CRYPTSETUP-LUKSADDKEY(8)     Maintenance Commands     CRYPTSETUP-LUKSADDKEY(8)

NAME
       cryptsetup-luksAddKey - add a new passphrase

SYNOPSIS
       cryptsetup luksAddKey [<options>] <device> [<key file with new key>]

DESCRIPTION
       Adds a keyslot protected by a new passphrase.  An existing passphrase
       must be supplied interactively, via --key-file or LUKS2 token (plugin).
       Alternatively to the existing passphrase, the user may pass directly
       the volume key (via --volume-key-file or --volume-key-keyring).	The
       new passphrase to be added can be specified interactively, read from
       the file given as the positional argument (also via --new-keyfile
       parameter) or via LUKS2 token.

       The --unbound option creates a new unbound LUKS2 keyslot.  An unbound
       keyslot stores an independent key that cannot be used for device
       activation.  A new random key is generated if you don’t pass a new key
       via the --volume-key-file option.  The existing passphrase for any
       active keyslot is not required.

       Some parameters are effective only if used with the LUKS2 format that
       supports per-keyslot parameters.	 For LUKS1, the PBKDF type and hash
       algorithm are always the same for all keyslots.

       <options> can be [--key-file, --keyfile-offset, --keyfile-size,
       --new-keyfile, --new-keyfile-offset, --new-keyfile-size, --key-slot,
       --new-key-slot, --volume-key-file, --volume-key-keyring,
       --force-password, --hash, --header, --disable-locks, --iter-time,
       --pbkdf, --pbkdf-force-iterations, --pbkdf-memory, --pbkdf-parallel,
       --unbound, --type, --keyslot-cipher, --keyslot-key-size, --key-size,
       --timeout, --token-id, --token-type, --token-only, --new-token-id,
       --verify-passphrase, --external-tokens-path].

OPTIONS
       --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.

       --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-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).

       --external-tokens-path <absolute path>
	   Override the system directory path where cryptsetup searches for
	   external token handlers (or token plugins).	It must be an absolute
	   path (starting with '/' character).

       --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>
	   The specified hash is used for PBKDF2 and the AF splitter.

       --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.

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

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

       --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.

	   The passphrase supplied via --key-file is always the passphrase for
	   the 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.

       --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
	   Provide volume key size in bits.  The argument has to be a multiple
	   of 8.

	   This option is required when the parameter --volume-key-file is
	   used to provide current volume key.	Also, it is used when a new
	   unbound keyslot is created by specifying --unbound parameter.

       --key-slot, -S <0-N>
	   When used together with the parameter --new-key-slot, this option
	   allows you to specify which keyslot is selected for unlocking the
	   volume key.

	   This option is ignored if the existing volume key gets unlocked via
	   LUKS2 token (--token-id, --token-type or --token-only parameters)
	   or when volume key is provided directly via --volume-key-file
	   parameter.

	   To maintain backward compatibility, without --new-key-slot
	   parameter, 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.

       --new-keyfile name
	   Read the passphrase for a new keyslot from a file.

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

	   This is an alternative method to positional argument when adding a
	   new passphrase via keyfile.

       --new-keyfile-offset value
	   Skip value bytes at the start when adding a new passphrase from the
	   key file.

       --new-keyfile-size value
	   Read a maximum of value bytes when adding a new passphrase from the
	   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.

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

       --new-key-slot <0-N>
	   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.

       --new-token-id <id>
	   Specify what token to use to get the passphrase for a new keyslot.

       --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.

       --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.

       --token-id
	   Specify what token to use when unlocking the existing keyslot to
	   get the volume key.

       --token-only
	   Use only LUKS2 tokens to unlock the existing volume key.

	   To create a new keyslot using the passphrase provided by a token,
	   use --new-token-id parameter.

       --token-type type
	   Specify what token type (all type tokens) to use when unlocking the
	   existing keyslot to get the volume key.

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

       --unbound
	   Creates a new LUKS2 unbound keyslot.

       --usage
	   Show short option help.

       --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.

	   This allows adding a new keyslot without having to know the
	   passphrase to the existing one.  It may also be used when no
	   keyslot is active.

	   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.

       --volume-key-keyring <key description>
	   Use a volume key stored in a keyring.  This allows one to open luks
	   and plain device types without giving a passphrase.

	   For LUKS, the key and associated type have to be readable from
	   userspace so that the volume key digest may be verified before
	   activation.	For devices in reencryption, the option may be used
	   twice to specify both old and new volume keys.

	   For PLAIN type, the user must ensure that the key in the keyring is
	   unchanged since activation.	Otherwise, reloading the key can cause
	   data corruption after an unexpected key change.

	   The <key description> uses keyctl-compatible syntax.	 This can
	   either be a numeric key ID or a string name in the format %<key
	   type>:<key name>.  See also the KEY IDENTIFIERS section of
	   keyctl(1).  When no %<key type>: prefix is specified, we assume the
	   key type is user (default type).

EXAMPLES
       The interactive passphrase prompt is always the default method when not
       specified otherwise.

       Add new keyslot using interactive passphrase prompt for both existing
       and new passphrases:

       cryptsetup luksAddKey /dev/device

       Add a new keyslot using LUKS2 tokens to unlock the existing keyslot
       with an interactive passphrase prompt for the new passphrase:

       cryptsetup luksAddKey --token-only /dev/device

       Add new keyslot using LUKS2 systemd-tpm2 tokens to unlock existing
       keyslot with interactive passphrase prompt for new passphrase
       (systemd-tpm2 token plugin must be available):

       cryptsetup luksAddKey --token-type systemd-tpm2 /dev/device

       Add new keyslot using interactive passphrase prompt for existing
       keyslot, reading new passphrase from key_file:

       cryptsetup luksAddKey --new-keyfile key_file /dev/device or cryptsetup
       luksAddKey /dev/device key_file

       Add new keyslot using volume stored in volume_key_file and LUKS2 token
       in slot 5 to get new keyslot passphrase (token in slot 5 must exist and
       respective token plugin must be available):

       cryptsetup luksAddKey --volume-key-file volume_key_file --new-token-id
       5 /dev/device

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-LUKSADDKEY(8)