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Cryptsetup, Luks, LVM Cheat Sheet

Installation

emerge --ask cryptsetup

I will use DRIVE="" fyi, change to your disk before you using any of the below commands, they are very powerful and will break your system if you doing it wrong! Be careful

DISK is entire HDD andm 1,2 and 3 is partition in this wiki

1 = `Grub`
2 = `Boot/Esp`
3 = `Root`
K = `KeyFile`
U = `USB Drive For Keep Our KEY!`
H = `Header Backup`
E = `External Encrypted Drive`

Variables For this page

DISKU="/dev/sda"
DISKE="/dev/sdb"
DISK1="/dev/nvme0n1"
DISK1_1="/dev/nvme0n1p3p1" 
DISK1_2="/dev/nvme0n1p3p2" 
DISK1_3="/dev/nvme0n1p3p3" 
DISK1_K="$(hostname)"
DISK1_H="$(hostname)_header_backup"

Generate 4096-bit random key file

dd if=/dev/urandom of=${DISK1_K} bs=8M count=1

Add a key file to next free key slot. This will prompt for a passphrase.

You can have up to 8 slots.

cryptsetup luksAddKey /dev/${DISK1} ${DISK1_K}

Add a key file to specific key slot, e.g slot 2

cryptsetup luksAddKey --key-slot 7 /dev/${DISK1_3} ${DISK1_K}.key

View key Slots

(use | grep Slot if needed)

`bash cryptsetup luksDump ${DISK1_3}

Remove key from key slot. Enter pasphrase or specify key file to remove.

The slot will automatically be detected and slot key removed.

cryptsetup luksRemoveKey ${DISK1_3}
cryptsetup luksRemoveKey ${DISK1_3} ${DISK1_K}.key

Add password to a luks volume when we only have a keyfile

cryptsetup -d ${DISK1_K}.key luksAddKey ${DISK1_3}

Create header backup

cryptsetup luksHeaderBackup ${DISK1_3} --header-backup-file ${DISK1_H}.img

Encrypt entire drive

Of course you shouldn't use "key.key", "key.txt" or similar on your keyfile, use something else eg: "today's_recipe.txt" or "empty.log" or whatever. I will use mcdonalds.txt in this example as keyname.

cryptsetup -d ${DISK1_K}.key \
    --key-description mcdonalds.txt \
    --cipher twofish-xts-plain64 \
    --hash sha512 \
    --iter-time 5000 \
    --use-urandom luksFormat ${DISK1}

Decrypt and luksOpen our Drive With keyFile

cryptsetup -d ${DISK1_K}.key luksOpen /dev/sdc usb

View status of the map

cryptsetup -v status /dev/mapper/rootfs'

Zero the partition prior to formatting

dd if=/dev/zero of=/dev/mapper/${DISK1_VGName} status=progress

Urandomize the partition prior to formatting

dd if=/dev/urandom of=/dev/mapper/${DISK1_VGName} status=progress

Format LUKS and use ext4 filesystem

mkfs.ext4 /dev/mapper/${DISK1_VGName}

Decrypt and Mount

cryptsetup luksOpen ${DISK1_3} <choosen_name>
mount /dev/mapper/${DISK1_3} /mnt/<choosen_name>

Close and Unmount the LUKS partition

cryptsetup luksClose /dev/mapper/${DISK1_VGname}

BE REALLY CAREFUL IN THIS STEP

For the lazy cows, edit $DRIVE

#!/bin/bash
### Author: wuseman
### Encrypt and mount hdd

DRIVE=""/dev/nvme0n1p4"
KEY=".key_files/virtual-vmware.key"
PVNAME="/dev/mapper/vmware"
LVMDRIVE="/dev/mapper/virtual-vmware"
MOUNTPATH="/mnt/vmware"

mkdir ~/.key_files
dd if=/dev/urandom of=${KEY} bs=8M count=1

cryptsetup -d ${KEY} \
    --iter-time 5000 \
    --use-random \
    --cipher twofish-xts-plain64 \
    --hash sha512 luksFormat ${DRIVE}

cryptsetup -d ${KEY} \
    luksOpen ${DRIVE} vmware

pvcreate ${PVNAME}
vgcreate virtual  ${PVNAME}
lvcreate -l1100%FREE -nvmware virtual
mkfs.ext4 ${LVMDRIVE}
mkdir ${MOUNTPATH}
mount ${LVMDRIVE} ${MOUNTPATH}

Encrypt folder with luks2

You can use dm-crypt for that. You need to create an empty file which will be used as a storage device. You can create one with a specific size with either dd or for example fallocate:

dd if=/dev/urandom of=pathName bs=1M count=1024
cryptsetup -d ${DISK1_K}.key \
    --key-description mcdonalds.txt \
    --cipher twofish-xts-plain64 \
    --hash sha512 \
    --iter-time 5000 \
    --use-urandom luksFormat pathName

This will create a 512 MB file in your home directory called cryptedDevice. Then you can set luks on top of that file cryptsetup -y luksFormat /home/user/cryptedDevice With Luks you can easily change size of the container etc.

To open the crypted file you can do

cryptsetup luksOpen /home/user/cryptedDevice pathName

Then you need to format this partition with a file system:

mkfs.ext4 -j /dev/mapper/pathName

And after that you can simply mount that device to a folder:

mount /dev/mapper/pathName /mnt/pathName

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Last update: December 6, 2022 16:13:32