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 and for TrueCrypt 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 <options> are type specific and are described below for individ‐
87 ual device types. For create, the order of the <name> and
88 <device> options is inverted for historical reasons, all other
89 aliases use the standard <device> <name> order.
90 close <name>
92 Removes the existing mapping <name> and wipes the key from ker‐
94 nel memory.
95 For backward compatibility there are close command aliases:
97 remove, plainClose, luksClose, loopaesClose, tcryptClose (all
98 behaves exactly the same, device type is determined automati‐
99 cally from active device).
100 <options> can be [--deferred]
102 status <name>
105 Reports the status for the mapping <name>.
107 resize <name>
109 Resizes an active mapping <name>.
111 If --size (in 512-bytes sectors) or --device-size are not speci‐
113 fied, the size is computed from the underlying device. For LUKS
114 it is the size of the underlying device without the area
115 reserved for LUKS header (see data payload offset in luksDump
116 command). For plain crypt device, the whole device size is
117 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
125 retrieve the key using a token and only if it failed it'd ask
126 for a passphrase to unlock a keyslot (LUKS) or to derive a vol‐
127 ume key again (plain mode). The kernel keyring is used by
128 default for LUKS2 devices.
129 With LUKS2 device additional <options> can be [--token-id,
131 --token-only, --key-slot, --key-file, --keyfile-size, --key‐
132 file-offset, --timeout, --disable-locks, --disable-keyring].
133 refresh <name>
136 Refreshes parameters of active mapping <name>.
138 Updates parameters of active device <name> without need to deac‐
140 tivate the device (and umount filesystem). Currently it supports
141 parameters refresh on following devices: LUKS1, LUKS2 (including
142 authenticated encryption), plain crypt and loopaes.
143 Mandatory parametrs are identical to those of an open action for
145 respective device type.
146 You may change following parameters on all devices
148 --perf-same_cpu_crypt, --perf-submit_from_crypt_cpus and
149 --allow-discards.
150 Refreshing device without any optional parameter will refresh
152 the device with default setting (respective to device type).
153 LUKS2 only:
155 --integrity-no-journal parameter affects only LUKS2 devices with
157 underlying dm-integrity device.
158 Adding option --persistent stores any combination of device
160 parameters above in LUKS2 metadata (only after successful
161 refresh operation).
162 --disable-keyring parameter refreshes a device with volume key
164 passed in dm-crypt driver.
165 reencrypt <device> or --active-name <name> [<new_name>]
168 Run resilient reencryption (LUKS2 device only).
170 There are 3 basic modes of operation:
172 · device reencryption (reencrypt)
174 · device encryption (reencrypt --encrypt)
176 · device decryption (reencrypt --decrypt)
178 <device> or --active-name <name> is mandatory parameter.
180 With <device> parameter cryptsetup looks up active <device> dm
182 mapping. If no active mapping is detected, it starts offline
183 reencryption otherwise online reencryption takes place.
184 Reencryption process may be safely interrupted by a user via
186 SIGTERM signal (ctrl+c).
187 To resume already initialized or interrupted reencryption, just
189 run the cryptsetup reencrypt command again to continue the reen‐
190 cryption operation. Reencryption may be resumed with different
191 --resilience or --hotzone-size unless implicit datashift
192 resilience mode is used (reencrypt --encrypt with --reduce-
193 device-size option).
194 If the reencryption process was interrupted abruptly (reencryp‐
196 tion process crash, system crash, poweroff) it may require
197 recovery. The recovery is currently run automatically on next
198 activation (action open) when needed.
199 Optional parameter <new_name> takes effect only with --encrypt
201 option and it activates device <new_name> immediately after
202 encryption initialization gets finished. That's useful when
203 device needs to be ready as soon as possible and mounted (used)
204 before full data area encryption is completed.
205 Action supports following additional <options> [--encrypt,
207 --decrypt, --device-size, --resilience, --resilience-hash,
208 --hotzone-size, --init-only, --resume-only,
209 --reduce-device-size].
210
213 Plain dm-crypt encrypts the device sector-by-sector with a single, non-
214 salted hash of the passphrase. No checks are performed, no metadata is
215 used. There is no formatting operation. When the raw device is mapped
216 (opened), the usual device operations can be used on the mapped device,
217 including filesystem creation. Mapped devices usually reside in
218 /dev/mapper/<name>.
219 The following are valid plain device type actions:
221 open --type plain <device> <name>
223 create <name> <device> (OBSOLETE syntax)
224 Opens (creates a mapping with) <name> backed by device <device>.
226 <options> can be [--hash, --cipher, --verify-passphrase, --sec‐
228 tor-size, --key-file, --keyfile-offset, --key-size, --offset,
229 --skip, --size, --readonly, --shared, --allow-discards,
230 --refresh]
231 Example: 'cryptsetup open --type plain /dev/sda10 e1' maps the
233 raw encrypted device /dev/sda10 to the mapped (decrypted) device
234 /dev/mapper/e1, which can then be mounted, fsck-ed or have a
235 filesystem created on it.
236
238 LUKS, the Linux Unified Key Setup, is a standard for disk encryption.
239 It adds a standardized header at the start of the device, a key-slot
240 area directly behind the header and the bulk data area behind that. The
241 whole set is called a 'LUKS container'. The device that a LUKS con‐
242 tainer resides on is called a 'LUKS device'. For most purposes, both
243 terms can be used interchangeably. But note that when the LUKS header
244 is at a nonzero offset in a device, then the device is not a LUKS
245 device anymore, but has a LUKS container stored in it at an offset.
246 LUKS can manage multiple passphrases that can be individually revoked
248 or changed and that can be securely scrubbed from persistent media due
249 to the use of anti-forensic stripes. Passphrases are protected against
250 brute-force and dictionary attacks by PBKDF2, which implements hash
251 iteration and salting in one function.
252 LUKS2 is a new version of header format that allows additional exten‐
254 sions like different PBKDF algorithm or authenticated encryption. You
255 can format device with LUKS2 header if you specify --type luks2 in
256 luksFormat command. For activation, the format is already recognized
257 automatically.
258 Each passphrase, also called a key in this document, is associated with
260 one of 8 key-slots. Key operations that do not specify a slot affect
261 the first slot that matches the supplied passphrase or the first empty
262 slot if a new passphrase is added.
263 The <device> parameter can also be specified by a LUKS UUID in the for‐
265 mat UUID=<uuid>. Translation to real device name uses symlinks in
266 /dev/disk/by-uuid directory.
267 To specify a detached header, the --header parameter can be used in all
269 LUKS commands and always takes precedence over the positional <device>
270 parameter.
271 The following are valid LUKS actions:
273 luksFormat <device> [<key file>]
275 Initializes a LUKS partition and sets the initial passphrase
277 (for key-slot 0), either via prompting or via <key file>. Note
278 that if the second argument is present, then the passphrase is
279 taken from the file given there, without the need to use the
280 --key-file option. Also note that for both forms of reading the
281 passphrase from a file you can give '-' as file name, which
282 results in the passphrase being read from stdin and the safety-
283 question being skipped.
284 You can only call luksFormat on a LUKS device that is not
286 mapped.
287 To use LUKS2, specify --type luks2.
289 <options> can be [--hash, --cipher, --verify-passphrase,
291 --key-size, --key-slot, --key-file (takes precedence over
292 optional second argument), --keyfile-offset, --keyfile-size,
293 --use-random | --use-urandom, --uuid, --master-key-file,
294 --iter-time, --header, --pbkdf-force-iterations, --force-pass‐
295 word, --disable-locks].
296 For LUKS2, additional <options> can be [--integrity,
298 --integrity-no-wipe, --sector-size, --label, --subsystem,
299 --pbkdf, --pbkdf-memory, --pbkdf-parallel, --disable-locks,
300 --disable-keyring, --luks2-metadata-size, --luks2-keyslots-size,
301 --keyslot-cipher, --keyslot-key-size].
302 WARNING: Doing a luksFormat on an existing LUKS container will
304 make all data the old container permanently irretrievable unless
305 you have a header backup.
306 open --type luks <device> <name>
308 luksOpen <device> <name> (old syntax)
309 Opens the LUKS device <device> and sets up a mapping <name>
311 after successful verification of the supplied passphrase.
312 First, the passphrase is searched in LUKS tokens. If it's not
314 found in any token and also the passphrase is not supplied via
315 --key-file, the command prompts for it interactively.
316 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
318 --readonly, --test-passphrase, --allow-discards, --header,
319 --key-slot, --master-key-file, --token-id, --token-only, --dis‐
320 able-keyring, --disable-locks, --type, --refresh, --serial‐
321 ize-memory-hard-pbkdf].
322 luksSuspend <name>
324 Suspends an active device (all IO operations will block and
326 accesses to the device will wait indefinitely) and wipes the
327 encryption key from kernel memory. Needs kernel 2.6.19 or later.
328 After this operation you have to use luksResume to reinstate the
330 encryption key and unblock the device or close to remove the
331 mapped device.
332 WARNING: never suspend the device on which the cryptsetup binary
334 resides.
335 <options> can be [--header, --disable-locks].
337 luksResume <name>
339 Resumes a suspended device and reinstates the encryption key.
341 Prompts interactively for a passphrase if --key-file is not
342 given.
343 <options> can be [--key-file, --keyfile-size, --header, --dis‐
345 able-keyring, --disable-locks, --type]
346 luksAddKey <device> [<key file with new key>]
348 Adds a new passphrase. An existing passphrase must be supplied
350 interactively or via --key-file. The new passphrase to be added
351 can be specified interactively or read from the file given as
352 positional argument.
353 NOTE: with --unbound option the action creates new unbound LUKS2
355 keyslot. The keyslot cannot be used for device activation. If
356 you don't pass new key via --master-key-file option, new random
357 key is generated. Existing passphrase for any active keyslot is
358 not required.
359 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
361 --new-keyfile-offset, --new-keyfile-size, --key-slot, --mas‐
362 ter-key-file, --force-password, --header, --disable-locks,
363 --iter-time, --pbkdf, --pbkdf-force-iterations, --unbound,
364 --type, --keyslot-cipher, --keyslot-key-size].
365 luksRemoveKey <device> [<key file with passphrase to be removed>]
367 Removes the supplied passphrase from the LUKS device. The
369 passphrase to be removed can be specified interactively, as the
370 positional argument or via --key-file.
371 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
373 --header, --disable-locks, --type]
374 WARNING: If you read the passphrase from stdin (without further
376 argument or with '-' as an argument to --key-file), batch-mode
377 (-q) will be implicitly switched on and no warning will be given
378 when you remove the last remaining passphrase from a LUKS con‐
379 tainer. Removing the last passphrase makes the LUKS container
380 permanently inaccessible.
381 luksChangeKey <device> [<new key file>]
383 Changes an existing passphrase. The passphrase to be changed
385 must be supplied interactively or via --key-file. The new
386 passphrase can be supplied interactively or in a file given as
387 positional argument.
388 If a key-slot is specified (via --key-slot), the passphrase for
390 that key-slot must be given and the new passphrase will over‐
391 write the specified key-slot. If no key-slot is specified and
392 there is still a free key-slot, then the new passphrase will be
393 put into a free key-slot before the key-slot containing the old
394 passphrase is purged. If there is no free key-slot, then the
395 key-slot with the old passphrase is overwritten directly.
396 WARNING: If a key-slot is overwritten, a media failure during
398 this operation can cause the overwrite to fail after the old
399 passphrase has been wiped and make the LUKS container inaccessi‐
400 ble.
401 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
403 --new-keyfile-offset, --iter-time, --pbkdf, --pbkdf-force-itera‐
404 tions, --new-keyfile-size, --key-slot, --force-password,
405 --header, --disable-locks, --type, --keyslot-cipher,
406 --keyslot-key-size].
407 luksConvertKey <device>
409 Converts an existing LUKS2 keyslot to new pbkdf parameters. The
411 passphrase for keyslot to be converted must be supplied interac‐
412 tively or via --key-file. If no --pbkdf parameters are specified
413 LUKS2 default pbkdf values will apply.
414 If a keyslot is specified (via --key-slot), the passphrase for
416 that keyslot must be given. If no keyslot is specified and there
417 is still a free keyslot, then the new parameters will be put
418 into a free keyslot before the keyslot containing the old param‐
419 eters is purged. If there is no free keyslot, then the keyslot
420 with the old parameters is overwritten directly.
421 WARNING: If a keyslot is overwritten, a media failure during
423 this operation can cause the overwrite to fail after the old
424 parameters have been wiped and make the LUKS container inacces‐
425 sible.
426 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
428 --key-slot, --header, --disable-locks, --iter-time, --pbkdf,
429 --pbkdf-force-iterations, --pbkdf-memory, --pbkdf-parallel,
430 --keyslot-cipher, --keyslot-key-size].
431 luksKillSlot <device> <key slot number>
433 Wipe the key-slot number <key slot> from the LUKS device. Except
435 running in batch-mode (-q) a remaining passphrase must be sup‐
436 plied, either interactively or via --key-file. This command can
437 remove the last remaining key-slot, but requires an interactive
438 confirmation when doing so. Removing the last passphrase makes a
439 LUKS container permanently inaccessible.
440 <options> can be [--key-file, --keyfile-offset, --keyfile-size,
442 --header, --disable-locks, --type].
443 WARNING: If you read the passphrase from stdin (without further
445 argument or with '-' as an argument to --key-file), batch-mode
446 (-q) will be implicitly switched on and no warning will be given
447 when you remove the last remaining passphrase from a LUKS con‐
448 tainer. Removing the last passphrase makes the LUKS container
449 permanently inaccessible.
450 NOTE: If there is no passphrase provided (on stdin or through
452 --key-file argument) and batch-mode (-q) is active, the key-slot
453 is removed without any other warning.
454 erase <device>
457 luksErase <device>
458 Erase all keyslots and make the LUKS container permanently inac‐
460 cessible. You do not need to provide any password for this
461 operation.
462 WARNING: This operation is irreversible.
464 luksUUID <device>
466 Print the UUID of a LUKS device.
468 Set new UUID if --uuid option is specified.
469 isLuks <device>
471 Returns true, if <device> is a LUKS device, false otherwise.
473 Use option -v to get human-readable feedback. 'Command success‐
474 ful.' means the device is a LUKS device.
475 By specifying --type you may query for specific LUKS version.
477 luksDump <device>
479 Dump the header information of a LUKS device.
481 If the --dump-master-key option is used, the LUKS device master
483 key is dumped instead of the keyslot info. Together with --mas‐
484 ter-key-file option, master key is dumped to a file instead of
485 standard output. Beware that the master key cannot be changed
486 without reencryption and can be used to decrypt the data stored
487 in the LUKS container without a passphrase and even without the
488 LUKS header. This means that if the master key is compromised,
489 the whole device has to be erased to prevent further access. Use
490 this option carefully.
491 To dump the master key, a passphrase has to be supplied, either
493 interactively or via --key-file.
494 <options> can be [--dump-master-key, --key-file, --keyfile-off‐
496 set, --keyfile-size, --header, --disable-locks, --mas‐
497 ter-key-file, --type].
498 WARNING: If --dump-master-key is used with --key-file and the
500 argument to --key-file is '-', no validation question will be
501 asked and no warning given.
502 luksHeaderBackup <device> --header-backup-file <file>
504 Stores a binary backup of the LUKS header and keyslot area.
506 Note: Using '-' as filename writes the header backup to a file
507 named '-'.
508 WARNING: This backup file and a passphrase valid at the time of
510 backup allows decryption of the LUKS data area, even if the
511 passphrase was later changed or removed from the LUKS device.
512 Also note that with a header backup you lose the ability to
513 securely wipe the LUKS device by just overwriting the header and
514 key-slots. You either need to securely erase all header backups
515 in addition or overwrite the encrypted data area as well. The
516 second option is less secure, as some sectors can survive, e.g.
517 due to defect management.
518 luksHeaderRestore <device> --header-backup-file <file>
520 Restores a binary backup of the LUKS header and keyslot area
522 from the specified file.
523 Note: Using '-' as filename reads the header backup from a file
524 named '-'.
525 WARNING: Header and keyslots will be replaced, only the
527 passphrases from the backup will work afterward.
528 This command requires that the master key size and data offset
530 of the LUKS header already on the device and of the header
531 backup match. Alternatively, if there is no LUKS header on the
532 device, the backup will also be written to it.
533 token <add|remove|import|export> <device>
535 Action add creates new keyring token to enable auto-activation
537 of the device. For the auto-activation, the passphrase must be
538 stored in keyring with the specified description. Usually, the
539 passphrase should be stored in user or user-session keyring.
540 The token command is supported only for LUKS2.
541 For adding new keyring token, option --key-description is manda‐
543 tory. Also, new token is assigned to key slot specified with
544 --key-slot option or to all active key slots in the case
545 --key-slot option is omitted.
546 To remove existing token, specify the token ID which should be
548 removed with --token-id option.
549 WARNING: The action token remove removes any token type, not
551 just keyring type from token slot specified by --token-id
552 option.
553 Action import can store arbitrary valid token json in LUKS2
555 header. It may be passed via standard input or via file passed
556 in --json-file option. If you specify --key-slot then success‐
557 fully imported token is also assigned to the key slot.
558 Action export writes requested token json to a file passed with
560 --json-file or to standard output.
561 <options> can be [--header, --token-id, --key-slot,
563 --key-description, --disable-locks, --disable-keyring,
564 --json-file].
565 convert <device> --type <format>
567 Converts the device between LUKS1 and LUKS2 format (if possi‐
569 ble). The conversion will not be performed if there is an addi‐
570 tional LUKS2 feature or LUKS1 has unsupported header size.
571 Conversion (both directions) must be performed on inactive
573 device. There must not be active dm-crypt mapping established
574 for LUKS header requested for conversion.
575 --type option is mandatory with following accepted values: luks1
577 or luks2.
578 WARNING: The convert action can destroy the LUKS header in the
580 case of a crash during conversion or if a media error occurs.
581 Always create a header backup before performing this operation!
582 <options> can be [--header, --type].
584 config <device>
586 Set permanent configuration options (store to LUKS header). The
588 config command is supported only for LUKS2.
589 The permanent options can be --priority to set priority (normal,
591 prefer, ignore) for keyslot (specified by --key-slot) or --label
592 and --subsystem.
593 <options> can be [--priority, --label, --subsystem, --key-slot,
595 --header].
596
599 cryptsetup supports mapping loop-AES encrypted partition using a com‐
600 patibility mode.
601 open --type loopaes <device> <name> --key-file <keyfile>
603 loopaesOpen <device> <name> --key-file <keyfile> (old syntax)
604 Opens the loop-AES <device> and sets up a mapping <name>.
606 If the key file is encrypted with GnuPG, then you have to use
608 --key-file=- and decrypt it before use, e.g. like this:
609 gpg --decrypt <keyfile> | cryptsetup loopaesOpen --key-file=-
610 <device> <name>
611 WARNING: The loop-AES extension cannot use the direct input of
613 key file on real terminal because the keys are separated by end-
614 of-line and only part of the multi-key file would be read.
615 If you need it in script, just use the pipe redirection:
616 echo $keyfile | cryptsetup loopaesOpen --key-file=- <device>
617 <name>
618 Use --keyfile-size to specify the proper key length if needed.
620 Use --offset to specify device offset. Note that the units need
622 to be specified in number of 512 byte sectors.
623 Use --skip to specify the IV offset. If the original device used
625 an offset and but did not use it in IV sector calculations, you
626 have to explicitly use --skip 0 in addition to the offset param‐
627 eter.
628 Use --hash to override the default hash function for passphrase
630 hashing (otherwise it is detected according to key size).
631 <options> can be [--key-file, --key-size, --offset, --skip,
633 --hash, --readonly, --allow-discards, --refresh].
634 See also section 7 of the FAQ and http://loop-aes.sourceforge.net for
636 more information regarding loop-AES.
637
639 cryptsetup supports mapping of TrueCrypt, tcplay or VeraCrypt (with
640 --veracrypt option) encrypted partition using a native Linux kernel
641 API. Header formatting and TCRYPT header change is not supported,
642 cryptsetup never changes TCRYPT header on-device.
643 TCRYPT extension requires kernel userspace crypto API to be available
645 (introduced in Linux kernel 2.6.38). If you are configuring kernel
646 yourself, enable "User-space interface for symmetric key cipher algo‐
647 rithms" in "Cryptographic API" section (CRYPTO_USER_API_SKCIPHER .con‐
648 fig option).
649 Because TCRYPT header is encrypted, you have to always provide valid
651 passphrase and keyfiles.
652 Cryptsetup should recognize all header variants, except legacy cipher
654 chains using LRW encryption mode with 64 bits encryption block (namely
655 Blowfish in LRW mode is not recognized, this is limitation of kernel
656 crypto API).
657 To recognize a VeraCrypt device use the --veracrypt option. VeraCrypt
659 is just extension of TrueCrypt header with increased iteration count so
660 unlocking can take quite a lot of time (in comparison with TCRYPT
661 device).
662 To open a VeraCrypt device with a custom Personal Iteration Multiplier
664 (PIM) value, additionally to --veracrypt use either the --ver‐
665 acrypt-pim=<PIM> option to directly specify the PIM on the command-
666 line or use --veracrypt-query-pim to be prompted for the PIM.
667 The PIM value affects the number of iterations applied during key
669 derivation. Please refer to https://www.veracrypt.fr/en/Per‐
670 sonal%20Iterations%20Multiplier%20%28PIM%29.html for more detailed
671 information.
672 NOTE: Activation with tcryptOpen is supported only for cipher chains
674 using LRW or XTS encryption modes.
675 The tcryptDump command should work for all recognized TCRYPT devices
677 and doesn't require superuser privilege.
678 To map system device (device with boot loader where the whole encrypted
680 system resides) use --tcrypt-system option. You can use partition
681 device as the parameter (parameter must be real partition device, not
682 an image in a file), then only this partition is mapped.
683 If you have the whole TCRYPT device as a file image and you want to map
685 multiple partition encrypted with system encryption, please create
686 loopback mapping with partitions first (losetup -P, see losetup(8) man
687 page for more info), and use loop partition as the device parameter.
688 If you use the whole base device as a parameter, one device for the
690 whole system encryption is mapped. This mode is available only for
691 backward compatibility with older cryptsetup versions which mapped
692 TCRYPT system encryption using the whole device.
693 To use hidden header (and map hidden device, if available), use
695 --tcrypt-hidden option.
696 To explicitly use backup (secondary) header, use --tcrypt-backup
698 option.
699 NOTE: There is no protection for a hidden volume if the outer volume is
701 mounted. The reason is that if there were any protection, it would
702 require some metadata describing what to protect in the outer volume
703 and the hidden volume would become detectable.
704 open --type tcrypt <device> <name>
707 tcryptOpen <device> <name> (old syntax)
708 Opens the TCRYPT (a TrueCrypt-compatible) <device> and sets up a
710 mapping <name>.
711 <options> can be [--key-file, --tcrypt-hidden, --tcrypt-system,
713 --tcrypt-backup, --readonly, --test-passphrase, --allow-dis‐
714 cards, --veracrypt, --veracrypt-pim, --veracrypt-query-pim].
715 The keyfile parameter allows a combination of file content with
717 the passphrase and can be repeated. Note that using keyfiles is
718 compatible with TCRYPT and is different from LUKS keyfile logic.
719 WARNING: Option --allow-discards cannot be combined with option
721 --tcrypt-hidden. For normal mapping, it can cause the destruc‐
722 tion of hidden volume (hidden volume appears as unused space for
723 outer volume so this space can be discarded).
724 tcryptDump <device>
727 Dump the header information of a TCRYPT device.
729 If the --dump-master-key option is used, the TCRYPT device mas‐
731 ter key is dumped instead of TCRYPT header info. Beware that the
732 master key (or concatenated master keys if cipher chain is used)
733 can be used to decrypt the data stored in the TCRYPT container
734 without a passphrase. This means that if the master key is com‐
735 promised, the whole device has to be erased to prevent further
736 access. Use this option carefully.
737 <options> can be [--dump-master-key, --key-file, --tcrypt-hid‐
739 den, --tcrypt-system, --tcrypt-backup].
740 The keyfile parameter allows a combination of file content with
742 the passphrase and can be repeated.
743 See also https://en.wikipedia.org/wiki/TrueCrypt for more information
745 regarding TrueCrypt.
746 Please note that cryptsetup does not use TrueCrypt code, please report
748 all problems related to this compatibility extension to the cryptsetup
749 project.
750
752 repair <device>
753 Tries to repair the device metadata if possible. Currently sup‐
755 ported only for LUKS device type.
756 This command is useful to fix some known benign LUKS metadata
758 header corruptions. Only basic corruptions of unused keyslot are
759 fixable. This command will only change the LUKS header, not any
760 key-slot data. You may enforce LUKS version by adding --type
761 option.
762 WARNING: Always create a binary backup of the original header
764 before calling this command.
765 benchmark <options>
767 Benchmarks ciphers and KDF (key derivation function). Without
769 parameters, it tries to measure few common configurations.
770 To benchmark other ciphers or modes, you need to specify
772 --cipher and --key-size options or --hash for KDF test.
773 NOTE: This benchmark is using memory only and is only informa‐
775 tive. You cannot directly predict real storage encryption speed
776 from it.
777 For testing block ciphers, this benchmark requires kernel
779 userspace crypto API to be available (introduced in Linux kernel
780 2.6.38). If you are configuring kernel yourself, enable "User-
781 space interface for symmetric key cipher algorithms" in "Crypto‐
782 graphic API" section (CRYPTO_USER_API_SKCIPHER .config option).
783 <options> can be [--cipher, --key-size, --hash].
785
787 --verbose, -v
788 Print more information on command execution.
789 --debug or --debug-json
791 Run in debug mode with full diagnostic logs. Debug output lines
792 are always prefixed by '#'. If --debug-json is used, additional
793 LUKS2 JSON data structures are printed.
794 --type <device-type>
796 Specifies required device type, for more info read BASIC COM‐
797 MANDS section.
798 --hash, -h <hash-spec>
800 Specifies the passphrase hash for open (for plain and loopaes
801 device types).
802 Specifies the hash used in the LUKS key setup scheme and volume
804 key digest for luksFormat. The specified hash is used as hash-
805 parameter for PBKDF2 and for the AF splitter.
806 The specified hash name is passed to the compiled-in crypto
808 backend. Different backends may support different hashes. For
809 luksFormat, the hash algorithm must provide at least 160 bits of
810 output, which excludes, e.g., MD5. Do not use a non-crypto hash
811 like "crc32" as this breaks security.
812 Values compatible with old version of cryptsetup are "ripemd160"
814 for open --type plain and "sha1" for luksFormat.
815 Use cryptsetup --help to show the defaults.
817 --cipher, -c <cipher-spec>
819 Set the cipher specification string.
820 cryptsetup --help shows the compiled-in defaults. The current
822 default in the distributed sources is "aes-cbc-essiv:sha256" for
823 plain dm-crypt and "aes-xts-plain64" for LUKS.
824 If a hash is part of the cipher specification, then it is used
826 as part of the IV generation. For example, ESSIV needs a hash
827 function, while "plain64" does not and hence none is specified.
828 For XTS mode you can optionally set a key size of 512 bits with
830 the -s option. Key size for XTS mode is twice that for other
831 modes for the same security level.
832 XTS mode requires kernel 2.6.24 or later and plain64 requires
834 kernel 2.6.33 or later. More information can be found in the
835 FAQ.
836 --verify-passphrase, -y
838 When interactively asking for a passphrase, ask for it twice and
839 complain if both inputs do not match. Advised when creating a
840 regular mapping for the first time, or when running luksFormat.
841 Ignored on input from file or stdin.
842 --key-file, -d name
844 Read the passphrase from file.
845 If the name given is "-", then the passphrase will be read from
847 stdin. In this case, reading will not stop at newline charac‐
848 ters.
849 With LUKS, passphrases supplied via --key-file are always the
851 existing passphrases requested by a command, except in the case
852 of luksFormat where --key-file is equivalent to the positional
853 key file argument.
854 If you want to set a new passphrase via key file, you have to
856 use a positional argument to luksAddKey.
857 See section NOTES ON PASSPHRASE PROCESSING for more information.
859 --keyfile-offset value
861 Skip value bytes at the beginning of the key file. Works with
862 all commands that accept key files.
863 --keyfile-size, -l value
865 Read a maximum of value bytes from the key file. The default is
866 to read the whole file up to the compiled-in maximum that can be
867 queried with --help. Supplying more data than the compiled-in
868 maximum aborts the operation.
869 This option is useful to cut trailing newlines, for example. If
871 --keyfile-offset is also given, the size count starts after the
872 offset. Works with all commands that accept key files.
873 --new-keyfile-offset value
875 Skip value bytes at the start when adding a new passphrase from
876 key file with luksAddKey.
877 --new-keyfile-size value
879 Read a maximum of value bytes when adding a new passphrase from
880 key file with luksAddKey. The default is to read the whole file
881 up to the compiled-in maximum length that can be queried with
882 --help. Supplying more than the compiled in maximum aborts the
883 operation. When --new-keyfile-offset is also given, reading
884 starts after the offset.
885 --master-key-file
887 Use a master key stored in a file.
888 For luksFormat this allows creating a LUKS header with this spe‐
890 cific master key. If the master key was taken from an existing
891 LUKS header and all other parameters are the same, then the new
892 header decrypts the data encrypted with the header the master
893 key was taken from.
894 Action luksDump together with --dump-master-key option: The vol‐
896 ume (master) key is stored in a file instead of being printed
897 out to standard output.
898 WARNING: If you create your own master key, you need to make
900 sure to do it right. Otherwise, you can end up with a low-
901 entropy or otherwise partially predictable master key which will
902 compromise security.
903 For luksAddKey this allows adding a new passphrase without hav‐
905 ing to know an existing one.
906 For open this allows one to open the LUKS device without giving
908 a passphrase.
909 --dump-master-key
911 For luksDump this option includes the master key in the dis‐
912 played information. Use with care, as the master key can be used
913 to bypass the passphrases, see also option --master-key-file.
914 --json-file
916 Read token json from a file or write token to it. See token
917 action for more information. --json-file=- reads json from stan‐
918 dard input or writes it to standard output respectively.
919 --use-random
921 --use-urandom
923 For luksFormat these options define which kernel random number
924 generator will be used to create the master key (which is a
925 long-term key).
926 See NOTES ON RANDOM NUMBER GENERATORS for more information. Use
928 cryptsetup --help to show the compiled-in default random number
929 generator.
930 WARNING: In a low-entropy situation (e.g. in an embedded sys‐
932 tem), both selections are problematic. Using /dev/urandom can
933 lead to weak keys. Using /dev/random can block a long time,
934 potentially forever, if not enough entropy can be harvested by
935 the kernel.
936 --key-slot, -S <0-7>
938 For LUKS operations that add key material, this options allows
939 you to specify which key slot is selected for the new key. This
940 option can be used for luksFormat, and luksAddKey.
941 In addition, for open, this option selects a specific key-slot
942 to compare the passphrase against. If the given passphrase
943 would only match a different key-slot, the operation fails.
944 --key-size, -s <bits>
946 Sets key size in bits. The argument has to be a multiple of 8.
947 The possible key-sizes are limited by the cipher and mode used.
948 See /proc/crypto for more information. Note that key-size in
950 /proc/crypto is stated in bytes.
951 This option can be used for open --type plain or luksFormat.
953 All other LUKS actions will use the key-size specified in the
954 LUKS header. Use cryptsetup --help to show the compiled-in
955 defaults.
956 --size, -b <number of 512 byte sectors>
958 Set the size of the device in sectors of 512 bytes. This option
959 is only relevant for the open and resize actions.
960 --offset, -o <number of 512 byte sectors>
962 Start offset in the backend device in 512-byte sectors. This
963 option is only relevant for the open action with plain or
964 loopaes device types or for LUKS devices in luksFormat.
965 For LUKS, the --offset option sets the data offset (payload) of
967 data device and must be be aligned to 4096-byte sectors (must be
968 multiple of 8). This option cannot be combined with
969 --align-payload option.
970 --skip, -p <number of 512 byte sectors>
972 Start offset used in IV calculation in 512-byte sectors (how
973 many sectors of the encrypted data to skip at the beginning).
974 This option is only relevant for the open action with plain or
975 loopaes device types.
976 Hence, if --offset n, and --skip s, sector n (the first sector
978 of the encrypted device) will get a sector number of s for the
979 IV calculation.
980 --device-size size[units]
982 Instead of real device size, use specified value.
983 With reencrypt action it means that only specified area (from
985 the start of the device to the specified size) will be reen‐
986 crypted.
987 With resize action it sets new size of the device.
989 If no unit suffix is specified, the size is in bytes.
991 Unit suffix can be S for 512 byte sectors, K/M/G/T (or
993 KiB,MiB,GiB,TiB) for units with 1024 base or KB/MB/GB/TB for
994 1000 base (SI scale).
995 WARNING: This is destructive operation when used with reencrypt
997 command.
998 --readonly, -r
1000 set up a read-only mapping.
1001 --shared
1003 Creates an additional mapping for one common ciphertext device.
1004 Arbitrary mappings are supported. This option is only relevant
1005 for the open --type plain action. Use --offset, --size and
1006 --skip to specify the mapped area.
1007 --pbkdf <PBKDF spec>
1009 Set Password-Based Key Derivation Function (PBKDF) algorithm for
1010 LUKS keyslot. The PBKDF can be: pbkdf2 (for PBKDF2 according to
1011 RFC2898), argon2i for Argon2i or argon2id for Argon2id (see
1012 https://www.cryptolux.org/index.php/Argon2 for more info).
1013 For LUKS1, only PBKDF2 is accepted (no need to use this option).
1015 The default PBKDF2 for LUKS2 is set during compilation time and
1016 is available in cryptsetup --help output.
1017 A PBKDF is used for increasing dictionary and brute-force attack
1019 cost for keyslot passwords. The parameters can be time, memory
1020 and parallel cost.
1021 For PBKDF2, only time cost (number of iterations) applies. For
1023 Argon2i/id, there is also memory cost (memory required during
1024 the process of key derivation) and parallel cost (number of
1025 threads that run in parallel during the key derivation.
1026 Note that increasing memory cost also increases time, so the
1028 final parameter values are measured by a benchmark. The bench‐
1029 mark tries to find iteration time (--iter-time) with required
1030 memory cost --pbkdf-memory. If it is not possible, the memory
1031 cost is decreased as well. The parallel cost --pbkdf-parallel
1032 is constant, is is checked against available CPU cores (if not
1033 available, it is decreased) and the maximum parallel cost is 4.
1034 You can see all PBKDF parameters for particular LUKS2 keyslot
1036 with luksDump command.
1037 NOTE: If you do not want to use benchmark and want to specify
1039 all parameters directly, use --pbkdf-force-iterations with
1040 --pbkdf-memory and --pbkdf-parallel. This will override the
1041 values without benchmarking. Note it can cause extremely long
1042 unlocking time. Use only is specified cases, for example, if you
1043 know that the formatted device will be used on some small embed‐
1044 ded system. In this case, the LUKS PBKDF2 digest will be set to
1045 the minimum iteration count.
1046 --iter-time, -i <number of milliseconds>
1048 The number of milliseconds to spend with PBKDF passphrase pro‐
1049 cessing. This option is only relevant for LUKS operations that
1050 set or change passphrases, such as luksFormat or luksAddKey.
1051 Specifying 0 as parameter selects the compiled-in default.
1052 --pbkdf-memory <number>
1054 Set the memory cost for PBKDF (for Argon2i/id the number repre‐
1055 sents kilobytes). Note that it is maximal value, PBKDF bench‐
1056 mark or available physical memory can decrease it. This option
1057 is not available for PBKDF2.
1058 --pbkdf-parallel <number>
1060 Set the parallel cost for PBKDF (number of threads, up to 4).
1061 Note that it is maximal value, it is decreased automatically if
1062 CPU online count is lower. This option is not available for
1063 PBKDF2.
1064 --pbkdf-force-iterations <num>
1066 Avoid PBKDF benchmark and set time cost (iterations) directly.
1067 It can be used for LUKS/LUKS2 device only. See --pbkdf option
1068 for more info.
1069 --batch-mode, -q
1071 Suppresses all confirmation questions. Use with care!
1072 If the -y option is not specified, this option also switches off
1074 the passphrase verification for luksFormat.
1075 --progress-frequency <seconds>
1077 Print separate line every <seconds> with wipe progress.
1078 --timeout, -t <number of seconds>
1080 The number of seconds to wait before timeout on passphrase input
1081 via terminal. It is relevant every time a passphrase is asked,
1082 for example for open, luksFormat or luksAddKey. It has no
1083 effect if used in conjunction with --key-file.
1084 This option is useful when the system should not stall if the
1085 user does not input a passphrase, e.g. during boot. The default
1086 is a value of 0 seconds, which means to wait forever.
1087 --tries, -T
1089 How often the input of the passphrase shall be retried. This
1090 option is relevant every time a passphrase is asked, for example
1091 for open, luksFormat or luksAddKey. The default is 3 tries.
1092 --align-payload <number of 512 byte sectors>
1094 Align payload at a boundary of value 512-byte sectors. This
1095 option is relevant for luksFormat.
1096 If not specified, cryptsetup tries to use the topology info pro‐
1098 vided by the kernel for the underlying device to get the optimal
1099 alignment. If not available (or the calculated value is a mul‐
1100 tiple of the default) data is by default aligned to a 1MiB
1101 boundary (i.e. 2048 512-byte sectors).
1102 For a detached LUKS header, this option specifies the offset on
1104 the data device. See also the --header option.
1105 WARNING: This option is DEPRECATED and has often unexpected
1107 impact to the data offset and keyslot area size (for LUKS2) due
1108 to the complex rounding. For fixed data device offset use
1109 --offset option instead.
1110 --uuid=UUID
1113 Use the provided UUID for the luksFormat command instead of gen‐
1114 erating a new one. Changes the existing UUID when used with the
1115 luksUUID command.
1116 The UUID must be provided in the standard UUID format, e.g.
1118 12345678-1234-1234-1234-123456789abc.
1119 --allow-discards
1121 Allow the use of discard (TRIM) requests for the device. This
1122 option is only relevant for open action.
1123 WARNING: This command can have a negative security impact
1125 because it can make filesystem-level operations visible on the
1126 physical device. For example, information leaking filesystem
1127 type, used space, etc. may be extractable from the physical
1128 device if the discarded blocks can be located later. If in
1129 doubt, do not use it.
1130 A kernel version of 3.1 or later is needed. For earlier kernels,
1132 this option is ignored.
1133 --perf-same_cpu_crypt
1135 Perform encryption using the same cpu that IO was submitted on.
1136 The default is to use an unbound workqueue so that encryption
1137 work is automatically balanced between available CPUs. This
1138 option is only relevant for open action.
1139 NOTE: This option is available only for low-level dm-crypt per‐
1141 formance tuning, use only if you need a change to default dm-
1142 crypt behaviour. Needs kernel 4.0 or later.
1143 --perf-submit_from_crypt_cpus
1145 Disable offloading writes to a separate thread after encryption.
1146 There are some situations where offloading write bios from the
1147 encryption threads to a single thread degrades performance sig‐
1148 nificantly. The default is to offload write bios to the same
1149 thread. This option is only relevant for open action.
1150 NOTE: This option is available only for low-level dm-crypt per‐
1152 formance tuning, use only if you need a change to default dm-
1153 crypt behaviour. Needs kernel 4.0 or later.
1154 --test-passphrase
1156 Do not activate the device, just verify passphrase. This option
1157 is only relevant for open action (the device mapping name is not
1158 mandatory if this option is used).
1159 --header <device or file storing the LUKS header>
1161 Use a detached (separated) metadata device or file where the
1162 LUKS header is stored. This option allows one to store cipher‐
1163 text and LUKS header on different devices.
1164 This option is only relevant for LUKS devices and can be used
1166 with the luksFormat, open, luksSuspend, luksResume, status and
1167 resize commands.
1168 For luksFormat with a file name as the argument to --header, the
1170 file will be automatically created if it does not exist. See
1171 the cryptsetup FAQ for header size calculation.
1172 For other commands that change the LUKS header (e.g. luksAdd‐
1174 Key), specify the device or file with the LUKS header directly
1175 as the LUKS device.
1176 If used with luksFormat, the --align-payload option is taken as
1178 absolute sector alignment on ciphertext device and can be zero.
1179 WARNING: There is no check whether the ciphertext device speci‐
1181 fied actually belongs to the header given. In fact, you can
1182 specify an arbitrary device as the ciphertext device for open
1183 with the --header option. Use with care.
1184 --header-backup-file <file>
1186 Specify file with header backup for luksHeaderBackup or luk‐
1187 sHeaderRestore actions.
1188 --force-password
1190 Do not use password quality checking for new LUKS passwords.
1191 This option applies only to luksFormat, luksAddKey and
1193 luksChangeKey and is ignored if cryptsetup is built without
1194 password quality checking support.
1195 For more info about password quality check, see the manual page
1197 for pwquality.conf(5) and passwdqc.conf(5).
1198 --deferred
1200 Defers device removal in close command until the last user
1201 closes it.
1202 --disable-locks
1204 Disable lock protection for metadata on disk. This option is
1205 valid only for LUKS2 and ignored for other formats.
1206 WARNING: Do not use this option unless you run cryptsetup in a
1208 restricted environment where locking is impossible to perform
1209 (where /run directory cannot be used).
1210 --disable-keyring
1212 Do not load volume key in kernel keyring and store it directly
1213 in the dm-crypt target instead. This option is supported only
1214 for the LUKS2 format.
1215 --key-description <text>
1217 Set key description in keyring for use with token command.
1218 --priority <normal|prefer|ignore>
1220 Set a priority for LUKS2 keyslot. The prefer priority marked
1221 slots are tried before normal priority. The ignored priority
1222 means, that slot is never used, if not explicitly requested by
1223 --key-slot option.
1224 --token-id
1226 Specify what token to use in actions token, open or resize. If
1227 omitted, all available tokens will be checked before proceeding
1228 further with passphrase prompt.
1229 --token-only
1231 Do not proceed further with action (any of token, open or
1232 resize) if token activation failed. Without the option, action
1233 asks for passphrase to proceed further.
1234 --sector-size <bytes>
1236 Set sector size for use with disk encryption. It must be power
1237 of two and in range 512 - 4096 bytes. The default is 512 bytes
1238 sectors. This option is available only in the LUKS2 mode.
1239 Note that if sector size is higher than underlying device hard‐
1241 ware sector and there is not integrity protection that uses data
1242 journal, using this option can increase risk on incomplete sec‐
1243 tor writes during a power fail.
1244 If used together with --integrity option and dm-integrity jour‐
1246 nal, the atomicity of writes is guaranteed in all cases (but it
1247 cost write performance - data has to be written twice).
1248 Increasing sector size from 512 bytes to 4096 bytes can provide
1250 better performance on most of the modern storage devices and
1251 also with some hw encryption accelerators.
1252 --persistent
1254 If used with LUKS2 devices and activation commands like open,
1255 the specified activation flags are persistently written into
1256 metadata and used next time automatically even for normal acti‐
1257 vation. (No need to use cryptab or other system configuration
1258 files.) Only --allow-discards, --perf-same_cpu_crypt,
1259 --perf-submit_from_crypt_cpus and --integrity-no-journal can be
1260 stored persistently.
1261 --refresh
1263 Refreshes an active device with new set of parameters. See
1264 action refresh description for more details.
1265 --label <LABEL>
1267 --subsystem <SUBSYSTEM> Set label and subsystem description for
1268 LUKS2 device, can be used in config and format actions. The
1269 label and subsystem are optional fields and can be later used in
1270 udev scripts for triggering user actions once device marked by
1271 these labels is detected.
1272 --integrity <integrity algorithm>
1274 Specify integrity algorithm to be used for authenticated disk
1275 encryption in LUKS2.
1276 WARNING: This extension is EXPERIMENTAL and requires dm-
1278 integrity kernel target (available since kernel version 4.12).
1279 For native AEAD modes, also enable "User-space interface for
1280 AEAD cipher algorithms" in "Cryptographic API" section (CON‐
1281 FIG_CRYPTO_USER_API_AEAD .config option).
1282 For more info, see AUTHENTICATED DISK ENCRYPTION section.
1284 --luks2-metadata-size <size>
1286 This option can be used to enlarge the LUKS2 metadata (JSON)
1287 area. The size includes 4096 bytes for binary metadata (usable
1288 JSON area is smaller of the binary area). According to LUKS2
1289 specification, only these values are valid: 16, 32, 64, 128,
1290 256, 512, 1024, 2048 and 4096 kB The <size> can be specified
1291 with unit suffix (for example 128k).
1292 --luks2-keyslots-size <size>
1294 This option can be used to set specific size of the LUKS2 binary
1295 keyslot area (key material is encrypted there). The value must
1296 be aligned to multiple of 4096 bytes with maximum size 128MB.
1297 The <size> can be specified with unit suffix (for example 128k).
1298 --keyslot-cipher <cipher-spec>
1300 This option can be used to set specific cipher encryption for
1301 the LUKS2 keyslot area.
1302 --keyslot-key-size <bits>
1304 This option can be used to set specific key size for the LUKS2
1305 keyslot area.
1306 --integrity-no-journal
1308 Activate device with integrity protection without using data
1309 journal (direct write of data and integrity tags). Note that
1310 without journal power fail can cause non-atomic write and data
1311 corruption. Use only if journalling is performed on a different
1312 storage layer.
1313 --integrity-no-wipe
1315 Skip wiping of device authentication (integrity) tags. If you
1316 skip this step, sectors will report invalid integrity tag until
1317 an application write to the sector.
1318 NOTE: Even some writes to the device can fail if the write is
1320 not aligned to page size and page-cache initiates read of a sec‐
1321 tor with invalid integrity tag.
1322 --unbound
1324 Creates new LUKS2 unbound keyslot. See luksAddKey action for
1326 more details.
1327 --tcrypt-hidden
1329 --tcrypt-system --tcrypt-backup Specify which TrueCrypt on-disk
1330 header will be used to open the device. See TCRYPT section for
1331 more info.
1332 --veracrypt
1334 Allow VeraCrypt compatible mode. Only for TCRYPT extension. See
1335 TCRYPT section for more info.
1336 --veracrypt-pim
1338 --veracrypt-query-pim Use a custom Personal Iteration Multiplier
1339 (PIM) for VeraCrypt device. See TCRYPT section for more info.
1340 --serialize-memory-hard-pbkdf
1342 Use a global lock to serialize unlocking of keyslots using mem‐
1343 ory-hard PBKDF.
1344 NOTE: This is (ugly) workaround for a specific situation when
1346 multiple devices are activated in parallel and system instead of
1347 reporting out of memory starts unconditionally stop processes
1348 using out-of-memory killer.
1349 DO NOT USE this switch until you are implementing boot environ‐
1351 ment with parallel devices activation!
1352 --encrypt
1354 Initialize (and run) device encryption (reencrypt action parame‐
1355 ter)
1356 --decrypt
1358 Initialize (and run) device decryption (reencrypt action parame‐
1359 ter)
1360 --init-only
1362 Initialize reencryption (any variant) operation in LUKS2 meta‐
1363 data only and exit. If any reencrypt operation is already ini‐
1364 tialized in metadata, the command with --init-only parameter
1365 fails.
1366 --resume-only
1368 Resume reencryption (any variant) operation already described in
1369 LUKS2 metadata. If no reencrypt operation is initialized, the
1370 command with --resume-only parameter fails. Useful for resuming
1371 reencrypt operation without accidentally triggering new reen‐
1372 cryption operation.
1373 --resilience <mode>
1375 Reencryption resilience mode can be one of checksum, journal or
1376 none.
1377 checksum: default mode, where individual checksums of ciphertext
1379 hotzone sectors are stored, so the recovery process can detect
1380 which sectors where already reencrypted. It requires that the
1381 device sector write is atomic.
1382 journal: the hotzone is journaled in the binary area (so the
1384 data are written twice).
1385 none: performance mode. There is no protection and the only way
1387 it's safe to interrupt the reencryption is similar to old off‐
1388 line reencryption utility. (ctrl+c).
1389 The option is ignored if reencryption with datashift mode is in
1391 progress.
1392 --resilience-hash <hash>
1394 The hash algorithm used with "--resilience checksum" only. The
1395 default hash is sha256. With other resilience modes, the hash
1396 parameter is ignored.
1397 --hotzone-size <size>
1399 This option can be used to set an upper limit on the size of
1400 reencryption area (hotzone). The <size> can be specified with
1401 unit suffix (for example 50M). Note that actual hotzone size may
1402 be less than specified <size> due to other limitations (free
1403 space in keyslots area or available memory).
1404 --reduce-device-size <size>
1406 Initialize LUKS2 reencryption with data device size reduction
1407 (currently only --encrypt variant is supported).
1408 Last <size> sectors of <device> will be used to properly ini‐
1410 tialize device reencryption. That means any data at last <size>
1411 sectors will be lost.
1412 It could be useful if you added some space to underlying parti‐
1414 tion or logical volume (so last <size> sectors contains no
1415 data).
1416 Recommended minimal size is twice the default LUKS2 header size
1418 (--reduce-device-size 32M) for --encrypt use case. Be sure to
1419 have enough (at least --reduce-device-size value of free space
1420 at the end of <device>).
1421 WARNING: This is a destructive operation and cannot be reverted.
1423 Use with extreme care - accidentally overwritten filesystems are
1424 usually unrecoverable.
1425 --version
1427 Show the program version.
1428 --usage
1430 Show short option help.
1431 --help, -?
1433 Show help text and default parameters.
1434
1436 Cryptsetup returns 0 on success and a non-zero value on error.
1437 Error codes are: 1 wrong parameters, 2 no permission (bad passphrase),
1439 3 out of memory, 4 wrong device specified, 5 device already exists or
1440 device is busy.
1441
1443 Note that no iterated hashing or salting is done in plain mode. If
1444 hashing is done, it is a single direct hash. This means that low-
1445 entropy passphrases are easy to attack in plain mode.
1446 From a terminal: The passphrase is read until the first newline, i.e.
1448 '\n'. The input without the newline character is processed with the
1449 default hash or the hash specified with --hash. The hash result will
1450 be truncated to the key size of the used cipher, or the size specified
1451 with -s.
1452 From stdin: Reading will continue until a newline (or until the maximum
1454 input size is reached), with the trailing newline stripped. The maximum
1455 input size is defined by the same compiled-in default as for the maxi‐
1456 mum key file size and can be overwritten using --keyfile-size option.
1457 The data read will be hashed with the default hash or the hash speci‐
1459 fied with --hash. The hash result will be truncated to the key size of
1460 the used cipher, or the size specified with -s.
1461 Note that if --key-file=- is used for reading the key from stdin,
1463 trailing newlines are not stripped from the input.
1464 If "plain" is used as argument to --hash, the input data will not be
1466 hashed. Instead, it will be zero padded (if shorter than the key size)
1467 or truncated (if longer than the key size) and used directly as the
1468 binary key. This is useful for directly specifying a binary key. No
1469 warning will be given if the amount of data read from stdin is less
1470 than the key size.
1471 From a key file: It will be truncated to the key size of the used
1473 cipher or the size given by -s and directly used as a binary key.
1474 WARNING: The --hash argument is being ignored. The --hash option is
1476 usable only for stdin input in plain mode.
1477 If the key file is shorter than the key, cryptsetup will quit with an
1479 error. The maximum input size is defined by the same compiled-in
1480 default as for the maximum key file size and can be overwritten using
1481 --keyfile-size option.
1482
1486 LUKS uses PBKDF2 to protect against dictionary attacks and to give some
1487 protection to low-entropy passphrases (see RFC 2898 and the cryptsetup
1488 FAQ).
1489 From a terminal: The passphrase is read until the first newline and
1491 then processed by PBKDF2 without the newline character.
1492 From stdin: LUKS will read passphrases from stdin up to the first new‐
1494 line character or the compiled-in maximum key file length. If --key‐
1495 file-size is given, it is ignored.
1496 From key file: The complete keyfile is read up to the compiled-in maxi‐
1498 mum size. Newline characters do not terminate the input. The --key‐
1499 file-size option can be used to limit what is read.
1500 Passphrase processing: Whenever a passphrase is added to a LUKS header
1502 (luksAddKey, luksFormat), the user may specify how much the time the
1503 passphrase processing should consume. The time is used to determine the
1504 iteration count for PBKDF2 and higher times will offer better protec‐
1505 tion for low-entropy passphrases, but open will take longer to com‐
1506 plete. For passphrases that have entropy higher than the used key
1507 length, higher iteration times will not increase security.
1508 The default setting of one or two seconds is sufficient for most prac‐
1510 tical cases. The only exception is a low-entropy passphrase used on a
1511 device with a slow CPU, as this will result in a low iteration count.
1512 On a slow device, it may be advisable to increase the iteration time
1513 using the --iter-time option in order to obtain a higher iteration
1514 count. This does slow down all later luksOpen operations accordingly.
1515
1517 LUKS checks for a valid passphrase when an encrypted partition is
1518 unlocked. The behavior of plain dm-crypt is different. It will always
1519 decrypt with the passphrase given. If the given passphrase is wrong,
1520 the device mapped by plain dm-crypt will essentially still contain
1521 encrypted data and will be unreadable.
1522
1524 The available combinations of ciphers, modes, hashes and key sizes
1525 depend on kernel support. See /proc/crypto for a list of available
1526 options. You might need to load additional kernel crypto modules in
1527 order to get more options.
1528 For the --hash option, if the crypto backend is libgcrypt, then all
1530 algorithms supported by the gcrypt library are available. For other
1531 crypto backends, some algorithms may be missing.
1532
1534 Mathematics can't be bribed. Make sure you keep your passphrases safe.
1535 There are a few nice tricks for constructing a fallback, when suddenly
1536 out of the blue, your brain refuses to cooperate. These fallbacks need
1537 LUKS, as it's only possible with LUKS to have multiple passphrases.
1538 Still, if your attacker model does not prevent it, storing your
1539 passphrase in a sealed envelope somewhere may be a good idea as well.
1540
1542 Random Number Generators (RNG) used in cryptsetup are always the kernel
1543 RNGs without any modifications or additions to data stream produced.
1544 There are two types of randomness cryptsetup/LUKS needs. One type
1546 (which always uses /dev/urandom) is used for salts, the AF splitter and
1547 for wiping deleted keyslots.
1548 The second type is used for the volume (master) key. You can switch
1550 between using /dev/random and /dev/urandom here, see --use-random and
1551 --use-urandom options. Using /dev/random on a system without enough
1552 entropy sources can cause luksFormat to block until the requested
1553 amount of random data is gathered. In a low-entropy situation (embedded
1554 system), this can take a very long time and potentially forever. At the
1555 same time, using /dev/urandom in a low-entropy situation will produce
1556 low-quality keys. This is a serious problem, but solving it is out of
1557 scope for a mere man-page. See urandom(4) for more information.
1558
1560 Since Linux kernel version 4.12 dm-crypt supports authenticated disk
1561 encryption.
1562 Normal disk encryption modes are length-preserving (plaintext sector is
1564 of the same size as a ciphertext sector) and can provide only confiden‐
1565 tiality protection, but not cryptographically sound data integrity pro‐
1566 tection.
1567 Authenticated modes require additional space per-sector for authentica‐
1569 tion tag and use Authenticated Encryption with Additional Data (AEAD)
1570 algorithms.
1571 If you configure LUKS2 device with data integrity protection, there
1573 will be an underlying dm-integrity device, which provides additional
1574 per-sector metadata space and also provide data journal protection to
1575 ensure atomicity of data and metadata update. Because there must be
1576 additional space for metadata and journal, the available space for the
1577 device will be smaller than for length-preserving modes.
1578 The dm-crypt device then resides on top of such a dm-integrity device.
1580 All activation and deactivation of this device stack is performed by
1581 cryptsetup, there is no difference in using luksOpen for integrity pro‐
1582 tected devices. If you want to format LUKS2 device with data integrity
1583 protection, use --integrity option.
1584 Some integrity modes requires two independent keys (key for encryption
1586 and for authentication). Both these keys are stored in one LUKS
1587 keyslot.
1588 WARNING: All support for authenticated modes is experimental and there
1590 are only some modes available for now. Note that there are a very few
1591 authenticated encryption algorithms that are suitable for disk encryp‐
1592 tion.
1593
1596 Cryptsetup is usually used directly on a block device (disk partition
1597 or LVM volume). However, if the device argument is a file, cryptsetup
1598 tries to allocate a loopback device and map it into this file. This
1599 mode requires Linux kernel 2.6.25 or more recent which supports the
1600 loop autoclear flag (loop device is cleared on the last close automati‐
1601 cally). Of course, you can always map a file to a loop-device manually.
1602 See the cryptsetup FAQ for an example.
1603 When device mapping is active, you can see the loop backing file in the
1605 status command output. Also see losetup(8).
1606
1608 The LUKS2 on-disk metadata is updated in several steps and to achieve
1609 proper atomic update, there is a locking mechanism. For an image in
1610 file, code uses flock(2) system call. For a block device, lock is per‐
1611 formed over a special file stored in a locking directory (by default
1612 /run/lock/cryptsetup). The locking directory should be created with
1613 the proper security context by the distribution during the boot-up
1614 phase. Only LUKS2 uses locks, other formats do not use this mechanism.
1615
1617 The reload action is no longer supported. Please use dmsetup(8) if you
1618 need to directly manipulate with the device mapping table.
1619 The luksDelKey was replaced with luksKillSlot.
1621
1623 Report bugs, including ones in the documentation, on the cryptsetup
1624 mailing list at <dm-crypt@saout.de> or in the 'Issues' section on LUKS
1625 website. Please attach the output of the failed command with the
1626 --debug option added.
1627
1629 cryptsetup originally written by Jana Saout <jana@saout.de>
1630 The LUKS extensions and original man page were written by Clemens Fruh‐
1631 wirth <clemens@endorphin.org>.
1632 Man page extensions by Milan Broz <gmazyland@gmail.com>.
1633 Man page rewrite and extension by Arno Wagner <arno@wagner.name>.
1634
1636 Copyright © 2004 Jana Saout
1637 Copyright © 2004-2006 Clemens Fruhwirth
1638 Copyright © 2012-2014 Arno Wagner
1639 Copyright © 2009-2019 Red Hat, Inc.
1640 Copyright © 2009-2019 Milan Broz
1641 This is free software; see the source for copying conditions. There is
1643 NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
1644 PURPOSE.
1645
1647 The LUKS website at https://gitlab.com/cryptsetup/cryptsetup/
1648 The cryptsetup FAQ, contained in the distribution package and online at
1650 https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions
1651 The cryptsetup mailing list and list archive, see FAQ entry 1.6.
1653 The LUKS on-disk format specification available at https://git‐
1655 lab.com/cryptsetup/cryptsetup/wikis/Specification
1656cryptsetup January 2019 CRYPTSETUP(8)