cryptsetup(8) — Linux manual page


CRYPTSETUP(8)               Maintenance Commands               CRYPTSETUP(8)

NAME         top

       cryptsetup - manage plain dm-crypt and LUKS encrypted volumes

SYNOPSIS         top

       cryptsetup <options> <action> <action args>

DESCRIPTION         top

       cryptsetup is used to conveniently setup dm-crypt managed device-
       mapper mappings. These include plain dm-crypt volumes and LUKS
       volumes. The difference is that LUKS uses a metadata header and can
       hence offer more features than plain dm-crypt. On the other hand, the
       header is visible and vulnerable to damage.

       In addition, cryptsetup provides limited support for the use of loop-
       AES volumes, TrueCrypt, VeraCrypt and BitLocker compatible volumes.


       Unless you understand the cryptographic background well, use LUKS.
       With plain dm-crypt there are a number of possible user errors that
       massively decrease security. While LUKS cannot fix them all, it can
       lessen the impact for many of them.

WARNINGS         top

       A lot of good information on the risks of using encrypted storage, on
       handling problems and on security aspects can be found in the
       Cryptsetup FAQ. Read it. Nonetheless, some risks deserve to be
       mentioned here.

       Backup: Storage media die. Encryption has no influence on that.
       Backup is mandatory for encrypted data as well, if the data has any
       worth. See the Cryptsetup FAQ for advice on how to do a backup of an
       encrypted volume.

       Character encoding: If you enter a passphrase with special symbols,
       the passphrase can change depending on character encoding. Keyboard
       settings can also change, which can make blind input hard or
       impossible. For example, switching from some ASCII 8-bit variant to
       UTF-8 can lead to a different binary encoding and hence different
       passphrase seen by cryptsetup, even if what you see on the terminal
       is exactly the same. It is therefore highly recommended to select
       passphrase characters only from 7-bit ASCII, as the encoding for
       7-bit ASCII stays the same for all ASCII variants and UTF-8.

       LUKS header: If the header of a LUKS volume gets damaged, all data is
       permanently lost unless you have a header-backup.  If a key-slot is
       damaged, it can only be restored from a header-backup or if another
       active key-slot with known passphrase is undamaged.  Damaging the
       LUKS header is something people manage to do with surprising
       frequency. This risk is the result of a trade-off between security
       and safety, as LUKS is designed for fast and secure wiping by just
       overwriting header and key-slot area.

       Previously used partitions: If a partition was previously used, it is
       a very good idea to wipe filesystem signatures, data, etc. before
       creating a LUKS or plain dm-crypt container on it.  For a quick
       removal of filesystem signatures, use "wipefs". Take care though that
       this may not remove everything. In particular, MD RAID signatures at
       the end of a device may survive. It also does not remove data. For a
       full wipe, overwrite the whole partition before container creation.
       If you do not know how to do that, the cryptsetup FAQ describes
       several options.

BASIC COMMANDS         top

       The following are valid actions for all supported device types.

       open <device> <name> --type <device_type>

              Opens (creates a mapping with) <name> backed by device

              Device type can be plain, luks (default), luks1, luks2,
              loopaes or tcrypt.

              For backward compatibility there are open command aliases:

              create (argument-order <name> <device>): open --type plain
              plainOpen: open --type plain
              luksOpen: open --type luks
              loopaesOpen: open --type loopaes
              tcryptOpen: open --type tcrypt
              bitlkOpen: open --type bitlk

              <options> are type specific and are described below for
              individual device types. For create, the order of the <name>
              and <device> options is inverted for historical reasons, all
              other aliases use the standard <device> <name> order.

       close <name>

              Removes the existing mapping <name> and wipes the key from
              kernel memory.

              For backward compatibility there are close command aliases:
              remove, plainClose, luksClose, loopaesClose, tcryptClose (all
              behaves exactly the same, device type is determined
              automatically from active device).

              <options> can be [--deferred]

       status <name>

              Reports the status for the mapping <name>.

       resize <name>

              Resizes an active mapping <name>.

              If --size (in 512-bytes sectors) or --device-size are not
              specified, the size is computed from the underlying device.
              For LUKS it is the size of the underlying device without the
              area reserved for LUKS header (see data payload offset in
              luksDump command).  For plain crypt device, the whole device
              size is used.

              Note that this does not change the raw device geometry, it
              just changes how many sectors of the raw device are
              represented in the mapped device.

              If cryptsetup detected volume key for active device loaded in
              kernel keyring service, resize action would first try to
              retrieve the key using a token and only if it failed it'd ask
              for a passphrase to unlock a keyslot (LUKS) or to derive a
              volume key again (plain mode).  The kernel keyring is used by
              default for LUKS2 devices.

              With LUKS2 device additional <options> can be [--token-id,
              --token-only, --key-slot, --key-file, --keyfile-size,
              --keyfile-offset, --timeout, --disable-locks,

       refresh <name>

              Refreshes parameters of active mapping <name>.

              Updates parameters of active device <name> without need to
              deactivate the device (and umount filesystem). Currently it
              supports parameters refresh on following devices: LUKS1, LUKS2
              (including authenticated encryption), plain crypt and loopaes.

              Mandatory parametrs are identical to those of an open action
              for respective device type.

              You may change following parameters on all devices
              --perf-same_cpu_crypt, --perf-submit_from_crypt_cpus, --perf-
              no_read_workqueue, --no_write_workqueue and --allow-discards.

              Refreshing device without any optional parameter will refresh
              the device with default setting (respective to device type).

              LUKS2 only:

              --integrity-no-journal parameter affects only LUKS2 devices
              with underlying dm-integrity device.

              Adding option --persistent stores any combination of device
              parameters above in LUKS2 metadata (only after successful
              refresh operation).

              --disable-keyring parameter refreshes a device with volume key
              passed in dm-crypt driver.

       reencrypt <device> or --active-name <name> [<new_name>]

              Run resilient reencryption (LUKS2 device only).

              There are 3 basic modes of operation:

              · device reencryption (reencrypt)

              · device encryption (reencrypt --encrypt)

              · device decryption (reencrypt --decrypt)

              <device> or --active-name <name> is mandatory parameter.

              With <device> parameter cryptsetup looks up active <device> dm
              mapping.  If no active mapping is detected, it starts offline
              reencryption otherwise online reencryption takes place.

              Reencryption process may be safely interrupted by a user via
              SIGTERM signal (ctrl+c).

              To resume already initialized or interrupted reencryption,
              just run the cryptsetup reencrypt command again to continue
              the reencryption operation.  Reencryption may be resumed with
              different --resilience or --hotzone-size unless implicit
              datashift resilience mode is used (reencrypt --encrypt with
              --reduce-device-size option).

              If the reencryption process was interrupted abruptly
              (reencryption process crash, system crash, poweroff) it may
              require recovery. The recovery is currently run automatically
              on next activation (action open) when needed.

              Optional parameter <new_name> takes effect only with --encrypt
              option and it activates device <new_name> immediately after
              encryption initialization gets finished. That's useful when
              device needs to be ready as soon as possible and mounted
              (used) before full data area encryption is completed.

              Action supports following additional <options> [--encrypt,
              --decrypt, --device-size, --resilience, --resilience-hash,
              --hotzone-size, --init-only, --resume-only,
              --reduce-device-size, --master-key-file, --key-size].

PLAIN MODE         top

       Plain dm-crypt encrypts the device sector-by-sector with a single,
       non-salted hash of the passphrase. No checks are performed, no
       metadata is used. There is no formatting operation.  When the raw
       device is mapped (opened), the usual device operations can be used on
       the mapped device, including filesystem creation.  Mapped devices
       usually reside in /dev/mapper/<name>.

       The following are valid plain device type actions:

       open --type plain <device> <name>
       create <name> <device> (OBSOLETE syntax)

              Opens (creates a mapping with) <name> backed by device

              <options> can be [--hash, --cipher, --verify-passphrase,
              --sector-size, --key-file, --keyfile-offset, --key-size,
              --offset, --skip, --size, --readonly, --shared,
              --allow-discards, --refresh]

              Example: 'cryptsetup open --type plain /dev/sda10 e1' maps the
              raw encrypted device /dev/sda10 to the mapped (decrypted)
              device /dev/mapper/e1, which can then be mounted, fsck-ed or
              have a filesystem created on it.

LUKS EXTENSION         top

       LUKS, the Linux Unified Key Setup, is a standard for disk encryption.
       It adds a standardized header at the start of the device, a key-slot
       area directly behind the header and the bulk data area behind that.
       The whole set is called a 'LUKS container'.  The device that a LUKS
       container resides on is called a 'LUKS device'.  For most purposes,
       both terms can be used interchangeably. But note that when the LUKS
       header is at a nonzero offset in a device, then the device is not a
       LUKS device anymore, but has a LUKS container stored in it at an

       LUKS can manage multiple passphrases that can be individually revoked
       or changed and that can be securely scrubbed from persistent media
       due to the use of anti-forensic stripes. Passphrases are protected
       against brute-force and dictionary attacks by PBKDF2, which
       implements hash iteration and salting in one function.

       LUKS2 is a new version of header format that allows additional
       extensions like different PBKDF algorithm or authenticated
       encryption.  You can format device with LUKS2 header if you specify
       --type luks2 in luksFormat command.  For activation, the format is
       already recognized automatically.

       Each passphrase, also called a key in this document, is associated
       with one of 8 key-slots.  Key operations that do not specify a slot
       affect the first slot that matches the supplied passphrase or the
       first empty slot if a new passphrase is added.

       The <device> parameter can also be specified by a LUKS UUID in the
       format UUID=<uuid>. Translation to real device name uses symlinks in
       /dev/disk/by-uuid directory.

       To specify a detached header, the --header parameter can be used in
       all LUKS commands and always takes precedence over the positional
       <device> parameter.

       The following are valid LUKS actions:

       luksFormat <device> [<key file>]

              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 can only call luksFormat on a LUKS device that is not

              To use LUKS2, specify --type luks2.

              <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, --master-key-file,
              --iter-time, --header, --pbkdf-force-iterations,
              --force-password, --disable-locks].

              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].

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

       open --type luks <device> <name>
       luksOpen <device> <name> (old syntax)

              Opens the LUKS device <device> and sets up a mapping <name>
              after successful verification of the supplied passphrase.

              First, the passphrase is searched in LUKS tokens. If it's not
              found in any token and also the passphrase is not supplied via
              --key-file, the command prompts for it interactively.

              <options> can be [--key-file, --keyfile-offset,
              --keyfile-size, --readonly, --test-passphrase,
              --allow-discards, --header, --key-slot, --master-key-file,
              --token-id, --token-only, --disable-keyring, --disable-locks,
              --type, --refresh, --serialize-memory-hard-pbkdf].

       luksSuspend <name>

              Suspends an active device (all IO operations will block and
              accesses to the device will wait indefinitely) and wipes the
              encryption key from kernel memory. Needs kernel 2.6.19 or

              After this operation you have to use luksResume to reinstate
              the encryption key and unblock the device or close to remove
              the mapped device.

              WARNING: never suspend the device on which the cryptsetup
              binary resides.

              <options> can be [--header, --disable-locks].

       luksResume <name>

              Resumes a suspended device and reinstates the encryption key.
              Prompts interactively for a passphrase if --key-file is not

              <options> can be [--key-file, --keyfile-size, --header,
              --disable-keyring, --disable-locks, --type]

       luksAddKey <device> [<key file with new key>]

              Adds a new passphrase. An existing passphrase must be supplied
              interactively or via --key-file.  The new passphrase to be
              added can be specified interactively or read from the file
              given as positional argument.

              NOTE: with --unbound option the action creates new unbound
              LUKS2 keyslot. The keyslot cannot be used for device
              activation.  If you don't pass new key via --master-key-file
              option, new random key is generated. Existing passphrase for
              any active keyslot is not required.

              <options> can be [--key-file, --keyfile-offset,
              --keyfile-size, --new-keyfile-offset, --new-keyfile-size,
              --key-slot, --master-key-file, --force-password, --header,
              --disable-locks, --iter-time, --pbkdf,
              --pbkdf-force-iterations, --unbound, --type, --keyslot-cipher,

       luksRemoveKey <device> [<key file with passphrase to be removed>]

              Removes the supplied passphrase from the LUKS device. The
              passphrase to be removed can be specified interactively, as
              the positional argument or via --key-file.

              <options> can be [--key-file, --keyfile-offset,
              --keyfile-size, --header, --disable-locks, --type]

              WARNING: If you read the passphrase from stdin (without
              further argument or with '-' as an argument to --key-file),
              batch-mode (-q) will be implicitly switched on and no warning
              will be given when you remove the last remaining passphrase
              from a LUKS container. Removing the last passphrase makes the
              LUKS container permanently inaccessible.

       luksChangeKey <device> [<new key file>]

              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
              positional argument.

              If a key-slot is specified (via --key-slot), the passphrase
              for that key-slot must be given and the new passphrase will
              overwrite the specified key-slot. If no key-slot is specified
              and there is still a free key-slot, then the new passphrase
              will be put into a free key-slot before the key-slot
              containing the old passphrase is purged. If there is no free
              key-slot, then the key-slot with the old passphrase is
              overwritten directly.

              WARNING: If a key-slot is overwritten, a media failure during
              this operation can cause the overwrite to fail after the old
              passphrase has been wiped and make the LUKS container

              <options> can be [--key-file, --keyfile-offset,
              --keyfile-size, --new-keyfile-offset, --iter-time, --pbkdf,
              --pbkdf-force-iterations, --new-keyfile-size, --key-slot,
              --force-password, --header, --disable-locks, --type,
              --keyslot-cipher, --keyslot-key-size].

       luksConvertKey <device>

              Converts an existing LUKS2 keyslot to new pbkdf parameters.
              The passphrase for keyslot to be converted must be supplied
              interactively or via --key-file. If no --pbkdf parameters are
              specified LUKS2 default pbkdf values will apply.

              If a keyslot is specified (via --key-slot), the passphrase for
              that keyslot must be given. If no keyslot is specified and
              there is still a free keyslot, then the new parameters will be
              put into a free keyslot before the keyslot containing the old
              parameters is purged. If there is no free keyslot, then the
              keyslot with the old parameters is overwritten directly.

              WARNING: If a keyslot is overwritten, a media failure during
              this operation can cause the overwrite to fail after the old
              parameters have been wiped and make the LUKS container

              <options> can be [--key-file, --keyfile-offset,
              --keyfile-size, --key-slot, --header, --disable-locks, --iter-
              time, --pbkdf, --pbkdf-force-iterations, --pbkdf-memory,
              --pbkdf-parallel, --keyslot-cipher, --keyslot-key-size].

       luksKillSlot <device> <key slot number>

              Wipe the key-slot number <key slot> from the LUKS device.
              Except running in batch-mode (-q) a remaining passphrase must
              be supplied, either interactively or via --key-file.  This
              command can remove the last remaining key-slot, but requires
              an interactive confirmation when doing so. Removing the last
              passphrase makes a LUKS container permanently inaccessible.

              <options> can be [--key-file, --keyfile-offset,
              --keyfile-size, --header, --disable-locks, --type].

              WARNING: If you read the passphrase from stdin (without
              further argument or with '-' as an argument to --key-file),
              batch-mode (-q) will be implicitly switched on and no warning
              will be given when you remove the last remaining passphrase
              from a LUKS container. Removing the last passphrase makes the
              LUKS container permanently inaccessible.

              NOTE: If there is no passphrase provided (on stdin or through
              --key-file argument) and batch-mode (-q) is active, the key-
              slot is removed without any other warning.

       erase <device>
       luksErase <device>

              Erase all keyslots and make the LUKS container permanently
              inaccessible.  You do not need to provide any password for
              this operation.

              WARNING: This operation is irreversible.

       luksUUID <device>

              Print the UUID of a LUKS device.
              Set new UUID if --uuid option is specified.

       isLuks <device>

              Returns true, if <device> is a LUKS device, false otherwise.
              Use option -v to get human-readable feedback. 'Command
              successful.'  means the device is a LUKS device.

              By specifying --type you may query for specific LUKS version.

       luksDump <device>

              Dump the header information of a LUKS device.

              If the --dump-master-key option is used, the LUKS device
              master key is dumped instead of the keyslot info. Together
              with --master-key-file option, master key is dumped to a file
              instead of standard output. Beware that the master key cannot
              be changed without reencryption and can be used to decrypt the
              data stored in the LUKS container without a passphrase and
              even without the LUKS header. This means that if the master
              key is compromised, the whole device has to be erased or
              reencrypted to prevent further access. Use this option

              To dump the master key, a passphrase has to be supplied,
              either interactively or via --key-file.

              To dump unbound key (LUKS2 format only), --unbound parameter,
              specific --key-slot id and proper passphrase has to be
              supplied, either interactively or via --key-file.  Optional
              --master-key-file parameter enables unbound keyslot dump to a

              <options> can be [--dump-master-key, --key-file,
              --keyfile-offset, --keyfile-size, --header, --disable-locks,
              --master-key-file, --type, --unbound, --key-slot].

              WARNING: If --dump-master-key is used with --key-file and the
              argument to --key-file is '-', no validation question will be
              asked and no warning given.

       luksHeaderBackup <device> --header-backup-file <file>

              Stores a binary backup of the LUKS header and keyslot area.
              Note: Using '-' as filename writes the header backup to a file
              named '-'.

              WARNING: This backup file and a passphrase valid at the time
              of backup allows decryption of the LUKS data area, even if the
              passphrase was later changed or removed from the LUKS device.
              Also note that with a header backup you lose the ability to
              securely wipe the LUKS device by just overwriting the header
              and key-slots. You either need to securely erase all header
              backups in addition or overwrite the encrypted data area as
              well.  The second option is less secure, as some sectors can
              survive, e.g. due to defect management.

       luksHeaderRestore <device> --header-backup-file <file>

              Restores a binary backup of the LUKS header and keyslot area
              from the specified file.
              Note: Using '-' as filename reads the header backup from a
              file named '-'.

              WARNING: Header and keyslots will be replaced, only the
              passphrases from the backup will work afterward.

              This command requires that the master key size and data offset
              of the LUKS header already on the device and of the header
              backup match. Alternatively, if there is no LUKS header on the
              device, the backup will also be written to it.

       token <add|remove|import|export> <device>

              Action add creates new keyring token to enable auto-activation
              of the device.  For the auto-activation, the passphrase must
              be stored in keyring with the specified description. Usually,
              the passphrase should be stored in user or user-session
              keyring.  The token command is supported only for LUKS2.

              For adding new keyring token, option --key-description is
              mandatory.  Also, new token is assigned to key slot specified
              with --key-slot option or to all active key slots in the case
              --key-slot option is omitted.

              To remove existing token, specify the token ID which should be
              removed with --token-id option.

              WARNING: The action token remove removes any token type, not
              just keyring type from token slot specified by --token-id

              Action import can store arbitrary valid token json in LUKS2
              header. It may be passed via standard input or via file passed
              in --json-file option. If you specify --key-slot then
              successfully imported token is also assigned to the key slot.

              Action export writes requested token json to a file passed
              with --json-file or to standard output.

              <options> can be [--header, --token-id, --key-slot,
              --key-description, --disable-locks, --disable-keyring,

       convert <device> --type <format>

              Converts the device between LUKS1 and LUKS2 format (if
              possible).  The conversion will not be performed if there is
              an additional LUKS2 feature or LUKS1 has unsupported header

              Conversion (both directions) must be performed on inactive
              device. There must not be active dm-crypt mapping established
              for LUKS header requested for conversion.

              --type option is mandatory with following accepted values:
              luks1 or luks2.

              WARNING: The convert action can destroy the LUKS header in the
              case of a crash during conversion or if a media error occurs.
              Always create a header backup before performing this

              <options> can be [--header, --type].

       config <device>

              Set permanent configuration options (store to LUKS header).
              The config command is supported only for LUKS2.

              The permanent options can be --priority to set priority
              (normal, prefer, ignore) for keyslot (specified by --key-slot)
              or --label and --subsystem.

              <options> can be [--priority, --label, --subsystem,
              --key-slot, --header].

loop-AES EXTENSION         top

       cryptsetup supports mapping loop-AES encrypted partition using a
       compatibility mode.

       open --type loopaes <device> <name> --key-file <keyfile>
       loopaesOpen <device> <name> --key-file <keyfile>  (old syntax)

              Opens the loop-AES <device> and sets up a mapping <name>.

              If the key file is encrypted with GnuPG, then you have to use
              --key-file=- and decrypt it before use, e.g. like this:
              gpg --decrypt <keyfile> | cryptsetup loopaesOpen --key-file=-
              <device> <name>

              WARNING: The loop-AES extension cannot use the direct input of
              key file on real terminal because the keys are separated by
              end-of-line and only part of the multi-key file would be read.
              If you need it in script, just use the pipe redirection:
              echo $keyfile | cryptsetup loopaesOpen --key-file=- <device>

              Use --keyfile-size to specify the proper key length if needed.

              Use --offset to specify device offset. Note that the units
              need to be specified in number of 512 byte sectors.

              Use --skip to specify the IV offset. If the original device
              used an offset and but did not use it in IV sector
              calculations, you have to explicitly use --skip 0 in addition
              to the offset parameter.

              Use --hash to override the default hash function for
              passphrase hashing (otherwise it is detected according to key

              <options> can be [--key-file, --key-size, --offset, --skip,
              --hash, --readonly, --allow-discards, --refresh].

       See also section 7 of the FAQ and for
       more information regarding loop-AES.

TCRYPT (TrueCrypt-compatible and VeraCrypt) EXTENSION         top

       cryptsetup supports mapping of TrueCrypt, tcplay or VeraCrypt (with
       --veracrypt option) encrypted partition using a native Linux kernel
       API.  Header formatting and TCRYPT header change is not supported,
       cryptsetup never changes TCRYPT header on-device.

       TCRYPT extension requires kernel userspace crypto API to be available
       (introduced in Linux kernel 2.6.38).  If you are configuring kernel
       yourself, enable "User-space interface for symmetric key cipher
       algorithms" in "Cryptographic API" section (CRYPTO_USER_API_SKCIPHER
       .config option).

       Because TCRYPT header is encrypted, you have to always provide valid
       passphrase and keyfiles.

       Cryptsetup should recognize all header variants, except legacy cipher
       chains using LRW encryption mode with 64 bits encryption block
       (namely Blowfish in LRW mode is not recognized, this is limitation of
       kernel crypto API).

       To recognize a VeraCrypt device use the --veracrypt option.
       VeraCrypt is just extension of TrueCrypt header with increased
       iteration count so unlocking can take quite a lot of time (in
       comparison with TCRYPT device).

       To open a VeraCrypt device with a custom Personal Iteration
       Multiplier (PIM) value, additionally to --veracrypt  use either the
       --veracrypt-pim=<PIM> option to directly specify the PIM on the
       command- line or use --veracrypt-query-pim to be prompted for the

       The PIM value affects the number of iterations applied during key
       derivation. Please refer to 
       for more detailed information.

       NOTE: Activation with tcryptOpen is supported only for cipher chains
       using LRW or XTS encryption modes.

       The tcryptDump command should work for all recognized TCRYPT devices
       and doesn't require superuser privilege.

       To map system device (device with boot loader where the whole
       encrypted system resides) use --tcrypt-system option.  You can use
       partition device as the parameter (parameter must be real partition
       device, not an image in a file), then only this partition is mapped.

       If you have the whole TCRYPT device as a file image and you want to
       map multiple partition encrypted with system encryption, please
       create loopback mapping with partitions first (losetup -P, see
       losetup(8) man page for more info), and use loop partition as the
       device parameter.

       If you use the whole base device as a parameter, one device for the
       whole system encryption is mapped. This mode is available only for
       backward compatibility with older cryptsetup versions which mapped
       TCRYPT system encryption using the whole device.

       To use hidden header (and map hidden device, if available), use
       --tcrypt-hidden option.

       To explicitly use backup (secondary) header, use --tcrypt-backup

       NOTE: There is no protection for a hidden volume if the outer volume
       is mounted. The reason is that if there were any protection, it would
       require some metadata describing what to protect in the outer volume
       and the hidden volume would become detectable.

       open --type tcrypt <device> <name>
       tcryptOpen <device> <name>  (old syntax)

              Opens the TCRYPT (a TrueCrypt-compatible) <device> and sets up
              a mapping <name>.

              <options> can be [--key-file, --tcrypt-hidden,
              --tcrypt-system, --tcrypt-backup, --readonly,
              --test-passphrase, --allow-discards, --veracrypt,
              --veracrypt-pim, --veracrypt-query-pim].

              The keyfile parameter allows a combination of file content
              with the passphrase and can be repeated. Note that using
              keyfiles is compatible with TCRYPT and is different from LUKS
              keyfile logic.

              WARNING: Option --allow-discards cannot be combined with
              option --tcrypt-hidden. For normal mapping, it can cause the
              destruction of hidden volume (hidden volume appears as unused
              space for outer volume so this space can be discarded).

       tcryptDump <device>

              Dump the header information of a TCRYPT device.

              If the --dump-master-key option is used, the TCRYPT device
              master key is dumped instead of TCRYPT header info. Beware
              that the master key (or concatenated master keys if cipher
              chain is used) can be used to decrypt the data stored in the
              TCRYPT container without a passphrase.  This means that if the
              master key is compromised, the whole device has to be erased
              to prevent further access. Use this option carefully.

              <options> can be [--dump-master-key, --key-file,
              --tcrypt-hidden, --tcrypt-system, --tcrypt-backup].

              The keyfile parameter allows a combination of file content
              with the passphrase and can be repeated.

       See also for more information
       regarding TrueCrypt.

       Please note that cryptsetup does not use TrueCrypt code, please
       report all problems related to this compatibility extension to the
       cryptsetup project.

BITLK (Windows BitLocker-compatible) EXTENSION (EXPERIMENTAL)         top

       cryptsetup supports mapping of BitLocker and BitLocker to Go
       encrypted partition using a native Linux kernel API.  Header
       formatting and BITLK header changes are not supported, cryptsetup
       never changes BITLK header on-device.

       WARNING: This extension is EXPERIMENTAL.

       BITLK extension requires kernel userspace crypto API to be available
       (for details see TCRYPT section).

       Cryptsetup should recognize all BITLK header variants, except legacy
       header used in Windows Vista systems and partially decrypted
       BitLocker devices.  Activation of legacy devices encrypted in CBC
       mode requires at least Linux kernel version 5.3 and for devices using
       Elephant diffuser kernel 5.6.

       The bitlkDump command should work for all recognized BITLK devices
       and doesn't require superuser privilege.

       For unlocking with the open a password or a recovery passphrase must
       be provided. Other unlocking methods (TPM, SmartCard) are not

       open --type bitlk <device> <name>
       bitlkOpen <device> <name>  (old syntax)

              Opens the BITLK (a BitLocker-compatible) <device> and sets up
              a mapping <name>.

              <options> can be [--key-file, --readonly, --test-passphrase,

       bitlkDump <device>

              Dump the header information of a BITLK device.

              Please note that cryptsetup does not use any Windows BitLocker
              code, please report all problems related to this compatibility
              extension to the cryptsetup project.


       repair <device>

              Tries to repair the device metadata if possible. Currently
              supported only for LUKS device type.

              This command is useful to fix some known benign LUKS metadata
              header corruptions. Only basic corruptions of unused keyslot
              are fixable. This command will only change the LUKS header,
              not any key-slot data. You may enforce LUKS version by adding
              --type option.

              WARNING: Always create a binary backup of the original header
              before calling this command.

       benchmark <options>

              Benchmarks ciphers and KDF (key derivation function).  Without
              parameters, it tries to measure few common configurations.

              To benchmark other ciphers or modes, you need to specify
              --cipher and --key-size options or --hash for KDF test.

              NOTE: This benchmark is using memory only and is only
              informative.  You cannot directly predict real storage
              encryption speed from it.

              For testing block ciphers, this benchmark requires kernel
              userspace crypto API to be available (introduced in Linux
              kernel 2.6.38).  If you are configuring kernel yourself,
              enable "User-space interface for symmetric key cipher
              algorithms" in "Cryptographic API" section
              (CRYPTO_USER_API_SKCIPHER .config option).

              <options> can be [--cipher, --key-size, --hash].

OPTIONS         top

       --verbose, -v
              Print more information on command execution.

       --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.

       --type <device-type>
              Specifies required device type, for more info read BASIC
              COMMANDS section.

       --hash, -h <hash-spec>
              Specifies the passphrase hash for open (for plain and loopaes
              device types).

              Specifies the hash used in the LUKS key setup scheme and
              volume key digest for luksFormat. The specified hash is used
              as hash-parameter for PBKDF2 and for the AF splitter.

              The specified hash name is passed to the compiled-in crypto
              backend.  Different backends may support different hashes.
              For luksFormat, the hash algorithm must provide at least 160
              bits of output, which excludes, e.g., MD5. Do not use a non-
              crypto hash like "crc32" as this breaks security.

              Values compatible with old version of cryptsetup are
              "ripemd160" for open --type plain and "sha1" for luksFormat.

              Use cryptsetup --help to show the defaults.

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

              cryptsetup --help shows the compiled-in defaults.  The current
              default in the distributed sources is "aes-cbc-essiv:sha256"
              for plain dm-crypt and "aes-xts-plain64" for LUKS.

              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

              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.

              XTS mode requires kernel 2.6.24 or later and plain64 requires
              kernel 2.6.33 or later. More information can be found in the

       --verify-passphrase, -y
              When interactively asking for a passphrase, ask for it twice
              and complain if both inputs do not match. Advised when
              creating a regular mapping for the first time, or when running
              luksFormat. Ignored on input from file or stdin.

       --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

              With LUKS, passphrases supplied via --key-file are always the
              existing passphrases requested by a command, except in the
              case of luksFormat where --key-file is equivalent to the
              positional key file argument.

              If you want to set a new passphrase via key file, you have to
              use a positional argument to luksAddKey.

              See section NOTES ON PASSPHRASE PROCESSING for more

       --keyfile-offset value
              Skip value bytes at the beginning of the key file.  Works with
              all commands that accept key files.

       --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.  Works with all commands that accept key files.

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

       --new-keyfile-size  value
              Read a maximum of value bytes when adding a new passphrase
              from key file with luksAddKey.  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.

              Use a master key stored in a file.

              For luksFormat this allows creating a LUKS header with this
              specific master key. If the master key was taken from an
              existing LUKS header and all other parameters are the same,
              then the new header decrypts the data encrypted with the
              header the master key was taken from.

              Action luksDump together with --dump-master-key option: The
              volume (master) key is stored in a file instead of being
              printed out to standard output.

              WARNING: If you create your own master key, you need to make
              sure to do it right. Otherwise, you can end up with a low-
              entropy or otherwise partially predictable master key which
              will compromise security.

              For luksAddKey this allows adding a new passphrase without
              having to know an existing one.

              For open this allows one to open the LUKS device without
              giving a passphrase.

              For luksDump this option includes the master key in the
              displayed information. Use with care, as the master key can be
              used to bypass the passphrases, see also option

              Read token json from a file or write token to it. See token
              action for more information. --json-file=- reads json from
              standard input or writes it to standard output respectively.


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

              See NOTES ON RANDOM NUMBER GENERATORS 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), 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.

       --key-slot, -S <0-7>
              For LUKS operations that add key material, this options allows
              you to specify which key slot is selected for the new key.
              This option can be used for luksFormat, and luksAddKey.
              In addition, for open, this option selects a specific key-slot
              to compare the passphrase against.  If the given passphrase
              would only match a different key-slot, the operation fails.

       --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

              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

       --size, -b <number of 512 byte sectors>
              Set the size of the device in sectors of 512 bytes.  This
              option is only relevant for the open and resize actions.

       --offset, -o <number of 512 byte sectors>
              Start offset in the backend device in 512-byte sectors.  This
              option is only relevant for the open action with plain or
              loopaes device types or for LUKS devices in luksFormat.

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

       --skip, -p <number of 512 byte sectors>
              Start offset used in IV calculation in 512-byte sectors (how
              many sectors of the encrypted data to skip at the beginning).
              This option is only relevant for the open action with plain or
              loopaes device types.

              Hence, if --offset n, and --skip s, sector n (the first sector
              of the encrypted device) will get a sector number of s for the
              IV calculation.

       --device-size size[units]
              Instead of real device size, use specified value.

              With reencrypt action it means that only specified area (from
              the start of the device to the specified size) will be

              With resize action it sets new size of the device.

              If no unit suffix is specified, the size is in bytes.

              Unit suffix can be S for 512 byte sectors, K/M/G/T (or
              KiB,MiB,GiB,TiB) for units with 1024 base or KB/MB/GB/TB for
              1000 base (SI scale).

              WARNING: This is destructive operation when used with
              reencrypt command.

       --readonly, -r
              set up a read-only mapping.

              Creates an additional mapping for one common ciphertext
              device. Arbitrary mappings are supported.  This option is only
              relevant for the open --type plain action. Use --offset,
              --size and --skip to specify the mapped area.

       --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 for
              more info).

              For LUKS1, only PBKDF2 is accepted (no need to use this
              option).  The default PBKDF2 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

              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, is is checked against available
              CPU cores (if not available, it is decreased) and the maximum
              parallel cost is 4.

              You can see all PBKDF parameters for particular LUKS2 keyslot
              with luksDump 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 is specified cases, for example, if
              you know that the formatted device will be used on some small
              embedded system.  In this case, the LUKS PBKDF2 digest will be
              set to the minimum iteration count.

       --iter-time, -i <number of milliseconds>
              The number of milliseconds to spend with PBKDF passphrase
              processing.  This option is only relevant for LUKS operations
              that set or change passphrases, such as luksFormat or
              luksAddKey.  Specifying 0 as parameter selects the compiled-in

       --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.

       --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.

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

              If the -y option is not specified, this option also switches
              off the passphrase verification for luksFormat.

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

       --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, for example for open, luksFormat or luksAddKey.  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.

       --tries, -T
              How often the input of the passphrase shall be retried.  This
              option is relevant every time a passphrase is asked, for
              example for open, luksFormat or luksAddKey.  The default is 3

       --align-payload <number of 512 byte sectors>
              Align payload at a boundary of value 512-byte sectors.  This
              option is relevant for luksFormat.

              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.

              Allow the use of discard (TRIM) requests for the device.  This
              option is only relevant for open action.  This is also not
              supported for LUKS2 devices with data integrity protection.

              WARNING: This command can have a negative security impact
              because it can make filesystem-level operations visible on the
              physical device. For example, information leaking filesystem
              type, used space, etc. may be extractable from the physical
              device if the discarded blocks can be located later. If in
              doubt, do not use it.

              A kernel version of 3.1 or later is needed. For earlier
              kernels, this option is ignored.

              Perform encryption using the same cpu that IO was submitted
              on.  The default is to use an unbound workqueue so that
              encryption work is automatically balanced between available
              CPUs.  This option is only relevant for open action.

              NOTE: This option is available only for low-level dm-crypt
              performance tuning, use only if you need a change to default
              dm-crypt behaviour. Needs kernel 4.0 or later.

              Disable offloading writes to a separate thread after
              encryption.  There are some situations where offloading write
              bios from the encryption threads to a single thread degrades
              performance significantly.  The default is to offload write
              bios to the same thread.  This option is only relevant for
              open action.

              NOTE: This option is available only for low-level dm-crypt
              performance tuning, use only if you need a change to default
              dm-crypt behaviour. Needs kernel 4.0 or later.

       --perf-no_read_workqueue, --perf-no_write_workqueue
              Bypass dm-crypt internal workqueue and process read or write
              requests synchronously.  This option is only relevant for open

              NOTE: These options are available only for low-level dm-crypt
              performance tuning, use only if you need a change to default
              dm-crypt behaviour. Needs kernel 5.9 or later.

              Do not activate the device, just verify passphrase.  This
              option is only relevant for open action (the device mapping
              name is not mandatory if this option is used).

       --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.

              This option is only relevant for LUKS devices and can be used
              with the luksFormat, open, luksSuspend, luksResume, status and
              resize commands.

              For luksFormat 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.

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

              If used with luksFormat, the --align-payload option is taken
              as absolute sector alignment on ciphertext device and can be

              WARNING: There is no check whether the ciphertext device
              specified actually belongs to the header given. In fact, you
              can specify an arbitrary device as the ciphertext device for
              open with the --header option. Use with care.

       --header-backup-file <file>
              Specify file with header backup for luksHeaderBackup or
              luksHeaderRestore actions.

              Do not use password quality checking for new LUKS passwords.

              This option applies only to luksFormat, luksAddKey and
              luksChangeKey and 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).

              Defers device removal in close command until the last user
              closes it.

              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 format.

       --key-description <text>
              Set key description in keyring for use with token command.

       --priority <normal|prefer|ignore>
              Set a priority for LUKS2 keyslot.  The prefer priority marked
              slots are tried before normal priority.  The ignored priority
              means, that slot is never used, if not explicitly requested by
              --key-slot option.

              Specify what token to use in actions token, open or resize.
              If omitted, all available tokens will be checked before
              proceeding further with passphrase prompt.

              Do not proceed further with action (any of token, open or
              resize) if token activation failed. Without the option, action
              asks for passphrase to proceed further.

       --sector-size <bytes>
              Set sector size for use with disk encryption. It must be power
              of two and in range 512 - 4096 bytes. The default is 512 bytes
              sectors.  This option is available only in the LUKS2 mode.

              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

              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.

              Count Initialization Vector (IV) in larger sector size (if
              set) instead of 512 bytes sectors. This option can be used
              only for open command and plain encryption type.

              NOTE: This option does not have any performance or security
              impact, use it only for accessing incompatible existing disk
              images from other systems that require this option.

              If used with LUKS2 devices and activation commands like open
              or refresh, the specified activation flags are persistently
              written into metadata and used next time automatically even
              for normal activation.  (No need to use cryptab or other
              system configuration files.)

              If you need to remove a persistent flag, use --persistent
              without the flag you want to remove (e.g. to disable
              persistently stored discard flag, use --persistent without

              Only --allow-discards, --perf-same_cpu_crypt,
              --perf-submit_from_crypt_cpus, --perf-no_read_workqueue,
              --perf-no_write_workqueue and --integrity-no-journal can be
              stored persistently.

              Refreshes an active device with new set of parameters. See
              action refresh description for more details.

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

       --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.

       --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).

       --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).

       --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.

              Activate device with integrity protection without using data
              journal (direct write of data and integrity tags).  Note that
              without journal power fail can cause non-atomic write and data
              corruption.  Use only if journalling is performed on a
              different storage layer.

              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.


              Creates new or dumps existing LUKS2 unbound keyslot. See
              luksAddKey or luksDump actions for more details.

              --tcrypt-system --tcrypt-backup Specify which TrueCrypt on-
              disk header will be used to open the device.  See TCRYPT
              section for more info.

              Allow VeraCrypt compatible mode. Only for TCRYPT extension.
              See TCRYPT section for more info.

              --veracrypt-query-pim Use a custom Personal Iteration
              Multiplier (PIM) for VeraCrypt device.  See TCRYPT section for
              more info.

              Use a global lock to serialize unlocking of keyslots using
              memory-hard PBKDF.

              NOTE: This is (ugly) workaround for a specific situation when
              multiple devices are activated in parallel and system instead
              of reporting out of memory starts unconditionally stop
              processes using out-of-memory killer.

              DO NOT USE this switch until you are implementing boot
              environment with parallel devices activation!

              Initialize (and run) device encryption (reencrypt action

              Initialize (and run) device decryption (reencrypt action

              Initialize reencryption (any variant) operation in LUKS2
              metadata only and exit. If any reencrypt operation is already
              initialized in metadata, the command with --init-only
              parameter fails.

              Resume reencryption (any variant) operation already described
              in LUKS2 metadata. If no reencrypt operation is initialized,
              the command with --resume-only parameter fails. Useful for
              resuming reencrypt operation without accidentally triggering
              new reencryption operation.

       --resilience <mode>
              Reencryption resilience mode can be one of checksum, journal
              or none.

              checksum: default mode, where individual checksums of
              ciphertext hotzone sectors are stored, so the recovery process
              can detect which sectors where already reencrypted. It
              requires that the device sector write is atomic.

              journal: the hotzone is journaled in the binary area (so the
              data are written twice).

              none: performance mode. There is no protection and the only
              way it's safe to interrupt the reencryption is similar to old
              offline reencryption utility. (ctrl+c).

              The option is ignored if reencryption with datashift mode is
              in progress.

       --resilience-hash <hash>
              The hash algorithm used with "--resilience checksum" only. The
              default hash is sha256. With other resilience modes, the hash
              parameter is ignored.

       --hotzone-size <size>
              This option can be used to set an upper limit on the size of
              reencryption area (hotzone).  The <size> can be specified with
              unit suffix (for example 50M). Note that actual hotzone size
              may be less than specified <size> due to other limitations
              (free space in keyslots area or available memory).

       --reduce-device-size <size>
              Initialize LUKS2 reencryption with data device size reduction
              (currently only --encrypt variant is supported).

              Last <size> sectors of <device> will be used to properly
              initialize device reencryption. That means any data at last
              <size> sectors will be lost.

              It could be useful if you added some space to underlying
              partition or logical volume (so last <size> sectors contains
              no data).

              Recommended minimal size is twice the default LUKS2 header
              size (--reduce-device-size 32M) for --encrypt use case. Be
              sure to have enough (at least --reduce-device-size value of
              free space at the end of <device>).

              WARNING: This is a destructive operation and cannot be
              reverted.  Use with extreme care - accidentally overwritten
              filesystems are usually unrecoverable.

              Show the program version.

              Show short option help.

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

RETURN CODES         top

       Cryptsetup returns 0 on success and a non-zero value on error.

       Error codes are: 1 wrong parameters, 2 no permission (bad
       passphrase), 3 out of memory, 4 wrong device specified, 5 device
       already exists or device is busy.


       Note that no iterated hashing or salting is done in plain mode.  If
       hashing is done, it is a single direct hash. This means that low-
       entropy passphrases are easy to attack in plain mode.

       From a terminal: The passphrase is read until the first newline, i.e.
       '\n'.  The input without the newline character is processed with the
       default hash or the hash specified with --hash.  The hash result will
       be truncated to the key size of the used cipher, or the size
       specified with -s.

       From stdin: Reading will continue until a newline (or until the
       maximum input size is reached), with the trailing newline stripped.
       The maximum input size is defined by the same compiled-in default as
       for the maximum key file size and can be overwritten using --keyfile-
       size option.

       The data read will be hashed with the default hash or the hash
       specified with --hash.  The hash result will be truncated to the key
       size of the used cipher, or the size specified with -s.

       Note that if --key-file=- is used for reading the key from stdin,
       trailing newlines are not stripped from the input.

       If "plain" is used as argument to --hash, the input data will not be
       hashed. Instead, it will be zero padded (if shorter than the key
       size) or truncated (if longer than the key size) and used directly as
       the binary key. This is useful for directly specifying a binary key.
       No warning will be given if the amount of data read from stdin is
       less than the key size.

       From a key file: It will be truncated to the key size of the used
       cipher or the size given by -s and directly used as a binary key.

       WARNING: The --hash argument is being ignored.  The --hash option is
       usable only for stdin input in plain mode.

       If the key file is shorter than the key, cryptsetup will quit with an
       error.  The maximum input size is defined by the same compiled-in
       default as for the maximum key file size and can be overwritten using
       --keyfile-size option.


       LUKS uses PBKDF2 to protect against dictionary attacks and to give
       some protection to low-entropy passphrases (see RFC 2898 and the
       cryptsetup FAQ).

       From a terminal: The passphrase is read until the first newline and
       then processed by PBKDF2 without the newline character.

       From stdin: LUKS will read passphrases from stdin up to the first
       newline character or the compiled-in maximum key file length. If
       --keyfile-size is given, it is ignored.

       From key file: The complete keyfile is read up to the compiled-in
       maximum size. Newline characters do not terminate the input. The
       --keyfile-size option can be used to limit what is read.

       Passphrase processing: Whenever a passphrase is added to a LUKS
       header (luksAddKey, luksFormat), the user may specify how much the
       time the passphrase processing should consume. The time is used to
       determine the iteration count for PBKDF2 and higher times will offer
       better protection for low-entropy passphrases, but open will take
       longer to complete. For passphrases that have entropy higher than the
       used key length, higher iteration times will not increase security.

       The default setting of one or two seconds is sufficient for most
       practical cases. The only exception is a low-entropy passphrase used
       on a device with a slow CPU, as this will result in a low iteration
       count. On a slow device, it may be advisable to increase the
       iteration time using the --iter-time option in order to obtain a
       higher iteration count. This does slow down all later luksOpen
       operations accordingly.


       LUKS checks for a valid passphrase when an encrypted partition is
       unlocked. The behavior of plain dm-crypt is different.  It will
       always decrypt with the passphrase given. If the given passphrase is
       wrong, the device mapped by plain dm-crypt will essentially still
       contain encrypted data and will be unreadable.


       The available combinations of ciphers, modes, hashes and key sizes
       depend on kernel support. See /proc/crypto for a list of available
       options. You might need to load additional kernel crypto modules in
       order to get more options.

       For the --hash option, if the crypto backend is libgcrypt, then all
       algorithms supported by the gcrypt library are available.  For other
       crypto backends, some algorithms may be missing.


       Mathematics can't be bribed. Make sure you keep your passphrases
       safe.  There are a few nice tricks for constructing a fallback, when
       suddenly out of the blue, your brain refuses to cooperate.  These
       fallbacks need LUKS, as it's only possible with LUKS to have multiple
       passphrases. Still, if your attacker model does not prevent it,
       storing your passphrase in a sealed envelope somewhere may be a good
       idea as well.


       Random Number Generators (RNG) used in cryptsetup are always the
       kernel RNGs without any modifications or additions to data stream

       There are two types of randomness cryptsetup/LUKS needs. One type
       (which always uses /dev/urandom) is used for salts, the AF splitter
       and for wiping deleted keyslots.

       The second type is used for the volume (master) key. You can switch
       between using /dev/random and /dev/urandom  here, see --use-random
       and --use-urandom options. Using /dev/random on a system without
       enough entropy sources can cause luksFormat to block until the
       requested amount of random data is gathered. In a low-entropy
       situation (embedded system), this can take a very long time and
       potentially forever. At the same time, using /dev/urandom in a low-
       entropy situation will produce low-quality keys. This is a serious
       problem, but solving it is out of scope for a mere man-page.  See
       urandom(4) for more information.


       Since Linux kernel version 4.12 dm-crypt supports authenticated disk

       Normal disk encryption modes are length-preserving (plaintext sector
       is of the same size as a ciphertext sector) and can provide only
       confidentiality protection, but not cryptographically sound data
       integrity protection.

       Authenticated modes require additional space per-sector for
       authentication tag and use Authenticated Encryption with Additional
       Data (AEAD) algorithms.

       If you configure LUKS2 device with data integrity protection, there
       will be an underlying dm-integrity device, which provides additional
       per-sector metadata space and also provide data journal protection to
       ensure atomicity of data and metadata update.  Because there must be
       additional space for metadata and journal, the available space for
       the device will be smaller than for length-preserving modes.

       The dm-crypt device then resides on top of such a dm-integrity
       device.  All activation and deactivation of this device stack is
       performed by cryptsetup, there is no difference in using luksOpen for
       integrity protected devices.  If you want to format LUKS2 device with
       data integrity protection, use --integrity option.

       Since dm-integrity doesn't support discards (TRIM), dm-crypt device
       on top of it inherits this, so integrity protection mode doesn't
       support discards either.

       Some integrity modes requires two independent keys (key for
       encryption and for authentication). Both these keys are stored in one
       LUKS keyslot.

       WARNING: All support for authenticated modes is experimental and
       there are only some modes available for now. Note that there are a
       very few authenticated encryption algorithms that are suitable for
       disk encryption.


       Cryptsetup is usually used directly on a block device (disk partition
       or LVM volume). However, if the device argument is a file, cryptsetup
       tries to allocate a loopback device and map it into this file. This
       mode requires Linux kernel 2.6.25 or more recent which supports the
       loop autoclear flag (loop device is cleared on the last close
       automatically). Of course, you can always map a file to a loop-device
       manually. See the cryptsetup FAQ for an example.

       When device mapping is active, you can see the loop backing file in
       the status command output. Also see losetup(8).

LUKS2 header locking         top

       The LUKS2 on-disk metadata is updated in several steps and to achieve
       proper atomic update, there is a locking mechanism.  For an image in
       file, code uses flock(2) system call.  For a block device, lock is
       performed over a special file stored in a locking directory (by
       default /run/lock/cryptsetup).  The locking directory should be
       created with the proper security context by the distribution during
       the boot-up phase.  Only LUKS2 uses locks, other formats do not use
       this mechanism.


       The reload action is no longer supported.  Please use dmsetup(8) if
       you need to directly manipulate with the device mapping table.

       The luksDelKey was replaced with luksKillSlot.

REPORTING BUGS         top

       Report bugs, including ones in the documentation, on the cryptsetup
       mailing list at <> or in the 'Issues' section on
       LUKS website.  Please attach the output of the failed command with
       the --debug option added.

AUTHORS         top

       cryptsetup originally written by Jana Saout <>
       The LUKS extensions and original man page were written by Clemens
       Fruhwirth <>.
       Man page extensions by Milan Broz <>.
       Man page rewrite and extension by Arno Wagner <>.

COPYRIGHT         top

       Copyright © 2004 Jana Saout
       Copyright © 2004-2006 Clemens Fruhwirth
       Copyright © 2012-2014 Arno Wagner
       Copyright © 2009-2020 Red Hat, Inc.
       Copyright © 2009-2020 Milan Broz

       This is free software; see the source for copying conditions.  There
       is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A

SEE ALSO         top

       The LUKS website at 

       The cryptsetup FAQ, contained in the distribution package and online

       The cryptsetup mailing list and list archive, see FAQ entry 1.6.

       The LUKS on-disk format specification available at 

COLOPHON         top

       This page is part of the Cryptsetup ((open-source disk encryption))
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report
       for this manual page, send it to  This page was
       obtained from the project's upstream Git repository
       ⟨⟩ on 2020-09-18.  (At
       that time, the date of the most recent commit that was found in the
       repository was 2020-09-06.)  If you discover any rendering problems
       in this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

cryptsetup                      January 2019                   CRYPTSETUP(8)

Pages that refer to this page: homectl(1)crypttab(5)cryptsetup-reencrypt(8)fsadm(8)integritysetup(8)systemd-cryptsetup(8)systemd-cryptsetup-generator(8)systemd-cryptsetup.service(8)systemd-cryptsetup@.service(8)systemd-gpt-auto-generator(8)systemd-growfs(8)systemd-growfs.service(8)systemd-growfs@.service(8)systemd-makefs(8)systemd-makefs.service(8)systemd-makefs@.service(8)systemd-mkswap.service(8)systemd-mkswap@.service(8)