cryptsetup(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | PLAIN DM-CRYPT OR LUKS? | WARNINGS | BASIC ACTIONS | PLAIN MODE | LUKS EXTENSION | loop-AES EXTENSION | TCRYPT (TrueCrypt-compatible and VeraCrypt) EXTENSION | BITLK (Windows BitLocker-compatible) EXTENSION (EXPERIMENTAL) | MISCELLANEOUS | OPTIONS | EXAMPLE | RETURN CODES | NOTES ON PASSPHRASE PROCESSING FOR PLAIN MODE | NOTES ON PASSPHRASE PROCESSING FOR LUKS | INCOHERENT BEHAVIOR FOR INVALID PASSPHRASES/KEYS | NOTES ON SUPPORTED CIPHERS, MODES, HASHES AND KEY SIZES | NOTES ON PASSPHRASES | NOTES ON RANDOM NUMBER GENERATORS | AUTHENTICATED DISK ENCRYPTION (EXPERIMENTAL) | NOTES ON LOOPBACK DEVICE USE | LUKS2 header locking | DEPRECATED ACTIONS | REPORTING BUGS | AUTHORS | COPYRIGHT | SEE ALSO | COLOPHON

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.

PLAIN DM-CRYPT OR LUKS?         top

       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 ACTIONS         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>.

              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] or [--cancel-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-external-tokens,
              --disable-locks, --disable-keyring].

       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 parameters 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, --perf-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
              <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 offset.

       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 cannot call luksFormat on a device or filesystem that
              is mapped or in use, e.g. mounted filesysem, used in LVM,
              active RAID member etc.  The device or filesystem has to
              be un-mounted in order to call luksFormat.

              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-external-tokens,
              --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 later.

              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 given.

              <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, --keyslot-key-size].

       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 inaccessible.

              <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 inaccessible.

              <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 carefully.

              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 file.

              To dump LUKS2 JSON metadata (without basic heade
              information like UUID) use --dump-json-metadata option.

              <options> can be [--dump-master-key, --dump-json-metadata,
              --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 option.

              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-external-tokens,
              --disable-locks, --disable-keyring, --json-file].

       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 size.

              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 operation!

              <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> <name>

              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 size).

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

       See also section 7 of the FAQ and http://loop-aes.sourceforge.net 
       for more information regarding loop-AES.

TCRYPT (TrueCrypt-compatible and VeraCrypt) EXTENSION         top

       cryptsetup supports mapping of TrueCrypt, tcplay or VeraCrypt
       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).

       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, 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 PIM.

       The PIM value affects the number of iterations applied during key
       derivation. Please refer to
       https://www.veracrypt.fr/en/Personal%20Iterations%20Multiplier%20%28PIM%29.html 
       for more detailed information.

       If you need to disable VeraCrypt device support, use
       --disable-veracrypt option.

       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
       option.

       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, --disable-veracrypt,
              --veracrypt-pim, --veracrypt-query-pim, --header,
              --cipher, --hash].

              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.

              If --PBKDF2 variants with the specified hash algorithms
              are checked. This could speed up unlocking the device (but
              also it reveals some information about the container).

              If you use --header in combination with hidden or system
              options, the header file must contain specific headers on
              the same positions as the original encrypted container.

              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,
              --cipher, --hash].

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

       See also https://en.wikipedia.org/wiki/TrueCrypt 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
       or a startup key must be provided.

       Additionally unlocking using master key is supported. You must
       provide BitLocker Full Volume Encryption Key (FVEK) using the
       --master-key-file option. The key must be decrypted and without
       the header (only 128/256/512 bits of key data depending on used
       cipher and mode).

       Other unlocking methods (TPM, SmartCard) are not supported.

       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, --allow-discards --master-key-file].

       bitlkDump <device>

              Dump the header information of a BITLK device.

              <options> can be [--dump-master-key --master-key-file].

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

MISCELLANEOUS         top

       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
              ACTIONS 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 specified.

              For XTS mode you can optionally set a key size of 512 bits
              with the -s option. Key size for XTS mode is twice that
              for other modes for the same security level.

              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 FAQ.

       --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 characters.

              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
              information.

       --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.

       --master-key-file
              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.

       --dump-json-metadata
              For luksDump (LUKS2 only) this option prints content of
              LUKS2 header JSON metadata area.

       --dump-master-key
              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
              --master-key-file.

       --json-file
              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.

       --use-random

       --use-urandom
              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 used.

              See /proc/crypto for more information. Note that key-size
              in /proc/crypto is stated in bytes.

              This option can be used for open --type plain or
              luksFormat.  All other LUKS actions will use the key-size
              specified in the LUKS header.  Use cryptsetup --help to
              show the compiled-in defaults.

       --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 reencrypted.

              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.

       --shared
              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
              https://www.cryptolux.org/index.php/Argon2 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
              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, 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 in specific 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 default.

       --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 tries.

       --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.

       --uuid=UUID
              Use the provided UUID for the luksFormat command instead
              of generating a new one. Changes the existing UUID when
              used with the luksUUID command.

              The UUID must be provided in the standard UUID format,
              e.g. 12345678-1234-1234-1234-123456789abc.

       --allow-discards
              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.

       --perf-same_cpu_crypt
              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.

       --perf-submit_from_crypt_cpus
              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 action.

              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.

       --test-passphrase
              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 zero.

              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.

       --force-password
              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).

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

       --cancel-deferred
              Removes a previously configured deferred device removal in
              close command.

       --disable-external-tokens
              Disable loading of plugins for external LUKS2 tokens.

       --disable-locks
              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).

       --disable-keyring
              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.

       --token-id
              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.

       --token-only
              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. This option is
              available only in the LUKS2 or plain modes.

              The default for plain mode is 512 bytes. For LUKS2 devices
              it's established during luksFormat operation based on
              parameters provided by underlying data device.  For native
              4K block devices it's 4096 bytes. For 4K/512e (4K physical
              sector size with 512 bytes emulation) it's 4096 bytes. For
              drives reporting only 512 bytes block size it remains 512
              bytes. If data device is regular file put in filesystem
              it's 4096 bytes.

              Note that if sector size is higher than underlying device
              hardware sector and there is not integrity protection that
              uses data journal, using this option can increase risk on
              incomplete sector writes during a power fail.

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

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

       --iv-large-sectors
              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.

       --persistent
              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
              --allow-discards).

              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.

       --refresh
              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.

       --integrity-no-journal
              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.

       --integrity-no-wipe
              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.

       --unbound

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

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

       --veracrypt
              This option is ignored as VeraCrypt compatible mode is
              supported by default.

       --disable-veracrypt
              This option can be used to disable VeraCrypt compatible
              mode (only TrueCrypt devices are recognized). Only for
              TCRYPT extension. See TCRYPT section for more info.

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

       --serialize-memory-hard-pbkdf
              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!

       --encrypt
              Initialize (and run) device encryption (reencrypt action
              parameter)

       --decrypt
              Initialize (and run) device decryption (reencrypt action
              parameter)

       --init-only
              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-only
              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.

       --version
              Show the program version.

       --usage
              Show short option help.

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

EXAMPLE         top

       Example 1: Create LUKS 2 container on block device /dev/sdX.
              sudo cryptsetup --type luks2 luksFormat /dev/sdX

       Example 2: Add an additional passphrase to key slot 5.
              sudo cryptsetup luksAddKey --key-slot 5 /dev/sdX

       Example 3: Create LUKS header backup and save it to file.
              sudo cryptsetup luksHeaderBackup /dev/sdX --header-backup-
              file /var/tmp/NameOfBackupFile

       Example 4: Open LUKS contaner on /dev/sdX and map it to
       sdX_crypt.
              sudo cryptsetup open /dev/sdX sdX_crypt

       WARNING: The command in example 5 will erase all key slots.
              Your cannot use your luks container afterwards anymore
              unless you have a backup to restore.

       Example 5: Erase all key slots on /dev/sdX.
              sudo cryptsetup erase /dev/sdX

       Example 6: Restore LUKS header from backup file.
              sudo cryptsetup luksHeaderRestore /dev/sdX --header-
              backup-file /var/tmp/NameOfBackupFile

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.

NOTES ON PASSPHRASE PROCESSING FOR PLAIN MODE         top

       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.

NOTES ON PASSPHRASE PROCESSING FOR LUKS         top

       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.

INCOHERENT BEHAVIOR FOR INVALID PASSPHRASES/KEYS         top

       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.

NOTES ON SUPPORTED CIPHERS, MODES, HASHES AND KEY SIZES         top

       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.

NOTES ON PASSPHRASES         top

       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.

NOTES ON RANDOM NUMBER GENERATORS         top

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

       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.

AUTHENTICATED DISK ENCRYPTION (EXPERIMENTAL)         top

       Since Linux kernel version 4.12 dm-crypt supports authenticated
       disk encryption.

       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. You also cannot use CRC32 or any other non-
       cryptographic checksums (other than the special integrity mode
       "none"). If for some reason you want to have integrity control
       without using authentication mode, then you should separately
       configure dm-integrity independently of LUKS2.

NOTES ON LOOPBACK DEVICE USE         top

       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.

DEPRECATED ACTIONS         top

       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 <dm-crypt@saout.de> 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 <jana@saout.de>
       The LUKS extensions and original man page were written by Clemens
       Fruhwirth <clemens@endorphin.org>.
       Man page extensions by Milan Broz <gmazyland@gmail.com>.
       Man page rewrite and extension by Arno Wagner <arno@wagner.name>.

COPYRIGHT         top

       Copyright © 2004 Jana Saout
       Copyright © 2004-2006 Clemens Fruhwirth
       Copyright © 2012-2014 Arno Wagner
       Copyright © 2009-2021 Red Hat, Inc.
       Copyright © 2009-2021 Milan Broz

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

SEE ALSO         top

       The LUKS website at https://gitlab.com/cryptsetup/cryptsetup/ 

       The cryptsetup FAQ, contained in the distribution package and
       online at
       https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions 

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

       The LUKS version 1 on-disk format specification available at
       https://gitlab.com/cryptsetup/cryptsetup/wikis/Specification and
       LUKS version 2 at https://gitlab.com/cryptsetup/LUKS2-docs .

COLOPHON         top

       This page is part of the Cryptsetup ((open-source disk
       encryption)) project.  Information about the project can be found
       at ⟨https://gitlab.com/cryptsetup/cryptsetup⟩.  If you have a bug
       report for this manual page, send it to dm-crypt@saout.de.  This
       page was obtained from the project's upstream Git repository
       ⟨https://gitlab.com/cryptsetup/cryptsetup.git⟩ on 2021-06-20.
       (At that time, the date of the most recent commit that was found
       in the repository was 2021-06-18.)  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
       man-pages@man7.org

cryptsetup                    January 2021                 CRYPTSETUP(8)

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