View source for LUKS

LUKS encryption

==Getting Started==
See [[Archwiki: dm-crypt/Device encryption]].

===Install cryptsetup===
<pre>
sudo apt install cryptsetup
</pre>

===Encrypting a device===
<syntaxhighlight lang="bash">
# Examples
DEVICE=/dev/sda
NAME=arr1

# Setup encryption
cryptsetup --type luks2 -v luksFormat "${DEVICE}"

# Open encrypted drive to /dev/mapper/$NAME
cryptsetup open "${DEVICE}" "${NAME}"

# Create a partition
mkfs.btrfs /dev/mapper/${NAME}

# Create a mountpoint and mount
mkdir -p /media/${NAME}
mount -t btrfs /dev/mapper/${NAME} /media/${NAME}

# Fill the drive to overwrite any existing raw data (optional)
dd if=/dev/zero of=/media/$NAME/file status=progress
</syntaxhighlight>

===Mounting===
<syntaxhighlight lang="bash">
# Open the encrypted drive
cryptsetup open "${DEVICE}" "${NAME}"
# Mount your partition
mount -t btrfs /dev/mapper/${NAME} "${MOUNT_LOCATION}"
</syntaxhighlight>

===Unmounting===
<syntaxhighlight lang="bash">
# Unmount your partition
umount "${MOUNT_LOCATION}"
# Close the decrypted drive
cryptsetup close ${NAME}
</syntaxhighlight>

===Encrpytion Options===

* You can see defaults using <code>cryptsetup --help</code>.
* <code>--type</code> [https://wiki.archlinux.org/index.php/Dm-crypt/Device_encryption#Encryption_options_with_dm-crypt options]
** <code>luks</code> defaults to <code>luks1</code> on cryptsetup < 2.1.0, <code>luks2</code> on cryptsetup >= 2.1.0
** <code>luks1</code> is the old version of LUKS.
** <code>luks2</code> is the current version released in Dec 2017. Older versions of Grub (before 2.06 or June 2020) do not support booting from LUKS2.
** <code>plain</code> is dm-crypt plain mode. Avoid this unless you know what you're doing.
** <code>loopaes</code> Avoid this as well.
** <code>tcrypt</code> Use this for mounting older truecrypt volumes.

* <code>--iter-time</code> dynamically determines the number of iterations used to hash your password. The number of iterations is determined when creating the luks key. E.g. <code>5000</code> means hash for 5 seconds worth of iterations on your particular CPU. You can see the number of iterations for each key with <code>cryptsetup luksDump &lt;device&gt;</code>.

{{ hidden | defaults |
defaults on Ubuntu 18.04
<pre>
Default compiled-in device cipher parameters:
	loop-AES: aes, Key 256 bits
	plain: aes-cbc-essiv:sha256, Key: 256 bits, Password hashing: ripemd160
	LUKS1: aes-xts-plain64, Key: 256 bits, LUKS header hashing: sha256, RNG: /dev/urandom
</pre>
}}

==Benchmark==
<pre>
cryptsetup benchmark
</pre>

{{ hidden | Example Output (i7-12700K) |
<pre>
# Tests are approximate using memory only (no storage IO).
PBKDF2-sha1      3057072 iterations per second for 256-bit key
PBKDF2-sha256    6452775 iterations per second for 256-bit key
PBKDF2-sha512    2432890 iterations per second for 256-bit key
PBKDF2-ripemd160 1289761 iterations per second for 256-bit key
PBKDF2-whirlpool 1148495 iterations per second for 256-bit key
argon2i      13 iterations, 1048576 memory, 4 parallel threads (CPUs) for 256-bit key (requested 2000 ms time)
argon2id     13 iterations, 1048576 memory, 4 parallel threads (CPUs) for 256-bit key (requested 2000 ms time)
#     Algorithm |       Key |      Encryption |      Decryption
        aes-cbc        128b      1976.6 MiB/s      7781.1 MiB/s
    serpent-cbc        128b       136.8 MiB/s       993.0 MiB/s
    twofish-cbc        128b       291.3 MiB/s       646.8 MiB/s
        aes-cbc        256b      1507.6 MiB/s      6406.3 MiB/s
    serpent-cbc        256b       138.2 MiB/s       984.0 MiB/s
    twofish-cbc        256b       295.3 MiB/s       647.1 MiB/s
        aes-xts        256b      6021.9 MiB/s      5909.9 MiB/s
    serpent-xts        256b       855.7 MiB/s       887.4 MiB/s
    twofish-xts        256b       597.8 MiB/s       608.0 MiB/s
        aes-xts        512b      5521.2 MiB/s      5505.7 MiB/s
    serpent-xts        512b       870.2 MiB/s       897.9 MiB/s
    twofish-xts        512b       602.9 MiB/s       607.1 MiB/s
</pre>
}}

==Adiantum==
If you're running a device which does not support hardware accelerated AES instructions (e.g. Raspberry Pi), you may be interested in Adiantum<ref name="adiantum">Google Blog: Introducing Adiantum: Encryption for the Next Billion Users [https://security.googleblog.com/2019/02/introducing-adiantum-encryption-for.html https://security.googleblog.com/2019/02/introducing-adiantum-encryption-for.html]</ref>.  
Adiantum is an encryption mode by Google which uses ChaCha12 for block encryption.
It is included in Linux kernel v5.0.

;Creation
<pre>
cryptsetup -v --type luks2 --cipher xchacha12,aes-adiantum --sector-size 4096 \
           --key-size 256 --hash sha512 --iter-time 5000 --use-urandom \
           --verify-passphrase luksFormat <device>
</pre>

;Benchmark<ref>[https://www.reddit.com/r/crypto/comments/b3we04/aesadiantum_new_mode_in_linux_kernel_5/ https://www.reddit.com/r/crypto/comments/b3we04/aesadiantum_new_mode_in_linux_kernel_5/]</ref>
<pre>
cryptsetup benchmark -c xchacha12,aes-adiantum
</pre>

==Scripts==

{{ hidden | mount_drives.sh |
<syntaxhighlight lang="bash">
#!/bin/bash

function mount_luks {
    local fstype=$1
    local device=$2
    local name=$3
    local mountpoint=$4
    if [ ! -b /dev/mapper/"$name" ]
    then
        sudo cryptsetup open "$device" "$name"
    fi
    sudo mkdir -p "$mountpoint"
    sudo mount -t $fstype /dev/mapper/"$name" "$mountpoint"
}

mount_luks btrfs /dev/disk/by-id/<drive> lukscrypt1 /media/lukscrypt1
</syntaxhighlight>
}}

{{ hidden | unmount_drives.sh |
<syntaxhighlight lang="bash">
#!/bin/bash

function unmount_luks {
    local name=$1
    local mountlocation=$2
    sudo umount "$mountlocation" && \
    sudo rm -r "$mountlocation"
    sudo cryptsetup close "$name"
}

unmount_luks lukscrypt1 /media/lukscrypt1
</syntaxhighlight>
}}

==Resources==
* [https://www.cyberciti.biz/hardware/howto-linux-hard-disk-encryption-with-luks-cryptsetup-command/ nixCraft How To Linux Hard Disk Encryption With LUKS]

==References==