Full Disk Encryption: Difference between revisions
imported>Makefu initial batch of nixos-users |
imported>Fadenb m Syntax highlighting |
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Sometimes it is necessary to boot a system without needing an Keyboard and Monitor. You will create a secret key, add it to a key slot and put it onto an usb stick. | Sometimes it is necessary to boot a system without needing an Keyboard and Monitor. You will create a secret key, add it to a key slot and put it onto an usb stick. | ||
< | <syntaxhighlight lang="bash"> | ||
cryptsetup luksAddKey /dev/sda1 ./hdd.key</ | dd if=/dev/urandom of=hdd.key bs=4096 count=1 | ||
cryptsetup luksAddKey /dev/sda1 ./hdd.key | |||
</syntaxhighlight> | |||
== Option 1: Write key onto the start of the stick == | == Option 1: Write key onto the start of the stick == | ||
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Then add the following configuration to your <code>configuration.nix</code>: | Then add the following configuration to your <code>configuration.nix</code>: | ||
< | <syntaxhighlight lang="nix">{ | ||
"..." | |||
boot.initrd.luks.devices = [ | boot.initrd.luks.devices = [ | ||
{ | { | ||
name = | name = "luksroot"; | ||
device = | device = "/dev/disk/by-id/<disk-name>-part2"; | ||
allowDiscards = true; | allowDiscards = true; | ||
keyFileSize = 4096; | keyFileSize = 4096; | ||
# pinning to /dev/disk/by-id/usbkey works | # pinning to /dev/disk/by-id/usbkey works | ||
keyFile = | keyFile = "/dev/sdb"; | ||
} | } | ||
]; | ]; | ||
}</ | }</syntaxhighlight> | ||
As of right now (2017-08-18) the NixOS options do not provide means to hide a key after the MBR as described in [https://bbs.archlinux.org/viewtopic.php?id=158507 this article in the archlinux forums]. More specificially you will need to be able to provide a keyOffset | As of right now (2017-08-18) the NixOS options do not provide means to hide a key after the MBR as described in [https://bbs.archlinux.org/viewtopic.php?id=158507 this article in the archlinux forums]. More specificially you will need to be able to provide a keyOffset | ||
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If you want to use your stick for other stuff or it already has other keys on it you can use the following method by Tzanko Matev. Add this to your <code>configuration.nix</code>: | If you want to use your stick for other stuff or it already has other keys on it you can use the following method by Tzanko Matev. Add this to your <code>configuration.nix</code>: | ||
< | <syntaxhighlight lang="nix"> | ||
PRIMARYUSBID = | let | ||
BACKUPUSBID = | PRIMARYUSBID = "b501f1b9-7714-472c-988f-3c997f146a17"; | ||
BACKUPUSBID = "b501f1b9-7714-472c-988f-3c997f146a18"; | |||
in { | in { | ||
"..." | |||
# Kernel modules needed for mounting USB VFAT devices in initrd stage | # Kernel modules needed for mounting USB VFAT devices in initrd stage | ||
boot.initrd.kernelModules = [ | boot.initrd.kernelModules = ["uas" "usbcore" "usb_storage" "vfat" "nls_cp437" "nls_iso8859_1"]; | ||
# Mount USB key before trying to decrypt root filesystem | # Mount USB key before trying to decrypt root filesystem | ||
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''; | ''; | ||
boot.initrd.luks.devices. | boot.initrd.luks.devices."crypted" = { | ||
keyFile = | keyFile = "/key/keyfile"; | ||
preLVM = false; # If this is true the decryption is attempted before the postDeviceCommands can run | preLVM = false; # If this is true the decryption is attempted before the postDeviceCommands can run | ||
}; | }; | ||
}</ | } | ||
</syntaxhighlight> | |||
== Option 3: Decryption via YubiKey == | == Option 3: Decryption via YubiKey == | ||
''TODO'', it works but needs to be described. | ''TODO'', it works but needs to be described. | ||
Revision as of 16:04, 27 August 2017
Basic installation
Unattended Boot via USB
Sometimes it is necessary to boot a system without needing an Keyboard and Monitor. You will create a secret key, add it to a key slot and put it onto an usb stick.
dd if=/dev/urandom of=hdd.key bs=4096 count=1
cryptsetup luksAddKey /dev/sda1 ./hdd.key
Option 1: Write key onto the start of the stick
This will make the usb-stick unusable for any other operations than being used for decryption. Write they key onto the stick: dd if=hdd.key of=/dev/sdb.
Then add the following configuration to your configuration.nix:
{
"..."
boot.initrd.luks.devices = [
{
name = "luksroot";
device = "/dev/disk/by-id/<disk-name>-part2";
allowDiscards = true;
keyFileSize = 4096;
# pinning to /dev/disk/by-id/usbkey works
keyFile = "/dev/sdb";
}
];
}
As of right now (2017-08-18) the NixOS options do not provide means to hide a key after the MBR as described in this article in the archlinux forums. More specificially you will need to be able to provide a keyOffset
Option 2: Copy Key as file onto a vfat usb stick
If you want to use your stick for other stuff or it already has other keys on it you can use the following method by Tzanko Matev. Add this to your configuration.nix:
let
PRIMARYUSBID = "b501f1b9-7714-472c-988f-3c997f146a17";
BACKUPUSBID = "b501f1b9-7714-472c-988f-3c997f146a18";
in {
"..."
# Kernel modules needed for mounting USB VFAT devices in initrd stage
boot.initrd.kernelModules = ["uas" "usbcore" "usb_storage" "vfat" "nls_cp437" "nls_iso8859_1"];
# Mount USB key before trying to decrypt root filesystem
boot.initrd.postDeviceCommands = pkgs.lib.mkBefore ''
mkdir -m 0755 -p /key
sleep 2 # To make sure the usb key has been loaded
mount -n -t vfat -o ro `findfs UUID=${PRIMARYUSBID}` /key || mount -n -t vfat -o ro `findfs UUID=${BACKUPUSBID}` /key
'';
boot.initrd.luks.devices."crypted" = {
keyFile = "/key/keyfile";
preLVM = false; # If this is true the decryption is attempted before the postDeviceCommands can run
};
}
Option 3: Decryption via YubiKey
TODO, it works but needs to be described.