Difference between revisions of "LUKS"

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Line 97: Line 97:
     local name=$1
     local name=$1
     local mountlocation=$2
     local mountlocation=$2
     sudo umount "$mountlocation"
     sudo umount "$mountlocation" && \
    sudo rm -r "$mountlocation"
     sudo cryptsetup close "$name"
     sudo cryptsetup close "$name"
    sudo rm -r "$mountlocation"

Revision as of 18:05, 27 July 2020

LUKS encryption

Getting Started

See Archwiki: dm-crypt/Device encryption.

Encrypting a device

  • Setup encryption
cryptsetup -v --type luks1 --cipher aes-xts-plain64 --key-size 512 --hash sha512 \
           --iter-time 5000 --use-urandom --verify-passphrase luksFormat <device>
  • Open encrypted drive
cryptsetup open <device> <name>
  • Create a partition
mkfs.fstype /dev/mapper/<name>
# E.g.
# mkfs.ext4 /dev/mapper/luksdrive1
  • Securely wipe the unused portion of the drive
    • Do this to prevent cryptographic attacks and to overwrite existing data on the drive
dd if=/dev/zero of=<file_somewhere> status=progress
# Delete the file afterwards

  • You can see defaults using cryptsetup --help.
  • --type options
    • luks defaults to luks1 on cryptsetup < 2.1.0, luks2 on cryptsetup >= 2.1.0
    • luks1 is the standard version of LUKS.
    • luks2 is a new version released in Dec 2017. Older versions of Grub (before 2.06 or June 2020) do not support booting from LUKS2.
    • plain is dm-crypt plain mode. Avoid this unless you know what you're doing.
    • loopaes Avoid this as well.
    • tcrypt Use this for mounting older truecrypt volumes.

defaults on Ubuntu 18.04

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


# Open the encrypted drive
cryptsetup open <device> <name>
# Mount your partition
mount -t <fstype> /dev/mapper/<name> <mountlocation>


# Unmount your partition
umount <mountlocation>
# Close the decrypted drive
cryptsetup close <name>



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

mount_luks ext4 /dev/disk/by-id/<drive> lukscrypt1 /media/lukscrypt1

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