NAME
cryptsetup-luksFormat - initialize a LUKS partition and set the initial passphraseSYNOPSIS
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.OPTIONS
--type <device-type>Specifies required device type, for more info
read BASIC ACTIONS section in cryptsetup(8).
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.
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.
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.
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.
Skip value bytes at the beginning of
the key file.
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.
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.
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.
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.
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.
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.
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.
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).
The number of milliseconds to spend with PBKDF
passphrase processing. Specifying 0 as parameter selects the compiled-in
default.
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.
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.
Avoid PBKDF benchmark and set time cost
(iterations) directly. It can be used for LUKS/LUKS2 device only. See
--pbkdf option for more info.
Print separate line every seconds with
wipe progress.
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):
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.
{ "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 }
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.
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.
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.
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.
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).
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).
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.
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.
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.
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).
Use inefficient legacy padding.
WARNING: Do not use this option until you need compatibility with
specific old kernel.
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).
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).
This option can be used to set specific cipher
encryption for the LUKS2 keyslot area.
This option can be used to set specific key
size for the LUKS2 keyslot area.
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.
Suppresses all confirmation questions. Use
with care!
If the --verify-passphrase option is not specified, this option also switches
off the passphrase verification.
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.
Show the program version.
Show short option help.
Show help text and default parameters.
REPORTING BUGS
Report bugs at cryptsetup <[email protected]>mailing or in Issues project section <https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.SEE ALSO
Cryptsetup FAQ <https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions>CRYPTSETUP
Part of cryptsetup project <https://gitlab.com/cryptsetup/cryptsetup/>.2023-12-18 | cryptsetup 2.6.1 |