1CRYPTSETUP(8) Maintenance Commands CRYPTSETUP(8)
2
6 cryptsetup - manage plain dm-crypt and LUKS encrypted volumes
7
9 cryptsetup <options> <action> <action args>
10
12 cryptsetup is used to conveniently setup dm-crypt managed device-mapper
13 mappings. These include plain dm-crypt volumes and LUKS volumes. The
14 difference is that LUKS uses a metadata header and can hence offer more
15 features than plain dm-crypt. On the other hand, the header is visible
16 and vulnerable to damage.
17 In addition, cryptsetup provides limited support for the use of loop-
19 AES volumes, TrueCrypt, VeraCrypt and BitLocker compatible volumes.
20
23 Unless you understand the cryptographic background well, use LUKS.
24 With plain dm-crypt there are a number of possible user errors that
25 massively decrease security. While LUKS cannot fix them all, it can
26 lessen the impact for many of them.
27
29 A lot of good information on the risks of using encrypted storage, on
30 handling problems and on security aspects can be found in the Crypt‐
31 setup FAQ. Read it. Nonetheless, some risks deserve to be mentioned
32 here.
33 Backup: Storage media die. Encryption has no influence on that. Backup
35 is mandatory for encrypted data as well, if the data has any worth. See
36 the Cryptsetup FAQ for advice on how to do a backup of an encrypted
37 volume.
38 Character encoding: If you enter a passphrase with special symbols, the
40 passphrase can change depending on character encoding. Keyboard set‐
41 tings can also change, which can make blind input hard or impossible.
42 For example, switching from some ASCII 8-bit variant to UTF-8 can lead
43 to a different binary encoding and hence different passphrase seen by
44 cryptsetup, even if what you see on the terminal is exactly the same.
45 It is therefore highly recommended to select passphrase characters only
46 from 7-bit ASCII, as the encoding for 7-bit ASCII stays the same for
47 all ASCII variants and UTF-8.
48 LUKS header: If the header of a LUKS volume gets damaged, all data is
50 permanently lost unless you have a header-backup. If a key-slot is
51 damaged, it can only be restored from a header-backup or if another
52 active key-slot with known passphrase is undamaged. Damaging the LUKS
53 header is something people manage to do with surprising frequency. This
54 risk is the result of a trade-off between security and safety, as LUKS
55 is designed for fast and secure wiping by just overwriting header and
56 key-slot area.
57 Previously used partitions: If a partition was previously used, it is a
59 very good idea to wipe filesystem signatures, data, etc. before creat‐
60 ing a LUKS or plain dm-crypt container on it. For a quick removal of
61 filesystem signatures, use "wipefs". Take care though that this may not
62 remove everything. In particular, MD RAID signatures at the end of a
63 device may survive. It also does not remove data. For a full wipe,
64 overwrite the whole partition before container creation. If you do not
65 know how to do that, the cryptsetup FAQ describes several options.
66
69 The following are valid actions for all supported device types.
70 open <device> <name> --type <device_type>
72 Opens (creates a mapping with) <name> backed by device <device>.
74 Device type can be plain, luks (default), luks1, luks2, loopaes
76 or tcrypt.
77 For backward compatibility there are open command aliases:
79 create (argument-order <name> <device>): open --type plain
81 plainOpen: open --type plain
82 luksOpen: open --type luks
83 loopaesOpen: open --type loopaes
84 tcryptOpen: open --type tcrypt
85 bitlkOpen: open --type bitlk
86 <options> are type specific and are described below for individ‐
88 ual device types. For create, the order of the <name> and
89 <device> options is inverted for historical reasons, all other
90 aliases use the standard <device> <name> order.
91 close <name>
93 Removes the existing mapping <name> and wipes the key from ker‐
95 nel memory.
96 For backward compatibility there are close command aliases:
98 remove, plainClose, luksClose, loopaesClose, tcryptClose (all
99 behaves exactly the same, device type is determined automati‐
100 cally from active device).
101 <options> can be [--deferred]
103 status <name>
106 Reports the status for the mapping <name>.
108 resize <name>
110 Resizes an active mapping <name>.
112 If --size (in 512-bytes sectors) or --device-size are not speci‐
114 fied, the size is computed from the underlying device. For LUKS
115 it is the size of the underlying device without the area
116 reserved for LUKS header (see data payload offset in luksDump
117 command). For plain crypt device, the whole device size is
118 used.
119 Note that this does not change the raw device geometry, it just
121 changes how many sectors of the raw device are represented in
122 the mapped device.
123 If cryptsetup detected volume key for active device loaded in
125 kernel keyring service, resize action would first try to
126 retrieve the key using a token and only if it failed it'd ask
127 for a passphrase to unlock a keyslot (LUKS) or to derive a vol‐
128 ume key again (plain mode). The kernel keyring is used by
129 default for LUKS2 devices.
130 With LUKS2 device additional <options> can be [--token-id,
132 --token-only, --key-slot, --key-file, --keyfile-size, --key‐
133 file-offset, --timeout, --disable-locks, --disable-keyring].
134 refresh <name>
137 Refreshes parameters of active mapping <name>.
139 Updates parameters of active device <name> without need to deac‐
141 tivate the device (and umount filesystem). Currently it supports
142 parameters refresh on following devices: LUKS1, LUKS2 (including
143 authenticated encryption), plain crypt and loopaes.
144 Mandatory parametrs are identical to those of an open action for
146 respective device type.
147 You may change following parameters on all devices
149 --perf-same_cpu_crypt, --perf-submit_from_crypt_cpus and
150 --allow-discards.
151 Refreshing device without any optional parameter will refresh
153 the device with default setting (respective to device type).
154 LUKS2 only:
156 --integrity-no-journal parameter affects only LUKS2 devices with
158 underlying dm-integrity device.
159 Adding option --persistent stores any combination of device
161 parameters above in LUKS2 metadata (only after successful
162 refresh operation).
163 --disable-keyring parameter refreshes a device with volume key
165 passed in dm-crypt driver.
166 reencrypt <device> or --active-name <name> [<new_name>]
169 Run resilient reencryption (LUKS2 device only).
171 There are 3 basic modes of operation:
173 · device reencryption (reencrypt)
175 · device encryption (reencrypt --encrypt)
177 · device decryption (reencrypt --decrypt)
179 <device> or --active-name <name> is mandatory parameter.
181 With <device> parameter cryptsetup looks up active <device> dm
183 mapping. If no active mapping is detected, it starts offline
184 reencryption otherwise online reencryption takes place.
185 Reencryption process may be safely interrupted by a user via
187 SIGTERM signal (ctrl+c).
188 To resume already initialized or interrupted reencryption, just
190 run the cryptsetup reencrypt command again to continue the reen‐
191 cryption operation. Reencryption may be resumed with different
192 --resilience or --hotzone-size unless implicit datashift
193 resilience mode is used (reencrypt --encrypt with --reduce-
194 device-size option).
195 If the reencryption process was interrupted abruptly (reencryp‐
197 tion process crash, system crash, poweroff) it may require
198 recovery. The recovery is currently run automatically on next
199 activation (action open) when needed.
200 Optional parameter <new_name> takes effect only with --encrypt
202 option and it activates device <new_name> immediately after
203 encryption initialization gets finished. That's useful when
204 device needs to be ready as soon as possible and mounted (used)
205 before full data area encryption is completed.
206 Action supports following additional <options> [--encrypt,
208 --decrypt, --device-size, --resilience, --resilience-hash,
209 --hotzone-size, --init-only, --resume-only,
210 --reduce-device-size].
211
214 Plain dm-crypt encrypts the device sector-by-sector with a single, non-
215 salted hash of the passphrase. No checks are performed, no metadata is
216 used. There is no formatting operation. When the raw device is mapped
217 (opened), the usual device operations can be used on the mapped device,
218 including filesystem creation. Mapped devices usually reside in
219 /dev/mapper/<name>.
220 The following are valid plain device type actions:
222 open --type plain <device> <name>
224 create <name> <device> (OBSOLETE syntax)
225 Opens (creates a mapping with) <name> backed by device <device>.
227 <options> can be [--hash, --cipher, --verify-passphrase, --sec‐
229 tor-size, --key-file, --keyfile-offset, --key-size, --offset,
230 --skip, --size, --readonly, --shared, --allow-discards,
231 --refresh]
232 Example: 'cryptsetup open --type plain /dev/sda10 e1' maps the
234 raw encrypted device /dev/sda10 to the mapped (decrypted) device
235 /dev/mapper/e1, which can then be mounted, fsck-ed or have a
236 filesystem created on it.
237
239 LUKS, the Linux Unified Key Setup, is a standard for disk encryption.
240 It adds a standardized header at the start of the device, a key-slot
241 area directly behind the header and the bulk data area behind that. The
242 whole set is called a 'LUKS container'. The device that a LUKS con‐
243 tainer resides on is called a 'LUKS device'. For most purposes, both
244 terms can be used interchangeably. But note that when the LUKS header
245 is at a nonzero offset in a device, then the device is not a LUKS
246 device anymore, but has a LUKS container stored in it at an offset.
247 LUKS can manage multiple passphrases that can be individually revoked
249 or changed and that can be securely scrubbed from persistent media due
250 to the use of anti-forensic stripes. Passphrases are protected against
251 brute-force and dictionary attacks by PBKDF2, which implements hash
252 iteration and salting in one function.
253 LUKS2 is a new version of header format that allows additional exten‐
255 sions like different PBKDF algorithm or authenticated encryption. You
256 can format device with LUKS2 header if you specify --type luks2 in
257 luksFormat command. For activation, the format is already recognized
258 automatically.
259 Each passphrase, also called a key in this document, is associated with
261 one of 8 key-slots. Key operations that do not specify a slot affect
262 the first slot that matches the supplied passphrase or the first empty
263 slot if a new passphrase is added.
264 The <device> parameter can also be specified by a LUKS UUID in the for‐
266 mat UUID=<uuid>. Translation to real device name uses symlinks in
267 /dev/disk/by-uuid directory.
268 To specify a detached header, the --header parameter can be used in all
270 LUKS commands and always takes precedence over the positional <device>
271 parameter.
272 The following are valid LUKS actions:
274 luksFormat <device> [<key file>]
276 Initializes a LUKS partition and sets the initial passphrase
278 (for key-slot 0), either via prompting or via <key file>. Note
279 that if the second argument is present, then the passphrase is
280 taken from the file given there, without the need to use the
281 --key-file option. Also note that for both forms of reading the
282 passphrase from a file you can give '-' as file name, which
283 results in the passphrase being read from stdin and the safety-
284 question being skipped.
285 You can only call luksFormat on a LUKS device that is not
287 mapped.
288 To use LUKS2, specify --type luks2.
290 <options> can be [--hash, --cipher, --verify-passphrase,
292 --key-size, --key-slot, --key-file (takes precedence over
293 optional second argument), --keyfile-offset, --keyfile-size,
294 --use-random | --use-urandom, --uuid, --master-key-file,
295 --iter-time, --header, --pbkdf-force-iterations, --force-pass‐
296 word, --disable-locks].
297 For LUKS2, additional <options> can be [--integrity,
299 --integrity-no-wipe, --sector-size, --label, --subsystem,
300 --pbkdf, --pbkdf-memory, --pbkdf-parallel, --disable-locks,
301 --disable-keyring, --luks2-metadata-size, --luks2-keyslots-size,
302 --keyslot-cipher, --keyslot-key-size].
303 WARNING: Doing a luksFormat on an existing LUKS container will
305 make all data the old container permanently irretrievable unless
306 you have a header backup.
307 open --type luks <device> <name>
309 luksOpen <device> <name> (old syntax)
310 Opens the LUKS device <device> and sets up a mapping <name>
312 after successful verification of the supplied passphrase.
313 First, the passphrase is searched in LUKS tokens. If it's not
315 found in any token and also the passphrase is not supplied via
316 --key-file, the command prompts for it interactively.
317 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
319 --readonly, --test-passphrase, --allow-discards, --header,
320 --key-slot, --master-key-file, --token-id, --token-only, --dis‐
321 able-keyring, --disable-locks, --type, --refresh, --serial‐
322 ize-memory-hard-pbkdf].
323 luksSuspend <name>
325 Suspends an active device (all IO operations will block and
327 accesses to the device will wait indefinitely) and wipes the
328 encryption key from kernel memory. Needs kernel 2.6.19 or later.
329 After this operation you have to use luksResume to reinstate the
331 encryption key and unblock the device or close to remove the
332 mapped device.
333 WARNING: never suspend the device on which the cryptsetup binary
335 resides.
336 <options> can be [--header, --disable-locks].
338 luksResume <name>
340 Resumes a suspended device and reinstates the encryption key.
342 Prompts interactively for a passphrase if --key-file is not
343 given.
344 <options> can be [--key-file, --keyfile-size, --header, --dis‐
346 able-keyring, --disable-locks, --type]
347 luksAddKey <device> [<key file with new key>]
349 Adds a new passphrase. An existing passphrase must be supplied
351 interactively or via --key-file. The new passphrase to be added
352 can be specified interactively or read from the file given as
353 positional argument.
354 NOTE: with --unbound option the action creates new unbound LUKS2
356 keyslot. The keyslot cannot be used for device activation. If
357 you don't pass new key via --master-key-file option, new random
358 key is generated. Existing passphrase for any active keyslot is
359 not required.
360 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
362 --new-keyfile-offset, --new-keyfile-size, --key-slot, --mas‐
363 ter-key-file, --force-password, --header, --disable-locks,
364 --iter-time, --pbkdf, --pbkdf-force-iterations, --unbound,
365 --type, --keyslot-cipher, --keyslot-key-size].
366 luksRemoveKey <device> [<key file with passphrase to be removed>]
368 Removes the supplied passphrase from the LUKS device. The
370 passphrase to be removed can be specified interactively, as the
371 positional argument or via --key-file.
372 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
374 --header, --disable-locks, --type]
375 WARNING: If you read the passphrase from stdin (without further
377 argument or with '-' as an argument to --key-file), batch-mode
378 (-q) will be implicitly switched on and no warning will be given
379 when you remove the last remaining passphrase from a LUKS con‐
380 tainer. Removing the last passphrase makes the LUKS container
381 permanently inaccessible.
382 luksChangeKey <device> [<new key file>]
384 Changes an existing passphrase. The passphrase to be changed
386 must be supplied interactively or via --key-file. The new
387 passphrase can be supplied interactively or in a file given as
388 positional argument.
389 If a key-slot is specified (via --key-slot), the passphrase for
391 that key-slot must be given and the new passphrase will over‐
392 write the specified key-slot. If no key-slot is specified and
393 there is still a free key-slot, then the new passphrase will be
394 put into a free key-slot before the key-slot containing the old
395 passphrase is purged. If there is no free key-slot, then the
396 key-slot with the old passphrase is overwritten directly.
397 WARNING: If a key-slot is overwritten, a media failure during
399 this operation can cause the overwrite to fail after the old
400 passphrase has been wiped and make the LUKS container inaccessi‐
401 ble.
402 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
404 --new-keyfile-offset, --iter-time, --pbkdf, --pbkdf-force-itera‐
405 tions, --new-keyfile-size, --key-slot, --force-password,
406 --header, --disable-locks, --type, --keyslot-cipher,
407 --keyslot-key-size].
408 luksConvertKey <device>
410 Converts an existing LUKS2 keyslot to new pbkdf parameters. The
412 passphrase for keyslot to be converted must be supplied interac‐
413 tively or via --key-file. If no --pbkdf parameters are specified
414 LUKS2 default pbkdf values will apply.
415 If a keyslot is specified (via --key-slot), the passphrase for
417 that keyslot must be given. If no keyslot is specified and there
418 is still a free keyslot, then the new parameters will be put
419 into a free keyslot before the keyslot containing the old param‐
420 eters is purged. If there is no free keyslot, then the keyslot
421 with the old parameters is overwritten directly.
422 WARNING: If a keyslot is overwritten, a media failure during
424 this operation can cause the overwrite to fail after the old
425 parameters have been wiped and make the LUKS container inacces‐
426 sible.
427 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
429 --key-slot, --header, --disable-locks, --iter-time, --pbkdf,
430 --pbkdf-force-iterations, --pbkdf-memory, --pbkdf-parallel,
431 --keyslot-cipher, --keyslot-key-size].
432 luksKillSlot <device> <key slot number>
434 Wipe the key-slot number <key slot> from the LUKS device. Except
436 running in batch-mode (-q) a remaining passphrase must be sup‐
437 plied, either interactively or via --key-file. This command can
438 remove the last remaining key-slot, but requires an interactive
439 confirmation when doing so. Removing the last passphrase makes a
440 LUKS container permanently inaccessible.
441 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
443 --header, --disable-locks, --type].
444 WARNING: If you read the passphrase from stdin (without further
446 argument or with '-' as an argument to --key-file), batch-mode
447 (-q) will be implicitly switched on and no warning will be given
448 when you remove the last remaining passphrase from a LUKS con‐
449 tainer. Removing the last passphrase makes the LUKS container
450 permanently inaccessible.
451 NOTE: If there is no passphrase provided (on stdin or through
453 --key-file argument) and batch-mode (-q) is active, the key-slot
454 is removed without any other warning.
455 erase <device>
458 luksErase <device>
459 Erase all keyslots and make the LUKS container permanently inac‐
461 cessible. You do not need to provide any password for this
462 operation.
463 WARNING: This operation is irreversible.
465 luksUUID <device>
467 Print the UUID of a LUKS device.
469 Set new UUID if --uuid option is specified.
470 isLuks <device>
472 Returns true, if <device> is a LUKS device, false otherwise.
474 Use option -v to get human-readable feedback. 'Command success‐
475 ful.' means the device is a LUKS device.
476 By specifying --type you may query for specific LUKS version.
478 luksDump <device>
480 Dump the header information of a LUKS device.
482 If the --dump-master-key option is used, the LUKS device master
484 key is dumped instead of the keyslot info. Together with --mas‐
485 ter-key-file option, master key is dumped to a file instead of
486 standard output. Beware that the master key cannot be changed
487 without reencryption and can be used to decrypt the data stored
488 in the LUKS container without a passphrase and even without the
489 LUKS header. This means that if the master key is compromised,
490 the whole device has to be erased to prevent further access. Use
491 this option carefully.
492 To dump the master key, a passphrase has to be supplied, either
494 interactively or via --key-file.
495 <options> can be [--dump-master-key, --key-file, --keyfile-off‐
497 set, --keyfile-size, --header, --disable-locks, --mas‐
498 ter-key-file, --type].
499 WARNING: If --dump-master-key is used with --key-file and the
501 argument to --key-file is '-', no validation question will be
502 asked and no warning given.
503 luksHeaderBackup <device> --header-backup-file <file>
505 Stores a binary backup of the LUKS header and keyslot area.
507 Note: Using '-' as filename writes the header backup to a file
508 named '-'.
509 WARNING: This backup file and a passphrase valid at the time of
511 backup allows decryption of the LUKS data area, even if the
512 passphrase was later changed or removed from the LUKS device.
513 Also note that with a header backup you lose the ability to
514 securely wipe the LUKS device by just overwriting the header and
515 key-slots. You either need to securely erase all header backups
516 in addition or overwrite the encrypted data area as well. The
517 second option is less secure, as some sectors can survive, e.g.
518 due to defect management.
519 luksHeaderRestore <device> --header-backup-file <file>
521 Restores a binary backup of the LUKS header and keyslot area
523 from the specified file.
524 Note: Using '-' as filename reads the header backup from a file
525 named '-'.
526 WARNING: Header and keyslots will be replaced, only the
528 passphrases from the backup will work afterward.
529 This command requires that the master key size and data offset
531 of the LUKS header already on the device and of the header
532 backup match. Alternatively, if there is no LUKS header on the
533 device, the backup will also be written to it.
534 token <add|remove|import|export> <device>
536 Action add creates new keyring token to enable auto-activation
538 of the device. For the auto-activation, the passphrase must be
539 stored in keyring with the specified description. Usually, the
540 passphrase should be stored in user or user-session keyring.
541 The token command is supported only for LUKS2.
542 For adding new keyring token, option --key-description is manda‐
544 tory. Also, new token is assigned to key slot specified with
545 --key-slot option or to all active key slots in the case
546 --key-slot option is omitted.
547 To remove existing token, specify the token ID which should be
549 removed with --token-id option.
550 WARNING: The action token remove removes any token type, not
552 just keyring type from token slot specified by --token-id
553 option.
554 Action import can store arbitrary valid token json in LUKS2
556 header. It may be passed via standard input or via file passed
557 in --json-file option. If you specify --key-slot then success‐
558 fully imported token is also assigned to the key slot.
559 Action export writes requested token json to a file passed with
561 --json-file or to standard output.
562 <options> can be [--header, --token-id, --key-slot,
564 --key-description, --disable-locks, --disable-keyring,
565 --json-file].
566 convert <device> --type <format>
568 Converts the device between LUKS1 and LUKS2 format (if possi‐
570 ble). The conversion will not be performed if there is an addi‐
571 tional LUKS2 feature or LUKS1 has unsupported header size.
572 Conversion (both directions) must be performed on inactive
574 device. There must not be active dm-crypt mapping established
575 for LUKS header requested for conversion.
576 --type option is mandatory with following accepted values: luks1
578 or luks2.
579 WARNING: The convert action can destroy the LUKS header in the
581 case of a crash during conversion or if a media error occurs.
582 Always create a header backup before performing this operation!
583 <options> can be [--header, --type].
585 config <device>
587 Set permanent configuration options (store to LUKS header). The
589 config command is supported only for LUKS2.
590 The permanent options can be --priority to set priority (normal,
592 prefer, ignore) for keyslot (specified by --key-slot) or --label
593 and --subsystem.
594 <options> can be [--priority, --label, --subsystem, --key-slot,
596 --header].
597
600 cryptsetup supports mapping loop-AES encrypted partition using a com‐
601 patibility mode.
602 open --type loopaes <device> <name> --key-file <keyfile>
604 loopaesOpen <device> <name> --key-file <keyfile> (old syntax)
605 Opens the loop-AES <device> and sets up a mapping <name>.
607 If the key file is encrypted with GnuPG, then you have to use
609 --key-file=- and decrypt it before use, e.g. like this:
610 gpg --decrypt <keyfile> | cryptsetup loopaesOpen --key-file=-
611 <device> <name>
612 WARNING: The loop-AES extension cannot use the direct input of
614 key file on real terminal because the keys are separated by end-
615 of-line and only part of the multi-key file would be read.
616 If you need it in script, just use the pipe redirection:
617 echo $keyfile | cryptsetup loopaesOpen --key-file=- <device>
618 <name>
619 Use --keyfile-size to specify the proper key length if needed.
621 Use --offset to specify device offset. Note that the units need
623 to be specified in number of 512 byte sectors.
624 Use --skip to specify the IV offset. If the original device used
626 an offset and but did not use it in IV sector calculations, you
627 have to explicitly use --skip 0 in addition to the offset param‐
628 eter.
629 Use --hash to override the default hash function for passphrase
631 hashing (otherwise it is detected according to key size).
632 <options> can be [--key-file, --key-size, --offset, --skip,
634 --hash, --readonly, --allow-discards, --refresh].
635 See also section 7 of the FAQ and http://loop-aes.sourceforge.net for
637 more information regarding loop-AES.
638
640 cryptsetup supports mapping of TrueCrypt, tcplay or VeraCrypt (with
641 --veracrypt option) encrypted partition using a native Linux kernel
642 API. Header formatting and TCRYPT header change is not supported,
643 cryptsetup never changes TCRYPT header on-device.
644 TCRYPT extension requires kernel userspace crypto API to be available
646 (introduced in Linux kernel 2.6.38). If you are configuring kernel
647 yourself, enable "User-space interface for symmetric key cipher algo‐
648 rithms" in "Cryptographic API" section (CRYPTO_USER_API_SKCIPHER .con‐
649 fig option).
650 Because TCRYPT header is encrypted, you have to always provide valid
652 passphrase and keyfiles.
653 Cryptsetup should recognize all header variants, except legacy cipher
655 chains using LRW encryption mode with 64 bits encryption block (namely
656 Blowfish in LRW mode is not recognized, this is limitation of kernel
657 crypto API).
658 To recognize a VeraCrypt device use the --veracrypt option. VeraCrypt
660 is just extension of TrueCrypt header with increased iteration count so
661 unlocking can take quite a lot of time (in comparison with TCRYPT
662 device).
663 To open a VeraCrypt device with a custom Personal Iteration Multiplier
665 (PIM) value, additionally to --veracrypt use either the --ver‐
666 acrypt-pim=<PIM> option to directly specify the PIM on the command-
667 line or use --veracrypt-query-pim to be prompted for the PIM.
668 The PIM value affects the number of iterations applied during key
670 derivation. Please refer to https://www.veracrypt.fr/en/Per‐
671 sonal%20Iterations%20Multiplier%20%28PIM%29.html for more detailed
672 information.
673 NOTE: Activation with tcryptOpen is supported only for cipher chains
675 using LRW or XTS encryption modes.
676 The tcryptDump command should work for all recognized TCRYPT devices
678 and doesn't require superuser privilege.
679 To map system device (device with boot loader where the whole encrypted
681 system resides) use --tcrypt-system option. You can use partition
682 device as the parameter (parameter must be real partition device, not
683 an image in a file), then only this partition is mapped.
684 If you have the whole TCRYPT device as a file image and you want to map
686 multiple partition encrypted with system encryption, please create
687 loopback mapping with partitions first (losetup -P, see losetup(8) man
688 page for more info), and use loop partition as the device parameter.
689 If you use the whole base device as a parameter, one device for the
691 whole system encryption is mapped. This mode is available only for
692 backward compatibility with older cryptsetup versions which mapped
693 TCRYPT system encryption using the whole device.
694 To use hidden header (and map hidden device, if available), use
696 --tcrypt-hidden option.
697 To explicitly use backup (secondary) header, use --tcrypt-backup
699 option.
700 NOTE: There is no protection for a hidden volume if the outer volume is
702 mounted. The reason is that if there were any protection, it would
703 require some metadata describing what to protect in the outer volume
704 and the hidden volume would become detectable.
705 open --type tcrypt <device> <name>
708 tcryptOpen <device> <name> (old syntax)
709 Opens the TCRYPT (a TrueCrypt-compatible) <device> and sets up a
711 mapping <name>.
712 <options> can be [--key-file, --tcrypt-hidden, --tcrypt-system,
714 --tcrypt-backup, --readonly, --test-passphrase, --allow-dis‐
715 cards, --veracrypt, --veracrypt-pim, --veracrypt-query-pim].
716 The keyfile parameter allows a combination of file content with
718 the passphrase and can be repeated. Note that using keyfiles is
719 compatible with TCRYPT and is different from LUKS keyfile logic.
720 WARNING: Option --allow-discards cannot be combined with option
722 --tcrypt-hidden. For normal mapping, it can cause the destruc‐
723 tion of hidden volume (hidden volume appears as unused space for
724 outer volume so this space can be discarded).
725 tcryptDump <device>
728 Dump the header information of a TCRYPT device.
730 If the --dump-master-key option is used, the TCRYPT device mas‐
732 ter key is dumped instead of TCRYPT header info. Beware that the
733 master key (or concatenated master keys if cipher chain is used)
734 can be used to decrypt the data stored in the TCRYPT container
735 without a passphrase. This means that if the master key is com‐
736 promised, the whole device has to be erased to prevent further
737 access. Use this option carefully.
738 <options> can be [--dump-master-key, --key-file, --tcrypt-hid‐
740 den, --tcrypt-system, --tcrypt-backup].
741 The keyfile parameter allows a combination of file content with
743 the passphrase and can be repeated.
744 See also https://en.wikipedia.org/wiki/TrueCrypt for more information
746 regarding TrueCrypt.
747 Please note that cryptsetup does not use TrueCrypt code, please report
749 all problems related to this compatibility extension to the cryptsetup
750 project.
751
754 cryptsetup supports mapping of BitLocker and BitLocker to Go encrypted
755 partition using a native Linux kernel API. Header formatting and BITLK
756 header changes are not supported, cryptsetup never changes BITLK header
757 on-device.
758 BITLK extension requires kernel userspace crypto API to be available
760 (for details see TCRYPT section).
761 Cryptsetup should recognize all BITLK header variants, except legacy
763 header used in Windows Vista systems and partially decrypted BitLocker
764 devices. Activation of legacy devices encrypted in CBC mode requires
765 at least Linux kernel version 5.3 and for devices using Elephant dif‐
766 fuser kernel 5.6.
767 The bitlkDump command should work for all recognized BITLK devices and
769 doesn't require superuser privilege.
770 For unlocking with the open a password or a recovery passphrase must be
772 provided. Other unlocking methods (TPM, SmartCard) are not supported.
773 open --type bitlk <device> <name>
776 bitlkOpen <device> <name> (old syntax)
777 Opens the BITLK (a BitLocker-compatible) <device> and sets up a
779 mapping <name>.
780 <options> can be [--key-file, --readonly, --test-passphrase,
782 --allow-discards].
783 bitlkDump <device>
786 Dump the header information of a BITLK device.
788 Please note that cryptsetup does not use any Windows BitLocker
790 code, please report all problems related to this compatibility
791 extension to the cryptsetup project.
792
794 repair <device>
795 Tries to repair the device metadata if possible. Currently sup‐
797 ported only for LUKS device type.
798 This command is useful to fix some known benign LUKS metadata
800 header corruptions. Only basic corruptions of unused keyslot are
801 fixable. This command will only change the LUKS header, not any
802 key-slot data. You may enforce LUKS version by adding --type
803 option.
804 WARNING: Always create a binary backup of the original header
806 before calling this command.
807 benchmark <options>
809 Benchmarks ciphers and KDF (key derivation function). Without
811 parameters, it tries to measure few common configurations.
812 To benchmark other ciphers or modes, you need to specify
814 --cipher and --key-size options or --hash for KDF test.
815 NOTE: This benchmark is using memory only and is only informa‐
817 tive. You cannot directly predict real storage encryption speed
818 from it.
819 For testing block ciphers, this benchmark requires kernel
821 userspace crypto API to be available (introduced in Linux kernel
822 2.6.38). If you are configuring kernel yourself, enable "User-
823 space interface for symmetric key cipher algorithms" in "Crypto‐
824 graphic API" section (CRYPTO_USER_API_SKCIPHER .config option).
825 <options> can be [--cipher, --key-size, --hash].
827
829 --verbose, -v
830 Print more information on command execution.
831 --debug or --debug-json
833 Run in debug mode with full diagnostic logs. Debug output lines
834 are always prefixed by '#'. If --debug-json is used, additional
835 LUKS2 JSON data structures are printed.
836 --type <device-type>
838 Specifies required device type, for more info read BASIC COM‐
839 MANDS section.
840 --hash, -h <hash-spec>
842 Specifies the passphrase hash for open (for plain and loopaes
843 device types).
844 Specifies the hash used in the LUKS key setup scheme and volume
846 key digest for luksFormat. The specified hash is used as hash-
847 parameter for PBKDF2 and for the AF splitter.
848 The specified hash name is passed to the compiled-in crypto
850 backend. Different backends may support different hashes. For
851 luksFormat, the hash algorithm must provide at least 160 bits of
852 output, which excludes, e.g., MD5. Do not use a non-crypto hash
853 like "crc32" as this breaks security.
854 Values compatible with old version of cryptsetup are "ripemd160"
856 for open --type plain and "sha1" for luksFormat.
857 Use cryptsetup --help to show the defaults.
859 --cipher, -c <cipher-spec>
861 Set the cipher specification string.
862 cryptsetup --help shows the compiled-in defaults. The current
864 default in the distributed sources is "aes-cbc-essiv:sha256" for
865 plain dm-crypt and "aes-xts-plain64" for LUKS.
866 If a hash is part of the cipher specification, then it is used
868 as part of the IV generation. For example, ESSIV needs a hash
869 function, while "plain64" does not and hence none is specified.
870 For XTS mode you can optionally set a key size of 512 bits with
872 the -s option. Key size for XTS mode is twice that for other
873 modes for the same security level.
874 XTS mode requires kernel 2.6.24 or later and plain64 requires
876 kernel 2.6.33 or later. More information can be found in the
877 FAQ.
878 --verify-passphrase, -y
880 When interactively asking for a passphrase, ask for it twice and
881 complain if both inputs do not match. Advised when creating a
882 regular mapping for the first time, or when running luksFormat.
883 Ignored on input from file or stdin.
884 --key-file, -d name
886 Read the passphrase from file.
887 If the name given is "-", then the passphrase will be read from
889 stdin. In this case, reading will not stop at newline charac‐
890 ters.
891 With LUKS, passphrases supplied via --key-file are always the
893 existing passphrases requested by a command, except in the case
894 of luksFormat where --key-file is equivalent to the positional
895 key file argument.
896 If you want to set a new passphrase via key file, you have to
898 use a positional argument to luksAddKey.
899 See section NOTES ON PASSPHRASE PROCESSING for more information.
901 --keyfile-offset value
903 Skip value bytes at the beginning of the key file. Works with
904 all commands that accept key files.
905 --keyfile-size, -l value
907 Read a maximum of value bytes from the key file. The default is
908 to read the whole file up to the compiled-in maximum that can be
909 queried with --help. Supplying more data than the compiled-in
910 maximum aborts the operation.
911 This option is useful to cut trailing newlines, for example. If
913 --keyfile-offset is also given, the size count starts after the
914 offset. Works with all commands that accept key files.
915 --new-keyfile-offset value
917 Skip value bytes at the start when adding a new passphrase from
918 key file with luksAddKey.
919 --new-keyfile-size value
921 Read a maximum of value bytes when adding a new passphrase from
922 key file with luksAddKey. The default is to read the whole file
923 up to the compiled-in maximum length that can be queried with
924 --help. Supplying more than the compiled in maximum aborts the
925 operation. When --new-keyfile-offset is also given, reading
926 starts after the offset.
927 --master-key-file
929 Use a master key stored in a file.
930 For luksFormat this allows creating a LUKS header with this spe‐
932 cific master key. If the master key was taken from an existing
933 LUKS header and all other parameters are the same, then the new
934 header decrypts the data encrypted with the header the master
935 key was taken from.
936 Action luksDump together with --dump-master-key option: The vol‐
938 ume (master) key is stored in a file instead of being printed
939 out to standard output.
940 WARNING: If you create your own master key, you need to make
942 sure to do it right. Otherwise, you can end up with a low-
943 entropy or otherwise partially predictable master key which will
944 compromise security.
945 For luksAddKey this allows adding a new passphrase without hav‐
947 ing to know an existing one.
948 For open this allows one to open the LUKS device without giving
950 a passphrase.
951 --dump-master-key
953 For luksDump this option includes the master key in the dis‐
954 played information. Use with care, as the master key can be used
955 to bypass the passphrases, see also option --master-key-file.
956 --json-file
958 Read token json from a file or write token to it. See token
959 action for more information. --json-file=- reads json from stan‐
960 dard input or writes it to standard output respectively.
961 --use-random
963 --use-urandom
965 For luksFormat these options define which kernel random number
966 generator will be used to create the master key (which is a
967 long-term key).
968 See NOTES ON RANDOM NUMBER GENERATORS for more information. Use
970 cryptsetup --help to show the compiled-in default random number
971 generator.
972 WARNING: In a low-entropy situation (e.g. in an embedded sys‐
974 tem), both selections are problematic. Using /dev/urandom can
975 lead to weak keys. Using /dev/random can block a long time,
976 potentially forever, if not enough entropy can be harvested by
977 the kernel.
978 --key-slot, -S <0-7>
980 For LUKS operations that add key material, this options allows
981 you to specify which key slot is selected for the new key. This
982 option can be used for luksFormat, and luksAddKey.
983 In addition, for open, this option selects a specific key-slot
984 to compare the passphrase against. If the given passphrase
985 would only match a different key-slot, the operation fails.
986 --key-size, -s <bits>
988 Sets key size in bits. The argument has to be a multiple of 8.
989 The possible key-sizes are limited by the cipher and mode used.
990 See /proc/crypto for more information. Note that key-size in
992 /proc/crypto is stated in bytes.
993 This option can be used for open --type plain or luksFormat.
995 All other LUKS actions will use the key-size specified in the
996 LUKS header. Use cryptsetup --help to show the compiled-in
997 defaults.
998 --size, -b <number of 512 byte sectors>
1000 Set the size of the device in sectors of 512 bytes. This option
1001 is only relevant for the open and resize actions.
1002 --offset, -o <number of 512 byte sectors>
1004 Start offset in the backend device in 512-byte sectors. This
1005 option is only relevant for the open action with plain or
1006 loopaes device types or for LUKS devices in luksFormat.
1007 For LUKS, the --offset option sets the data offset (payload) of
1009 data device and must be be aligned to 4096-byte sectors (must be
1010 multiple of 8). This option cannot be combined with
1011 --align-payload option.
1012 --skip, -p <number of 512 byte sectors>
1014 Start offset used in IV calculation in 512-byte sectors (how
1015 many sectors of the encrypted data to skip at the beginning).
1016 This option is only relevant for the open action with plain or
1017 loopaes device types.
1018 Hence, if --offset n, and --skip s, sector n (the first sector
1020 of the encrypted device) will get a sector number of s for the
1021 IV calculation.
1022 --device-size size[units]
1024 Instead of real device size, use specified value.
1025 With reencrypt action it means that only specified area (from
1027 the start of the device to the specified size) will be reen‐
1028 crypted.
1029 With resize action it sets new size of the device.
1031 If no unit suffix is specified, the size is in bytes.
1033 Unit suffix can be S for 512 byte sectors, K/M/G/T (or
1035 KiB,MiB,GiB,TiB) for units with 1024 base or KB/MB/GB/TB for
1036 1000 base (SI scale).
1037 WARNING: This is destructive operation when used with reencrypt
1039 command.
1040 --readonly, -r
1042 set up a read-only mapping.
1043 --shared
1045 Creates an additional mapping for one common ciphertext device.
1046 Arbitrary mappings are supported. This option is only relevant
1047 for the open --type plain action. Use --offset, --size and
1048 --skip to specify the mapped area.
1049 --pbkdf <PBKDF spec>
1051 Set Password-Based Key Derivation Function (PBKDF) algorithm for
1052 LUKS keyslot. The PBKDF can be: pbkdf2 (for PBKDF2 according to
1053 RFC2898), argon2i for Argon2i or argon2id for Argon2id (see
1054 https://www.cryptolux.org/index.php/Argon2 for more info).
1055 For LUKS1, only PBKDF2 is accepted (no need to use this option).
1057 The default PBKDF2 for LUKS2 is set during compilation time and
1058 is available in cryptsetup --help output.
1059 A PBKDF is used for increasing dictionary and brute-force attack
1061 cost for keyslot passwords. The parameters can be time, memory
1062 and parallel cost.
1063 For PBKDF2, only time cost (number of iterations) applies. For
1065 Argon2i/id, there is also memory cost (memory required during
1066 the process of key derivation) and parallel cost (number of
1067 threads that run in parallel during the key derivation.
1068 Note that increasing memory cost also increases time, so the
1070 final parameter values are measured by a benchmark. The bench‐
1071 mark tries to find iteration time (--iter-time) with required
1072 memory cost --pbkdf-memory. If it is not possible, the memory
1073 cost is decreased as well. The parallel cost --pbkdf-parallel
1074 is constant, is is checked against available CPU cores (if not
1075 available, it is decreased) and the maximum parallel cost is 4.
1076 You can see all PBKDF parameters for particular LUKS2 keyslot
1078 with luksDump command.
1079 NOTE: If you do not want to use benchmark and want to specify
1081 all parameters directly, use --pbkdf-force-iterations with
1082 --pbkdf-memory and --pbkdf-parallel. This will override the
1083 values without benchmarking. Note it can cause extremely long
1084 unlocking time. Use only is specified cases, for example, if you
1085 know that the formatted device will be used on some small embed‐
1086 ded system. In this case, the LUKS PBKDF2 digest will be set to
1087 the minimum iteration count.
1088 --iter-time, -i <number of milliseconds>
1090 The number of milliseconds to spend with PBKDF passphrase pro‐
1091 cessing. This option is only relevant for LUKS operations that
1092 set or change passphrases, such as luksFormat or luksAddKey.
1093 Specifying 0 as parameter selects the compiled-in default.
1094 --pbkdf-memory <number>
1096 Set the memory cost for PBKDF (for Argon2i/id the number repre‐
1097 sents kilobytes). Note that it is maximal value, PBKDF bench‐
1098 mark or available physical memory can decrease it. This option
1099 is not available for PBKDF2.
1100 --pbkdf-parallel <number>
1102 Set the parallel cost for PBKDF (number of threads, up to 4).
1103 Note that it is maximal value, it is decreased automatically if
1104 CPU online count is lower. This option is not available for
1105 PBKDF2.
1106 --pbkdf-force-iterations <num>
1108 Avoid PBKDF benchmark and set time cost (iterations) directly.
1109 It can be used for LUKS/LUKS2 device only. See --pbkdf option
1110 for more info.
1111 --batch-mode, -q
1113 Suppresses all confirmation questions. Use with care!
1114 If the -y option is not specified, this option also switches off
1116 the passphrase verification for luksFormat.
1117 --progress-frequency <seconds>
1119 Print separate line every <seconds> with wipe progress.
1120 --timeout, -t <number of seconds>
1122 The number of seconds to wait before timeout on passphrase input
1123 via terminal. It is relevant every time a passphrase is asked,
1124 for example for open, luksFormat or luksAddKey. It has no
1125 effect if used in conjunction with --key-file.
1126 This option is useful when the system should not stall if the
1127 user does not input a passphrase, e.g. during boot. The default
1128 is a value of 0 seconds, which means to wait forever.
1129 --tries, -T
1131 How often the input of the passphrase shall be retried. This
1132 option is relevant every time a passphrase is asked, for example
1133 for open, luksFormat or luksAddKey. The default is 3 tries.
1134 --align-payload <number of 512 byte sectors>
1136 Align payload at a boundary of value 512-byte sectors. This
1137 option is relevant for luksFormat.
1138 If not specified, cryptsetup tries to use the topology info pro‐
1140 vided by the kernel for the underlying device to get the optimal
1141 alignment. If not available (or the calculated value is a mul‐
1142 tiple of the default) data is by default aligned to a 1MiB
1143 boundary (i.e. 2048 512-byte sectors).
1144 For a detached LUKS header, this option specifies the offset on
1146 the data device. See also the --header option.
1147 WARNING: This option is DEPRECATED and has often unexpected
1149 impact to the data offset and keyslot area size (for LUKS2) due
1150 to the complex rounding. For fixed data device offset use
1151 --offset option instead.
1152 --uuid=UUID
1155 Use the provided UUID for the luksFormat command instead of gen‐
1156 erating a new one. Changes the existing UUID when used with the
1157 luksUUID command.
1158 The UUID must be provided in the standard UUID format, e.g.
1160 12345678-1234-1234-1234-123456789abc.
1161 --allow-discards
1163 Allow the use of discard (TRIM) requests for the device. This
1164 option is only relevant for open action. This is also not sup‐
1165 ported for LUKS2 devices with data integrity protection.
1166 WARNING: This command can have a negative security impact
1168 because it can make filesystem-level operations visible on the
1169 physical device. For example, information leaking filesystem
1170 type, used space, etc. may be extractable from the physical
1171 device if the discarded blocks can be located later. If in
1172 doubt, do not use it.
1173 A kernel version of 3.1 or later is needed. For earlier kernels,
1175 this option is ignored.
1176 --perf-same_cpu_crypt
1178 Perform encryption using the same cpu that IO was submitted on.
1179 The default is to use an unbound workqueue so that encryption
1180 work is automatically balanced between available CPUs. This
1181 option is only relevant for open action.
1182 NOTE: This option is available only for low-level dm-crypt per‐
1184 formance tuning, use only if you need a change to default dm-
1185 crypt behaviour. Needs kernel 4.0 or later.
1186 --perf-submit_from_crypt_cpus
1188 Disable offloading writes to a separate thread after encryption.
1189 There are some situations where offloading write bios from the
1190 encryption threads to a single thread degrades performance sig‐
1191 nificantly. The default is to offload write bios to the same
1192 thread. This option is only relevant for open action.
1193 NOTE: This option is available only for low-level dm-crypt per‐
1195 formance tuning, use only if you need a change to default dm-
1196 crypt behaviour. Needs kernel 4.0 or later.
1197 --test-passphrase
1199 Do not activate the device, just verify passphrase. This option
1200 is only relevant for open action (the device mapping name is not
1201 mandatory if this option is used).
1202 --header <device or file storing the LUKS header>
1204 Use a detached (separated) metadata device or file where the
1205 LUKS header is stored. This option allows one to store cipher‐
1206 text and LUKS header on different devices.
1207 This option is only relevant for LUKS devices and can be used
1209 with the luksFormat, open, luksSuspend, luksResume, status and
1210 resize commands.
1211 For luksFormat with a file name as the argument to --header, the
1213 file will be automatically created if it does not exist. See
1214 the cryptsetup FAQ for header size calculation.
1215 For other commands that change the LUKS header (e.g. luksAdd‐
1217 Key), specify the device or file with the LUKS header directly
1218 as the LUKS device.
1219 If used with luksFormat, the --align-payload option is taken as
1221 absolute sector alignment on ciphertext device and can be zero.
1222 WARNING: There is no check whether the ciphertext device speci‐
1224 fied actually belongs to the header given. In fact, you can
1225 specify an arbitrary device as the ciphertext device for open
1226 with the --header option. Use with care.
1227 --header-backup-file <file>
1229 Specify file with header backup for luksHeaderBackup or luk‐
1230 sHeaderRestore actions.
1231 --force-password
1233 Do not use password quality checking for new LUKS passwords.
1234 This option applies only to luksFormat, luksAddKey and
1236 luksChangeKey and is ignored if cryptsetup is built without
1237 password quality checking support.
1238 For more info about password quality check, see the manual page
1240 for pwquality.conf(5) and passwdqc.conf(5).
1241 --deferred
1243 Defers device removal in close command until the last user
1244 closes it.
1245 --disable-locks
1247 Disable lock protection for metadata on disk. This option is
1248 valid only for LUKS2 and ignored for other formats.
1249 WARNING: Do not use this option unless you run cryptsetup in a
1251 restricted environment where locking is impossible to perform
1252 (where /run directory cannot be used).
1253 --disable-keyring
1255 Do not load volume key in kernel keyring and store it directly
1256 in the dm-crypt target instead. This option is supported only
1257 for the LUKS2 format.
1258 --key-description <text>
1260 Set key description in keyring for use with token command.
1261 --priority <normal|prefer|ignore>
1263 Set a priority for LUKS2 keyslot. The prefer priority marked
1264 slots are tried before normal priority. The ignored priority
1265 means, that slot is never used, if not explicitly requested by
1266 --key-slot option.
1267 --token-id
1269 Specify what token to use in actions token, open or resize. If
1270 omitted, all available tokens will be checked before proceeding
1271 further with passphrase prompt.
1272 --token-only
1274 Do not proceed further with action (any of token, open or
1275 resize) if token activation failed. Without the option, action
1276 asks for passphrase to proceed further.
1277 --sector-size <bytes>
1279 Set sector size for use with disk encryption. It must be power
1280 of two and in range 512 - 4096 bytes. The default is 512 bytes
1281 sectors. This option is available only in the LUKS2 mode.
1282 Note that if sector size is higher than underlying device hard‐
1284 ware sector and there is not integrity protection that uses data
1285 journal, using this option can increase risk on incomplete sec‐
1286 tor writes during a power fail.
1287 If used together with --integrity option and dm-integrity jour‐
1289 nal, the atomicity of writes is guaranteed in all cases (but it
1290 cost write performance - data has to be written twice).
1291 Increasing sector size from 512 bytes to 4096 bytes can provide
1293 better performance on most of the modern storage devices and
1294 also with some hw encryption accelerators.
1295 --persistent
1297 If used with LUKS2 devices and activation commands like open,
1298 the specified activation flags are persistently written into
1299 metadata and used next time automatically even for normal acti‐
1300 vation. (No need to use cryptab or other system configuration
1301 files.) Only --allow-discards, --perf-same_cpu_crypt,
1302 --perf-submit_from_crypt_cpus and --integrity-no-journal can be
1303 stored persistently.
1304 --refresh
1306 Refreshes an active device with new set of parameters. See
1307 action refresh description for more details.
1308 --label <LABEL>
1310 --subsystem <SUBSYSTEM> Set label and subsystem description for
1311 LUKS2 device, can be used in config and format actions. The
1312 label and subsystem are optional fields and can be later used in
1313 udev scripts for triggering user actions once device marked by
1314 these labels is detected.
1315 --integrity <integrity algorithm>
1317 Specify integrity algorithm to be used for authenticated disk
1318 encryption in LUKS2.
1319 WARNING: This extension is EXPERIMENTAL and requires dm-
1321 integrity kernel target (available since kernel version 4.12).
1322 For native AEAD modes, also enable "User-space interface for
1323 AEAD cipher algorithms" in "Cryptographic API" section (CON‐
1324 FIG_CRYPTO_USER_API_AEAD .config option).
1325 For more info, see AUTHENTICATED DISK ENCRYPTION section.
1327 --luks2-metadata-size <size>
1329 This option can be used to enlarge the LUKS2 metadata (JSON)
1330 area. The size includes 4096 bytes for binary metadata (usable
1331 JSON area is smaller of the binary area). According to LUKS2
1332 specification, only these values are valid: 16, 32, 64, 128,
1333 256, 512, 1024, 2048 and 4096 kB The <size> can be specified
1334 with unit suffix (for example 128k).
1335 --luks2-keyslots-size <size>
1337 This option can be used to set specific size of the LUKS2 binary
1338 keyslot area (key material is encrypted there). The value must
1339 be aligned to multiple of 4096 bytes with maximum size 128MB.
1340 The <size> can be specified with unit suffix (for example 128k).
1341 --keyslot-cipher <cipher-spec>
1343 This option can be used to set specific cipher encryption for
1344 the LUKS2 keyslot area.
1345 --keyslot-key-size <bits>
1347 This option can be used to set specific key size for the LUKS2
1348 keyslot area.
1349 --integrity-no-journal
1351 Activate device with integrity protection without using data
1352 journal (direct write of data and integrity tags). Note that
1353 without journal power fail can cause non-atomic write and data
1354 corruption. Use only if journalling is performed on a different
1355 storage layer.
1356 --integrity-no-wipe
1358 Skip wiping of device authentication (integrity) tags. If you
1359 skip this step, sectors will report invalid integrity tag until
1360 an application write to the sector.
1361 NOTE: Even some writes to the device can fail if the write is
1363 not aligned to page size and page-cache initiates read of a sec‐
1364 tor with invalid integrity tag.
1365 --unbound
1367 Creates new LUKS2 unbound keyslot. See luksAddKey action for
1369 more details.
1370 --tcrypt-hidden
1372 --tcrypt-system --tcrypt-backup Specify which TrueCrypt on-disk
1373 header will be used to open the device. See TCRYPT section for
1374 more info.
1375 --veracrypt
1377 Allow VeraCrypt compatible mode. Only for TCRYPT extension. See
1378 TCRYPT section for more info.
1379 --veracrypt-pim
1381 --veracrypt-query-pim Use a custom Personal Iteration Multiplier
1382 (PIM) for VeraCrypt device. See TCRYPT section for more info.
1383 --serialize-memory-hard-pbkdf
1385 Use a global lock to serialize unlocking of keyslots using mem‐
1386 ory-hard PBKDF.
1387 NOTE: This is (ugly) workaround for a specific situation when
1389 multiple devices are activated in parallel and system instead of
1390 reporting out of memory starts unconditionally stop processes
1391 using out-of-memory killer.
1392 DO NOT USE this switch until you are implementing boot environ‐
1394 ment with parallel devices activation!
1395 --encrypt
1397 Initialize (and run) device encryption (reencrypt action parame‐
1398 ter)
1399 --decrypt
1401 Initialize (and run) device decryption (reencrypt action parame‐
1402 ter)
1403 --init-only
1405 Initialize reencryption (any variant) operation in LUKS2 meta‐
1406 data only and exit. If any reencrypt operation is already ini‐
1407 tialized in metadata, the command with --init-only parameter
1408 fails.
1409 --resume-only
1411 Resume reencryption (any variant) operation already described in
1412 LUKS2 metadata. If no reencrypt operation is initialized, the
1413 command with --resume-only parameter fails. Useful for resuming
1414 reencrypt operation without accidentally triggering new reen‐
1415 cryption operation.
1416 --resilience <mode>
1418 Reencryption resilience mode can be one of checksum, journal or
1419 none.
1420 checksum: default mode, where individual checksums of ciphertext
1422 hotzone sectors are stored, so the recovery process can detect
1423 which sectors where already reencrypted. It requires that the
1424 device sector write is atomic.
1425 journal: the hotzone is journaled in the binary area (so the
1427 data are written twice).
1428 none: performance mode. There is no protection and the only way
1430 it's safe to interrupt the reencryption is similar to old off‐
1431 line reencryption utility. (ctrl+c).
1432 The option is ignored if reencryption with datashift mode is in
1434 progress.
1435 --resilience-hash <hash>
1437 The hash algorithm used with "--resilience checksum" only. The
1438 default hash is sha256. With other resilience modes, the hash
1439 parameter is ignored.
1440 --hotzone-size <size>
1442 This option can be used to set an upper limit on the size of
1443 reencryption area (hotzone). The <size> can be specified with
1444 unit suffix (for example 50M). Note that actual hotzone size may
1445 be less than specified <size> due to other limitations (free
1446 space in keyslots area or available memory).
1447 --reduce-device-size <size>
1449 Initialize LUKS2 reencryption with data device size reduction
1450 (currently only --encrypt variant is supported).
1451 Last <size> sectors of <device> will be used to properly ini‐
1453 tialize device reencryption. That means any data at last <size>
1454 sectors will be lost.
1455 It could be useful if you added some space to underlying parti‐
1457 tion or logical volume (so last <size> sectors contains no
1458 data).
1459 Recommended minimal size is twice the default LUKS2 header size
1461 (--reduce-device-size 32M) for --encrypt use case. Be sure to
1462 have enough (at least --reduce-device-size value of free space
1463 at the end of <device>).
1464 WARNING: This is a destructive operation and cannot be reverted.
1466 Use with extreme care - accidentally overwritten filesystems are
1467 usually unrecoverable.
1468 --version
1470 Show the program version.
1471 --usage
1473 Show short option help.
1474 --help, -?
1476 Show help text and default parameters.
1477
1479 Cryptsetup returns 0 on success and a non-zero value on error.
1480 Error codes are: 1 wrong parameters, 2 no permission (bad passphrase),
1482 3 out of memory, 4 wrong device specified, 5 device already exists or
1483 device is busy.
1484
1486 Note that no iterated hashing or salting is done in plain mode. If
1487 hashing is done, it is a single direct hash. This means that low-
1488 entropy passphrases are easy to attack in plain mode.
1489 From a terminal: The passphrase is read until the first newline, i.e.
1491 '\n'. The input without the newline character is processed with the
1492 default hash or the hash specified with --hash. The hash result will
1493 be truncated to the key size of the used cipher, or the size specified
1494 with -s.
1495 From stdin: Reading will continue until a newline (or until the maximum
1497 input size is reached), with the trailing newline stripped. The maximum
1498 input size is defined by the same compiled-in default as for the maxi‐
1499 mum key file size and can be overwritten using --keyfile-size option.
1500 The data read will be hashed with the default hash or the hash speci‐
1502 fied with --hash. The hash result will be truncated to the key size of
1503 the used cipher, or the size specified with -s.
1504 Note that if --key-file=- is used for reading the key from stdin,
1506 trailing newlines are not stripped from the input.
1507 If "plain" is used as argument to --hash, the input data will not be
1509 hashed. Instead, it will be zero padded (if shorter than the key size)
1510 or truncated (if longer than the key size) and used directly as the
1511 binary key. This is useful for directly specifying a binary key. No
1512 warning will be given if the amount of data read from stdin is less
1513 than the key size.
1514 From a key file: It will be truncated to the key size of the used
1516 cipher or the size given by -s and directly used as a binary key.
1517 WARNING: The --hash argument is being ignored. The --hash option is
1519 usable only for stdin input in plain mode.
1520 If the key file is shorter than the key, cryptsetup will quit with an
1522 error. The maximum input size is defined by the same compiled-in
1523 default as for the maximum key file size and can be overwritten using
1524 --keyfile-size option.
1525
1529 LUKS uses PBKDF2 to protect against dictionary attacks and to give some
1530 protection to low-entropy passphrases (see RFC 2898 and the cryptsetup
1531 FAQ).
1532 From a terminal: The passphrase is read until the first newline and
1534 then processed by PBKDF2 without the newline character.
1535 From stdin: LUKS will read passphrases from stdin up to the first new‐
1537 line character or the compiled-in maximum key file length. If --key‐
1538 file-size is given, it is ignored.
1539 From key file: The complete keyfile is read up to the compiled-in maxi‐
1541 mum size. Newline characters do not terminate the input. The --key‐
1542 file-size option can be used to limit what is read.
1543 Passphrase processing: Whenever a passphrase is added to a LUKS header
1545 (luksAddKey, luksFormat), the user may specify how much the time the
1546 passphrase processing should consume. The time is used to determine the
1547 iteration count for PBKDF2 and higher times will offer better protec‐
1548 tion for low-entropy passphrases, but open will take longer to com‐
1549 plete. For passphrases that have entropy higher than the used key
1550 length, higher iteration times will not increase security.
1551 The default setting of one or two seconds is sufficient for most prac‐
1553 tical cases. The only exception is a low-entropy passphrase used on a
1554 device with a slow CPU, as this will result in a low iteration count.
1555 On a slow device, it may be advisable to increase the iteration time
1556 using the --iter-time option in order to obtain a higher iteration
1557 count. This does slow down all later luksOpen operations accordingly.
1558
1560 LUKS checks for a valid passphrase when an encrypted partition is
1561 unlocked. The behavior of plain dm-crypt is different. It will always
1562 decrypt with the passphrase given. If the given passphrase is wrong,
1563 the device mapped by plain dm-crypt will essentially still contain
1564 encrypted data and will be unreadable.
1565
1567 The available combinations of ciphers, modes, hashes and key sizes
1568 depend on kernel support. See /proc/crypto for a list of available
1569 options. You might need to load additional kernel crypto modules in
1570 order to get more options.
1571 For the --hash option, if the crypto backend is libgcrypt, then all
1573 algorithms supported by the gcrypt library are available. For other
1574 crypto backends, some algorithms may be missing.
1575
1577 Mathematics can't be bribed. Make sure you keep your passphrases safe.
1578 There are a few nice tricks for constructing a fallback, when suddenly
1579 out of the blue, your brain refuses to cooperate. These fallbacks need
1580 LUKS, as it's only possible with LUKS to have multiple passphrases.
1581 Still, if your attacker model does not prevent it, storing your
1582 passphrase in a sealed envelope somewhere may be a good idea as well.
1583
1585 Random Number Generators (RNG) used in cryptsetup are always the kernel
1586 RNGs without any modifications or additions to data stream produced.
1587 There are two types of randomness cryptsetup/LUKS needs. One type
1589 (which always uses /dev/urandom) is used for salts, the AF splitter and
1590 for wiping deleted keyslots.
1591 The second type is used for the volume (master) key. You can switch
1593 between using /dev/random and /dev/urandom here, see --use-random and
1594 --use-urandom options. Using /dev/random on a system without enough
1595 entropy sources can cause luksFormat to block until the requested
1596 amount of random data is gathered. In a low-entropy situation (embedded
1597 system), this can take a very long time and potentially forever. At the
1598 same time, using /dev/urandom in a low-entropy situation will produce
1599 low-quality keys. This is a serious problem, but solving it is out of
1600 scope for a mere man-page. See urandom(4) for more information.
1601
1603 Since Linux kernel version 4.12 dm-crypt supports authenticated disk
1604 encryption.
1605 Normal disk encryption modes are length-preserving (plaintext sector is
1607 of the same size as a ciphertext sector) and can provide only confiden‐
1608 tiality protection, but not cryptographically sound data integrity pro‐
1609 tection.
1610 Authenticated modes require additional space per-sector for authentica‐
1612 tion tag and use Authenticated Encryption with Additional Data (AEAD)
1613 algorithms.
1614 If you configure LUKS2 device with data integrity protection, there
1616 will be an underlying dm-integrity device, which provides additional
1617 per-sector metadata space and also provide data journal protection to
1618 ensure atomicity of data and metadata update. Because there must be
1619 additional space for metadata and journal, the available space for the
1620 device will be smaller than for length-preserving modes.
1621 The dm-crypt device then resides on top of such a dm-integrity device.
1623 All activation and deactivation of this device stack is performed by
1624 cryptsetup, there is no difference in using luksOpen for integrity pro‐
1625 tected devices. If you want to format LUKS2 device with data integrity
1626 protection, use --integrity option.
1627 Since dm-integrity doesn't support discards (TRIM), dm-crypt device on
1629 top of it inherits this, so integrity protection mode doesn't support
1630 discards either.
1631 Some integrity modes requires two independent keys (key for encryption
1633 and for authentication). Both these keys are stored in one LUKS
1634 keyslot.
1635 WARNING: All support for authenticated modes is experimental and there
1637 are only some modes available for now. Note that there are a very few
1638 authenticated encryption algorithms that are suitable for disk encryp‐
1639 tion.
1640
1643 Cryptsetup is usually used directly on a block device (disk partition
1644 or LVM volume). However, if the device argument is a file, cryptsetup
1645 tries to allocate a loopback device and map it into this file. This
1646 mode requires Linux kernel 2.6.25 or more recent which supports the
1647 loop autoclear flag (loop device is cleared on the last close automati‐
1648 cally). Of course, you can always map a file to a loop-device manually.
1649 See the cryptsetup FAQ for an example.
1650 When device mapping is active, you can see the loop backing file in the
1652 status command output. Also see losetup(8).
1653
1655 The LUKS2 on-disk metadata is updated in several steps and to achieve
1656 proper atomic update, there is a locking mechanism. For an image in
1657 file, code uses flock(2) system call. For a block device, lock is per‐
1658 formed over a special file stored in a locking directory (by default
1659 /run/lock/cryptsetup). The locking directory should be created with
1660 the proper security context by the distribution during the boot-up
1661 phase. Only LUKS2 uses locks, other formats do not use this mechanism.
1662
1664 The reload action is no longer supported. Please use dmsetup(8) if you
1665 need to directly manipulate with the device mapping table.
1666 The luksDelKey was replaced with luksKillSlot.
1668
1670 Report bugs, including ones in the documentation, on the cryptsetup
1671 mailing list at <dm-crypt@saout.de> or in the 'Issues' section on LUKS
1672 website. Please attach the output of the failed command with the
1673 --debug option added.
1674
1676 cryptsetup originally written by Jana Saout <jana@saout.de>
1677 The LUKS extensions and original man page were written by Clemens Fruh‐
1678 wirth <clemens@endorphin.org>.
1679 Man page extensions by Milan Broz <gmazyland@gmail.com>.
1680 Man page rewrite and extension by Arno Wagner <arno@wagner.name>.
1681
1683 Copyright © 2004 Jana Saout
1684 Copyright © 2004-2006 Clemens Fruhwirth
1685 Copyright © 2012-2014 Arno Wagner
1686 Copyright © 2009-2020 Red Hat, Inc.
1687 Copyright © 2009-2020 Milan Broz
1688 This is free software; see the source for copying conditions. There is
1690 NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
1691 PURPOSE.
1692
1694 The LUKS website at https://gitlab.com/cryptsetup/cryptsetup/
1695 The cryptsetup FAQ, contained in the distribution package and online at
1697 https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions
1698 The cryptsetup mailing list and list archive, see FAQ entry 1.6.
1700 The LUKS on-disk format specification available at https://git‐
1702 lab.com/cryptsetup/cryptsetup/wikis/Specification
1703cryptsetup January 2019 CRYPTSETUP(8)