man `8 cryptsetup-luksFormat`

CRYPTSETUP-LUKSFORMAT(8) Maintenance Commands CRYPTSETUP-LUKSFORMAT(8)

NAME
cryptsetup-luksFormat - initialize a LUKS partition and set the initial
passphrase

SYNOPSIS
cryptsetup luksFormat [<options>] <device> [<key file>]

DESCRIPTION
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 filesystem, used in LVM, active RAID member, etc.
The device or filesystem has to be un-mounted in order to call
luksFormat.

To use specific version of LUKS format, use --type luks1 or type luks2.
To use OPAL hardware encryption on a self-encrypting drive, use
--hw-opal or --hw-opal-only.

<options> 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, --volume-key-file, --iter-time, --header,
--pbkdf-force-iterations, --force-password, --disable-locks, --timeout,
--type, --offset, --align-payload (deprecated)].

For LUKS2, additional <options> 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, --integrity-legacy-padding, --hw-opal,
--hw-opal-only].

WARNING: Doing a luksFormat on an existing LUKS container will make all
data in the old container permanently irretrievable unless you have a
header backup.

OPTIONS
--align-payload <number of 512 byte sectors>
Align payload at a boundary of value 512-byte sectors.

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.

WARNING: 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 --offset option
instead.

--batch-mode, -q
Suppresses all confirmation questions. Use with care!

If the --verify-passphrase option is not specified, this option
also switches off the passphrase verification.

--cipher, -c <cipher-spec>
Set the cipher specification string.

cryptsetup --help shows the compiled-in defaults.

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.

--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.

--disable-blkid
Disable use of blkid library for checking and wiping on-disk
signatures.

--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 type.

--disable-locks
Disable lock protection for metadata on disk. This option is valid
only for LUKS2 and ignored for other formats.

WARNING: 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).

--force-password
Do not use password quality checking for new LUKS passwords.

This option is ignored if cryptsetup is built without password
quality checking support.

For more info about password quality check, see the manual page for
pwquality.conf(5) and passwdqc.conf(5).

--hash, -h <hash-spec>
Specifies the hash used in the LUKS key setup scheme and volume key
digest. The specified hash is used for PBKDF2 and AF splitter.

The hash algorithm must provide at least 160 bits of output. Do not
use a non-crypto hash like xxhash as this breaks security. Use
cryptsetup --help to show the defaults.

--header <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.

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.

The --align-payload option is taken as absolute sector alignment on
ciphertext device and can be zero.

--help, -?
Show help text and default parameters.

--hw-opal
Format LUKS2 device with dm-crypt encryption stacked on top HW
based encryption configured on SED OPAL locking range. This option
enables both SW and HW based data encryption.

--hw-opal-only
Format LUKS2 device with HW based encryption configured on SED OPAL
locking range only. LUKS2 format only manages locking range unlock
key. This option enables HW based data encryption managed by SED
OPAL drive only.

NOTE: Please note that with OPAL-only (--hw-opal-only) encryption,
the configured OPAL administrator PIN (passphrase) allows unlocking
all configured locking ranges without LUKS keyslot decryption
(without knowledge of LUKS passphrase). Because of many observed
problems with compatibility, cryptsetup currently DOES NOT use OPAL
single-user mode, which would allow such decoupling of OPAL admin
PIN access.

--integrity <integrity algorithm>
Specify integrity algorithm to be used for authenticated disk
encryption in LUKS2.

WARNING: This extension is EXPERIMENTAL 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 AUTHENTICATED DISK ENCRYPTION section in
cryptsetup(8).

--integrity-legacy-padding
Use inefficient legacy padding.

WARNING: Do not use this option until you need compatibility with
specific old kernel.

--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.

NOTE: 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.

--iter-time, -i <number of milliseconds>
The number of milliseconds to spend with PBKDF passphrase
processing. Specifying 0 as parameter selects the compiled-in
default.

--key-file, -d name
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.

See section NOTES ON PASSPHRASE PROCESSING in cryptsetup(8) for
more information.

--keyfile-offset value
Skip value bytes at the beginning of the key file.

--keyfile-size, -l value
Read a maximum of value 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.

--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 open --type plain or luksFormat. All
other LUKS actions will use the key-size specified in the LUKS
header. Use cryptsetup --help to show the compiled-in defaults.

--key-slot, -S <0-N>
For LUKS operations that add key material, this option allows you
to specify which key slot is selected for the new key.

The maximum number of key slots depends on the LUKS version. LUKS1
can have up to 8 key slots. LUKS2 can have up to 32 key slots based
on key slot area size and key size, but a valid key slot ID can
always be between 0 and 31 for LUKS2.

--keyslot-cipher <cipher-spec>
This option can be used to set specific cipher encryption for the
LUKS2 keyslot area.

--keyslot-key-size <bits>
This option can be used to set specific key size for the LUKS2
keyslot area.

--label <LABEL> --subsystem <SUBSYSTEM>
Set label and subsystem description for LUKS2 device. The label and
subsystem are optional fields and can be later used in udev scripts
for triggering user actions once the device marked by these labels
is detected.

--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).

--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).

--offset, -o <number of 512 byte sectors>
Start offset in the backend device in 512-byte sectors.

The --offset option sets the data offset (payload) of data device
and must be aligned to 4096-byte sectors (must be multiple of 8).
This option cannot be combined with --align-payload option.

--pbkdf <PBKDF spec>
Set Password-Based Key Derivation Function (PBKDF) algorithm for
LUKS keyslot. The PBKDF can be: pbkdf2 (for PBKDF2 according to
RFC2898), argon2i for Argon2i or argon2id for Argon2id (see Argon2
<https://www.cryptolux.org/index.php/Argon2> for more info).

For LUKS1, only PBKDF2 is accepted (no need to use this option).
The default PBKDF for LUKS2 is set during compilation time and is
available in cryptsetup --help 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 (--iter-time) with required memory cost
--pbkdf-memory. If it is not possible, the memory cost is decreased
as well. The parallel cost --pbkdf-parallel is constant and is
checked against available CPU cores.

You can see all PBKDF parameters for particular LUKS2 keyslot with
cryptsetup-luksDump(8) command.

NOTE: If you do not want to use benchmark and want to specify all
parameters directly, use --pbkdf-force-iterations with
--pbkdf-memory and --pbkdf-parallel. This will override the values
without benchmarking. Note it can cause extremely long unlocking
time or cause out-of-memory conditions with unconditional process
termination. Use only in specific cases, for example, if you know
that the formatted device will be used on some small embedded
system.

MINIMAL AND MAXIMAL PBKDF COSTS: For PBKDF2, the minimum iteration
count is 1000 and maximum is 4294967295 (maximum for 32bit unsigned
integer). Memory and parallel costs are unused for PBKDF2. For
Argon2i and Argon2id, minimum iteration count (CPU cost) is 4 and
maximum is 4294967295 (maximum for 32bit unsigned integer). Minimum
memory cost is 32 KiB and maximum is 4 GiB. (Limited by addressable
memory on some CPU platforms.) If the memory cost parameter is
benchmarked (not specified by a parameter) it is always in range
from 64 MiB to 1 GiB. The parallel cost minimum is 1 and maximum 4
(if enough CPUs cores are available, otherwise it is decreased).

--pbkdf-force-iterations <num>
Avoid PBKDF benchmark and set time cost (iterations) directly. It
can be used for LUKS/LUKS2 device only. See --pbkdf option for more
info.

--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.

--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.

--progress-frequency seconds
Print separate line every seconds with wipe progress.

--progress-json
Prints progress data in JSON format suitable mostly for machine
processing. It prints separate line every half second (or based on
--progress-frequency value). The JSON output looks as follows
during progress (except it's compact single line):

{
"device":"/dev/sda", // backing device or file
"device_bytes":"8192", // bytes of I/O so far
"device_size":"44040192", // total bytes of I/O to go
"speed":"126877696", // calculated speed in bytes per second (based on progress so far)
"eta_ms":"2520012", // estimated time to finish an operation in milliseconds
"time_ms":"5561235" // total time spent in IO operation in milliseconds
}

Note on numbers in JSON output: Due to JSON parsers limitations all
numbers are represented in a string format due to need of full
64bit unsigned integers.

--sector-size bytes
Set sector size for use with disk encryption. It must be power of
two and in range 512 - 4096 bytes. This option is available only
with LUKS2 format.

For LUKS2 devices it's established based on parameters provided by
underlying data device. For native 4K block devices it's 4096
bytes. For 4K/512e (4K physical sector size with 512 bytes
emulation) it's 4096 bytes. For drives reporting only 512 bytes
block size it remains 512 bytes. If data device is regular file put
in filesystem it's 4096 bytes.

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 --integrity 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.

--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. It
has no effect if used in conjunction with --key-file.

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.

--type <device-type>
Specifies required device type, for more info read BASIC ACTIONS
section in cryptsetup(8).

--usage
Show short option help.

--use-random, --use-urandom
For luksFormat these options define which kernel random number
generator will be used to create the volume key (which is a
long-term key).

See NOTES ON RANDOM NUMBER GENERATORS in cryptsetup(8) for more
information. Use cryptsetup --help to show the compiled-in default
random number generator.

WARNING: In a low-entropy situation (e.g. in an embedded system)
and older kernels, 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.

--uuid <UUID>
Use the provided UUID for the luksFormat command instead of
generating a new one. Changes the existing UUID when used with the
luksUUID command.

The UUID must be provided in the standard UUID format, e.g.
12345678-1234-1234-1234-123456789abc.

--verify-passphrase, -y
When interactively asking for a passphrase, ask for it twice and
complain if both inputs do not match. Ignored on input from file or
stdin.

--version, -V
Show the program version.

--volume-key-file, --master-key-file (OBSOLETE alias)
Use a volume key stored in a file. WARNING: If you create your own
volume key, you need to make sure to do it right. Otherwise, you
can end up with a low-entropy or otherwise partially predictable
volume key which will compromise security.

REPORTING BUGS
Report bugs at cryptsetup mailing list <cryptsetup@lists.linux.dev> or
in Issues project section
<https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.

Please attach output of the failed command with --debug option added.

SEE ALSO
Cryptsetup FAQ
<https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions>

cryptsetup(8), integritysetup(8) and veritysetup(8)

CRYPTSETUP
Part of cryptsetup project <https://gitlab.com/cryptsetup/cryptsetup/>.

cryptsetup 2.7.2 2025-06-13 CRYPTSETUP-LUKSFORMAT(8)

man 8 cryptsetup-luksFormat

man `8 cryptsetup-luksFormat`