Imported Upstream version 2.3.7

[platform/upstream/cryptsetup.git] / man / cryptsetup.8

.TH CRYPTSETUP "8" "January 2021" "cryptsetup" "Maintenance Commands"
.SH NAME
cryptsetup - manage plain dm-crypt and LUKS encrypted volumes
.SH SYNOPSIS
.B cryptsetup <options> <action> <action args>
.SH DESCRIPTION
.PP
cryptsetup is used to conveniently setup dm-crypt managed
device-mapper mappings. These include plain dm-crypt volumes and
LUKS volumes. The difference is that LUKS uses a metadata header
and can hence offer more features than plain dm-crypt. On the other
hand, the header is visible and vulnerable to damage.

In addition, cryptsetup provides limited support for the use of
loop-AES volumes, TrueCrypt, VeraCrypt and BitLocker compatible volumes.

.SH PLAIN DM-CRYPT OR LUKS?
.PP
Unless you understand the cryptographic background well, use LUKS.
With plain dm-crypt there are a number of possible user errors
that massively decrease security. While LUKS cannot fix them
all, it can lessen the impact for many of them.
.SH WARNINGS
.PP
A lot of good information on the risks of using encrypted storage,
on handling problems and on security aspects can be found in the
\fICryptsetup FAQ\fR. Read it. Nonetheless, some risks deserve
to be mentioned here.

\fBBackup:\fR Storage media die. Encryption has no influence on that.
Backup is mandatory for encrypted data as well, if the data has any
worth. See the Cryptsetup FAQ for advice on how to do a backup of an
encrypted volume.

\fBCharacter encoding:\fR If you enter a
passphrase with special symbols, the passphrase can change
depending on character encoding. Keyboard settings can also change,
which can make blind input hard or impossible. For
example, switching from some ASCII 8-bit variant to UTF-8
can lead to a different binary encoding and hence different
passphrase seen by cryptsetup, even if what you see on
the terminal is exactly the same. It is therefore highly
recommended to select passphrase characters only from 7-bit
ASCII, as the encoding for 7-bit ASCII stays the same for
all ASCII variants and UTF-8.

\fBLUKS header:\fR If the header of a LUKS volume gets damaged,
all data is permanently lost unless you have a header-backup.
If a key-slot is damaged, it can only be restored from a header-backup
or if another active key-slot with known passphrase is undamaged.
Damaging the LUKS header is something people manage to do with
surprising frequency. This risk is the result of a trade-off
between security and safety, as LUKS is designed for fast and
secure wiping by just overwriting header and key-slot area.

\fBPreviously used partitions:\fR If a partition was previously used,
it is a very good idea to wipe filesystem signatures, data, etc. before
creating a LUKS or plain dm-crypt container on it.
For a quick removal of filesystem signatures, use "wipefs". Take care
though that this may not remove everything. In particular, MD RAID
signatures at the end of a device may survive. It also does not
remove data. For a full wipe, overwrite the whole partition before
container creation. If you do not know how to do that, the
cryptsetup FAQ describes several options.

.SH BASIC ACTIONS
The following are valid actions for all supported device types.

\fIopen\fR <device> <name> \-\-type <device_type>
.IP
Opens (creates a mapping with) <name> backed by device <device>.

Device type can be \fIplain\fR, \fIluks\fR (default), \fIluks1\fR, \fIluks2\fR,
\fIloopaes\fR or \fItcrypt\fR.

For backward compatibility there are \fBopen\fR command aliases:

\fBcreate\fR (argument-order <name> <device>): open \-\-type plain
.br
\fBplainOpen\fR: open \-\-type plain
.br
\fBluksOpen\fR: open \-\-type luks
.br
\fBloopaesOpen\fR: open \-\-type loopaes
.br
\fBtcryptOpen\fR: open \-\-type tcrypt
.br
\fBbitlkOpen\fR: open \-\-type bitlk

\fB<options>\fR are type specific and are described below
for individual device types. For \fBcreate\fR, the order of the <name>
and <device> options is inverted for historical reasons, all other
aliases use the standard \fB<device> <name>\fR order.
.PP
\fIclose\fR <name>
.IP
Removes the existing mapping <name> and wipes the key from kernel memory.

For backward compatibility there are \fBclose\fR command aliases:
\fBremove\fR, \fBplainClose\fR, \fBluksClose\fR, \fBloopaesClose\fR,
\fBtcryptClose\fR (all behaves exactly the same, device type is
determined automatically from active device).

\fB<options>\fR can be [\-\-deferred]

.PP
\fIstatus\fR <name>
.IP
Reports the status for the mapping <name>.
.PP
\fIresize\fR <name>
.IP
Resizes an active mapping <name>.

If \-\-size (in 512-bytes sectors) or \-\-device\-size are not specified,
the size is computed from the underlying device. For LUKS it is the size
of the underlying device without the area reserved for LUKS header
(see data payload offset in \fBluksDump\fR command).
For plain crypt device, the whole device size is used.

Note that this does not change the raw device geometry, it just
changes how many sectors of the raw device are represented
in the mapped device.

If cryptsetup detected volume key for active device loaded in kernel keyring
service, resize action would first try to retrieve
the key using a token and only if it failed it'd ask for a passphrase
to unlock a keyslot (LUKS) or to derive a volume key again (plain mode).
The kernel keyring is used by default for LUKS2 devices.

With LUKS2 device additional \fB<options>\fR can be [\-\-token\-id, \-\-token\-only,
\-\-key\-slot, \-\-key\-file, \-\-keyfile\-size, \-\-keyfile\-offset, \-\-timeout,
\-\-disable\-locks, \-\-disable\-keyring].

.PP
\fIrefresh\fR <name>
.IP
Refreshes parameters of active mapping <name>.

Updates parameters of active device <name> without need to deactivate the device
(and umount filesystem). Currently it supports parameters refresh on following
devices: LUKS1, LUKS2 (including authenticated encryption), plain crypt
and loopaes.

Mandatory parameters are identical to those of an open action for respective
device type.

You may change following parameters on all devices \-\-perf\-same_cpu_crypt,
\-\-perf\-submit_from_crypt_cpus, \-\-perf-no_read_workqueue, \-\-perf-no_write_workqueue
and \-\-allow\-discards.

Refreshing device without any optional parameter will refresh the device
with default setting (respective to device type).

\fBLUKS2 only:\fR

\-\-integrity\-no\-journal parameter affects only LUKS2 devices with
underlying dm-integrity device.

Adding option \-\-persistent stores any combination of device parameters
above in LUKS2 metadata (only after successful refresh operation).

\-\-disable\-keyring parameter refreshes a device with volume key passed
in dm-crypt driver.

.PP
\fIreencrypt\fR <device> or --active-name <name> [<new_name>]
.IP
Run resilient reencryption (LUKS2 device only).

There are 3 basic modes of operation:

\(bu device reencryption (\fIreencrypt\fR)

\(bu device encryption (\fIreencrypt\fR \-\-encrypt)

\(bu device decryption (\fIreencrypt\fR \-\-decrypt)

<device> or --active-name <name> is mandatory parameter.

With <device> parameter cryptsetup looks up active <device> dm mapping.
If no active mapping is detected, it starts offline reencryption otherwise online
reencryption takes place.

Reencryption process may be safely interrupted by a user via SIGTERM signal (ctrl+c).

To resume already initialized or interrupted reencryption, just run the cryptsetup
\fIreencrypt\fR command again to continue the reencryption operation.
Reencryption may be resumed with different \-\-resilience or \-\-hotzone\-size unless
implicit datashift resilience mode is used (reencrypt \-\-encrypt with \-\-reduce-device-size
option).

If the reencryption process was interrupted abruptly (reencryption process crash, system crash, poweroff)
it may require recovery. The recovery is currently run automatically on next activation (action \fIopen\fR)
when needed.

Optional parameter <new_name> takes effect only with \-\-encrypt option and it activates device <new_name>
immediately after encryption initialization gets finished. That's useful when device needs to be ready
as soon as possible and mounted (used) before full data area encryption is completed.

Action supports following additional \fB<options>\fR [\-\-encrypt, \-\-decrypt, \-\-device\-size,
\-\-resilience, \-\-resilience-hash, \-\-hotzone-size, \-\-init\-only, \-\-resume\-only,
\-\-reduce\-device\-size, \-\-master\-key\-file, \-\-key\-size].

.SH PLAIN MODE
Plain dm-crypt encrypts the device sector-by-sector with a
single, non-salted hash of the passphrase. No checks
are performed, no metadata is used. There is no formatting operation.
When the raw device is mapped (opened), the usual device operations
can be used on the mapped device, including filesystem creation.
Mapped devices usually reside in /dev/mapper/<name>.

The following are valid plain device type actions:

\fIopen\fR \-\-type plain <device> <name>
.br
\fIcreate\fR <name> <device> (\fBOBSOLETE syntax\fR)
.IP
Opens (creates a mapping with) <name> backed by device <device>.

\fB<options>\fR can be [\-\-hash, \-\-cipher, \-\-verify-passphrase,
\-\-sector\-size, \-\-key-file, \-\-keyfile-offset, \-\-key-size,
\-\-offset, \-\-skip, \-\-size, \-\-readonly, \-\-shared, \-\-allow\-discards,
\-\-refresh]

Example: 'cryptsetup open \-\-type plain /dev/sda10 e1' maps the raw
encrypted device /dev/sda10 to the mapped (decrypted) device
/dev/mapper/e1, which can then be mounted, fsck-ed or have a
filesystem created on it.
.SH LUKS EXTENSION
LUKS, the Linux Unified Key Setup, is a standard for disk encryption.
It adds a standardized header at the start of the device,
a key-slot area directly behind the header and the bulk
data area behind that. The whole set is called a 'LUKS container'.
The device that a LUKS container resides on is called a 'LUKS device'.
For most purposes, both terms can be used interchangeably. But
note that when the LUKS header is at a nonzero offset
in a device, then the device is not a LUKS device anymore, but
has a LUKS container stored in it at an offset.

LUKS can manage multiple passphrases that can be individually revoked
or changed and that can be securely scrubbed from persistent
media due to the use of anti-forensic stripes. Passphrases
are protected against brute-force and dictionary
attacks by PBKDF2, which implements hash iteration and salting
in one function.

LUKS2 is a new version of header format that allows additional
extensions like different PBKDF algorithm or authenticated encryption.
You can format device with LUKS2 header if you specify
\fI\-\-type luks2\fR in \fIluksFormat\fR command.
For activation, the format is already recognized automatically.

Each passphrase, also called a
.B key
in this document, is associated with one of 8 key-slots.
Key operations that do not specify a slot affect the first slot
that matches the supplied passphrase or the first empty slot if
a new passphrase is added.

The \fB<device>\fR parameter can also be specified by a LUKS UUID in the
format UUID=<uuid>. Translation to real device name uses symlinks
in /dev/disk/by-uuid directory.

To specify a detached header, the \fB\-\-header\fR parameter can be used
in all LUKS commands and always takes precedence over the positional
\fB<device>\fR parameter.

The following are valid LUKS actions:

\fIluksFormat\fR <device> [<key file>]
.IP
Initializes a LUKS partition and sets the initial passphrase
(for key-slot 0),
either via prompting or via <key file>. Note that
if the second argument is present, then the passphrase
is taken from the file given there, without the need
to use the \-\-key-file option. Also note that for both forms
of reading the passphrase from a file you can
give '-' as file name, which results in the passphrase being read
from stdin and the safety-question being skipped.

You cannot call luksFormat on a device or filesystem that is mapped or in use,
e.g. mounted filesysem, used in LVM, active RAID member etc.
The device or filesystem has to be un-mounted in order to call luksFormat.

To use LUKS2, specify \fI\-\-type luks2\fR.

\fB<options>\fR can be [\-\-hash, \-\-cipher, \-\-verify\-passphrase,
\-\-key\-size, \-\-key\-slot,
\-\-key\-file (takes precedence over optional second argument),
\-\-keyfile\-offset, \-\-keyfile\-size, \-\-use\-random | \-\-use\-urandom,
\-\-uuid, \-\-master\-key\-file, \-\-iter\-time, \-\-header,
\-\-pbkdf\-force\-iterations,
\-\-force\-password, \-\-disable-locks].

For LUKS2, additional \fB<options>\fR can be
[\-\-integrity, \-\-integrity\-no\-wipe, \-\-sector\-size,
\-\-label, \-\-subsystem,
\-\-pbkdf, \-\-pbkdf\-memory, \-\-pbkdf\-parallel,
\-\-disable\-locks, \-\-disable\-keyring,
\-\-luks2\-metadata\-size, \-\-luks2\-keyslots\-size,
\-\-keyslot\-cipher, \-\-keyslot\-key\-size].

\fBWARNING:\fR Doing a luksFormat on an existing LUKS container will
make all data the old container permanently irretrievable unless
you have a header backup.
.PP
\fIopen\fR \-\-type luks <device> <name>
.br
\fIluksOpen\fR <device> <name> (\fBold syntax\fR)
.IP
Opens the LUKS device <device> and sets up a mapping <name> after
successful verification of the supplied passphrase.

First, the passphrase is searched in LUKS tokens. If it's not
found in any token and also the passphrase is not supplied via \-\-key-file,
the command prompts for it interactively.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-offset,
\-\-keyfile\-size, \-\-readonly, \-\-test\-passphrase,
\-\-allow\-discards, \-\-header, \-\-key-slot, \-\-master\-key\-file, \-\-token\-id,
\-\-token\-only, \-\-disable\-keyring, \-\-disable\-locks, \-\-type, \-\-refresh,
\-\-serialize\-memory\-hard\-pbkdf].
.PP
\fIluksSuspend\fR <name>
.IP
Suspends an active device (all IO operations will block
and accesses to the device will wait indefinitely)
and wipes the encryption
key from kernel memory. Needs kernel 2.6.19 or later.

After this operation you have to use \fIluksResume\fR to reinstate
the encryption key and unblock the device or \fIclose\fR to remove
the mapped device.

\fBWARNING:\fR never suspend the device on which the cryptsetup binary resides.

\fB<options>\fR can be [\-\-header, \-\-disable\-locks].
.PP
\fIluksResume\fR <name>
.IP
Resumes a suspended device and reinstates the encryption key.
Prompts interactively for a passphrase if \-\-key-file is not given.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-size, \-\-header,
\-\-disable\-keyring, \-\-disable\-locks, \-\-type]
.PP
\fIluksAddKey\fR <device> [<key file with new key>]
.IP
Adds a new passphrase. An existing passphrase must be supplied
interactively or via \-\-key-file.
The new passphrase to be added can be specified interactively
or read from the file given as positional argument.

\fBNOTE:\fR with \-\-unbound option the action creates new unbound
LUKS2 keyslot. The keyslot cannot be used for device activation.
If you don't pass new key via \-\-master\-key\-file option,
new random key is generated. Existing passphrase for any active keyslot
is not required.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-offset,
\-\-keyfile\-size, \-\-new\-keyfile\-offset,
\-\-new\-keyfile\-size, \-\-key\-slot, \-\-master\-key\-file,
\-\-force\-password, \-\-header, \-\-disable\-locks,
\-\-iter-time, \-\-pbkdf, \-\-pbkdf\-force\-iterations,
\-\-unbound, \-\-type, \-\-keyslot\-cipher, \-\-keyslot\-key\-size].
.PP
\fIluksRemoveKey\fR <device> [<key file with passphrase to be removed>]
.IP
Removes the supplied passphrase from the LUKS device. The
passphrase to be removed can be specified interactively,
as the positional argument or via \-\-key-file.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-offset,
\-\-keyfile\-size, \-\-header, \-\-disable\-locks, \-\-type]

\fBWARNING:\fR If you read the passphrase from stdin
(without further argument or with '-' as an argument
to \-\-key\-file), batch-mode (\-q) will be implicitly
switched on and no warning will be given when you remove the
last remaining passphrase from a LUKS container. Removing
the last passphrase makes the LUKS container permanently
inaccessible.
.PP
\fIluksChangeKey\fR <device> [<new key file>]
.IP
Changes an existing passphrase. The passphrase
to be changed must be supplied interactively or via \-\-key\-file.
The new passphrase can be supplied interactively or in
a file given as positional argument.

If a key-slot is specified (via \-\-key-slot), the passphrase
for that key-slot must be given and the new passphrase
will overwrite the specified key-slot. If no key-slot
is specified and there is still a free key-slot, then
the new passphrase will be put into a free key-slot before the
key-slot containing the old passphrase is purged. If there is
no free key-slot, then the key-slot with the old passphrase is
overwritten directly.

\fBWARNING:\fR If a key-slot is overwritten, a media failure
during this operation can cause the overwrite to fail after
the old passphrase has been wiped and make the LUKS container
inaccessible.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-offset,
\-\-keyfile\-size, \-\-new\-keyfile\-offset,
\-\-iter-time, \-\-pbkdf, \-\-pbkdf\-force\-iterations,
\-\-new\-keyfile\-size, \-\-key\-slot, \-\-force\-password, \-\-header,
\-\-disable\-locks, \-\-type, \-\-keyslot\-cipher, \-\-keyslot\-key\-size].
.PP
.PP
\fIluksConvertKey\fR <device>
.IP
Converts an existing LUKS2 keyslot to new pbkdf parameters. The
passphrase for keyslot to be converted must be supplied interactively
or via \-\-key\-file. If no \-\-pbkdf parameters are specified LUKS2
default pbkdf values will apply.

If a keyslot is specified (via \-\-key\-slot), the passphrase for that
keyslot must be given. If no keyslot is specified and there is still
a free keyslot, then the new parameters will be put into a free
keyslot before the keyslot containing the old parameters is
purged. If there is no free keyslot, then the keyslot with the old
parameters is overwritten directly.

\fBWARNING:\fR If a keyslot is overwritten, a media failure during
this operation can cause the overwrite to fail after the old
parameters have been wiped and make the LUKS container inaccessible.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-offset,
\-\-keyfile\-size, \-\-key\-slot, \-\-header, \-\-disable\-locks,
\-\-iter-time, \-\-pbkdf, \-\-pbkdf\-force\-iterations,
\-\-pbkdf\-memory, \-\-pbkdf\-parallel,
\-\-keyslot\-cipher, \-\-keyslot\-key\-size].
.PP
\fIluksKillSlot\fR <device> <key slot number>
.IP
Wipe the key-slot number <key slot> from the LUKS device. Except running
in batch-mode (\-q) a remaining passphrase must be supplied,
either interactively or via \-\-key-file.
This command can remove the last remaining key-slot, but requires
an interactive confirmation when doing so. Removing the last
passphrase makes a LUKS container permanently inaccessible.

\fB<options>\fR can be [\-\-key\-file, \-\-keyfile\-offset,
\-\-keyfile\-size, \-\-header, \-\-disable\-locks, \-\-type].

\fBWARNING:\fR If you read the passphrase from stdin
(without further argument or with '-' as an argument
to \-\-key-file), batch-mode (\-q) will be implicitly
switched on and no warning will be given when you remove the
last remaining passphrase from a LUKS container. Removing
the last passphrase makes the LUKS container permanently
inaccessible.

\fBNOTE:\fR If there is no passphrase provided (on stdin or through
\-\-key-file argument) and batch-mode (\-q) is active, the
key-slot is removed without any other warning.

.PP
\fIerase\fR <device>
.br
\fIluksErase\fR <device>
.IP
Erase all keyslots and make the LUKS container permanently inaccessible.
You do not need to provide any password for this operation.

\fBWARNING:\fR This operation is irreversible.
.PP
\fIluksUUID\fR <device>
.IP
Print the UUID of a LUKS device.
.br
Set new UUID if \fI\-\-uuid\fR option is specified.
.PP
\fIisLuks\fR <device>
.IP
Returns true, if <device> is a LUKS device, false otherwise.
Use option \-v to get human-readable feedback. 'Command successful.'
means the device is a LUKS device.

By specifying \-\-type you may query for specific LUKS version.
.PP
\fIluksDump\fR <device>
.IP
Dump the header information of a LUKS device.

If the \-\-dump\-master\-key option is used, the LUKS device master key is
dumped instead of the keyslot info. Together with \-\-master\-key\-file option,
master key is dumped to a file instead of standard output. Beware that the
master key cannot be changed without reencryption and can be used to decrypt
the data stored in the LUKS container without a passphrase and even without the
LUKS header. This means that if the master key is compromised, the whole device
has to be erased or reencrypted to prevent further access. Use this option carefully.

To dump the master key, a passphrase has to be supplied,
either interactively or via \-\-key\-file.

To dump unbound key (LUKS2 format only), \-\-unbound parameter, specific \-\-key-slot
id and proper passphrase has to be supplied, either interactively or via \-\-key\-file.
Optional \-\-master\-key\-file parameter enables unbound keyslot dump to a file.

\fB<options>\fR can be [\-\-dump\-master\-key, \-\-key\-file,
\-\-keyfile\-offset, \-\-keyfile\-size, \-\-header, \-\-disable\-locks,
\-\-master\-key\-file, \-\-type, \-\-unbound, \-\-key-slot].

\fBWARNING:\fR If \-\-dump\-master\-key is used with \-\-key\-file
and the argument to \-\-key\-file is '-', no validation question
will be asked and no warning given.
.PP
\fIluksHeaderBackup\fR <device> \-\-header\-backup\-file <file>
.IP
Stores a binary backup of the LUKS header and keyslot area.
.br
Note: Using '-' as filename writes the header backup to a file named '-'.

\fBWARNING:\fR This backup file and a passphrase valid
at the time of backup allows decryption of the
LUKS data area, even if the passphrase was later changed or
removed from the LUKS device. Also note that with a header
backup you lose the ability to securely wipe the LUKS
device by just overwriting the header and key-slots. You
either need to securely erase all header backups in
addition or overwrite the encrypted data area as well.
The second option is less secure, as some sectors
can survive, e.g. due to defect management.
.PP
\fIluksHeaderRestore\fR <device> \-\-header\-backup\-file <file>
.IP
Restores a binary backup of the LUKS header and keyslot area
from the specified file.
.br
Note: Using '-' as filename reads the header backup from a file named '-'.

\fBWARNING:\fR Header and keyslots will be replaced, only
the passphrases from the backup will work afterward.

This command requires that the master key size and data offset
of the LUKS header already on the device and of the header backup
match. Alternatively, if there is no LUKS header on the device,
the backup will also be written to it.
.PP
\fItoken\fR <add|remove|import|export> <device>
.IP
Action \fIadd\fR creates new keyring token to enable auto-activation of the device.
For the auto-activation, the passphrase must be stored in keyring with the specified
description. Usually, the passphrase should be stored in \fIuser\fR or
\fIuser-session\fR keyring.
The \fItoken\fR command is supported only for LUKS2.

For adding new keyring token, option \-\-key\-description is mandatory.
Also, new token is assigned to key slot specified with \-\-key\-slot option or to all
active key slots in the case \-\-key\-slot option is omitted.

To remove existing token, specify the token ID which should be removed with
\-\-token\-id option.

\fBWARNING:\fR The action \fItoken remove\fR removes any token type, not just \fIkeyring\fR
type from token slot specified by \-\-token\-id option.

Action \fIimport\fR can store arbitrary valid token json in LUKS2 header. It may be passed via
standard input or via file passed in \-\-json\-file option. If you specify \-\-key\-slot then
successfully imported token is also assigned to the key slot.

Action \fIexport\fR writes requested token json to a file passed with \-\-json\-file or
to standard output.

\fB<options>\fR can be [\-\-header, \-\-token\-id, \-\-key\-slot, \-\-key\-description,
\-\-disable\-locks, \-\-disable\-keyring, \-\-json\-file].
.PP
\fIconvert\fR <device> \-\-type <format>
.IP
Converts the device between LUKS1 and LUKS2 format (if possible).
The conversion will not be performed if there is an additional LUKS2 feature or LUKS1 has
unsupported header size.

Conversion (both directions) must be performed on inactive device. There must not be active
dm-crypt mapping established for LUKS header requested for conversion.

\fB\-\-type\fR option is mandatory with following accepted values: \fIluks1\fR or \fIluks2\fR.

\fBWARNING:\fR The \fIconvert\fR action can destroy the LUKS header in the case of a crash
during conversion or if a media error occurs.
Always create a header backup before performing this operation!

\fB<options>\fR can be [\-\-header, \-\-type].
.PP
\fIconfig\fR <device>
.IP
Set permanent configuration options (store to LUKS header).
The \fIconfig\fR command is supported only for LUKS2.

The permanent options can be \fI\-\-priority\fR to set priority (normal, prefer, ignore)
for keyslot (specified by \fI\-\-key\-slot\fR) or \fI\-\-label\fR and \fI\-\-subsystem\fR.

\fB<options>\fR can be [\-\-priority, \-\-label, \-\-subsystem, \-\-key\-slot, \-\-header].

.SH loop-AES EXTENSION
cryptsetup supports mapping loop-AES encrypted partition using
a compatibility mode.
.PP
\fIopen\fR \-\-type loopaes <device> <name> \-\-key\-file <keyfile>
.br
\fIloopaesOpen\fR <device> <name> \-\-key\-file <keyfile>  (\fBold syntax\fR)
.IP
Opens the loop-AES <device> and sets up a mapping <name>.

If the key file is encrypted with GnuPG, then you have to use
\-\-key\-file=\- and decrypt it before use, e.g. like this:
.br
gpg \-\-decrypt <keyfile> | cryptsetup loopaesOpen \-\-key\-file=\-
<device> <name>

\fBWARNING:\fR The loop-AES extension cannot use the direct input of key file
on real terminal because the keys are separated by end-of-line and only part
of the multi-key file would be read.
.br
If you need it in script, just use the pipe redirection:
.br
echo $keyfile | cryptsetup loopaesOpen \-\-key\-file=\- <device> <name>

Use \fB\-\-keyfile\-size\fR to specify the proper key length if needed.

Use \fB\-\-offset\fR to specify device offset. Note that the units
need to be specified in number of 512 byte sectors.

Use \fB\-\-skip\fR to specify the IV offset. If the original device
used an offset and but did not use it in IV sector calculations,
you have to explicitly use \fB\-\-skip 0\fR in addition to the offset
parameter.

Use \fB\-\-hash\fR to override the default hash function for
passphrase hashing (otherwise it is detected according to key
size).

\fB<options>\fR can be [\-\-key\-file, \-\-key\-size, \-\-offset, \-\-skip,
\-\-hash, \-\-readonly, \-\-allow\-discards, \-\-refresh].
.PP
See also section 7 of the FAQ and \fBhttp://loop-aes.sourceforge.net\fR
for more information regarding loop-AES.
.SH TCRYPT (TrueCrypt-compatible and VeraCrypt) EXTENSION
cryptsetup supports mapping of TrueCrypt, tcplay or VeraCrypt
(with \fB\-\-veracrypt\fR option) encrypted partition
using a native Linux kernel API.
Header formatting and TCRYPT header change is not supported, cryptsetup
never changes TCRYPT header on-device.

TCRYPT extension requires kernel userspace
crypto API to be available (introduced in Linux kernel 2.6.38).
If you are configuring kernel yourself, enable
"User-space interface for symmetric key cipher algorithms" in
"Cryptographic API" section (CRYPTO_USER_API_SKCIPHER .config option).

Because TCRYPT header is encrypted, you have to always provide valid
passphrase and keyfiles.

Cryptsetup should recognize all header variants, except legacy cipher chains
using LRW encryption mode with 64 bits encryption block (namely Blowfish
in LRW mode is not recognized, this is limitation of kernel crypto API).

To recognize a VeraCrypt device use the \fB\-\-veracrypt\fR option.
VeraCrypt is just extension of TrueCrypt header with increased
iteration count so unlocking can take quite a lot of time (in comparison
with TCRYPT device).

To open a VeraCrypt device with a custom Personal Iteration Multiplier (PIM)
value, \fBadditionally to \-\-veracrypt \fR use either the
\fB\-\-veracrypt\-pim=<PIM>\fR option to directly specify the PIM on the command-
line or use \fB\-\-veracrypt\-query\-pim\fR to be prompted for the PIM.

The PIM value affects the number of iterations applied during key derivation. Please refer to
\fBhttps://www.veracrypt.fr/en/Personal%20Iterations%20Multiplier%20%28PIM%29.html\fR
for more detailed information.

\fBNOTE:\fR Activation with \fBtcryptOpen\fR is supported only for cipher chains
using LRW or XTS encryption modes.

The \fBtcryptDump\fR command should work for all recognized TCRYPT devices
and doesn't require superuser privilege.

To map system device (device with boot loader where the whole encrypted
system resides) use \fB\-\-tcrypt\-system\fR option.
You can use partition device as the parameter (parameter must be real partition
device, not an image in a file), then only this partition is mapped.

If you have the whole TCRYPT device as a file image and you want to map multiple
partition encrypted with system encryption, please create loopback mapping
with partitions first (\fBlosetup \-P\fR, see \fPlosetup(8)\fR man page for more info),
and use loop partition as the device parameter.

If you use the whole base device as a parameter, one device for the whole system
encryption is mapped. This mode is available only for backward compatibility
with older cryptsetup versions which mapped TCRYPT system encryption
using the whole device.

To use hidden header (and map hidden device, if available),
use \fB\-\-tcrypt\-hidden\fR option.

To explicitly use backup (secondary) header, use \fB\-\-tcrypt\-backup\fR
option.

\fBNOTE:\fR There is no protection for a hidden volume if
the outer volume is mounted. The reason is that if there
were any protection, it would require some metadata describing
what to protect in the outer volume and the hidden volume would
become detectable.

.PP
\fIopen\fR \-\-type tcrypt <device> <name>
.br
\fItcryptOpen\fR <device> <name>  (\fBold syntax\fR)
.IP
Opens the TCRYPT (a TrueCrypt-compatible) <device> and sets up
a mapping <name>.

\fB<options>\fR can be [\-\-key\-file, \-\-tcrypt\-hidden,
\-\-tcrypt\-system, \-\-tcrypt\-backup, \-\-readonly, \-\-test\-passphrase,
\-\-allow-discards, \-\-veracrypt, \-\-veracrypt\-pim, \-\-veracrypt\-query\-pim,
\-\-header].

The keyfile parameter allows a combination of file content with the
passphrase and can be repeated. Note that using keyfiles is compatible
with TCRYPT and is different from LUKS keyfile logic.

If you use \fB\-\-header\fR in combination with hidden or system options,
the header file must contain specific headers on the same positions as the original
encrypted container.

\fBWARNING:\fR Option \fB\-\-allow\-discards\fR cannot be combined with
option \fB\-\-tcrypt\-hidden\fR. For normal mapping, it can cause
the \fBdestruction of hidden volume\fR (hidden volume appears as unused space
for outer volume so this space can be discarded).

.PP
\fItcryptDump\fR <device>
.IP
Dump the header information of a TCRYPT device.

If the \-\-dump\-master\-key option is used, the TCRYPT device master key
is dumped instead of TCRYPT header info. Beware that the master key
(or concatenated master keys if cipher chain is used)
can be used to decrypt the data stored in the TCRYPT container without
a passphrase.
This means that if the master key is compromised, the whole device has
to be erased to prevent further access. Use this option carefully.

\fB<options>\fR can be [\-\-dump\-master\-key, \-\-key\-file,
\-\-tcrypt\-hidden, \-\-tcrypt\-system, \-\-tcrypt\-backup].

The keyfile parameter allows a combination of file content with the
passphrase and can be repeated.
.PP
See also \fBhttps://en.wikipedia.org/wiki/TrueCrypt\fR for more information regarding
TrueCrypt.

Please note that cryptsetup does not use TrueCrypt code, please report
all problems related to this compatibility extension to the cryptsetup project.

.SH BITLK (Windows BitLocker-compatible) EXTENSION (EXPERIMENTAL)
cryptsetup supports mapping of BitLocker and BitLocker to Go encrypted partition
using a native Linux kernel API.
Header formatting and BITLK header changes are not supported, cryptsetup
never changes BITLK header on-device.

\fBWARNING:\fR This extension is EXPERIMENTAL.

BITLK extension requires kernel userspace crypto API to be available
(for details see TCRYPT section).

Cryptsetup should recognize all BITLK header variants, except legacy
header used in Windows Vista systems and partially decrypted BitLocker devices.
Activation of legacy devices encrypted in CBC mode requires at least
Linux kernel version 5.3 and for devices using Elephant diffuser kernel 5.6.

The \fBbitlkDump\fR command should work for all recognized BITLK devices
and doesn't require superuser privilege.

For unlocking with the \fBopen\fR a password or a recovery passphrase must
be provided. Other unlocking methods (TPM, SmartCard) are not supported.

.PP
\fIopen\fR \-\-type bitlk <device> <name>
.br
\fIbitlkOpen\fR <device> <name>  (\fBold syntax\fR)
.IP
Opens the BITLK (a BitLocker-compatible) <device> and sets up
a mapping <name>.

\fB<options>\fR can be [\-\-key\-file, \-\-readonly, \-\-test\-passphrase,
\-\-allow-discards].

.PP
\fIbitlkDump\fR <device>
.IP
Dump the header information of a BITLK device.

Please note that cryptsetup does not use any Windows BitLocker code, please report
all problems related to this compatibility extension to the cryptsetup project.
.SH MISCELLANEOUS
.PP
\fIrepair\fR <device>
.IP
Tries to repair the device metadata if possible. Currently supported only
for LUKS device type.

This command is useful to fix some known benign LUKS metadata
header corruptions. Only basic corruptions of unused keyslot
are fixable. This command will only change the LUKS header, not
any key-slot data. You may enforce LUKS version by adding \-\-type
option.

It also repairs (upgrades) LUKS2 reencryption metadata by adding
metadata digest that protects it against malicious changes.

If LUKS2 reencryption was interrupted in the middle of writting
reencryption segment the repair command can be used to perform
reencryption recovery so that reencryption can continue later.

\fBWARNING:\fR Always create a binary backup of the original
header before calling this command.
.PP
\fIbenchmark\fR <options>
.IP
Benchmarks ciphers and KDF (key derivation function).
Without parameters, it tries to measure few common configurations.

To benchmark other ciphers or modes, you need to specify \fB\-\-cipher\fR
and \fB\-\-key\-size\fR options or \fB\-\-hash\fR for KDF test.

\fBNOTE:\fR This benchmark is using memory only and is only informative.
You cannot directly predict real storage encryption speed from it.

For testing block ciphers, this benchmark requires kernel userspace
crypto API to be available (introduced in Linux kernel 2.6.38).
If you are configuring kernel yourself, enable
"User-space interface for symmetric key cipher algorithms" in
"Cryptographic API" section (CRYPTO_USER_API_SKCIPHER .config option).

\fB<options>\fR can be [\-\-cipher, \-\-key\-size, \-\-hash].
.SH OPTIONS
.TP
.B "\-\-verbose, \-v"
Print more information on command execution.
.TP
.B "\-\-debug or \-\-debug\-json"
Run in debug mode with full diagnostic logs. Debug output
lines are always prefixed by '#'.
If \-\-debug\-json is used, additional LUKS2 JSON data structures are printed.
.TP
.B "\-\-type <device-type>
Specifies required device type, for more info read \fIBASIC ACTIONS\fR section.
.TP
.B "\-\-hash, \-h \fI<hash\-spec>\fR"
Specifies the passphrase hash for \fIopen\fR (for plain and
loopaes device types).

Specifies the hash used in the LUKS key setup scheme and volume key digest
for \fIluksFormat\fR. The specified hash is used as hash-parameter
for PBKDF2 and for the AF splitter.

The specified hash name is passed to the compiled-in crypto backend.
Different backends may support different hashes.
For \fIluksFormat\fR, the hash
algorithm must provide at least 160 bits of output, which
excludes, e.g., MD5. Do not use a non-crypto hash like
\fB"crc32"\fR as this breaks security.

Values compatible with old version of cryptsetup are
\fB"ripemd160"\fR for \fIopen \-\-type plain\fR and
\fB"sha1"\fR for \fIluksFormat\fR.

Use \fIcryptsetup \-\-help\fR to show the defaults.
.TP
.B "\-\-cipher, \-c \fI<cipher\-spec>\fR"
Set the cipher specification string.

\fIcryptsetup \-\-help\fR shows the compiled-in defaults.
The current default in the distributed sources is
"aes-cbc-essiv:sha256" for plain dm-crypt and
"aes-xts-plain64" for LUKS.

If a hash is part of the cipher specification, then it is
used as part of the IV generation. For example, ESSIV
needs a hash function, while "plain64" does not and
hence none is specified.

For XTS mode you can optionally set a key size of
512 bits with the \-s option. Key size for XTS
mode is twice that for other modes for the same
security level.

XTS mode requires kernel 2.6.24 or later and plain64 requires
kernel 2.6.33 or later. More information can be found in the FAQ.
.TP
.B "\-\-verify-passphrase, \-y"
When interactively asking for a passphrase, ask for it twice
and complain if both inputs do not match. Advised when creating
a regular mapping for the first time, or when running
\fIluksFormat\fR. Ignored on input from file or stdin.
.TP
.B "\-\-key-file, \-d \fIname\fR"
Read the passphrase from file.

If the name given is "-", then the passphrase will be read from stdin.
In this case, reading will not stop at newline characters.

With LUKS, passphrases supplied via \-\-key\-file are always
the existing passphrases requested by a command, except in
the case of \fIluksFormat\fR where \-\-key\-file is equivalent
to the positional key file argument.

If you want to set a new passphrase via key file, you have to
use a positional argument to \fIluksAddKey\fR.

See section \fBNOTES ON PASSPHRASE PROCESSING\fR for more information.
.TP
.B "\-\-keyfile\-offset \fIvalue\fR"
Skip \fIvalue\fR bytes at the beginning of the key file.
Works with all commands that accept key files.
.TP
.B "\-\-keyfile\-size, \-l \fIvalue\fR"
Read a maximum of \fIvalue\fR bytes from the key file.
The default is to read the whole file up to the compiled-in
maximum that can be queried with \-\-help. Supplying more
data than the compiled-in maximum aborts the operation.

This option is useful
to cut trailing newlines, for example. If \-\-keyfile\-offset
is also given, the size count starts after the offset.
Works with all commands that accept key files.
.TP
.B "\-\-new\-keyfile\-offset \fIvalue\fR"
Skip \fIvalue\fR bytes at the start when
adding a new passphrase from key file with
\fIluksAddKey\fR.
.TP
.B "\-\-new\-keyfile\-size  \fIvalue\fR"
Read a maximum of \fIvalue\fR bytes when adding
a new passphrase from key file with \fIluksAddKey\fR.
The default is to read the whole file up to the compiled-in
maximum length that can be queried with \-\-help.
Supplying more than the compiled in maximum aborts the
operation.
When \-\-new\-keyfile\-offset is also given, reading starts
after the offset.
.TP
.B "\-\-master\-key\-file"
Use a master key stored in a file.

For \fIluksFormat\fR this
allows creating a LUKS header with this specific
master key. If the master key was taken from an existing
LUKS header and all other parameters are the same,
then the new header decrypts the data encrypted with the
header the master key was taken from.

Action \fIluksDump\fR together with \-\-dump\-master\-key
option: The volume (master) key is stored in a file instead of
being printed out to standard output.

\fBWARNING:\fR If you create your own master key, you
need to make sure to do it right. Otherwise, you can end
up with a low-entropy or otherwise partially predictable
master key which will compromise security.

For \fIluksAddKey\fR this allows adding a new passphrase
without having to know an existing one.

For \fIopen\fR this allows one to open the LUKS device
without giving a passphrase.
.TP
.B "\-\-dump\-master\-key"
For \fIluksDump\fR this option includes the master key in the displayed
information. Use with care, as the master key can be used to
bypass the passphrases, see also option \-\-master\-key\-file.
.TP
.B "\-\-json\-file"
Read token json from a file or write token to it. See \fItoken\fR action for more
information. \-\-json\-file=- reads json from standard input or writes it to
standard output respectively.
.TP
.B "\-\-use\-random"
.TP
.B "\-\-use\-urandom"
For \fIluksFormat\fR these options define which kernel random number
generator will be used to create the master key (which is a
long-term key).

See \fBNOTES ON RANDOM NUMBER GENERATORS\fR for more
information. Use \fIcryptsetup \-\-help\fR
to show the compiled-in default random number generator.

\fBWARNING:\fR In a low-entropy situation (e.g. in an
embedded system), both selections are problematic.
Using /dev/urandom can lead to weak keys.
Using /dev/random can block a long time, potentially
forever, if not enough entropy can be harvested by
the kernel.
.TP
.B "\-\-key\-slot, \-S <0\-7>"
For LUKS operations that add key material, this options allows you
to specify which key slot is selected for the new key.
This option can be used for \fIluksFormat\fR,
and \fIluksAddKey\fR.
.br
In addition, for \fIopen\fR, this option selects a
specific key-slot to compare the passphrase against.
If the given passphrase would only match a different key-slot,
the operation fails.
.TP
.B "\-\-key\-size, \-s <bits>"
Sets key size in bits. The argument has to be a multiple of
8. The possible key-sizes are limited by the cipher and
mode used.

See /proc/crypto for more information. Note that key-size
in /proc/crypto is stated in bytes.

This option can be used for \fIopen \-\-type plain\fR or \fIluksFormat\fR.
All other LUKS actions will use the key-size specified in the LUKS header.
Use \fIcryptsetup \-\-help\fR to show the compiled-in defaults.
.TP
.B "\-\-size, \-b <number of 512 byte sectors>"
Set the size of the device in sectors of 512 bytes.
This option is only relevant for the \fIopen\fR and \fIresize\fR
actions.
.TP
.B "\-\-offset, \-o <number of 512 byte sectors>"
Start offset in the backend device in 512-byte sectors.
This option is only relevant for the \fIopen\fR action with plain
or loopaes device types or for LUKS devices in \fIluksFormat\fR.

For LUKS, the \-\-offset option sets the data offset (payload) of data
device and must be be aligned to 4096-byte sectors (must be multiple of 8).
This option cannot be combined with \-\-align\-payload option.
.TP
.B "\-\-skip, \-p <number of 512 byte sectors>"
Start offset used in IV calculation in 512-byte sectors
(how many sectors of the encrypted data to skip at the beginning).
This option is only relevant for the \fIopen\fR action with plain
or loopaes device types.

Hence, if \-\-offset \fIn\fR, and \-\-skip \fIs\fR, sector \fIn\fR
(the first sector of the encrypted device) will get a sector number
of \fIs\fR for the IV calculation.
.TP
.B "\-\-device\-size \fIsize[units]\fR"
Instead of real device size, use specified value.

With \fIreencrypt\fR action it means that only specified area
(from the start of the device to the specified size) will be
reencrypted.

With \fIresize\fR action it sets new size of the device.

If no unit suffix is specified, the size is in bytes.

Unit suffix can be S for 512 byte sectors, K/M/G/T (or KiB,MiB,GiB,TiB)
for units with 1024 base or KB/MB/GB/TB for 1000 base (SI scale).

\fBWARNING:\fR This is destructive operation when used with reencrypt command.
.TP
.B "\-\-readonly, \-r"
set up a read-only mapping.
.TP
.B "\-\-shared"
Creates an additional mapping for one common
ciphertext device. Arbitrary mappings are supported.
This option is only relevant for the
\fIopen \-\-type plain\fR action. Use \-\-offset, \-\-size and \-\-skip to
specify the mapped area.
.TP
.B "\-\-pbkdf <PBKDF spec>"
Set Password-Based Key Derivation Function (PBKDF) algorithm for LUKS keyslot.
The PBKDF can be: \fIpbkdf2\fR (for PBKDF2 according to RFC2898),
\fIargon2i\fR for Argon2i or \fIargon2id\fR for Argon2id
(see https://www.cryptolux.org/index.php/Argon2 for more info).

For LUKS1, only PBKDF2 is accepted (no need to use this option).
The default PBKDF2 for LUKS2 is set during compilation time
and is available in \fIcryptsetup \-\-help\fR output.

A PBKDF is used for increasing dictionary and brute-force attack cost
for keyslot passwords. The parameters can be time, memory and parallel cost.

For PBKDF2, only time cost (number of iterations) applies.
For Argon2i/id, there is also memory cost (memory required during
the process of key derivation) and parallel cost (number of threads
that run in parallel during the key derivation.

Note that increasing memory cost also increases time, so the final
parameter values are measured by a benchmark. The benchmark
tries to find iteration time (\fI\-\-iter\-time\fR) with required
memory cost \fI\-\-pbkdf\-memory\fR. If it is not possible,
the memory cost is decreased as well.
The parallel cost \fI\-\-pbkdf\-parallel\fR is constant, is is checked
against available CPU cores (if not available, it is decreased) and the maximum
parallel cost is 4.

You can see all PBKDF parameters for particular LUKS2 keyslot with
\fIluksDump\fR command.

\fBNOTE:\fR If you do not want to use benchmark and want to specify
all parameters directly, use \fI\-\-pbkdf\-force\-iterations\fR with
\fI\-\-pbkdf\-memory\fR and \fI\-\-pbkdf\-parallel\fR.
This will override the values without benchmarking.
Note it can cause extremely long unlocking time. Use only in specific
cases, for example, if you know that the formatted device will
be used on some small embedded system.
In this case, the LUKS PBKDF2 digest will be set to the minimum iteration count.
.TP
.B "\-\-iter\-time, \-i <number of milliseconds>"
The number of milliseconds to spend with PBKDF passphrase processing.
This option is only relevant for LUKS operations that set or change
passphrases, such as \fIluksFormat\fR or \fIluksAddKey\fR.
Specifying 0 as parameter selects the compiled-in default.
.TP
.B "\-\-pbkdf\-memory <number>"
Set the memory cost for PBKDF (for Argon2i/id the number represents kilobytes).
Note that it is maximal value, PBKDF benchmark or available physical memory
can decrease it.
This option is not available for PBKDF2.
.TP
.B "\-\-pbkdf\-parallel <number>"
Set the parallel cost for PBKDF (number of threads, up to 4).
Note that it is maximal value, it is decreased automatically if
CPU online count is lower.
This option is not available for PBKDF2.
.TP
.B "\-\-pbkdf\-force\-iterations <num>"
Avoid PBKDF benchmark and set time cost (iterations) directly.
It can be used for LUKS/LUKS2 device only.
See \fI\-\-pbkdf\fR option for more info.
.TP
.B "\-\-batch\-mode, \-q"
Suppresses all confirmation questions. Use with care!

If the \-y option is not specified, this option also switches off
the passphrase verification for \fIluksFormat\fR.
.TP
.B "\-\-progress-frequency <seconds>"
Print separate line every <seconds> with wipe progress.
.TP
.B "\-\-timeout, \-t <number of seconds>"
The number of seconds to wait before timeout on passphrase input
via terminal. It is relevant every time a passphrase is asked,
for example for \fIopen\fR, \fIluksFormat\fR or \fIluksAddKey\fR.
It has no effect if used in conjunction with \-\-key-file.
.br
This option is useful when the system
should not stall if the user does not input a passphrase,
e.g. during boot. The default is a value of 0 seconds,
which means to wait forever.
.TP
.B "\-\-tries, \-T"
How often the input of the passphrase shall be retried.
This option is relevant
every time a passphrase is asked, for example for
\fIopen\fR, \fIluksFormat\fR or \fIluksAddKey\fR.
The default is 3 tries.
.TP
.B "\-\-align\-payload <number of 512 byte sectors>"
Align payload at a boundary of \fIvalue\fR 512-byte sectors.
This option is relevant for \fIluksFormat\fR.

If not specified, cryptsetup tries to use the topology info
provided by the kernel for the underlying device to get the optimal alignment.
If not available (or the calculated value is a multiple of the default)
data is by default aligned to a 1MiB boundary (i.e. 2048 512-byte sectors).

For a detached LUKS header, this option specifies the offset on the
data device. See also the \-\-header option.

\fBWARNING:\fR This option is DEPRECATED and has often unexpected impact
to the data offset and keyslot area size (for LUKS2) due to the complex rounding.
For fixed data device offset use \fI\-\-offset\fR option instead.

.TP
.B "\-\-uuid=\fIUUID\fR"
Use the provided \fIUUID\fR for the \fIluksFormat\fR command
instead of generating a new one. Changes the existing UUID when
used with the \fIluksUUID\fR command.

The UUID must be provided in the standard UUID format,
e.g. 12345678-1234-1234-1234-123456789abc.
.TP
.B "\-\-allow\-discards\fR"
Allow the use of discard (TRIM) requests for the device.
This option is only relevant for \fIopen\fR action.
This is also not supported for LUKS2 devices with data integrity protection.

\fBWARNING:\fR This command can have a negative security impact
because it can make filesystem-level operations visible on
the physical device. For example, information leaking
filesystem type, used space, etc. may be extractable from
the physical device if the discarded blocks can be located
later. If in doubt, do not use it.

A kernel version of 3.1 or later is needed. For earlier kernels,
this option is ignored.
.TP
.B "\-\-perf\-same_cpu_crypt\fR"
Perform encryption using the same cpu that IO was submitted on.
The default is to use an unbound workqueue so that encryption work
is automatically balanced between available CPUs.
This option is only relevant for \fIopen\fR action.

\fBNOTE:\fR This option is available only for low-level dm-crypt
performance tuning, use only if you need a change to default dm-crypt
behaviour. Needs kernel 4.0 or later.
.TP
.B "\-\-perf\-submit_from_crypt_cpus\fR"
Disable offloading writes to a separate thread after encryption.
There are some situations where offloading write bios from the
encryption threads to a single thread degrades performance
significantly.  The default is to offload write bios to the same
thread.
This option is only relevant for \fIopen\fR action.

\fBNOTE:\fR This option is available only for low-level dm-crypt
performance tuning, use only if you need a change to default dm-crypt
behaviour. Needs kernel 4.0 or later.
.TP
.B "\-\-perf\-no_read_workqueue, \-\-perf\-no_write_workqueue\fR"
Bypass dm-crypt internal workqueue and process read or write requests
synchronously.
This option is only relevant for \fIopen\fR action.

\fBNOTE:\fR These options are available only for low-level dm-crypt
performance tuning, use only if you need a change to default dm-crypt
behaviour. Needs kernel 5.9 or later.
.TP
.B "\-\-test\-passphrase\fR"
Do not activate the device, just verify passphrase.
This option is only relevant for \fIopen\fR action (the device
mapping name is not mandatory if this option is used).
.TP
.B "\-\-header\fR <device or file storing the LUKS header>"
Use a detached (separated) metadata device or file where the
LUKS header is stored. This option allows one to store ciphertext
and LUKS header on different devices.

This option is only relevant for LUKS devices and can be
used with the \fIluksFormat\fR, \fIopen\fR, \fIluksSuspend\fR,
\fIluksResume\fR, \fIstatus\fR and \fIresize\fR commands.

For \fIluksFormat\fR with a file name as the argument to \-\-header,
the file will be automatically created if it does not exist.
See the cryptsetup FAQ for header size calculation.

For other commands that change the LUKS header (e.g. \fIluksAddKey\fR),
specify the device or file with the LUKS header directly as the
LUKS device.

If used with \fIluksFormat\fR, the \-\-align\-payload option is taken
as absolute sector alignment on ciphertext device and can be zero.

\fBWARNING:\fR There is no check whether the ciphertext device specified
actually belongs to the header given. In fact, you can specify an
arbitrary device as the ciphertext device for \fIopen\fR
with the \-\-header option. Use with care.
.TP
.B "\-\-header\-backup\-file <file>"
Specify file with header backup for \fIluksHeaderBackup\fR or
\fIluksHeaderRestore\fR actions.
.TP
.B "\-\-force\-password"
Do not use password quality checking for new LUKS passwords.

This option applies only to \fIluksFormat\fR, \fIluksAddKey\fR and
\fIluksChangeKey\fR and is ignored if cryptsetup is built without
password quality checking support.

For more info about password quality check, see the manual page
for \fBpwquality.conf(5)\fR and \fBpasswdqc.conf(5)\fR.
.TP
.B "\-\-deferred"
Defers device removal in \fIclose\fR command until the last user closes it.
.TP
.B "\-\-disable\-locks"
Disable lock protection for metadata on disk.
This option is valid only for LUKS2 and ignored for other formats.

\fBWARNING:\fR Do not use this option unless you run cryptsetup in
a restricted environment where locking is impossible to perform
(where /run directory cannot be used).
.TP
.B "\-\-disable\-keyring"
Do not load volume key in kernel keyring and store it directly
in the dm-crypt target instead.
This option is supported only for the LUKS2 format.
.TP
.B "\-\-key\-description <text>"
Set key description in keyring for use with \fItoken\fR command.
.TP
.B "\-\-priority <normal|prefer|ignore>"
Set a priority for LUKS2 keyslot.
The \fIprefer\fR priority marked slots are tried before \fInormal\fR priority.
The \fIignored\fR priority means, that slot is never used, if not explicitly
requested by \fI\-\-key\-slot\fR option.
.TP
.B "\-\-token\-id"
Specify what token to use in actions \fItoken\fR, \fIopen\fR or \fIresize\fR.
If omitted, all available tokens will be checked before proceeding further with
passphrase prompt.
.TP
.B "\-\-token\-only"
Do not proceed further with action (any of \fItoken\fR, \fIopen\fR or
\fIresize\fR) if token activation failed. Without the option,
action asks for passphrase to proceed further.
.TP
.B "\-\-sector\-size <bytes>"
Set sector size for use with disk encryption. It must be power of two
and in range 512 - 4096 bytes. The default is 512 bytes sectors.
This option is available only in the LUKS2 mode.

Note that if sector size is higher than underlying device hardware sector
and there is not integrity protection that uses data journal, using
this option can increase risk on incomplete sector writes during a power fail.

If used together with \fI\-\-integrity\fR option and dm-integrity journal,
the atomicity of writes is guaranteed in all cases (but it cost write
performance - data has to be written twice).

Increasing sector size from 512 bytes to 4096 bytes can provide better
performance on most of the modern storage devices and also with some
hw encryption accelerators.
.TP
.B "\-\-iv-large-sectors"
Count Initialization Vector (IV) in larger sector size (if set) instead
of 512 bytes sectors. This option can be used only for \fIopen\fR command
and \fIplain\fR encryption type.

\fBNOTE:\fR This option does not have any performance or security impact,
use it only for accessing incompatible existing disk images from other systems
that require this option.
.TP
.B "\-\-persistent"
If used with LUKS2 devices and activation commands like \fIopen\fR or \fIrefresh\fR,
the specified activation flags are persistently written into metadata
and used next time automatically even for normal activation.
(No need to use cryptab or other system configuration files.)

If you need to remove a persistent flag, use \fI\-\-persistent\fR without
the flag you want to remove (e.g. to disable persistently stored discard flag,
use \fI\-\-persistent\fR without \fI\-\-allow-discards\fR).

Only \fI\-\-allow-discards\fR, \fI\-\-perf\-same_cpu_crypt\fR,
\fI\-\-perf\-submit_from_crypt_cpus\fR, \fI\-\-perf\-no_read_workqueue\fR,
\fI\-\-perf\-no_write_workqueue\fR and \fI\-\-integrity\-no\-journal\fR
can be stored persistently.
.TP
.B "\-\-refresh"
Refreshes an active device with new set of parameters. See action \fIrefresh\fR description
for more details.
.TP
.B "\-\-label <LABEL>"
.B "\-\-subsystem <SUBSYSTEM>"
Set label and subsystem description for LUKS2 device, can be used
in \fIconfig\fR and \fIformat\fR actions.
The label and subsystem are optional fields and can be later used in udev scripts
for triggering user actions once device marked by these labels is detected.
.TP
.B "\-\-integrity <integrity algorithm>"
Specify integrity algorithm to be used for authenticated disk encryption in LUKS2.

\fBWARNING: This extension is EXPERIMENTAL\fR and requires dm-integrity
kernel target (available since kernel version 4.12).
For native AEAD modes, also enable "User-space interface for AEAD cipher algorithms"
in "Cryptographic API" section (CONFIG_CRYPTO_USER_API_AEAD .config option).

For more info, see \fIAUTHENTICATED DISK ENCRYPTION\fR section.
.TP
.B "\-\-luks2\-metadata\-size <size>"
This option can be used to enlarge the LUKS2 metadata (JSON) area.
The size includes 4096 bytes for binary metadata (usable JSON area is smaller
of the binary area).
According to LUKS2 specification, only these values are valid:
16, 32, 64, 128, 256, 512, 1024, 2048 and 4096 kB
The <size> can be specified with unit suffix (for example 128k).
.TP
.B "\-\-luks2\-keyslots\-size <size>"
This option can be used to set specific size of the LUKS2 binary keyslot area
(key material is encrypted there). The value must be aligned to multiple
of 4096 bytes with maximum size 128MB.
The <size> can be specified with unit suffix (for example 128k).
.TP
.B "\-\-keyslot\-cipher <cipher\-spec>"
This option can be used to set specific cipher encryption for the LUKS2 keyslot area.
.TP
.B "\-\-keyslot\-key\-size <bits>"
This option can be used to set specific key size for the LUKS2 keyslot area.
.TP
.B "\-\-integrity\-no\-journal"
Activate device with integrity protection without using data journal (direct
write of data and integrity tags).
Note that without journal power fail can cause non-atomic write and data corruption.
Use only if journalling is performed on a different storage layer.
.TP
.B "\-\-integrity\-no\-wipe"
Skip wiping of device authentication (integrity) tags. If you skip this
step, sectors will report invalid integrity tag until an application write
to the sector.

\fBNOTE:\fR Even some writes to the device can fail if the write is not
aligned to page size and page-cache initiates read of a sector with invalid
integrity tag.
.TP
.B "\-\-unbound"

Creates new or dumps existing LUKS2 unbound keyslot. See \fIluksAddKey\fR or
\fIluksDump\fR actions for more details.

.TP
.B "\-\-tcrypt\-hidden"
.B "\-\-tcrypt\-system"
.B "\-\-tcrypt\-backup"
Specify which TrueCrypt on-disk header will be used to open the device.
See \fITCRYPT\fR section for more info.
.TP
.B "\-\-veracrypt"
Allow VeraCrypt compatible mode. Only for TCRYPT extension.
See \fITCRYPT\fR section for more info.
.TP
.B "\-\-veracrypt\-pim"
.B "\-\-veracrypt\-query\-pim"
Use a custom Personal Iteration Multiplier (PIM) for VeraCrypt device.
See \fITCRYPT\fR section for more info.
.TP
.B "\-\-serialize\-memory\-hard\-pbkdf"
Use a global lock to serialize unlocking of keyslots using memory-hard PBKDF.

\fBNOTE:\fR This is (ugly) workaround for a specific situation when multiple
devices are activated in parallel and system instead of reporting out of memory
starts unconditionally stop processes using out-of-memory killer.

\fBDO NOT USE\fR this switch until you are implementing boot environment
with parallel devices activation!
.TP
.B "\-\-encrypt"
Initialize (and run) device encryption (\fIreencrypt\fR action parameter)
.TP
.B "\-\-decrypt"
Initialize (and run) device decryption (\fIreencrypt\fR action parameter)
.TP
.B "\-\-init\-only"
Initialize reencryption (any variant) operation in LUKS2 metadata only and exit. If any
reencrypt operation is already initialized in metadata, the command with \-\-init\-only
parameter fails.
.TP
.B "\-\-resume\-only"
Resume reencryption (any variant) operation already described in LUKS2 metadata. If no
reencrypt operation is initialized, the command with \-\-resume\-only
parameter fails. Useful for resuming reencrypt operation without accidentally triggering
new reencryption operation.
.TP
.B "\-\-resilience <mode>"
Reencryption resilience mode can be one of \fIchecksum\fR, \fIjournal\fR or \fInone\fR.

\fIchecksum\fR: default mode, where individual checksums of ciphertext hotzone sectors are stored,
so the recovery process can detect which sectors where already reencrypted.
It requires that the device sector write is atomic.

\fIjournal\fR: the hotzone is journaled in the binary area (so the data are written twice).

\fInone\fR: performance mode. There is no protection and the only way it's safe to interrupt
the reencryption is similar to old offline reencryption utility. (ctrl+c).

The option is ignored if reencryption with datashift mode is in progress.
.TP
.B "\-\-resilience-hash <hash>"
The hash algorithm used with "\-\-resilience checksum" only.
The default hash is sha256. With other resilience modes, the hash parameter is ignored.
.TP
.B "\-\-hotzone-size <size>"
This option can be used to set an upper limit on the size of reencryption area (hotzone).
The <size> can be specified with unit suffix (for example 50M). Note that actual hotzone
size may be less than specified <size> due to other limitations (free space in keyslots area or
available memory).
.TP
.B "\-\-reduce\-device\-size <size>"
Initialize LUKS2 reencryption with data device size reduction
(currently only \-\-encrypt variant is supported).

Last <size> sectors of <device> will be used to properly initialize device reencryption.
That means any data at last <size> sectors will be lost.

It could be useful if you added some space to underlying partition or logical volume
(so last <size> sectors contains no data).

Recommended minimal size is twice the default LUKS2 header size (\-\-reduce\-device\-size 32M)
for \-\-encrypt use case. Be sure to have enough (at least \-\-reduce\-device\-size value
        of free space at the end of <device>).

WARNING: This is a destructive operation and cannot be reverted.
Use with extreme care - accidentally overwritten filesystems are usually unrecoverable.
.TP
.B "\-\-version"
Show the program version.
.TP
.B "\-\-usage"
Show short option help.
.TP
.B "\-\-help, \-?"
Show help text and default parameters.
.SH EXAMPLE
.TP
Example 1: Create LUKS 2 container on block device /dev/sdX.
sudo cryptsetup --type luks2 luksFormat /dev/sdX
.TP
Example 2: Add an additional passphrase to key slot 5.
sudo cryptsetup luksAddKey --key-slot 5 /dev/sdX
.TP
Example 3: Create LUKS header backup and save it to file.
sudo cryptsetup luksHeaderBackup /dev/sdX --header-backup-file /var/tmp/NameOfBackupFile
.TP
Example 4: Open LUKS contaner on /dev/sdX and map it to sdX_crypt.
sudo cryptsetup open /dev/sdX sdX_crypt
.TP
.B WARNING: The command in example 5 will erase all key slots.
Your cannot use your luks container afterwards anymore unless you have a backup to restore.
.TP
Example 5: Erase all key slots on /dev/sdX.
sudo cryptsetup erase /dev/sdX
.TP
Example 6: Restore LUKS header from backup file.
sudo cryptsetup luksHeaderRestore /dev/sdX --header-backup-file /var/tmp/NameOfBackupFile
.SH RETURN CODES
Cryptsetup returns 0 on success and a non-zero value on error.

Error codes are: 1 wrong parameters, 2 no permission (bad passphrase),
3 out of memory, 4 wrong device specified, 5 device already exists
or device is busy.
.SH NOTES ON PASSPHRASE PROCESSING FOR PLAIN MODE
Note that no iterated hashing or salting is done in plain mode.
If hashing is done, it is a single direct hash. This means that
low-entropy passphrases are easy to attack in plain mode.

\fBFrom a terminal\fR: The passphrase is read until the
first newline, i.e. '\\n'.
The input without the newline character is processed with
the default hash or the hash specified with \-\-hash.
The hash result will be truncated to the key size
of the used cipher, or the size specified with \-s.

\fBFrom stdin\fR: Reading will continue until a newline (or until
the maximum input size is reached), with the trailing newline
stripped. The maximum input size is defined by the same
compiled-in default as for the maximum key file size and can
be overwritten using \-\-keyfile-size option.

The data read will be hashed with the default hash
or the hash specified with \-\-hash.
The hash result will be truncated to the key size
of the used cipher, or the size specified with \-s.

Note that if \-\-key-file=- is used for reading the key
from stdin, trailing newlines are not stripped from the input.

If "plain" is used as argument to \-\-hash, the input
data will not be hashed. Instead, it will be zero padded (if
shorter than the key size) or truncated (if longer than the
key size) and used directly as the binary key. This is useful for
directly specifying a binary key.
No warning will be given if the amount of data read from stdin is
less than the key size.

\fBFrom a key file\fR: It will be truncated to the
key size of the used cipher or the size given by \-s
and directly used as a binary key.

\fBWARNING\fR: The \-\-hash argument is being ignored.
The \-\-hash option is usable only for stdin input in plain mode.

If the key file is shorter than the key, cryptsetup
will quit with an error.
The maximum input size is defined by the same
compiled-in default as for the maximum key file size and can
be overwritten using \-\-keyfile-size option.


.SH NOTES ON PASSPHRASE PROCESSING FOR LUKS
LUKS uses PBKDF2 to protect against dictionary attacks
and to give some protection to low-entropy passphrases
(see RFC 2898 and the cryptsetup FAQ).

\fBFrom a terminal\fR: The passphrase is read until the
first newline and then processed by PBKDF2 without
the newline character.

\fBFrom stdin\fR:
LUKS will read passphrases from stdin up to the
first newline character or the compiled-in
maximum key file length. If \-\-keyfile\-size is
given, it is ignored.

\fBFrom key file\fR:
The complete keyfile is read up to the compiled-in
maximum size. Newline characters do not terminate the
input. The \-\-keyfile\-size option can be used to limit
what is read.

\fBPassphrase processing\fR:
Whenever a passphrase is added to a LUKS header (luksAddKey, luksFormat),
the user may specify how much the time the passphrase processing
should consume. The time is used to determine the iteration count
for PBKDF2 and higher times will offer better protection for
low-entropy passphrases, but open will take longer to
complete. For passphrases that have entropy higher than the
used key length, higher iteration times will not increase security.

The default setting of one or two seconds is sufficient for most
practical cases. The only exception is a low-entropy
passphrase used on a device with a slow CPU, as this will
result in a low iteration count. On a slow device, it may
be advisable to increase the iteration time using the
\-\-iter\-time option in order to obtain a higher
iteration count. This does slow down all later luksOpen
operations accordingly.
.SH INCOHERENT BEHAVIOR FOR INVALID PASSPHRASES/KEYS
LUKS checks for a valid passphrase when an encrypted partition
is unlocked. The behavior of plain dm-crypt is different.
It will always decrypt with the passphrase given. If the
given passphrase is wrong, the device mapped by plain
dm-crypt will essentially still contain encrypted data and
will be unreadable.
.SH NOTES ON SUPPORTED CIPHERS, MODES, HASHES AND KEY SIZES
The available combinations of ciphers, modes, hashes and key sizes
depend on kernel support. See /proc/crypto for a list of available
options. You might need to load additional kernel crypto modules
in order to get more options.

For the \-\-hash option, if the crypto backend is libgcrypt,
then all algorithms supported by the gcrypt library are available.
For other crypto backends, some algorithms may be missing.
.SH NOTES ON PASSPHRASES
Mathematics can't be bribed. Make sure you keep your passphrases safe.
There are a few nice tricks for constructing a fallback, when suddenly
out of the blue, your brain refuses to cooperate.
These fallbacks need LUKS, as it's only possible with LUKS
to have multiple passphrases. Still, if your attacker model does
not prevent it, storing your passphrase in a sealed envelope somewhere
may be a good idea as well.
.SH NOTES ON RANDOM NUMBER GENERATORS
Random Number Generators (RNG) used in cryptsetup are always the
kernel RNGs without any modifications or additions to data stream
produced.

There are two types of randomness cryptsetup/LUKS needs. One type
(which always uses /dev/urandom) is used for salts, the AF splitter
and for wiping deleted keyslots.

The second type is used for the volume (master) key. You can switch
between using /dev/random and /dev/urandom  here, see
\fP\-\-use\-random\fR and \fP\-\-use\-urandom\fR
options. Using /dev/random on a system without enough entropy sources
can cause \fPluksFormat\fR to block until the requested amount of
random data is gathered. In a low-entropy situation (embedded system),
this can take a very long time and potentially forever. At the same
time, using /dev/urandom in a low-entropy situation will
produce low-quality keys. This is a serious problem, but solving
it is out of scope for a mere man-page.
See \fPurandom(4)\fR for more information.
.SH AUTHENTICATED DISK ENCRYPTION (EXPERIMENTAL)
Since Linux kernel version 4.12 dm-crypt supports authenticated
disk encryption.

Normal disk encryption modes are length-preserving (plaintext sector
is of the same size as a ciphertext sector) and can provide only
confidentiality protection, but not cryptographically sound
data integrity protection.

Authenticated modes require additional space per-sector for
authentication tag and use Authenticated Encryption with Additional
Data (AEAD) algorithms.

If you configure LUKS2 device with data integrity protection,
there will be an underlying dm-integrity device, which provides
additional per-sector metadata space and also provide data
journal protection to ensure atomicity of data and metadata update.
Because there must be additional space for metadata and journal,
the available space for the device will be smaller than for
length-preserving modes.

The dm-crypt device then resides on top of such a dm-integrity device.
All activation and deactivation of this device stack is performed
by cryptsetup, there is no difference in using \fIluksOpen\fR
for integrity protected devices.
If you want to format LUKS2 device with data integrity protection,
use \fI\-\-integrity\fR option.

Since dm-integrity doesn't support discards (TRIM), dm-crypt device on top of it
inherits this, so integrity protection mode doesn't support discards either.

Some integrity modes requires two independent keys (key for encryption
and for authentication). Both these keys are stored in one LUKS keyslot.

\fBWARNING:\fR All support for authenticated modes is experimental
and there are only some modes available for now. Note that there
are a very few authenticated encryption algorithms that are suitable
for disk encryption. You also cannot use CRC32 or any other non-cryptographic
checksums (other than the special integrity mode "none"). If for some reason
you want to have integrity control without using authentication mode, then you
should separately configure dm-integrity independently of LUKS2.

.SH NOTES ON LOOPBACK DEVICE USE
Cryptsetup is usually used directly on a block device (disk
partition or LVM volume). However, if the device argument is a
file, cryptsetup tries to allocate a loopback device
and map it into this file. This mode requires Linux kernel 2.6.25
or more recent which supports the loop autoclear flag (loop device is
cleared on the last close automatically). Of course, you can
always map a file to a loop-device manually. See the
cryptsetup FAQ for an example.

When device mapping is active, you can see the loop backing file in
the status command output. Also see losetup(8).
.SH LUKS2 header locking
.PP
The LUKS2 on-disk metadata is updated in several steps and
to achieve proper atomic update, there is a locking mechanism.
For an image in file, code uses \fIflock(2)\fR system call.
For a block device, lock is performed over a special file stored
in a locking directory (by default \fI/run/lock/cryptsetup\fR).
The locking directory should be created with the proper security
context by the distribution during the boot-up phase.
Only LUKS2 uses locks, other formats do not use this mechanism.
.SH DEPRECATED ACTIONS
.PP
The \fIreload\fR action is no longer supported.
Please use \fIdmsetup(8)\fR if you need to
directly manipulate with the device mapping table.
.PP
The \fIluksDelKey\fR was replaced with \fIluksKillSlot\fR.
.PP
.SH REPORTING BUGS
Report bugs, including ones in the documentation, on
the cryptsetup mailing list at <dm-crypt@saout.de>
or in the 'Issues' section on LUKS website.
Please attach the output of the failed command with the
\-\-debug option added.
.SH AUTHORS
cryptsetup originally written by Jana Saout <jana@saout.de>
.br
The LUKS extensions and original man page were written by
Clemens Fruhwirth <clemens@endorphin.org>.
.br
Man page extensions by Milan Broz <gmazyland@gmail.com>.
.br
Man page rewrite and extension by Arno Wagner <arno@wagner.name>.
.SH COPYRIGHT
Copyright \(co 2004 Jana Saout
.br
Copyright \(co 2004-2006 Clemens Fruhwirth
.br
Copyright \(co 2012-2014 Arno Wagner
.br
Copyright \(co 2009-2021 Red Hat, Inc.
.br
Copyright \(co 2009-2021 Milan Broz

This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH SEE ALSO
The LUKS website at \fBhttps://gitlab.com/cryptsetup/cryptsetup/\fR

The cryptsetup FAQ, contained in the distribution package and
online at
\fBhttps://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions\fR

The cryptsetup mailing list and list archive, see FAQ entry 1.6.

The LUKS version 1 on-disk format specification available at
\fBhttps://gitlab.com/cryptsetup/cryptsetup/wikis/Specification\fR and
LUKS version 2 at \fBhttps://gitlab.com/cryptsetup/LUKS2-docs\fR.