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 passphrase via prompting or
       <key file>.  Note that if the second argument is present, the
       passphrase is taken from the file given there, without using the
       --key-file option.  Also note that for both forms of reading the
       passphrase from a file, you can give '-' as a 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., a mounted filesystem, used in LVM, active RAID member,
       etc.  The device or filesystem has to be unmounted in order to call
       luksFormat.

       To enforce a specific version of LUKS format, use --type luks1 or type
       luks2.  The default format is LUKS2.

       To use hardware encryption on an OPAL self-encrypting drive, use
       --hw-opal or --hw-opal-only.  Note that some OPAL drives can require a
       PSID reset (with deletion of data) before using the LUKS format with
       OPAL options.  See --hw-opal-factory-reset option in cryptsetup erase
       command.

       Doing a luksFormat on an existing LUKS container will regenerate the
       volume key.  Unless you have a header backup, all old encrypted data in
       the container will be permanently irretrievable.	 Note that luksFormat
       does not wipe or overwrite the data area.  It only creates a new LUKS
       header with fresh keyslots.  See cryptsetup FAQ for more info on how to
       wipe the whole device, including encrypted data.

       <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].

OPTIONS
       --align-payload <number of 512 byte sectors> (DEPRECATED, use --offset)
	   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.

	   This option is DEPRECATED and has an unexpected impact on 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 the blkid library for checking and wiping on-disk
	   signatures.

       --disable-keyring
	   Do not load the volume key in the kernel keyring; 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 is 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 the 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 the 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
	   the 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 of
	   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 the locking range
	   unlock key.	This option enables HW-based data encryption managed
	   by the SED OPAL drive only.

	   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 the integrity algorithm to be used for authenticated disk
	   encryption in LUKS2.

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

	   For more info, see the AUTHENTICATED DISK ENCRYPTION section in
	   cryptsetup(8).

       --integrity-inline
	   Store integrity tags in hardware sector integrity fields.  The
	   device must support sectors with additional protection information
	   (PI, also known as DIF - data integrity field) of the requested
	   size.  Another storage subsystem must not use the additional field
	   (the device must present a "nop" profile in the kernel).  Note that
	   some devices must be reformatted at a low level to support this
	   option; for NVMe devices, see nvme(1) id-ns LBA profiles.

	   No journal or bitmap is used in this mode.  The device should
	   operate with native speed (without any overhead).  This option is
	   available since the Linux kernel version 6.11.

       --integrity-key-size bytes
	   The size of the data integrity key.	Configurable only for HMAC
	   integrity.  The default integrity key size is set to the same as
	   the hash output length.

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

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

       --integrity-no-wipe
	   Skip wiping of device authentication (integrity) tags.  If you skip
	   this step, sectors will report an invalid integrity tag until an
	   application writes to the sector.

	   Skipping this step could also cause write failures due to IO
	   operation alignments.  For example, kernel page cache can request a
	   read of a full page that fails due to an uninitialized integrity
	   tag.	 It is usually a bug in the application that tries to read
	   data that was not written before.

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

       --key-description text
	   Set the key description in the keyring that will be used for
	   passphrase retrieval.

       --key-file, -d file
	   Read the passphrase from the 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 the 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 keyslot is selected for the new key.

	   The maximum number of keyslots depends on the LUKS version.	LUKS1
	   can have up to 8 keyslots.  LUKS2 can have up to 32 keyslots based
	   on keyslot area size and key size, but a valid keyslot 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 a specific key size for the LUKS2
	   keyslot area.

       --label <label>,	 --subsystem <subsystem>
	   Set label and subsystem description for LUKS2 device.  These are
	   similar to filesystem labels.  The label and subsystem are optional
	   fields and can be later used in udev scripts to trigger user
	   actions once the device marked by these labels is detected.

       --luks2-keyslots-size size
	   This option can be used to set a specific size of the LUKS2 binary
	   keyslot area (key material is encrypted there).  The value must be
	   aligned to a multiple of 4096 bytes with a maximum size 128MB.  The
	   <size> can be specified with a 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 the LUKS2
	   specification, only these values are valid: 16, 32, 64, 128, 256,
	   512, 1024, 2048 and 4096 kB.	 The <size> can be specified with a
	   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 the data
	   device and must be aligned to 4096-byte sectors (must be a 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 the cryptsetup --help output.

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

	   For PBKDF2, only the 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 a particular LUKS2 keyslot
	   with the cryptsetup-luksDump(8) command.

	   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 the maximum is 4294967295 (maximum for 32-bit
	   unsigned integer).  Memory and parallel costs are not supported for
	   PBKDF2.  For Argon2i and Argon2id, the minimum iteration count (CPU
	   cost) is 4, and the maximum is 4294967295 (maximum for a 32-bit
	   unsigned integer).  Minimum memory cost is 32 KiB and maximum is 4
	   GiB.	 If the memory cost parameter is benchmarked (not specified by
	   a parameter), it is always in the range from 64 MiB to 1 GiB.
	   Memory cost above 1GiB (up to the 4GiB maximum) can be setup only
	   by the --pbkdf-memory parameter.  The parallel cost minimum is 1
	   and maximum 4 (if enough CPU cores are available, otherwise it is
	   decreased by the available CPU cores).

	   WARNING: Increasing PBKDF computational costs above the mentioned
	   limits provides negligible additional security improvement.	While
	   elevated costs significantly increase brute-force overhead, they
	   offer negligible protection against dictionary attacks.  The
	   marginal cost increase for processing an entire dictionary remains
	   fundamentally insufficient.

	   The hardcoded PBKDF limits represent engineered trade-offs between
	   cryptographic security and operational usability.  LUKS maintains
	   portability and must be used within a reasonable time on
	   resource-constrained systems.

	   Cryptsetup deliberately restricts maximum memory cost (4 GiB) and
	   parallel cost (4) parameters due to architectural limitations (like
	   embedded and legacy systems).

	   PBKDF memory cost mandates actual physical RAM allocation with
	   intensive write operations that must remain in physical RAM.	 Any
	   swap usage results in unacceptable performance degradation.	Memory
	   management often overcommits allocations beyond available physical
	   memory, expecting most allocated memory to remain unused.  In such
	   situations, as PBKDF always uses all allocated memory, it
	   frequently causes out-of-memory failures that abort cryptsetup
	   operations.

       --pbkdf-force-iterations number
	   Avoid the PBKDF benchmark and set the time cost (iterations)
	   directly.  It can be used only for a LUKS/LUKS2 device.  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 the 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 the maximal value; it is decreased automatically if the
	   CPU online count is lower.  This option is not available for
	   PBKDF2.

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

       --progress-json
	   Prints progress data in JSON format, which is suitable mostly for
	   machine processing.	It prints a separate line every half second
	   (or based on --progress-frequency value).  The JSON output looks as
	   follows during progress (except it’s a 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 parser limitations, all
	   numbers are represented in a string format due to the need for full
	   64-bit unsigned integers.

       --sector-size bytes
	   Set encryption sector size for use with LUKS2 device type.  It must
	   be a power of two and in the 512 - 4096 bytes range.

	   The encryption sector size is set based on the underlying data
	   device if not specified explicitly.	For native 4096-byte physical
	   sector devices, it is set to 4096 bytes.  For 4096/512e (4096-byte
	   physical sector size with 512-byte sector emulation), it is set to
	   4096 bytes.	For drives reporting only a 512-byte physical sector
	   size, it is set to 512 bytes.  If the data device is a regular file
	   (container), it is set to 4096 bytes.

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

	   Increasing sector size from 512 to 4096 bytes can provide better
	   performance on most modern storage devices and with some hardware
	   encryption accelerators.

	   Note that using a sector size larger than the underlying storage
	   device’s physical sector size may result in data corruption during
	   unexpected power failures.  A power failure during write operations
	   may result in only partial completion of the encryption sector
	   write, leaving encrypted data in an inconsistent state that cannot
	   be properly decrypted.

       --timeout, -t seconds
	   The number of seconds to wait before a 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 type
	   Specifies required device type, for more info, read the 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).

	   Do not use these options with recent kernels (later than version
	   5.6).  For more details, see NOTES ON RANDOM NUMBER GENERATORS in
	   cryptsetup(8) and urandom(4).

       --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 file, --master-key-file 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 the 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 2.8.1		  2025-08-13	      CRYPTSETUP-LUKSFORMAT(8)