuming that Slackware will be the only Operating System on your
+computer. In case you already have an OS installed (such as MS Windows), the
+procedure may be a little different because you can not always install lilo to
+the MBR. After booting from the Slackware installation medium, we will
+create a small unencrypted partition that will contain the Linux kernels and
+the initrd image(s). The rest of the disk's free space will be dedicated to
+a single partition which we are going to encrypt. On top of the encrypted
+volume, we are going to create several Logical Volumes, and these LV's
+are going to be formatted as our Slackware partitions ('/', '/home' and
+'swap'). These are the steps in more detail:
+
+* Use (c)fdisk to create your partitions. For the sake of this example, I
+am going to assume that /dev/sdx1 is a 100 MB large partition and /dev/sdx2
+is the large partition that eats up the remainder of your disk's free space.
+
+* First, create a LUKS-encrypted volume on top of /dev/sdx2 after you
+have optionally filled the partition with random data (read the section
+"Encrypting your '/home' partition" for more information about why you
+would want to fill your partition with random data first):
+
+ # dd if=/dev/urandom of=/dev/sdx2
+
+* Prepare the partition for encryption. You will be asked twice to enter
+a passphrase. Note that a passphrase is not limited to a single word. The
+passphrase may contain spaces. We will use a key size of 256 bits. The
+default cipher is 'aes', with mode 'cbc-essiv:sha256' which is safe enough.
+
+ # cryptsetup -s 256 -y luksFormat /dev/sdx2
+
+* Open the encrypted partition so that we can start using the mapped device
+which exposes the partition as an unencrypted block device. The command
+will ask you for the passphrase which you entered during the "luksFormat"
+operation. The last argument that the command takes is the name of the mapped
+device. We will call our mapped device 'slackluks' because I am not feeling
+original today. The mapped device which we will be using for unencrypted
+operations will therefore be '/dev/mapper/slackluks'.
+
+ # cryptsetup luksOpen /dev/sdx2 slackluks
+
+* The LVM part is next. Create a Physical Volume (PV) on device
+'/dev/mapper/slackluks', a Volume Group (VG) called 'cryptvg' - any name will
+do - on the PV, and three Logical Volumes (LV's) in the VG, one for your
+root partition (5 GB in size), one for the /home partition (10 GB in size)
+and a third which we will use for swap (1 GB in size). You will probably
+use different sizes depending on your environment and wishes, but keep the
+sum of the LV sizes less than the total size of the Physical Volume:
+
+ # pvcreate /dev/mapper/slackluks
+
+ # vgcreate cryptvg /dev/mapper/slackluks
+
+ # lvcreate -L 5G -n root cryptvg
+
+ # lvcreate -L 10G -n home cryptvg
+
+ # lvcreate -L 1G -n swap cryptvg
+
+* Create the device nodes needed before activating the volumes, and finally
+activate the volumes so that we can format the 'swap' volume.
+
+ # vgscan --mknodes
+
+ # vgchange -ay
+
+* Finally, run 'mkswap' so that the 'setup' program will identify the 'swap'
+LV as a valid swap partition:
+
+ # mkswap /dev/cryptvg/swap
+
+* With the system properly prepared, you can launch 'setup'. The 'setup'
+program will identify the LV swap volume and activate it. When appointing
+the partitions to use for your filesystems, select '/dev/cryptvg/root' for the
+root partition, next select '/dev/cryptvg/home' to be used for your /home .
+And lastly, assign the partition /dev/sdx1 to a /boot filesystem. This
+'/boot' filesystem will be the only unencrypted part of your computer.
+
+ You will notice that there are several more devices to select from but
+*don't* touch these! The devices such as /dev/mapper/* are the underlying
+device names for the encrypted and LVM volumes. If you choose to touch any
+of these, you will destroy the data on the /dev/cryptvg/* volumes which you
+are using.
+After partitioning, we end up with a filesystem configuration like this:
+
+ /dev/cryptvg/root /
+ /dev/cryptvg/home /home
+ /dev/sdx1 /boot
+
+* When installation of the packages has finished, the system configuration will
+start, and one of the dialogs will be for 'liloconfig'. The assumption is that
+you are installing Slackware as the only OS on your computer. This means that
+you must install lilo to the MBR. Even if you have another OS like MS Windows
+installed already, Slackware's lilo bootloader will be able to boot Windows
+if you install lilo to the MBR. Choose "expert lilo configuration" with the
+option "Install to Master Boot Record (MBR)". Select '/dev/cryptvg/root' as
+the root partition to boot. Add any Windows partition to lilo if you want to
+dual-boot Windows. Finally, when liloconfig installs the bootloader, you may
+see an error message stating that the "installation failed". Ignore this,
+because we will have to add an initrd to '/etc/lilo.conf' anyway and re-run
+lilo. We will do this after the Slackware installation has come to it's end.
+
+* Let the installation complete, and after you select "EXIT" you will be
+returned to the command prompt. DO NOT reboot just yet! This is the moment
+where we fix our bootloader. To do so, we will 'chroot' (change root) into
+our freshly installed Slackware filesystem. The setup program has done all
+the preparations already, such as re-mounting /sys and /proc below /mnt and
+generating LVM device nodes in /mnt . Enter the 'chroot' using the command:
+
+ # chroot /mnt
+
+* In the chroot, you create an initrd image with LVM and CRYPT support -
+or else your Slackware computer will not be able to proceed past the initial
+stage of booting the kernel. The initial ramdisk (initrd) contains a small
+filesystem with the tools needed to unlock the root filesystem, so that
+the kernel can start the init program. In the example command line below
+which creates the 'initrd.gz' image I assume that you formatted the root
+filesystem as 'ext3', and will be running the Slackware 13.0 default SMP
+kernel '2.6.29.6-smp' :
+
+ # mkinitrd -c -k 2.6.29.6-smp -m ext3 -f ext3 -r /dev/cryptvg/root -C /dev/sdx2 -L
+
+NOTE: if you use a non-US keyboard and need to enter a passphrase during boot,
+ this may be problematic if the keyboard mapping is US while Slackware
+ runs from the initrd filesystem. In this case, add support for your
+ keyboard to the initrd image using this additional parameter to the
+ 'mkinitrd' command above: "-l <language>". The string <language> is the
+ same as the one you select in the installer when your keyboard is
+ non-US. Example for a dutch keyboard: "-l nl".
+
+* The resulting initrd image will be written to the file '/boot/initrd.gz'
+by default. We still need to tell lilo about this initrd, so open the
+configuration file '/etc/lilo.conf' in an editor such as vi or pico -
+it should already have been generated by the 'liloconfig' part of setup.
+Look for the "Linux bootable partition config" and add a line for the initrd.
+We also need to change the kernel file to a generic kernel, because lilo
+is unable to combine the 'huge' kernels in Slackware 13.0 with an initrd
+image - it will complain about "The initial RAM disk is too big to fit
+between the kernel and the 15M-16M memory hole" if you try a 'huge'
+kernel. We can live with that, since the 'huge' kernels are not meant
+for day-to-day use anyway. They are meant to install Slackware on a wide
+range of computers and that is why they are 'huge'. The linux part of
+'/etc/lilo.conf' should end up looking somewhat like this:
+
+image = /boot/vmlinuz-generic-smp-2.6.29.6-smp
+ initrd = /boot/initrd.gz
+ root = /dev/cryptvg/root
+ label = linux
+ read-only
+
+ If you add the above section as an extra instead of editing what's
+already present, make sure that the label you use ('linux' in the example
+above) is unique in the configuration file.
+
+ We are done. Save your changes, exit the editor and run the command
+'lilo'. Lilo will issue a couple of warnings concerning a difference in
+what '/proc/partitions' reports and what lilo thinks are the available
+partitions, but it is safe to ignore these. Reboot now, and you will be
+presented with a "Enter passphrase: " prompt. After entering the passphrase
+which unlocks your encrypted partition, the system will boot into Slackware.
+You will be able to work as usual, and when you shut the machine down (or
+suspend to disk using the swap partition) all your data (including swap)
+will be encrypted when stored on disk.
+
+ As you may have noticed, there was no need to create a file '/etc/crypttab'
+this time. Also, there is only a single passphrase to enter. Additionally,
+the swap is encrypted by default which is a big plus if you intend to use a
+laptop and carry it around with you in a hibernated state. All considered,
+this is the most elegant way of encrypting your Slackware computer if you
+do not mind using LVM.
+
+
+Additional passphrases, keyfiles
+--------------------------------
+
+The cryptsetup program assigns 7 'key slots' to any partition or volume
+it encrypts. Each of those seven slots can contain a key to unlock the
+partition's data. The key can be a passphrase, but the content of a
+*keyfile* is another option. You can then pass the name of a file as a
+parameter to cryptsetup in order to unlock an encrypted volume so that
+you won't have to type a passphrase. This creates the possibility to
+use a keyfile on a removable USB flash disk for unlocking your Slackware
+computer. Slackware has partial support for keyfiles: if the file can be
+found, it will be used and you won't have to type a passphrase. A file on a
+USB stick will *not* be found on boot because the stick's filesystem is not
+mounted. Future versions of Slackware may support USB sticks as unlocking
+mechanism. For now, if you encrypt your root filesystem, you will have to
+enter a passphrase to boot into it. After the root filesystem is unlocked
+and mounted, it is completely safe to have a keyfile for _additional_
+encrypted filesystems stored in for instance the '/root' directory. That
+way, you have only one passphrase to type.
+
+
+Hibernation (suspend-to-disk)
+-----------------------------
+
+ I will touch briefly on the subject of enabling 'suspend-to-disk'
+because it is not documented properly anywhere else. Configuring your
+Slackware computer for hibernation can be done at any time, it is not
+required to do this during installation of Slackware. Suppose you want
+to use the swap partition '/dev/cryptvg/swap' for hibernation, then you
+must perform the following two steps:
+(1) add "resume=/dev/cryptvg/swap" to the 'append =' line in your
+ '/etc/lilo.conf' file. The 'append' line may end up looking like this:
+ append = "vt.default_utf8=0 resume=/dev/cryptvg/swap"
+(2) add "-h /dev/cryptvg/swap" as an extra parameter to your mkinitrd command
+ to create an initrd with support for resuming from a swap partition.
+ Do not forget to run 'lilo' after creating the new initrd.gz file!
+
+
+A note on custom kernels
+------------------------
+
+ If you want to compile your own custom kernel to work with LUKS encrypted
+partitions, you need to enable at least the following two options in your
+kernel configuration:
+
+Multiple devices driver support (RAID and LVM) --->
+ <*> Device mapper support
+ <*> Crypt target support
+
+This is equivalent to the following options in your .config file:
+
+CONFIG_BLK_DEV_DM=y
+CONFIG_DM_CRYPT=y
+
+Do not compile these as module! They are required in your kernel.
+
+
+A mkinitrd helper script
+------------------------
+
+ The mkinitrd package in Slackware 13.0 ships with a script called
+'mkinitrd_command_generator.sh'. If you run this script, it will analyze
+your Slackware configuration and make a smart suggestion about the 'mkinitrd'
+command you have to type in order to create an initrd.gz with all the bells
+& whistles. The script will recognize your kernel version, root partition
+and filesystem, it will find out if you are using LUKS and/or LVM and will
+determine what kernel modules your initrd needs to mount the root filesystem.
+The following command will save you the headache of figuring this out all
+by yourself:
+
+ # /usr/share/mkinitrd/mkinitrd_command_generator.sh -r
+
+It should emit a string like this (your system will probably give different
+parameter values):
+
+mkinitrd -c -k 2.6.29.6-smp -m ext3 -f ext3 -r /dev/cryptvg/root -C /dev/sdx2 -L
+
+You can copy and paste this output to your command prompt, and add any other
+parameters you need such as "-h" to indicate a hibernation partition or
+"-l" to indicate you are using a non-US keyboard layout. You can even run
+the script in full interactive mode by using the "-i" parameter, and it will
+guide you through the process of generating a mkinitrd commandline.
+
+
+==============================================================================
+
+Good luck with your fresh Slackware installion on encrypted partition(s)!
+
+==============================================================================
+Author:
+ Eric Hameleers <alien@slackware.com> 23-jul-2009
+URLs:
+ http://www.slackware.com/~alien/dokuwiki/doku.php?id=slackware:setup
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