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 ac‐
52 tive 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 <de‐
89 vice> 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: re‐
98 move, plainClose, luksClose, loopaesClose, tcryptClose (all be‐
99 haves exactly the same, device type is determined automatically
100 from active device).
101 <options> can be [--deferred] or [--cancel-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 re‐
116 served for LUKS header (see data payload offset in luksDump com‐
117 mand). For plain crypt device, the whole device size is used.
118 Note that this does not change the raw device geometry, it just
120 changes how many sectors of the raw device are represented in
121 the mapped device.
122 If cryptsetup detected volume key for active device loaded in
124 kernel keyring service, resize action would first try to re‐
125 trieve the key using a token and only if it failed it'd ask for
126 a passphrase to unlock a keyslot (LUKS) or to derive a volume
127 key again (plain mode). The kernel keyring is used by default
128 for LUKS2 devices.
129 With LUKS2 device additional <options> can be [--token-id, --to‐
131 ken-only, --token-type, --key-slot, --key-file, --keyfile-size,
132 --keyfile-offset, --timeout, --disable-external-tokens, --dis‐
133 able-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 parameters are identical to those of an open action
146 for respective device type.
147 You may change following parameters on all devices
149 --perf-same_cpu_crypt, --perf-submit_from_crypt_cpus, --perf-
150 no_read_workqueue, --perf-no_write_workqueue and --allow-dis‐
151 cards.
152 Refreshing device without any optional parameter will refresh
154 the device with default setting (respective to device type).
155 LUKS2 only:
157 --integrity-no-journal parameter affects only LUKS2 devices with
159 underlying dm-integrity device.
160 Adding option --persistent stores any combination of device pa‐
162 rameters above in LUKS2 metadata (only after successful refresh
163 operation).
164 --disable-keyring parameter refreshes a device with volume key
166 passed in dm-crypt driver.
167 reencrypt <device> or --active-name <name> [<new_name>]
170 Run resilient reencryption (LUKS2 device only).
172 There are 3 basic modes of operation:
174 • device reencryption (reencrypt)
176 • device encryption (reencrypt --encrypt)
178 • device decryption (reencrypt --decrypt)
180 <device> or --active-name <name> is mandatory parameter.
182 With <device> parameter cryptsetup looks up active <device> dm
184 mapping. If no active mapping is detected, it starts offline
185 reencryption otherwise online reencryption takes place.
186 Reencryption process may be safely interrupted by a user via
188 SIGTERM signal (ctrl+c).
189 To resume already initialized or interrupted reencryption, just
191 run the cryptsetup reencrypt command again to continue the reen‐
192 cryption operation. Reencryption may be resumed with different
193 --resilience or --hotzone-size unless implicit datashift re‐
194 silience mode is used (reencrypt --encrypt with --reduce-device-
195 size option).
196 If the reencryption process was interrupted abruptly (reencryp‐
198 tion process crash, system crash, poweroff) it may require re‐
199 covery. The recovery is currently run automatically on next ac‐
200 tivation (action open) when needed.
201 Optional parameter <new_name> takes effect only with --encrypt
203 option and it activates device <new_name> immediately after en‐
204 cryption initialization gets finished. That's useful when device
205 needs to be ready as soon as possible and mounted (used) before
206 full data area encryption is completed.
207 Action supports following additional <options> [--encrypt, --de‐
209 crypt, --device-size, --resilience, --resilience-hash, --hot‐
210 zone-size, --init-only, --resume-only, --reduce-device-size,
211 --master-key-file, --key-size].
212
215 Plain dm-crypt encrypts the device sector-by-sector with a single, non-
216 salted hash of the passphrase. No checks are performed, no metadata is
217 used. There is no formatting operation. When the raw device is mapped
218 (opened), the usual device operations can be used on the mapped device,
219 including filesystem creation. Mapped devices usually reside in
220 /dev/mapper/<name>.
221 The following are valid plain device type actions:
223 open --type plain <device> <name>
225 create <name> <device> (OBSOLETE syntax)
226 Opens (creates a mapping with) <name> backed by device <device>.
228 <options> can be [--hash, --cipher, --verify-passphrase, --sec‐
230 tor-size, --key-file, --keyfile-offset, --key-size, --offset,
231 --skip, --size, --readonly, --shared, --allow-discards, --re‐
232 fresh]
233 Example: 'cryptsetup open --type plain /dev/sda10 e1' maps the
235 raw encrypted device /dev/sda10 to the mapped (decrypted) device
236 /dev/mapper/e1, which can then be mounted, fsck-ed or have a
237 filesystem created on it.
238
240 LUKS, the Linux Unified Key Setup, is a standard for disk encryption.
241 It adds a standardized header at the start of the device, a key-slot
242 area directly behind the header and the bulk data area behind that. The
243 whole set is called a 'LUKS container'. The device that a LUKS con‐
244 tainer resides on is called a 'LUKS device'. For most purposes, both
245 terms can be used interchangeably. But note that when the LUKS header
246 is at a nonzero offset in a device, then the device is not a LUKS de‐
247 vice anymore, but has a LUKS container stored in it at an offset.
248 LUKS can manage multiple passphrases that can be individually revoked
250 or changed and that can be securely scrubbed from persistent media due
251 to the use of anti-forensic stripes. Passphrases are protected against
252 brute-force and dictionary attacks by PBKDF2, which implements hash it‐
253 eration and salting in one function.
254 LUKS2 is a new version of header format that allows additional exten‐
256 sions like different PBKDF algorithm or authenticated encryption. You
257 can format device with LUKS2 header if you specify --type luks2 in
258 luksFormat command. For activation, the format is already recognized
259 automatically.
260 Each passphrase, also called a key in this document, is associated with
262 one of 8 key-slots. Key operations that do not specify a slot affect
263 the first slot that matches the supplied passphrase or the first empty
264 slot if a new passphrase is added.
265 The <device> parameter can also be specified by a LUKS UUID in the for‐
267 mat UUID=<uuid>. Translation to real device name uses symlinks in
268 /dev/disk/by-uuid directory.
269 To specify a detached header, the --header parameter can be used in all
271 LUKS commands and always takes precedence over the positional <device>
272 parameter.
273 The following are valid LUKS actions:
275 luksFormat <device> [<key file>]
277 Initializes a LUKS partition and sets the initial passphrase
279 (for key-slot 0), either via prompting or via <key file>. Note
280 that if the second argument is present, then the passphrase is
281 taken from the file given there, without the need to use the
282 --key-file option. Also note that for both forms of reading the
283 passphrase from a file you can give '-' as file name, which re‐
284 sults in the passphrase being read from stdin and the safety-
285 question being skipped.
286 You cannot call luksFormat on a device or filesystem that is
288 mapped or in use, e.g. mounted filesysem, used in LVM, active
289 RAID member etc. The device or filesystem has to be un-mounted
290 in order to call luksFormat.
291 To use LUKS2, specify --type luks2.
293 <options> can be [--hash, --cipher, --verify-passphrase,
295 --key-size, --key-slot, --key-file (takes precedence over op‐
296 tional second argument), --keyfile-offset, --keyfile-size,
297 --use-random | --use-urandom, --uuid, --master-key-file,
298 --iter-time, --header, --pbkdf-force-iterations, --force-pass‐
299 word, --disable-locks].
300 For LUKS2, additional <options> can be [--integrity, --integ‐
302 rity-no-wipe, --sector-size, --label, --subsystem, --pbkdf,
303 --pbkdf-memory, --pbkdf-parallel, --disable-locks, --dis‐
304 able-keyring, --luks2-metadata-size, --luks2-keyslots-size,
305 --keyslot-cipher, --keyslot-key-size].
306 WARNING: Doing a luksFormat on an existing LUKS container will
308 make all data the old container permanently irretrievable unless
309 you have a header backup.
310 open --type luks <device> <name>
312 luksOpen <device> <name> (old syntax)
313 Opens the LUKS device <device> and sets up a mapping <name> af‐
315 ter successful verification of the supplied passphrase.
316 First, the passphrase is searched in LUKS tokens. If it's not
318 found in any token and also the passphrase is not supplied via
319 --key-file, the command prompts for it interactively.
320 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
322 --readonly, --test-passphrase, --allow-discards, --header,
323 --key-slot, --master-key-file, --token-id, --token-only, --to‐
324 ken-type, --disable-external-tokens, --disable-keyring, --dis‐
325 able-locks, --type, --refresh, --serialize-memory-hard-pbkdf].
326 luksSuspend <name>
328 Suspends an active device (all IO operations will block and ac‐
330 cesses to the device will wait indefinitely) and wipes the en‐
331 cryption key from kernel memory. Needs kernel 2.6.19 or later.
332 After this operation you have to use luksResume to reinstate the
334 encryption key and unblock the device or close to remove the
335 mapped device.
336 WARNING: never suspend the device on which the cryptsetup binary
338 resides.
339 <options> can be [--header, --disable-locks].
341 luksResume <name>
343 Resumes a suspended device and reinstates the encryption key.
345 Prompts interactively for a passphrase if --key-file is not
346 given.
347 <options> can be [--key-file, --keyfile-size, --header, --dis‐
349 able-keyring, --disable-locks, --type]
350 luksAddKey <device> [<key file with new key>]
352 Adds a new passphrase. An existing passphrase must be supplied
354 interactively or via --key-file. The new passphrase to be added
355 can be specified interactively or read from the file given as
356 positional argument.
357 NOTE: with --unbound option the action creates new unbound LUKS2
359 keyslot. The keyslot cannot be used for device activation. If
360 you don't pass new key via --master-key-file option, new random
361 key is generated. Existing passphrase for any active keyslot is
362 not required.
363 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
365 --new-keyfile-offset, --new-keyfile-size, --key-slot, --mas‐
366 ter-key-file, --force-password, --header, --disable-locks,
367 --iter-time, --pbkdf, --pbkdf-force-iterations, --unbound,
368 --type, --keyslot-cipher, --keyslot-key-size].
369 luksRemoveKey <device> [<key file with passphrase to be removed>]
371 Removes the supplied passphrase from the LUKS device. The
373 passphrase to be removed can be specified interactively, as the
374 positional argument or via --key-file.
375 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
377 --header, --disable-locks, --type]
378 WARNING: If you read the passphrase from stdin (without further
380 argument or with '-' as an argument to --key-file), batch-mode
381 (-q) will be implicitly switched on and no warning will be given
382 when you remove the last remaining passphrase from a LUKS con‐
383 tainer. Removing the last passphrase makes the LUKS container
384 permanently inaccessible.
385 luksChangeKey <device> [<new key file>]
387 Changes an existing passphrase. The passphrase to be changed
389 must be supplied interactively or via --key-file. The new
390 passphrase can be supplied interactively or in a file given as
391 positional argument.
392 If a key-slot is specified (via --key-slot), the passphrase for
394 that key-slot must be given and the new passphrase will over‐
395 write the specified key-slot. If no key-slot is specified and
396 there is still a free key-slot, then the new passphrase will be
397 put into a free key-slot before the key-slot containing the old
398 passphrase is purged. If there is no free key-slot, then the
399 key-slot with the old passphrase is overwritten directly.
400 WARNING: If a key-slot is overwritten, a media failure during
402 this operation can cause the overwrite to fail after the old
403 passphrase has been wiped and make the LUKS container inaccessi‐
404 ble.
405 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
407 --new-keyfile-offset, --iter-time, --pbkdf, --pbkdf-force-itera‐
408 tions, --new-keyfile-size, --key-slot, --force-password,
409 --header, --disable-locks, --type, --keyslot-cipher,
410 --keyslot-key-size].
411 luksConvertKey <device>
413 Converts an existing LUKS2 keyslot to new pbkdf parameters. The
415 passphrase for keyslot to be converted must be supplied interac‐
416 tively or via --key-file. If no --pbkdf parameters are specified
417 LUKS2 default pbkdf values will apply.
418 If a keyslot is specified (via --key-slot), the passphrase for
420 that keyslot must be given. If no keyslot is specified and there
421 is still a free keyslot, then the new parameters will be put
422 into a free keyslot before the keyslot containing the old param‐
423 eters is purged. If there is no free keyslot, then the keyslot
424 with the old parameters is overwritten directly.
425 WARNING: If a keyslot is overwritten, a media failure during
427 this operation can cause the overwrite to fail after the old pa‐
428 rameters have been wiped and make the LUKS container inaccessi‐
429 ble.
430 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
432 --key-slot, --header, --disable-locks, --iter-time, --pbkdf,
433 --pbkdf-force-iterations, --pbkdf-memory, --pbkdf-parallel,
434 --keyslot-cipher, --keyslot-key-size].
435 luksKillSlot <device> <key slot number>
437 Wipe the key-slot number <key slot> from the LUKS device. Except
439 running in batch-mode (-q) a remaining passphrase must be sup‐
440 plied, either interactively or via --key-file. This command can
441 remove the last remaining key-slot, but requires an interactive
442 confirmation when doing so. Removing the last passphrase makes a
443 LUKS container permanently inaccessible.
444 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
446 --header, --disable-locks, --type].
447 WARNING: If you read the passphrase from stdin (without further
449 argument or with '-' as an argument to --key-file), batch-mode
450 (-q) will be implicitly switched on and no warning will be given
451 when you remove the last remaining passphrase from a LUKS con‐
452 tainer. Removing the last passphrase makes the LUKS container
453 permanently inaccessible.
454 NOTE: If there is no passphrase provided (on stdin or through
456 --key-file argument) and batch-mode (-q) is active, the key-slot
457 is removed without any other warning.
458 erase <device>
461 luksErase <device>
462 Erase all keyslots and make the LUKS container permanently inac‐
464 cessible. You do not need to provide any password for this op‐
465 eration.
466 WARNING: This operation is irreversible.
468 luksUUID <device>
470 Print the UUID of a LUKS device.
472 Set new UUID if --uuid option is specified.
473 isLuks <device>
475 Returns true, if <device> is a LUKS device, false otherwise.
477 Use option -v to get human-readable feedback. 'Command success‐
478 ful.' means the device is a LUKS device.
479 By specifying --type you may query for specific LUKS version.
481 luksDump <device>
483 Dump the header information of a LUKS device.
485 If the --dump-master-key option is used, the LUKS device master
487 key is dumped instead of the keyslot info. Together with --mas‐
488 ter-key-file option, master key is dumped to a file instead of
489 standard output. Beware that the master key cannot be changed
490 without reencryption and can be used to decrypt the data stored
491 in the LUKS container without a passphrase and even without the
492 LUKS header. This means that if the master key is compromised,
493 the whole device has to be erased or reencrypted to prevent fur‐
494 ther access. Use this option carefully.
495 To dump the master key, a passphrase has to be supplied, either
497 interactively or via --key-file.
498 To dump unbound key (LUKS2 format only), --unbound parameter,
500 specific --key-slot id and proper passphrase has to be supplied,
501 either interactively or via --key-file. Optional --mas‐
502 ter-key-file parameter enables unbound keyslot dump to a file.
503 To dump LUKS2 JSON metadata (without basic heade information
505 like UUID) use --dump-json-metadata option.
506 <options> can be [--dump-master-key, --dump-json-metadata,
508 --key-file, --keyfile-offset, --keyfile-size, --header, --dis‐
509 able-locks, --master-key-file, --type, --unbound, --key-slot].
510 WARNING: If --dump-master-key is used with --key-file and the
512 argument to --key-file is '-', no validation question will be
513 asked and no warning given.
514 luksHeaderBackup <device> --header-backup-file <file>
516 Stores a binary backup of the LUKS header and keyslot area.
518 Note: Using '-' as filename writes the header backup to a file
519 named '-'.
520 WARNING: This backup file and a passphrase valid at the time of
522 backup allows decryption of the LUKS data area, even if the
523 passphrase was later changed or removed from the LUKS device.
524 Also note that with a header backup you lose the ability to se‐
525 curely wipe the LUKS device by just overwriting the header and
526 key-slots. You either need to securely erase all header backups
527 in addition or overwrite the encrypted data area as well. The
528 second option is less secure, as some sectors can survive, e.g.
529 due to defect management.
530 luksHeaderRestore <device> --header-backup-file <file>
532 Restores a binary backup of the LUKS header and keyslot area
534 from the specified file.
535 Note: Using '-' as filename reads the header backup from a file
536 named '-'.
537 WARNING: Header and keyslots will be replaced, only the
539 passphrases from the backup will work afterward.
540 This command requires that the master key size and data offset
542 of the LUKS header already on the device and of the header
543 backup match. Alternatively, if there is no LUKS header on the
544 device, the backup will also be written to it.
545 token <add|remove|import|export> <device>
547 Action add creates new keyring token to enable auto-activation
549 of the device. For the auto-activation, the passphrase must be
550 stored in keyring with the specified description. Usually, the
551 passphrase should be stored in user or user-session keyring.
552 The token command is supported only for LUKS2.
553 For adding new keyring token, option --key-description is manda‐
555 tory. Also, new token is assigned to key slot specified with
556 --key-slot option or to all active key slots in the case
557 --key-slot option is omitted.
558 To remove existing token, specify the token ID which should be
560 removed with --token-id option.
561 WARNING: The action token remove removes any token type, not
563 just keyring type from token slot specified by --token-id op‐
564 tion.
565 Action import can store arbitrary valid token json in LUKS2
567 header. It may be passed via standard input or via file passed
568 in --json-file option. If you specify --key-slot then success‐
569 fully imported token is also assigned to the key slot.
570 Action export writes requested token json to a file passed with
572 --json-file or to standard output.
573 <options> can be [--header, --token-id, --key-slot, --key-de‐
575 scription, --disable-external-tokens, --disable-locks, --dis‐
576 able-keyring, --json-file].
577 convert <device> --type <format>
579 Converts the device between LUKS1 and LUKS2 format (if possi‐
581 ble). The conversion will not be performed if there is an addi‐
582 tional LUKS2 feature or LUKS1 has unsupported header size.
583 Conversion (both directions) must be performed on inactive de‐
585 vice. There must not be active dm-crypt mapping established for
586 LUKS header requested for conversion.
587 --type option is mandatory with following accepted values: luks1
589 or luks2.
590 WARNING: The convert action can destroy the LUKS header in the
592 case of a crash during conversion or if a media error occurs.
593 Always create a header backup before performing this operation!
594 <options> can be [--header, --type].
596 config <device>
598 Set permanent configuration options (store to LUKS header). The
600 config command is supported only for LUKS2.
601 The permanent options can be --priority to set priority (normal,
603 prefer, ignore) for keyslot (specified by --key-slot) or --label
604 and --subsystem.
605 <options> can be [--priority, --label, --subsystem, --key-slot,
607 --header].
608
611 cryptsetup supports mapping loop-AES encrypted partition using a com‐
612 patibility mode.
613 open --type loopaes <device> <name> --key-file <keyfile>
615 loopaesOpen <device> <name> --key-file <keyfile> (old syntax)
616 Opens the loop-AES <device> and sets up a mapping <name>.
618 If the key file is encrypted with GnuPG, then you have to use
620 --key-file=- and decrypt it before use, e.g. like this:
621 gpg --decrypt <keyfile> | cryptsetup loopaesOpen --key-file=-
622 <device> <name>
623 WARNING: The loop-AES extension cannot use the direct input of
625 key file on real terminal because the keys are separated by end-
626 of-line and only part of the multi-key file would be read.
627 If you need it in script, just use the pipe redirection:
628 echo $keyfile | cryptsetup loopaesOpen --key-file=- <device>
629 <name>
630 Use --keyfile-size to specify the proper key length if needed.
632 Use --offset to specify device offset. Note that the units need
634 to be specified in number of 512 byte sectors.
635 Use --skip to specify the IV offset. If the original device used
637 an offset and but did not use it in IV sector calculations, you
638 have to explicitly use --skip 0 in addition to the offset param‐
639 eter.
640 Use --hash to override the default hash function for passphrase
642 hashing (otherwise it is detected according to key size).
643 <options> can be [--key-file, --key-size, --offset, --skip,
645 --hash, --readonly, --allow-discards, --refresh].
646 See also section 7 of the FAQ and http://loop-aes.sourceforge.net for
648 more information regarding loop-AES.
649
651 cryptsetup supports mapping of TrueCrypt, tcplay or VeraCrypt encrypted
652 partition using a native Linux kernel API. Header formatting and
653 TCRYPT header change is not supported, cryptsetup never changes TCRYPT
654 header on-device.
655 TCRYPT extension requires kernel userspace crypto API to be available
657 (introduced in Linux kernel 2.6.38). If you are configuring kernel
658 yourself, enable "User-space interface for symmetric key cipher algo‐
659 rithms" in "Cryptographic API" section (CRYPTO_USER_API_SKCIPHER .con‐
660 fig option).
661 Because TCRYPT header is encrypted, you have to always provide valid
663 passphrase and keyfiles.
664 Cryptsetup should recognize all header variants, except legacy cipher
666 chains using LRW encryption mode with 64 bits encryption block (namely
667 Blowfish in LRW mode is not recognized, this is limitation of kernel
668 crypto API).
669 VeraCrypt is just extension of TrueCrypt header with increased itera‐
671 tion count so unlocking can take quite a lot of time (in comparison
672 with TCRYPT device).
673 To open a VeraCrypt device with a custom Personal Iteration Multiplier
675 (PIM) value, use either the --veracrypt-pim=<PIM> option to directly
676 specify the PIM on the command- line or use --veracrypt-query-pim to be
677 prompted for the PIM.
678 The PIM value affects the number of iterations applied during key deri‐
680 vation. Please refer to https://www.veracrypt.fr/en/Personal%20Itera‐
681 tions%20Multiplier%20%28PIM%29.html for more detailed information.
682 If you need to disable VeraCrypt device support, use --disable-ver‐
684 acrypt option.
685 NOTE: Activation with tcryptOpen is supported only for cipher chains
687 using LRW or XTS encryption modes.
688 The tcryptDump command should work for all recognized TCRYPT devices
690 and doesn't require superuser privilege.
691 To map system device (device with boot loader where the whole encrypted
693 system resides) use --tcrypt-system option. You can use partition de‐
694 vice as the parameter (parameter must be real partition device, not an
695 image in a file), then only this partition is mapped.
696 If you have the whole TCRYPT device as a file image and you want to map
698 multiple partition encrypted with system encryption, please create
699 loopback mapping with partitions first (losetup -P, see losetup(8) man
700 page for more info), and use loop partition as the device parameter.
701 If you use the whole base device as a parameter, one device for the
703 whole system encryption is mapped. This mode is available only for
704 backward compatibility with older cryptsetup versions which mapped
705 TCRYPT system encryption using the whole device.
706 To use hidden header (and map hidden device, if available), use
708 --tcrypt-hidden option.
709 To explicitly use backup (secondary) header, use --tcrypt-backup op‐
711 tion.
712 NOTE: There is no protection for a hidden volume if the outer volume is
714 mounted. The reason is that if there were any protection, it would re‐
715 quire some metadata describing what to protect in the outer volume and
716 the hidden volume would become detectable.
717 open --type tcrypt <device> <name>
720 tcryptOpen <device> <name> (old syntax)
721 Opens the TCRYPT (a TrueCrypt-compatible) <device> and sets up a
723 mapping <name>.
724 <options> can be [--key-file, --tcrypt-hidden, --tcrypt-system,
726 --tcrypt-backup, --readonly, --test-passphrase, --allow-dis‐
727 cards, --disable-veracrypt, --veracrypt-pim, --ver‐
728 acrypt-query-pim, --header, --cipher, --hash].
729 The keyfile parameter allows a combination of file content with
731 the passphrase and can be repeated. Note that using keyfiles is
732 compatible with TCRYPT and is different from LUKS keyfile logic.
733 If --PBKDF2 variants with the specified hash algorithms are
735 checked. This could speed up unlocking the device (but also it
736 reveals some information about the container).
737 If you use --header in combination with hidden or system op‐
739 tions, the header file must contain specific headers on the same
740 positions as the original encrypted container.
741 WARNING: Option --allow-discards cannot be combined with option
743 --tcrypt-hidden. For normal mapping, it can cause the destruc‐
744 tion of hidden volume (hidden volume appears as unused space for
745 outer volume so this space can be discarded).
746 tcryptDump <device>
749 Dump the header information of a TCRYPT device.
751 If the --dump-master-key option is used, the TCRYPT device mas‐
753 ter key is dumped instead of TCRYPT header info. Beware that the
754 master key (or concatenated master keys if cipher chain is used)
755 can be used to decrypt the data stored in the TCRYPT container
756 without a passphrase. This means that if the master key is com‐
757 promised, the whole device has to be erased to prevent further
758 access. Use this option carefully.
759 <options> can be [--dump-master-key, --key-file, --tcrypt-hid‐
761 den, --tcrypt-system, --tcrypt-backup, --cipher, --hash].
762 The keyfile parameter allows a combination of file content with
764 the passphrase and can be repeated.
765 See also https://en.wikipedia.org/wiki/TrueCrypt for more information
767 regarding TrueCrypt.
768 Please note that cryptsetup does not use TrueCrypt code, please report
770 all problems related to this compatibility extension to the cryptsetup
771 project.
772
775 cryptsetup supports mapping of BitLocker and BitLocker to Go encrypted
776 partition using a native Linux kernel API. Header formatting and BITLK
777 header changes are not supported, cryptsetup never changes BITLK header
778 on-device.
779 WARNING: This extension is EXPERIMENTAL.
781 BITLK extension requires kernel userspace crypto API to be available
783 (for details see TCRYPT section).
784 Cryptsetup should recognize all BITLK header variants, except legacy
786 header used in Windows Vista systems and partially decrypted BitLocker
787 devices. Activation of legacy devices encrypted in CBC mode requires
788 at least Linux kernel version 5.3 and for devices using Elephant dif‐
789 fuser kernel 5.6.
790 The bitlkDump command should work for all recognized BITLK devices and
792 doesn't require superuser privilege.
793 For unlocking with the open a password or a recovery passphrase or a
795 startup key must be provided.
796 Additionally unlocking using master key is supported. You must provide
798 BitLocker Full Volume Encryption Key (FVEK) using the --master-key-file
799 option. The key must be decrypted and without the header (only
800 128/256/512 bits of key data depending on used cipher and mode).
801 Other unlocking methods (TPM, SmartCard) are not supported.
803 open --type bitlk <device> <name>
806 bitlkOpen <device> <name> (old syntax)
807 Opens the BITLK (a BitLocker-compatible) <device> and sets up a
809 mapping <name>.
810 <options> can be [--key-file, --readonly, --test-passphrase,
812 --allow-discards --master-key-file].
813 bitlkDump <device>
816 Dump the header information of a BITLK device.
818 <options> can be [--dump-master-key --master-key-file].
820 Please note that cryptsetup does not use any Windows BitLocker code,
823 please report all problems related to this compatibility extension to
824 the cryptsetup project.
825
828 repair <device>
829 Tries to repair the device metadata if possible. Currently sup‐
831 ported only for LUKS device type.
832 This command is useful to fix some known benign LUKS metadata
834 header corruptions. Only basic corruptions of unused keyslot are
835 fixable. This command will only change the LUKS header, not any
836 key-slot data. You may enforce LUKS version by adding --type op‐
837 tion.
838 WARNING: Always create a binary backup of the original header
840 before calling this command.
841 benchmark <options>
843 Benchmarks ciphers and KDF (key derivation function). Without
845 parameters, it tries to measure few common configurations.
846 To benchmark other ciphers or modes, you need to specify --ci‐
848 pher and --key-size options or --hash for KDF test.
849 NOTE: This benchmark is using memory only and is only informa‐
851 tive. You cannot directly predict real storage encryption speed
852 from it.
853 For testing block ciphers, this benchmark requires kernel
855 userspace crypto API to be available (introduced in Linux kernel
856 2.6.38). If you are configuring kernel yourself, enable "User-
857 space interface for symmetric key cipher algorithms" in "Crypto‐
858 graphic API" section (CRYPTO_USER_API_SKCIPHER .config option).
859 <options> can be [--cipher, --key-size, --hash].
861
863 --verbose, -v
864 Print more information on command execution.
865 --debug or --debug-json
867 Run in debug mode with full diagnostic logs. Debug output lines
868 are always prefixed by '#'. If --debug-json is used, additional
869 LUKS2 JSON data structures are printed.
870 --type <device-type>
872 Specifies required device type, for more info read BASIC ACTIONS
873 section.
874 --hash, -h <hash-spec>
876 Specifies the passphrase hash for open (for plain and loopaes
877 device types).
878 Specifies the hash used in the LUKS key setup scheme and volume
880 key digest for luksFormat. The specified hash is used as hash-
881 parameter for PBKDF2 and for the AF splitter.
882 The specified hash name is passed to the compiled-in crypto
884 backend. Different backends may support different hashes. For
885 luksFormat, the hash algorithm must provide at least 160 bits of
886 output, which excludes, e.g., MD5. Do not use a non-crypto hash
887 like "crc32" as this breaks security.
888 Values compatible with old version of cryptsetup are "ripemd160"
890 for open --type plain and "sha1" for luksFormat.
891 Use cryptsetup --help to show the defaults.
893 --cipher, -c <cipher-spec>
895 Set the cipher specification string.
896 cryptsetup --help shows the compiled-in defaults. The current
898 default in the distributed sources is "aes-cbc-essiv:sha256" for
899 plain dm-crypt and "aes-xts-plain64" for LUKS.
900 If a hash is part of the cipher specification, then it is used
902 as part of the IV generation. For example, ESSIV needs a hash
903 function, while "plain64" does not and hence none is specified.
904 For XTS mode you can optionally set a key size of 512 bits with
906 the -s option. Key size for XTS mode is twice that for other
907 modes for the same security level.
908 XTS mode requires kernel 2.6.24 or later and plain64 requires
910 kernel 2.6.33 or later. More information can be found in the
911 FAQ.
912 --verify-passphrase, -y
914 When interactively asking for a passphrase, ask for it twice and
915 complain if both inputs do not match. Advised when creating a
916 regular mapping for the first time, or when running luksFormat.
917 Ignored on input from file or stdin.
918 --key-file, -d name
920 Read the passphrase from file.
921 If the name given is "-", then the passphrase will be read from
923 stdin. In this case, reading will not stop at newline charac‐
924 ters.
925 With LUKS, passphrases supplied via --key-file are always the
927 existing passphrases requested by a command, except in the case
928 of luksFormat where --key-file is equivalent to the positional
929 key file argument.
930 If you want to set a new passphrase via key file, you have to
932 use a positional argument to luksAddKey.
933 See section NOTES ON PASSPHRASE PROCESSING for more information.
935 --keyfile-offset value
937 Skip value bytes at the beginning of the key file. Works with
938 all commands that accept key files.
939 --keyfile-size, -l value
941 Read a maximum of value bytes from the key file. The default is
942 to read the whole file up to the compiled-in maximum that can be
943 queried with --help. Supplying more data than the compiled-in
944 maximum aborts the operation.
945 This option is useful to cut trailing newlines, for example. If
947 --keyfile-offset is also given, the size count starts after the
948 offset. Works with all commands that accept key files.
949 --new-keyfile-offset value
951 Skip value bytes at the start when adding a new passphrase from
952 key file with luksAddKey.
953 --new-keyfile-size value
955 Read a maximum of value bytes when adding a new passphrase from
956 key file with luksAddKey. The default is to read the whole file
957 up to the compiled-in maximum length that can be queried with
958 --help. Supplying more than the compiled in maximum aborts the
959 operation. When --new-keyfile-offset is also given, reading
960 starts after the offset.
961 --master-key-file
963 Use a master key stored in a file.
964 For luksFormat this allows creating a LUKS header with this spe‐
966 cific master key. If the master key was taken from an existing
967 LUKS header and all other parameters are the same, then the new
968 header decrypts the data encrypted with the header the master
969 key was taken from.
970 Action luksDump together with --dump-master-key option: The vol‐
972 ume (master) key is stored in a file instead of being printed
973 out to standard output.
974 WARNING: If you create your own master key, you need to make
976 sure to do it right. Otherwise, you can end up with a low-en‐
977 tropy or otherwise partially predictable master key which will
978 compromise security.
979 For luksAddKey this allows adding a new passphrase without hav‐
981 ing to know an existing one.
982 For open this allows one to open the LUKS device without giving
984 a passphrase.
985 --dump-json-metadata
987 For luksDump (LUKS2 only) this option prints content of LUKS2
988 header JSON metadata area.
989 --dump-master-key
991 For luksDump this option includes the master key in the dis‐
992 played information. Use with care, as the master key can be used
993 to bypass the passphrases, see also option --master-key-file.
994 --json-file
996 Read token json from a file or write token to it. See token ac‐
997 tion for more information. --json-file=- reads json from stan‐
998 dard input or writes it to standard output respectively.
999 --use-random
1001 --use-urandom
1003 For luksFormat these options define which kernel random number
1004 generator will be used to create the master key (which is a
1005 long-term key).
1006 See NOTES ON RANDOM NUMBER GENERATORS for more information. Use
1008 cryptsetup --help to show the compiled-in default random number
1009 generator.
1010 WARNING: In a low-entropy situation (e.g. in an embedded sys‐
1012 tem), both selections are problematic. Using /dev/urandom can
1013 lead to weak keys. Using /dev/random can block a long time, po‐
1014 tentially forever, if not enough entropy can be harvested by the
1015 kernel.
1016 --key-slot, -S <0-N>
1018 For LUKS operations that add key material, this options allows
1019 you to specify which key slot is selected for the new key. This
1020 option can be used for luksFormat, and luksAddKey.
1021 In addition, for open, this option selects a specific key-slot
1022 to compare the passphrase against. If the given passphrase
1023 would only match a different key-slot, the operation fails.
1024 Maximum number of key slots depends on LUKS version. LUKS1 can
1026 have up to 8 key slots. LUKS2 can have up to 32 key slots based
1027 on key slot area size and key size, but a valid key slot ID can
1028 always be between 0 and 31 for LUKS2.
1029 --key-size, -s <bits>
1031 Sets key size in bits. The argument has to be a multiple of 8.
1032 The possible key-sizes are limited by the cipher and mode used.
1033 See /proc/crypto for more information. Note that key-size in
1035 /proc/crypto is stated in bytes.
1036 This option can be used for open --type plain or luksFormat.
1038 All other LUKS actions will use the key-size specified in the
1039 LUKS header. Use cryptsetup --help to show the compiled-in de‐
1040 faults.
1041 --size, -b <number of 512 byte sectors>
1043 Set the size of the device in sectors of 512 bytes. This option
1044 is only relevant for the open and resize actions.
1045 --offset, -o <number of 512 byte sectors>
1047 Start offset in the backend device in 512-byte sectors. This
1048 option is only relevant for the open action with plain or
1049 loopaes device types or for LUKS devices in luksFormat.
1050 For LUKS, the --offset option sets the data offset (payload) of
1052 data device and must be be aligned to 4096-byte sectors (must be
1053 multiple of 8). This option cannot be combined with
1054 --align-payload option.
1055 --skip, -p <number of 512 byte sectors>
1057 Start offset used in IV calculation in 512-byte sectors (how
1058 many sectors of the encrypted data to skip at the beginning).
1059 This option is only relevant for the open action with plain or
1060 loopaes device types.
1061 Hence, if --offset n, and --skip s, sector n (the first sector
1063 of the encrypted device) will get a sector number of s for the
1064 IV calculation.
1065 --device-size size[units]
1067 Instead of real device size, use specified value.
1068 With reencrypt action it means that only specified area (from
1070 the start of the device to the specified size) will be reen‐
1071 crypted.
1072 With resize action it sets new size of the device.
1074 If no unit suffix is specified, the size is in bytes.
1076 Unit suffix can be S for 512 byte sectors, K/M/G/T (or
1078 KiB,MiB,GiB,TiB) for units with 1024 base or KB/MB/GB/TB for
1079 1000 base (SI scale).
1080 WARNING: This is destructive operation when used with reencrypt
1082 command.
1083 --readonly, -r
1085 set up a read-only mapping.
1086 --shared
1088 Creates an additional mapping for one common ciphertext device.
1089 Arbitrary mappings are supported. This option is only relevant
1090 for the open --type plain action. Use --offset, --size and
1091 --skip to specify the mapped area.
1092 --pbkdf <PBKDF spec>
1094 Set Password-Based Key Derivation Function (PBKDF) algorithm for
1095 LUKS keyslot. The PBKDF can be: pbkdf2 (for PBKDF2 according to
1096 RFC2898), argon2i for Argon2i or argon2id for Argon2id (see
1097 https://www.cryptolux.org/index.php/Argon2 for more info).
1098 For LUKS1, only PBKDF2 is accepted (no need to use this option).
1100 The default PBKDF2 for LUKS2 is set during compilation time and
1101 is available in cryptsetup --help output.
1102 A PBKDF is used for increasing dictionary and brute-force attack
1104 cost for keyslot passwords. The parameters can be time, memory
1105 and parallel cost.
1106 For PBKDF2, only time cost (number of iterations) applies. For
1108 Argon2i/id, there is also memory cost (memory required during
1109 the process of key derivation) and parallel cost (number of
1110 threads that run in parallel during the key derivation.
1111 Note that increasing memory cost also increases time, so the fi‐
1113 nal parameter values are measured by a benchmark. The benchmark
1114 tries to find iteration time (--iter-time) with required memory
1115 cost --pbkdf-memory. If it is not possible, the memory cost is
1116 decreased as well. The parallel cost --pbkdf-parallel is con‐
1117 stant and is checked against available CPU cores.
1118 You can see all PBKDF parameters for particular LUKS2 keyslot
1120 with luksDump command.
1121 NOTE: If you do not want to use benchmark and want to specify
1123 all parameters directly, use --pbkdf-force-iterations with
1124 --pbkdf-memory and --pbkdf-parallel. This will override the
1125 values without benchmarking. Note it can cause extremely long
1126 unlocking time. Use only in specific cases, for example, if you
1127 know that the formatted device will be used on some small embed‐
1128 ded system.
1129 MINIMAL AND MAXIMAL PBKDF COSTS: For PBKDF2, the minimum itera‐
1131 tion count is 1000 and maximum is 4294967295 (maximum for 32bit
1132 unsigned integer). Memory and parallel costs are unused for
1133 PBKDF2. For Argon2i and Argon2id, minimum iteration count (CPU
1134 cost) is 4 and maximum is 4294967295 (maximum for 32bit unsigned
1135 integer). Minimum memory cost is 32 KiB and maximum is 4 GiB.
1136 (Limited by addresable memory on some CPU platforms.) If the
1137 memory cost parameter is benchmarked (not specified by a parame‐
1138 ter) it is always in range from 64 MiB to 1 GiB. The parallel
1139 cost minimum is 1 and maximum 4 (if enough CPUs cores are avail‐
1140 able, otherwise it is decreased).
1141 --iter-time, -i <number of milliseconds>
1143 The number of milliseconds to spend with PBKDF passphrase pro‐
1144 cessing. This option is only relevant for LUKS operations that
1145 set or change passphrases, such as luksFormat or luksAddKey.
1146 Specifying 0 as parameter selects the compiled-in default.
1147 --pbkdf-memory <number>
1149 Set the memory cost for PBKDF (for Argon2i/id the number repre‐
1150 sents kilobytes). Note that it is maximal value, PBKDF bench‐
1151 mark or available physical memory can decrease it. This option
1152 is not available for PBKDF2.
1153 --pbkdf-parallel <number>
1155 Set the parallel cost for PBKDF (number of threads, up to 4).
1156 Note that it is maximal value, it is decreased automatically if
1157 CPU online count is lower. This option is not available for
1158 PBKDF2.
1159 --pbkdf-force-iterations <num>
1161 Avoid PBKDF benchmark and set time cost (iterations) directly.
1162 It can be used for LUKS/LUKS2 device only. See --pbkdf option
1163 for more info.
1164 --batch-mode, -q
1166 Suppresses all confirmation questions. Use with care!
1167 If the -y option is not specified, this option also switches off
1169 the passphrase verification for luksFormat.
1170 --progress-frequency <seconds>
1172 Print separate line every <seconds> with wipe progress.
1173 --timeout, -t <number of seconds>
1175 The number of seconds to wait before timeout on passphrase input
1176 via terminal. It is relevant every time a passphrase is asked,
1177 for example for open, luksFormat or luksAddKey. It has no ef‐
1178 fect if used in conjunction with --key-file.
1179 This option is useful when the system should not stall if the
1180 user does not input a passphrase, e.g. during boot. The default
1181 is a value of 0 seconds, which means to wait forever.
1182 --tries, -T
1184 How often the input of the passphrase shall be retried. This
1185 option is relevant every time a passphrase is asked, for example
1186 for open, luksFormat or luksAddKey. The default is 3 tries.
1187 --align-payload <number of 512 byte sectors>
1189 Align payload at a boundary of value 512-byte sectors. This op‐
1190 tion is relevant for luksFormat.
1191 If not specified, cryptsetup tries to use the topology info pro‐
1193 vided by the kernel for the underlying device to get the optimal
1194 alignment. If not available (or the calculated value is a mul‐
1195 tiple of the default) data is by default aligned to a 1MiB
1196 boundary (i.e. 2048 512-byte sectors).
1197 For a detached LUKS header, this option specifies the offset on
1199 the data device. See also the --header option.
1200 WARNING: This option is DEPRECATED and has often unexpected im‐
1202 pact to the data offset and keyslot area size (for LUKS2) due to
1203 the complex rounding. For fixed data device offset use --offset
1204 option instead.
1205 --uuid=UUID
1208 Use the provided UUID for the luksFormat command instead of gen‐
1209 erating a new one. Changes the existing UUID when used with the
1210 luksUUID command.
1211 The UUID must be provided in the standard UUID format, e.g.
1213 12345678-1234-1234-1234-123456789abc.
1214 --allow-discards
1216 Allow the use of discard (TRIM) requests for the device. This
1217 option is only relevant for open action. This is also not sup‐
1218 ported for LUKS2 devices with data integrity protection.
1219 WARNING: This command can have a negative security impact be‐
1221 cause it can make filesystem-level operations visible on the
1222 physical device. For example, information leaking filesystem
1223 type, used space, etc. may be extractable from the physical de‐
1224 vice if the discarded blocks can be located later. If in doubt,
1225 do not use it.
1226 A kernel version of 3.1 or later is needed. For earlier kernels,
1228 this option is ignored.
1229 --perf-same_cpu_crypt
1231 Perform encryption using the same cpu that IO was submitted on.
1232 The default is to use an unbound workqueue so that encryption
1233 work is automatically balanced between available CPUs. This op‐
1234 tion is only relevant for open action.
1235 NOTE: This option is available only for low-level dm-crypt per‐
1237 formance tuning, use only if you need a change to default dm-
1238 crypt behaviour. Needs kernel 4.0 or later.
1239 --perf-submit_from_crypt_cpus
1241 Disable offloading writes to a separate thread after encryption.
1242 There are some situations where offloading write bios from the
1243 encryption threads to a single thread degrades performance sig‐
1244 nificantly. The default is to offload write bios to the same
1245 thread. This option is only relevant for open action.
1246 NOTE: This option is available only for low-level dm-crypt per‐
1248 formance tuning, use only if you need a change to default dm-
1249 crypt behaviour. Needs kernel 4.0 or later.
1250 --perf-no_read_workqueue, --perf-no_write_workqueue
1252 Bypass dm-crypt internal workqueue and process read or write re‐
1253 quests synchronously. This option is only relevant for open ac‐
1254 tion.
1255 NOTE: These options are available only for low-level dm-crypt
1257 performance tuning, use only if you need a change to default dm-
1258 crypt behaviour. Needs kernel 5.9 or later.
1259 --test-passphrase
1261 Do not activate the device, just verify passphrase. This option
1262 is only relevant for open action (the device mapping name is not
1263 mandatory if this option is used).
1264 --header <device or file storing the LUKS header>
1266 Use a detached (separated) metadata device or file where the
1267 LUKS header is stored. This option allows one to store cipher‐
1268 text and LUKS header on different devices.
1269 This option is only relevant for LUKS devices and can be used
1271 with the luksFormat, open, luksSuspend, luksResume, status and
1272 resize commands.
1273 For luksFormat with a file name as the argument to --header, the
1275 file will be automatically created if it does not exist. See
1276 the cryptsetup FAQ for header size calculation.
1277 For other commands that change the LUKS header (e.g. luksAdd‐
1279 Key), specify the device or file with the LUKS header directly
1280 as the LUKS device.
1281 If used with luksFormat, the --align-payload option is taken as
1283 absolute sector alignment on ciphertext device and can be zero.
1284 WARNING: There is no check whether the ciphertext device speci‐
1286 fied actually belongs to the header given. In fact, you can
1287 specify an arbitrary device as the ciphertext device for open
1288 with the --header option. Use with care.
1289 --header-backup-file <file>
1291 Specify file with header backup for luksHeaderBackup or luk‐
1292 sHeaderRestore actions.
1293 --force-password
1295 Do not use password quality checking for new LUKS passwords.
1296 This option applies only to luksFormat, luksAddKey and
1298 luksChangeKey and is ignored if cryptsetup is built without
1299 password quality checking support.
1300 For more info about password quality check, see the manual page
1302 for pwquality.conf(5) and passwdqc.conf(5).
1303 --deferred
1305 Defers device removal in close command until the last user
1306 closes it.
1307 --cancel-deferred
1309 Removes a previously configured deferred device removal in close
1310 command.
1311 --disable-external-tokens
1313 Disable loading of plugins for external LUKS2 tokens.
1314 --disable-locks
1316 Disable lock protection for metadata on disk. This option is
1317 valid only for LUKS2 and ignored for other formats.
1318 WARNING: Do not use this option unless you run cryptsetup in a
1320 restricted environment where locking is impossible to perform
1321 (where /run directory cannot be used).
1322 --disable-keyring
1324 Do not load volume key in kernel keyring and store it directly
1325 in the dm-crypt target instead. This option is supported only
1326 for the LUKS2 format.
1327 --key-description <text>
1329 Set key description in keyring for use with token command.
1330 --priority <normal|prefer|ignore>
1332 Set a priority for LUKS2 keyslot. The prefer priority marked
1333 slots are tried before normal priority. The ignored priority
1334 means, that slot is never used, if not explicitly requested by
1335 --key-slot option.
1336 --token-id
1338 Specify what token to use in actions token, open or resize. If
1339 omitted, all available tokens will be checked before proceeding
1340 further with passphrase prompt.
1341 --token-only
1343 Do not proceed further with action (any of token, open or re‐
1344 size) if token activation failed. Without the option, action
1345 asks for passphrase to proceed further.
1346 --token-type
1348 Restrict tokens eligible for operation to specific token type
1349 (name). Mostly useful when no --token-id is specified.
1350 --sector-size <bytes>
1352 Set sector size for use with disk encryption. It must be power
1353 of two and in range 512 - 4096 bytes. This option is available
1354 only in the LUKS2 or plain modes.
1355 The default for plain mode is 512 bytes. For LUKS2 devices it's
1357 established during luksFormat operation based on parameters pro‐
1358 vided by underlying data device. For native 4K block devices
1359 it's 4096 bytes. For 4K/512e (4K physical sector size with 512
1360 bytes emulation) it's 4096 bytes. For drives reporting only 512
1361 bytes block size it remains 512 bytes. If data device is regular
1362 file put in filesystem it's 4096 bytes.
1363 Note that if sector size is higher than underlying device hard‐
1365 ware sector and there is not integrity protection that uses data
1366 journal, using this option can increase risk on incomplete sec‐
1367 tor writes during a power fail.
1368 If used together with --integrity option and dm-integrity jour‐
1370 nal, the atomicity of writes is guaranteed in all cases (but it
1371 cost write performance - data has to be written twice).
1372 Increasing sector size from 512 bytes to 4096 bytes can provide
1374 better performance on most of the modern storage devices and
1375 also with some hw encryption accelerators.
1376 --iv-large-sectors
1378 Count Initialization Vector (IV) in larger sector size (if set)
1379 instead of 512 bytes sectors. This option can be used only for
1380 open command and plain encryption type.
1381 NOTE: This option does not have any performance or security im‐
1383 pact, use it only for accessing incompatible existing disk im‐
1384 ages from other systems that require this option.
1385 --persistent
1387 If used with LUKS2 devices and activation commands like open or
1388 refresh, the specified activation flags are persistently written
1389 into metadata and used next time automatically even for normal
1390 activation. (No need to use cryptab or other system configura‐
1391 tion files.)
1392 If you need to remove a persistent flag, use --persistent with‐
1394 out the flag you want to remove (e.g. to disable persistently
1395 stored discard flag, use --persistent without --allow-discards).
1396 Only --allow-discards, --perf-same_cpu_crypt, --perf-sub‐
1398 mit_from_crypt_cpus, --perf-no_read_workqueue,
1399 --perf-no_write_workqueue and --integrity-no-journal can be
1400 stored persistently.
1401 --refresh
1403 Refreshes an active device with new set of parameters. See ac‐
1404 tion refresh description for more details.
1405 --label <LABEL>
1407 --subsystem <SUBSYSTEM> Set label and subsystem description for
1408 LUKS2 device, can be used in config and format actions. The la‐
1409 bel and subsystem are optional fields and can be later used in
1410 udev scripts for triggering user actions once device marked by
1411 these labels is detected.
1412 --integrity <integrity algorithm>
1414 Specify integrity algorithm to be used for authenticated disk
1415 encryption in LUKS2.
1416 WARNING: This extension is EXPERIMENTAL and requires dm-integ‐
1418 rity kernel target (available since kernel version 4.12). For
1419 native AEAD modes, also enable "User-space interface for AEAD
1420 cipher algorithms" in "Cryptographic API" section (CON‐
1421 FIG_CRYPTO_USER_API_AEAD .config option).
1422 For more info, see AUTHENTICATED DISK ENCRYPTION section.
1424 --luks2-metadata-size <size>
1426 This option can be used to enlarge the LUKS2 metadata (JSON)
1427 area. The size includes 4096 bytes for binary metadata (usable
1428 JSON area is smaller of the binary area). According to LUKS2
1429 specification, only these values are valid: 16, 32, 64, 128,
1430 256, 512, 1024, 2048 and 4096 kB The <size> can be specified
1431 with unit suffix (for example 128k).
1432 --luks2-keyslots-size <size>
1434 This option can be used to set specific size of the LUKS2 binary
1435 keyslot area (key material is encrypted there). The value must
1436 be aligned to multiple of 4096 bytes with maximum size 128MB.
1437 The <size> can be specified with unit suffix (for example 128k).
1438 --keyslot-cipher <cipher-spec>
1440 This option can be used to set specific cipher encryption for
1441 the LUKS2 keyslot area.
1442 --keyslot-key-size <bits>
1444 This option can be used to set specific key size for the LUKS2
1445 keyslot area.
1446 --integrity-no-journal
1448 Activate device with integrity protection without using data
1449 journal (direct write of data and integrity tags). Note that
1450 without journal power fail can cause non-atomic write and data
1451 corruption. Use only if journalling is performed on a different
1452 storage layer.
1453 --integrity-no-wipe
1455 Skip wiping of device authentication (integrity) tags. If you
1456 skip this step, sectors will report invalid integrity tag until
1457 an application write to the sector.
1458 NOTE: Even some writes to the device can fail if the write is
1460 not aligned to page size and page-cache initiates read of a sec‐
1461 tor with invalid integrity tag.
1462 --unbound
1464 Creates new or dumps existing LUKS2 unbound keyslot. See luksAd‐
1466 dKey or luksDump actions for more details.
1467 --tcrypt-hidden
1470 --tcrypt-system --tcrypt-backup Specify which TrueCrypt on-disk
1471 header will be used to open the device. See TCRYPT section for
1472 more info.
1473 --veracrypt
1475 This option is ignored as VeraCrypt compatible mode is supported
1476 by default.
1477 --disable-veracrypt
1479 This option can be used to disable VeraCrypt compatible mode
1480 (only TrueCrypt devices are recognized). Only for TCRYPT exten‐
1481 sion. See TCRYPT section for more info.
1482 --veracrypt-pim
1484 --veracrypt-query-pim Use a custom Personal Iteration Multiplier
1485 (PIM) for VeraCrypt device. See TCRYPT section for more info.
1486 --serialize-memory-hard-pbkdf
1488 Use a global lock to serialize unlocking of keyslots using mem‐
1489 ory-hard PBKDF.
1490 NOTE: This is (ugly) workaround for a specific situation when
1492 multiple devices are activated in parallel and system instead of
1493 reporting out of memory starts unconditionally stop processes
1494 using out-of-memory killer.
1495 DO NOT USE this switch until you are implementing boot environ‐
1497 ment with parallel devices activation!
1498 --encrypt
1500 Initialize (and run) device encryption (reencrypt action parame‐
1501 ter)
1502 --decrypt
1504 Initialize (and run) device decryption (reencrypt action parame‐
1505 ter)
1506 --init-only
1508 Initialize reencryption (any variant) operation in LUKS2 meta‐
1509 data only and exit. If any reencrypt operation is already ini‐
1510 tialized in metadata, the command with --init-only parameter
1511 fails.
1512 --resume-only
1514 Resume reencryption (any variant) operation already described in
1515 LUKS2 metadata. If no reencrypt operation is initialized, the
1516 command with --resume-only parameter fails. Useful for resuming
1517 reencrypt operation without accidentally triggering new reen‐
1518 cryption operation.
1519 --resilience <mode>
1521 Reencryption resilience mode can be one of checksum, journal or
1522 none.
1523 checksum: default mode, where individual checksums of ciphertext
1525 hotzone sectors are stored, so the recovery process can detect
1526 which sectors were already reencrypted. It requires that the
1527 device sector write is atomic.
1528 journal: the hotzone is journaled in the binary area (so the
1530 data are written twice).
1531 none: performance mode. There is no protection and the only way
1533 it's safe to interrupt the reencryption is similar to old off‐
1534 line reencryption utility. (ctrl+c).
1535 The option is ignored if reencryption with datashift mode is in
1537 progress.
1538 --resilience-hash <hash>
1540 The hash algorithm used with "--resilience checksum" only. The
1541 default hash is sha256. With other resilience modes, the hash
1542 parameter is ignored.
1543 --hotzone-size <size>
1545 This option can be used to set an upper limit on the size of
1546 reencryption area (hotzone). The <size> can be specified with
1547 unit suffix (for example 50M). Note that actual hotzone size may
1548 be less than specified <size> due to other limitations (free
1549 space in keyslots area or available memory).
1550 --reduce-device-size <size>
1552 Initialize LUKS2 reencryption with data device size reduction
1553 (currently only --encrypt variant is supported).
1554 Last <size> sectors of <device> will be used to properly ini‐
1556 tialize device reencryption. That means any data at last <size>
1557 sectors will be lost.
1558 It could be useful if you added some space to underlying parti‐
1560 tion or logical volume (so last <size> sectors contains no
1561 data).
1562 Recommended minimal size is twice the default LUKS2 header size
1564 (--reduce-device-size 32M) for --encrypt use case. Be sure to
1565 have enough (at least --reduce-device-size value of free
1566 space at the end of <device>).
1567 WARNING: This is a destructive operation and cannot be reverted.
1569 Use with extreme care - accidentally overwritten filesystems are
1570 usually unrecoverable.
1571 --version
1573 Show the program version.
1574 --usage
1576 Show short option help.
1577 --help, -?
1579 Show help text and default parameters.
1580
1582 Example 1: Create LUKS 2 container on block device /dev/sdX.
1583 sudo cryptsetup --type luks2 luksFormat /dev/sdX
1584 Example 2: Add an additional passphrase to key slot 5.
1586 sudo cryptsetup luksAddKey --key-slot 5 /dev/sdX
1587 Example 3: Create LUKS header backup and save it to file.
1589 sudo cryptsetup luksHeaderBackup /dev/sdX --header-backup-file
1590 /var/tmp/NameOfBackupFile
1591 Example 4: Open LUKS contaner on /dev/sdX and map it to sdX_crypt.
1593 sudo cryptsetup open /dev/sdX sdX_crypt
1594 WARNING: The command in example 5 will erase all key slots.
1596 Your cannot use your luks container afterwards anymore unless
1597 you have a backup to restore.
1598 Example 5: Erase all key slots on /dev/sdX.
1600 sudo cryptsetup erase /dev/sdX
1601 Example 6: Restore LUKS header from backup file.
1603 sudo cryptsetup luksHeaderRestore /dev/sdX --header-backup-file
1604 /var/tmp/NameOfBackupFile
1605
1607 Cryptsetup returns 0 on success and a non-zero value on error.
1608 Error codes are: 1 wrong parameters, 2 no permission (bad passphrase),
1610 3 out of memory, 4 wrong device specified, 5 device already exists or
1611 device is busy.
1612
1614 Note that no iterated hashing or salting is done in plain mode. If
1615 hashing is done, it is a single direct hash. This means that low-en‐
1616 tropy passphrases are easy to attack in plain mode.
1617 From a terminal: The passphrase is read until the first newline, i.e.
1619 '\n'. The input without the newline character is processed with the
1620 default hash or the hash specified with --hash. The hash result will
1621 be truncated to the key size of the used cipher, or the size specified
1622 with -s.
1623 From stdin: Reading will continue until a newline (or until the maximum
1625 input size is reached), with the trailing newline stripped. The maximum
1626 input size is defined by the same compiled-in default as for the maxi‐
1627 mum key file size and can be overwritten using --keyfile-size option.
1628 The data read will be hashed with the default hash or the hash speci‐
1630 fied with --hash. The hash result will be truncated to the key size of
1631 the used cipher, or the size specified with -s.
1632 Note that if --key-file=- is used for reading the key from stdin,
1634 trailing newlines are not stripped from the input.
1635 If "plain" is used as argument to --hash, the input data will not be
1637 hashed. Instead, it will be zero padded (if shorter than the key size)
1638 or truncated (if longer than the key size) and used directly as the bi‐
1639 nary key. This is useful for directly specifying a binary key. No
1640 warning will be given if the amount of data read from stdin is less
1641 than the key size.
1642 From a key file: It will be truncated to the key size of the used ci‐
1644 pher or the size given by -s and directly used as a binary key.
1645 WARNING: The --hash argument is being ignored. The --hash option is
1647 usable only for stdin input in plain mode.
1648 If the key file is shorter than the key, cryptsetup will quit with an
1650 error. The maximum input size is defined by the same compiled-in de‐
1651 fault as for the maximum key file size and can be overwritten using
1652 --keyfile-size option.
1653
1657 LUKS uses PBKDF2 to protect against dictionary attacks and to give some
1658 protection to low-entropy passphrases (see RFC 2898 and the cryptsetup
1659 FAQ).
1660 From a terminal: The passphrase is read until the first newline and
1662 then processed by PBKDF2 without the newline character.
1663 From stdin: LUKS will read passphrases from stdin up to the first new‐
1665 line character or the compiled-in maximum key file length. If --key‐
1666 file-size is given, it is ignored.
1667 From key file: The complete keyfile is read up to the compiled-in maxi‐
1669 mum size. Newline characters do not terminate the input. The --key‐
1670 file-size option can be used to limit what is read.
1671 Passphrase processing: Whenever a passphrase is added to a LUKS header
1673 (luksAddKey, luksFormat), the user may specify how much the time the
1674 passphrase processing should consume. The time is used to determine the
1675 iteration count for PBKDF2 and higher times will offer better protec‐
1676 tion for low-entropy passphrases, but open will take longer to com‐
1677 plete. For passphrases that have entropy higher than the used key
1678 length, higher iteration times will not increase security.
1679 The default setting of one or two seconds is sufficient for most prac‐
1681 tical cases. The only exception is a low-entropy passphrase used on a
1682 device with a slow CPU, as this will result in a low iteration count.
1683 On a slow device, it may be advisable to increase the iteration time
1684 using the --iter-time option in order to obtain a higher iteration
1685 count. This does slow down all later luksOpen operations accordingly.
1686
1688 LUKS checks for a valid passphrase when an encrypted partition is un‐
1689 locked. The behavior of plain dm-crypt is different. It will always
1690 decrypt with the passphrase given. If the given passphrase is wrong,
1691 the device mapped by plain dm-crypt will essentially still contain en‐
1692 crypted data and will be unreadable.
1693
1695 The available combinations of ciphers, modes, hashes and key sizes de‐
1696 pend on kernel support. See /proc/crypto for a list of available op‐
1697 tions. You might need to load additional kernel crypto modules in order
1698 to get more options.
1699 For the --hash option, if the crypto backend is libgcrypt, then all al‐
1701 gorithms supported by the gcrypt library are available. For other
1702 crypto backends, some algorithms may be missing.
1703
1705 Mathematics can't be bribed. Make sure you keep your passphrases safe.
1706 There are a few nice tricks for constructing a fallback, when suddenly
1707 out of the blue, your brain refuses to cooperate. These fallbacks need
1708 LUKS, as it's only possible with LUKS to have multiple passphrases.
1709 Still, if your attacker model does not prevent it, storing your
1710 passphrase in a sealed envelope somewhere may be a good idea as well.
1711
1713 Random Number Generators (RNG) used in cryptsetup are always the kernel
1714 RNGs without any modifications or additions to data stream produced.
1715 There are two types of randomness cryptsetup/LUKS needs. One type
1717 (which always uses /dev/urandom) is used for salts, the AF splitter and
1718 for wiping deleted keyslots.
1719 The second type is used for the volume (master) key. You can switch be‐
1721 tween using /dev/random and /dev/urandom here, see --use-random and
1722 --use-urandom options. Using /dev/random on a system without enough en‐
1723 tropy sources can cause luksFormat to block until the requested amount
1724 of random data is gathered. In a low-entropy situation (embedded sys‐
1725 tem), this can take a very long time and potentially forever. At the
1726 same time, using /dev/urandom in a low-entropy situation will produce
1727 low-quality keys. This is a serious problem, but solving it is out of
1728 scope for a mere man-page. See urandom(4) for more information.
1729
1731 Since Linux kernel version 4.12 dm-crypt supports authenticated disk
1732 encryption.
1733 Normal disk encryption modes are length-preserving (plaintext sector is
1735 of the same size as a ciphertext sector) and can provide only confiden‐
1736 tiality protection, but not cryptographically sound data integrity pro‐
1737 tection.
1738 Authenticated modes require additional space per-sector for authentica‐
1740 tion tag and use Authenticated Encryption with Additional Data (AEAD)
1741 algorithms.
1742 If you configure LUKS2 device with data integrity protection, there
1744 will be an underlying dm-integrity device, which provides additional
1745 per-sector metadata space and also provide data journal protection to
1746 ensure atomicity of data and metadata update. Because there must be
1747 additional space for metadata and journal, the available space for the
1748 device will be smaller than for length-preserving modes.
1749 The dm-crypt device then resides on top of such a dm-integrity device.
1751 All activation and deactivation of this device stack is performed by
1752 cryptsetup, there is no difference in using luksOpen for integrity pro‐
1753 tected devices. If you want to format LUKS2 device with data integrity
1754 protection, use --integrity option.
1755 Since dm-integrity doesn't support discards (TRIM), dm-crypt device on
1757 top of it inherits this, so integrity protection mode doesn't support
1758 discards either.
1759 Some integrity modes requires two independent keys (key for encryption
1761 and for authentication). Both these keys are stored in one LUKS
1762 keyslot.
1763 WARNING: All support for authenticated modes is experimental and there
1765 are only some modes available for now. Note that there are a very few
1766 authenticated encryption algorithms that are suitable for disk encryp‐
1767 tion. You also cannot use CRC32 or any other non-cryptographic check‐
1768 sums (other than the special integrity mode "none"). If for some reason
1769 you want to have integrity control without using authentication mode,
1770 then you should separately configure dm-integrity independently of
1771 LUKS2.
1772
1775 Cryptsetup is usually used directly on a block device (disk partition
1776 or LVM volume). However, if the device argument is a file, cryptsetup
1777 tries to allocate a loopback device and map it into this file. This
1778 mode requires Linux kernel 2.6.25 or more recent which supports the
1779 loop autoclear flag (loop device is cleared on the last close automati‐
1780 cally). Of course, you can always map a file to a loop-device manually.
1781 See the cryptsetup FAQ for an example.
1782 When device mapping is active, you can see the loop backing file in the
1784 status command output. Also see losetup(8).
1785
1787 The LUKS2 on-disk metadata is updated in several steps and to achieve
1788 proper atomic update, there is a locking mechanism. For an image in
1789 file, code uses flock(2) system call. For a block device, lock is per‐
1790 formed over a special file stored in a locking directory (by default
1791 /run/lock/cryptsetup). The locking directory should be created with
1792 the proper security context by the distribution during the boot-up
1793 phase. Only LUKS2 uses locks, other formats do not use this mechanism.
1794
1796 The reload action is no longer supported. Please use dmsetup(8) if you
1797 need to directly manipulate with the device mapping table.
1798 The luksDelKey was replaced with luksKillSlot.
1800
1802 Report bugs, including ones in the documentation, on the cryptsetup
1803 mailing list at <dm-crypt@saout.de> or in the 'Issues' section on LUKS
1804 website. Please attach the output of the failed command with the --de‐
1805 bug option added.
1806
1808 cryptsetup originally written by Jana Saout <jana@saout.de>
1809 The LUKS extensions and original man page were written by Clemens Fruh‐
1810 wirth <clemens@endorphin.org>.
1811 Man page extensions by Milan Broz <gmazyland@gmail.com>.
1812 Man page rewrite and extension by Arno Wagner <arno@wagner.name>.
1813
1815 Copyright © 2004 Jana Saout
1816 Copyright © 2004-2006 Clemens Fruhwirth
1817 Copyright © 2012-2014 Arno Wagner
1818 Copyright © 2009-2021 Red Hat, Inc.
1819 Copyright © 2009-2021 Milan Broz
1820 This is free software; see the source for copying conditions. There is
1822 NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
1823 PURPOSE.
1824
1826 The LUKS website at https://gitlab.com/cryptsetup/cryptsetup/
1827 The cryptsetup FAQ, contained in the distribution package and online at
1829 https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions
1830 The cryptsetup mailing list and list archive, see FAQ entry 1.6.
1832 The LUKS version 1 on-disk format specification available at
1834 https://gitlab.com/cryptsetup/cryptsetup/wikis/Specification and LUKS
1835 version 2 at https://gitlab.com/cryptsetup/LUKS2-docs.
1836cryptsetup January 2021 CRYPTSETUP(8)