NAME
cryptsetup-luksChangeKey - change an existing passphraseSYNOPSIS
cryptsetup luksChangeKey [<options>] <device> [<new key file>]DESCRIPTION
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 the positional argument.OPTIONS
--type <device-type>Specifies required device type, for more info
read BASIC ACTIONS section in cryptsetup(8).
The specified hash is used for PBKDF2 and AF
splitter.
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.
The passphrase supplied via --key-file is always the passphrase for existing
keyslot requested by the command.
If you want to set a new passphrase via key file, you have to use a positional
argument or parameter --new-keyfile.
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.
Skip value bytes at the start when
adding a new passphrase from key file.
Read a maximum of value bytes when
adding a new passphrase from key file. 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.
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.
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.
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.
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.
For commands that change the LUKS header (e.g. luksAddKey), specify the
device or file with the LUKS header directly as the LUKS device.
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).
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.
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 |