The name of your additional volume may be different, eg sda
or other, depending on the Instance type and OS. Replace with the name corresponding to your volume where necessary.
Encrypting volumes for sensitive data
- encryption
- Cryptsetup
To protect sensitive commercial or client data stored on your Instances, encryption is paramount. The repercussions of such data falling into unauthorized hands can be detrimental to your business. Encrypting the entire volume is the optimal strategy, alleviating concerns about individual folders. By using this method, all sensitive information can reside on an encrypted volume, fortified by an extra layer of security. This tutorial will walk you through the process of encrypting an additional volume using Cryptsetup with LUKS, a universally recognized on-disk format employed in various encryption tools.
Before you start
To complete the actions presented below, you must have:
- A Scaleway account logged into the console
- Owner status or IAM permissions allowing you to perform actions in the intended Organization
- An SSH key
- An Instance
- A Block Storage volume connected to the Instance
sudo
privileges or access to the root user
Installing Cryptsetup
- Connect to your Instance via SSH.
- Update the apt sources and the software already installed on the Instance:
apt update && apt upgrade -y
- Install Cryptsetup on the Instance:
apt install cryptsetup-bin
- Enter the command
lsblk
. This lists your volumes to help you determine which is the additional volume to encrypt:root@encrypted-disk:~# lsblkNAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTvda 252:0 0 46.6G 0 disk|-vda1 252:1 0 46.5G 0 part /`-vda15 252:15 0 100M 0 part /boot/efivdb 252:16 0 46.6G 0 disk
In this example, the space of vdb
is not mounted and represents the additional volume of the Instance.
Encrypting the volume
-
Encrypt the volume vdb with Cryptsetup:
cryptsetup luksFormat /dev/vdbTipOn low memory Instances, you may run into
out of memory
(OOM) errors when runningcryptsetup luks{Format,Open}
commands on large volumes. To avoid them, add--pbkdf pbkdf2
to your command:cryptsetup luksFormat --pbkdf pbkdf2 /dev/vdbA warning appears, reminding you that all data on the volume will be lost.
WARNING!========This will overwrite data on /dev/vdb irrevocably.Are you sure? (Type uppercase yes): -
Type
YES
and press the Enter key, to confirm you want to overwrite the data.ImportantMake sure you have a backup of your data on this volume before you launch Cryptsetup. Your data will be irrevocably overwritten and lost.
A message appears, asking you to configure a passphrase. A passphrase is the key to decrypt the data on the volume.
-
Type your passphrase and press Enter. For increased security, your passphrase should be a secure and random phrase. If required, you may use a Passphrase generator.
A message appears, asking you to verify your passphrase.
-
Type your passphrase again to confirm it, then press Enter on your keyboard to encrypt the disk.
ImportantIf you forget your passphrase, you will not be able to recover your data. Make sure that you store your password securely.
Your volume is now encrypted.
Mapping the encrypted volume
-
Type the following command to create a mapping (
crypthome
) of the volume:cryptsetup luksOpen /dev/vdb crypthome -
Enter your passphrase when requested, and press the Enter key on your keyboard:
Enter passphrase for /dev/vdb: -
Run the following command to verify the status of the encrypted volume:
cryptsetup -v status crypthomeAn output similar to the following appears:
/dev/mapper/crypthome is active.type: LUKS1cipher: aes-xts-plain64keysize: 256 bitskey location: dm-cryptdevice: /dev/vdbsector size: 512offset: 4096 sectorssize: 97652154 sectorsmode: read/writeCommand successful.
Formatting the encrypted volume
Start by writing zeros to the encrypted volume. This allocates zeros to block data, to ensure that it appears as random data. This provides protection against disclosure of usage patterns:
-
Install
pv
(if not already installed) by running the following command:apt install pv -
Launch the following command to run
dd
:pv -tpreb /dev/zero | dd of=/dev/mapper/crypthome bs=128MImportantDepending on the size of your volume this may take some hours to finish.
Once finished, a message similar to the following displays:
dd: error writing '/dev/mapper/crypthome': No space left on device <=> ]46.6GiB 0:05:29 [ 144MiB/s] [ <=> ]56+64649 records in56+64648 records out49997902848 bytes (50 GB, 47 GiB) copied, 331.56 s, 151 MB/s -
Create a filesystem on the encrypted volume by running the following command:
mkfs.ext4 /dev/mapper/crypthomeAn output similar to the following displays once the filesystem is created:
mke2fs 1.44.1 (24-Mar-2018)Creating filesystem with 12206519 4k blocks and 3055616 inodesFilesystem UUID: 80b43994-affd-4687-b7d2-8cfa91303694Superblock backups stored on blocks:32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,4096000, 7962624, 11239424Allocating group tables: doneWriting inode tables: doneCreating journal (65536 blocks): doneWriting superblocks and filesystem accounting information: done
Mounting the encrypted volume
-
Create a folder to mount the volume:
mkdir /mnt/crypthome -
Mount the encrypted volume with the following command:
mount /dev/mapper/crypthome /mnt/crypthome/ -
Verify with
lsblk
that the volume is mounted:NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTvda 252:0 0 46.6G 0 disk|-vda1 252:1 0 46.5G 0 part /`-vda15 252:15 0 100M 0 part /boot/efivdb 252:16 0 46.6G 0 disk`-crypthome 253:0 0 46.6G 0 crypt /mnt/crypthomeThe encrypted volume is now mounted at
/mnt/crypthome
and you can transfer your sensitive data to the volume.
Unmounting the encrypted volume
-
Unmount the volume from your Instance:
umount /mnt/crypthome -
Close the LUKS session with Cryptsetup:
cryptsetup luksClose crypthome -
Verify that the volume has been unmounted with
lsblk
:NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTvda 252:0 0 46.6G 0 disk|-vda1 252:1 0 46.5G 0 part /`-vda15 252:15 0 100M 0 part /boot/efivdb 252:16 0 46.6G 0 diskAs you can see, the following lines have disappeared:
vdb 252:16 0 46.6G 0 disk`-crypthome 253:0 0 46.6G 0 crypt /mnt/crypthome
Remounting the encrypted volume
-
Use Cryptsetup to open the LUKS session and enter the passphrase when prompted:
cryptsetup luksOpen /dev/vdb crypthome -
Mount the volume in the Instance:
mount /dev/mapper/crypthome /mnt/crypthome -
Verify that the volume appears with
lsblk
:NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTvda 252:0 0 46.6G 0 disk|-vda1 252:1 0 46.5G 0 part /`-vda15 252:15 0 100M 0 part /boot/efivdb 252:16 0 46.6G 0 disk`-crypthome 253:0 0 46.6G 0 crypt /mnt/crypthomeAs you can see, the following lines have reappeared. This means your encrypted volume is mounted again and you can use it to store or access your sensitive data:
vdb 252:16 0 46.6G 0 disk`-crypthome 253:0 0 46.6G 0 crypt /mnt/crypthome
Changing the LUKS passphrase
LUKS supports up to 8 passphrases for each encrypted volume. You may wish to change the passphrase of your encrypted volume, which you can do as follows:
-
Check if there is still space available by retrieving the LUKS headers:
cryptsetup luksDump /dev/vdbThe list of available key slots displays:
Key Slot 1: DISABLEDKey Slot 2: DISABLEDKey Slot 3: DISABLEDKey Slot 4: DISABLEDKey Slot 5: DISABLEDKey Slot 6: DISABLEDKey Slot 7: DISABLEDAs you can see 7 slots are available for the volume.
-
Type the following command and enter any current passphrase:
cryptsetup luksAddKey /dev/vdbWhen prompted, enter the new passphrase and its confirmation:
Enter new passphrase for key slot:Verify passphrase: -
Verify that the new passphrase has been taken into account by retrieving the LUKS headers:
cryptsetup luksDump /dev/vdbScroll down to the list of available keys, the output should be similar to the following:
Key Slot 2: DISABLEDKey Slot 3: DISABLEDKey Slot 4: DISABLEDKey Slot 5: DISABLEDKey Slot 6: DISABLEDKey Slot 7: DISABLEDAs you can see only 6 slots are available now, meaning that the new key has been configured.
-
Remove the old passphrase with the following command:
cryptsetup luksRemoveKey /dev/vdbEnter the passphrase to delete and confirm by pressing Enter.
-
Verify that the key has been removed by retrieving the LUKS headers:
cryptsetup luksDump /dev/vdbIn the list of available key slots, 7 slots are available again.