8 6. Backup and Data Recovery
9 7. Issues with Specific Versions of cryptsetup
18 This is the FAQ (Frequently Asked Questions) for cryptsetup. It
19 covers Linux disk encryption with plain dm-crypt (one passphrase,
20 no management, no descriptor on disk) and LUKS (multiple user keys
21 with one master key, anti-forensics, descriptor block at start of
22 device, ...). The latest version should usually be available at
23 http://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQuestions
25 ATTENTION: If you are going to read just one thing, make it the
26 section on Backup and Data Recovery. By far the most questions on
27 the cryptsetup mailing list are from people that just managed to
28 somehow format or overwrite the start of their LUKS partitions.
29 Usually, there is nothing that can be done to help these poor souls
30 recover their data. Make sure you understand the problem and
31 limitations imposed by the LUKS security model BEFORE you face such
37 Current FAQ maintainer is Arno Wagner <arno@wagner.name>. Other
38 contributors are listed at the end. If you want to contribute, send
39 your article, including a descriptive headline, to the maintainer,
40 or the dm-crypt mailing list with something like "FAQ ..." in the
41 subject. Please note that by contributing to this FAQ, you accept
42 the license described below.
44 This work is under the "Attribution-Share Alike 3.0 Unported"
45 license, which means distribution is unlimited, you may create
46 derived works, but attributions to original authors and this
47 license statement must be retained and the derived work must be
48 under the same license. See
49 http://creativecommons.org/licenses/by-sa/3.0/ for more details of
52 Side note: I did text license research some time ago and I think
53 this license is best suited for the purpose at hand and creates the
60 * Can I encrypt an already existing, non-empty partition to use
63 There is no converter, and it is not really needed. The way to do
64 this is to make a backup of the device in question, securely wipe
65 the device (as LUKS device initialization does not clear away old
66 data), do a luksFormat, optionally overwrite the encrypted device,
67 create a new filesystem and restore your backup on the now
68 encrypted device. Also refer to sections "Security Aspects" and
69 "Backup and Data Recovery".
71 For backup, plain GNU tar works well and backs up anything likely
72 to be in a filesystem.
75 * How do I use LUKS with a loop-device?
77 Just the same as with any block device. If you want, for example,
78 to use a 100MiB file as LUKS container, do something like this:
80 head -c 100M /dev/zero > luksfile # create empty file
81 losetup /dev/loop0 luksfile # map luksfile to /dev/loop0
82 cryptsetup luksFormat /dev/loop0 # create LUKS on the loop device
84 Afterwards just use /dev/loop0 as a you would use a LUKS partition.
85 To unmap the file when done, use "losetup -d /dev/loop0".
88 * When I add a new key-slot to LUKS, it asks for a passphrase but
89 then complains about there not being a key-slot with that
92 That is as intended. You are asked a passphrase of an existing
93 key-slot first, before you can enter the passphrase for the new
94 key-slot. Otherwise you could break the encryption by just adding a
95 new key-slot. This way, you have to know the passphrase of one of
96 the already configured key-slots in order to be able to configure a
100 * How do I read a dm-crypt key from file?
102 Note that the file will still be hashed first, just like keyboard
103 input. Use the --key-file option, like this:
105 cryptsetup create --key-file keyfile e1 /dev/loop0
108 * How do I read a LUKS slot key from file?
110 What you really do here is to read a passphrase from file, just as
111 you would with manual entry of a passphrase for a key-slot. You can
112 add a new passphrase to a free key-slot, set the passphrase of an
113 specific key-slot or put an already configured passphrase into a
114 file. In the last case make sure no trailing newline (0x0a) is
115 contained in the key file, or the passphrase will not work because
116 the whole file is used as input.
118 To add a new passphrase to a free key slot from file, use something
121 cryptsetup luksAddKey /dev/loop0 keyfile
123 To add a new passphrase to a specific key-slot, use something like
126 cryptsetup luksAddKey --key-slot 7 /dev/loop0 keyfile
128 To supply a key from file to any LUKS command, use the --key-file
129 option, e.g. like this:
131 cryptsetup luksOpen --key-file keyfile /dev/loop0 e1
134 * How do I read the LUKS master key from file?
136 The question you should ask yourself first, is why you would want
137 to do this. The only legitimate reason I can think of is if you
138 want to have two LUKS devices with the same master key. Even then,
139 I think it would be preferable to just use key-slots with the same
140 passphrase, or to use plain dm-crypt instead. If you really have a
141 good reason, please tell me. If I am convinced, I will add how to
145 * What are the security requirements for a key read from file?
147 A file-stored key or passphrase has the same security requirements
148 as one entered interactively, however you can use random bytes and
149 thereby use bytes you cannot type on the keyboard. You can use any
150 file you like as key file, for example a plain text file with a
151 human readable passphrase. To generate a file with random bytes,
152 use something like this:
154 head -c 256 /dev/random > keyfile
157 * If I map a journaled file system using dm-crypt/LUKS, does it
158 still provide its usual transactional guarantees?
160 As far as I know you do (but I may be wrong), but please note that
161 these "guarantees" are far weaker than they appear to be. For
162 example, you not not get a hard flush to disk surface even on a
163 call to fsync. In addition, the HDD itself may do independent
164 write reordering. Some other things can go wrong as well. The
165 filesystem developers are aware of these problems and typically
166 can make it work anyways. That said, dm-crypt/LUKS should not make
169 Personally, I have several instances of ext3 on dm-crypt and have
170 not noticed any specific issues so far.
172 Update: I did run into frequent small freezes (1-2 sec) when putting
173 a vmware image on ext3 over dm-crypt. This does indicate that the
174 transactional guarantees are in place, but at a cost. When I went
175 back to ext2, the problem went away.
178 * Can I use LUKS or cryptsetup with a more secure (external) medium
179 for key storage, e.g. TPM or a smartcard?
181 Yes, see the answers on using a file-supplied key. You do have to
182 write the glue-logic yourself though. Basically you can have
183 cryptsetup read the key from STDIN and write it there with your
184 own tool that in turn gets the key from the more secure key
188 * Can I resize a dm-crypt or LUKS partition?
190 Yes, you can, as neither dm-crypt nor LUKS stores partition size.
191 Whether you should is a different question. Personally I recommend
192 backup, recreation of the encrypted partition with new size,
193 recreation of the filesystem and restore. This gets around the
194 tricky business of resizing the filesystem. The backup is really
195 non-optional here, as a lot can go wrong, resulting in partial or
196 complete data loss. Using something like gparted to resize an
197 encrypted partition is slow, but pretty safe and should be fine.
198 This will not change the size of the filesystem hidden under the
201 You also need to be aware of size-based limitations. The one
202 currently relevant is that aes-xts-plain should not be used for
203 encrypted container sizes larger than 2TiB. Use aes-xts-plain64
210 * My dm-crypt/LUKS mapping does not work! What general steps are
211 there to investigate the problem?
213 If you get a specific error message, investigate what it claims
214 first. If not, you may want to check the following things.
216 - Check that "/dev", including "/dev/mapper/control" is there. If it is
217 missing, you may have a problem with the "/dev" tree itself or you
218 may have broken udev rules.
220 - Check that you have the device mapper and the crypt target in your kernel.
221 The output of "dmsetup targets" should list a "crypt" target. If it
222 is not there or the command fails, add device mapper and
223 crypt-target to the kernel.
225 - Check that the hash-functions and ciphers you want to use are in the kernel.
226 The output of "cat /proc/crypto" needs to list them.
229 * My dm-crypt mapping suddenly stopped when upgrading cryptsetup.
231 The default cipher, hash or mode may have changed (the mode changed
232 from 1.0.x to 1.1.x). See under "Issues With Specific Versions of
236 * When I call cryptsetup from cron/CGI, I get errors about unknown
239 If you get errors about unknown parameters or the like that are not
240 present when cryptsetup is called from the shell, make sure you
241 have no older version of cryptsetup on your system that then gets
242 called by cron/CGI.For example some distributions install
243 cryptsetup into /usr/sbin, while a manual install could go to
244 /usr/local/sbin. As a debugging aid, call "cryptsetup --version"
245 from cron/CGI or the non-shell mechanism to be sure you have the
249 * Unlocking a LUKS device takes very long. Why?
251 The iteration time for every key-slot (iteration is needed to
252 prevent dictionary attacks) is calculated during the luksFormat
253 operation. By default it is 1 second on the machine where the
254 format operation is done. If you format a device on a fast machine
255 and then unlock it on a slow machine, the unlocking time can be
256 much more longer. Also take into account that up to 8 key-slots
257 have to be tried in order to find the right one.
259 If this is problem, you can add another key-slot using the slow
260 machine with the same passphrase and then remove the old key-slot.
261 The new key-slot will have an iteration count adjusted to 1 second
262 on the slow machine. Use luksKeyAdd and then luksKillSlot or
263 luksRemoveKey. However, this operation will not change volume key
264 iteration count. In order to change that, you will have to backup
265 the data in the LUKS container, luksFormat on the slow machine and
269 * "blkid" sees a LUKS UUID and an ext2/swap UUID on the same device.
272 Some old versions of cryptsetup have a bug where the header does
273 not get completely wiped during LUKS format and an older ext2/swap
274 signature remains on the device. This confuses blkid.
276 Fix: Wipe the unused header areas by doing a backup and restore of
277 the header with cryptsetup 1.1.x:
279 cryptsetup luksHeaderBackup --header-backup-file <file> <device>
280 cryptsetup luksHeaderRestore --header-backup-file <file> <device>
282 If you cannot use a 1.1.x cryptsetup, you can also do a manual wipe
283 of the area in question with the command below. Be very, VERY,
284 careful and make sure to do a backup of the header before. If you
285 get this wrong, your device may become permanently inaccessible.
287 dd if=/dev/zero of=<device> bs=512 seek=2 count=6
290 * cryptsetup segfaults on Gentoo amd64 hardened ...
292 There seems to be some inteference between the hardening and and
293 the way cryptsetup benchmarks PBKDF2. The solution to this is
294 currently not quite clear for an encrypted root filesystem. For
295 other uses, you can apparently specify USE="dynamic" as compile
296 flag, see http://bugs.gentoo.org/show_bug.cgi?id=283470
302 * Can a bad RAM module cause problems?
304 LUKS and dm-crypt can give the RAM quite a workout, especially when
305 combined with software RAID. In particular the combination RAID5 +
306 LUKS + XFS seems to uncover RAM problems that never caused obvious
307 problems before. Symptoms vary, but often the problem manifest
308 itself when copying large amounts of data, typically several times
309 larger than your main memory.
311 Side note: One thing you should always do on large data movements is
312 to run a verify, for example with the "-d" option of "tar" or by
313 doing a set of MD5 checksums on the source or target with
315 find . -type f -exec md5sum \{\} \; > checksum-file
317 and then a "md5sum -c checksum-file" on the other side. If you get
318 mismatches here, RAM is the primary suspect. A lesser suspect is
319 an overclocked CPU. I have found countless hardware problems in
320 verify runs after copying or making backups. Bit errors are much
321 more common than most people think.
323 Some RAM issues are even worse and corrupt structures in one of the
324 layers. This typically results in lockups, CPU state dumps in the
325 system logs, kernel panic or other things. It is quite possible to
326 have the problem with an encrypted device, but not with an
327 otherwise the same unencrypted device. The reason for that is that
328 encryption has an error amplification property: You flip one bit
329 in an encrypted data block, and the decrypted version has half of
330 its bits flipped. This is an important security property for modern
331 ciphers. With the usual modes in cryptsetup (CBC, ESSIV, XTS), you
332 get up to a completely changed 512 byte block per bit error. A
333 corrupt block causes a lot more havoc than the occasionally
334 flipped single bit and can result various obscure errors.
336 Note however that a verify run on copying between encrypted or
337 unencrypted devices can also show you corruption when the copying
338 itself did not report any problems. If you find defect RAM, assume
339 all backups and copied data to be suspect, unless you did a verify.
344 First you should know that overclocking often makes memory problems
345 worse. So if you overclock (which I strongly recommend against in a
346 system holding data that has some worth), run the tests with the
349 There are two good options. One is Memtest86+ and the other is
350 "memtester" by Charles Cazabon. Memtest86+ requires a reboot and
351 then takes over the machine, while memtester runs from a
352 root-shell. Both use different testing methods and I have found
353 problems fast with each one that the other needed long to find. I
354 recommend running the following procedure until the first error is
357 - Run Memtest86+ for one cycle
358 - Run memterster for one cycle (shut down as many other applications as possible)
359 - Run Memtest86+ for 24h or more
360 - Run memtester for 24h or more
361 If all that does not produce error messages, your RAM may be sound,
362 but I have had one weak bit that Memtest86+ needed around 60 hours
363 to find. If you can reproduce the original problem reliably, a good
364 additional test may be to remove half of the RAM (if you have more
365 than one module) and try whether the problem is still there and if
366 so, try with the other half. If you just have one module, get a
367 different one and try with that. If you do overclocking, reduce
368 the settings to the most conservative ones available and try with
375 * Should I initialize (overwrite) a new LUKS/dm-crypt partition?
377 If you just create a filesystem on it, most of the old data will
378 still be there. If the old data is sensitive, you should overwrite
379 it before encrypting. In any case, not initializing will leave the
380 old data there until the specific sector gets written. That may
381 enable an attacker to determine how much and where on the
382 partition data was written. If you think this is a risk, you can
383 prevent this by overwriting the encrypted device (here assumed to
384 be named "e1") with zeros like this:
386 dd_rescue -w /dev/zero /dev/mapper/e1
388 or alternatively with one of the following more standard commands:
390 cat /dev/zero > /dev/mapper/e1
391 dd if=/dev/zero of=/dev/mapper/e1
394 * How do I securely erase a LUKS (or other) partition?
396 For LUKS, if you are in a desperate hurry, overwrite the first few
397 kilobytes of the LUKS partition. This erases the salts and makes
398 access impossible. However a LUKS header backup or full backup will
399 still grant access to most or all data.
401 To do this right, overwrite the whole LUKS partition with a single
402 pass of zeros. This is enough for current HDDs. For SDDs you may
403 want to erase the whole drive several times to be sure data is not
404 retained by wear leveling. This is possibly insecure as SDD
405 technology is not fully understood in this regard. Still, due to
406 the anti-forensic properties of the LUKS key-slots, a single
407 overwrite of an SSD could be enough. If in doubt, use physical
408 destruction in addition. Keep in mind to also erase all backups.
410 Example for a zero-overwrite erase of partition sda10 done with
413 dd_rescue -w /dev/zero /dev/sda10
416 * How do I securely erase a backup of a LUKS partition or header?
418 That depends on the medium it is stored on. For HDD and SSD, use
419 overwrite with zeros. For an SSD, you may want to overwrite the
420 complete SSD several times and use physical destruction in addition,
421 see last item. Treat USB flash drives the same as SSDs. For
422 re-writable CD/DVD, a single overwrite should also be enough, due
423 to the anti-forensic properties of the LUKS keyslots. For
424 write-once media, use physical destruction. For low security
425 requirements, just cut the CD/DVD into several parts. For high
426 security needs, shred or burn the medium. If your backup is on
427 magnetic tape, I advise physical destruction by shredding or
428 burning. The problem with magnetic tape is that it has a higher
429 dynamic range than HDDs and older data may well be recoverable
430 after overwrites. Also write-head alignment issues can lead to
431 data not actually being deleted at all during overwrites.
434 * What about backup? Does it compromise security?
436 That depends. See next section.
439 * Why was the default aes-cbc-plain replaced with aes-cbc-essiv?
441 The problem is that cbc-plain has a fingerprint vulnerability, where
442 a specially crafted file placed into the crypto-container can be
443 recognized from the outside. The issue here is that for cbc-plain
444 the initialization vector (IV) is the sector number. The IV gets
445 XORed to the first data chunk of the sector to be encrypted. If you
446 make sure that the first data block to be stored in a sector
447 contains the sector number as well, the first data block to be
448 encrypted is all zeros and always encrypted to the same ciphertext.
449 This also works if the first data chunk just has a constant XOR
450 with the sector number. By having several shifted patterns you can
451 take care of the case of a non-power-of-two start sector number of
454 This mechanism allows you to create a pattern of sectors that have
455 the same first ciphertext block and signal one bit per sector to the
456 outside, allowing you to e.g. mark media files that way for
457 recognition without decryption. For large files this is a
458 practical attack. For small ones, you do not have enough blocks to
459 signal and take care of different file starting offsets.
461 In order to prevent this attack, the default was changed to
462 cbc-essiv. ESSIV uses a keyed hash of the sector number, with the
463 encryption key as key. This makes the IV unpredictable without
464 knowing the encryption key and the watermarking attack fails.
467 * Are there any problems with "plain" IV? What is "plain64"?
469 First, "plain" and "plain64" are both not safe to use with CBC, see
472 However there are modes, like XTS, that are secure with "plain" IV.
473 The next limit is that "plain" is 64 bit, with the upper 32 bit set
474 to zero. This means that on volumes larger than 2TiB, the IV
475 repeats, creating a vulnerability that potentially leaks some
476 data. To avoid this, use "plain64", which uses the full sector
477 number up to 64 bit. Note that "plain64" requires a kernel >=
478 2.6.33. Also note that "plain64" is backwards compatible for
479 volume sizes <= 2TiB, but not for those > 2TiB. Finally, "plain64"
480 does not cause any performance penalty compared to "plain".
483 * What about XTS mode?
485 XTS mode is potentially even more secure than cbc-essiv (but only if
486 cbc-essiv is insecure in your scenario). It is a NIST standard and
487 used, e.g. in Truecrypt. At the moment, if you want to use it, you
488 have to specify it manually as "aes-xts-plain", i.e.
490 cryptsetup -c aes-xts-plain luksFormat <device>
492 For volumes >2TiB and kernels >= 2.6.33 use "plain64" (see FAQ
493 item on "plain" and "plain64"):
495 cryptsetup -c aes-xts-plain64 luksFormat <device>
497 There is a potential security issue with XTS mode and large blocks.
498 LUKS and dm-crypt always use 512B blocks and the issue does not
502 6. Backup and Data Recovery
505 * Does a backup compromise security?
507 Depends on how you do it. First, a backup is non-optional with
508 encrypted data just the same way it is with non-encrypted data.
509 Disks do break and they do not care whether they make plain or
510 encrypted data inaccessible.
512 However there are risks introduced by backups. For example if you
513 change/disable a key-slot in LUKS, a binary backup of the partition
514 will still have the old key-slot. To deal with this, you have to
515 be able to change the key-slot on the backup as well, or use a
516 different set-up. One option is to have a different passphrase on
517 the backup and to make the backup with both containers open.
518 Another one is to make a backup of the original, opened container to
519 a single file, e.g. with tar, and to encrypt that file with
520 public-key-cryptography, e.g. with GnuPG. You can then keep the
521 secret key in a safe place, because it is only used to decrypt a
522 backup. The key the backup is encrypted with can be stored without
523 special security measures, as long as an attacker cannot replace
526 If you use dm-crypt, backup is simpler: As there is no key
527 management, the main risk is that you cannot wipe the backup when
528 wiping the original. However wiping the original for dm-crypt
529 should consist of forgetting the passphrase and that you can do
530 without actual access to the backup.
532 In both cases, there is an additional (usually small) risk: An
533 attacker can see how many sectors and which ones have been changed
534 since the backup. This is not possible with the public-key method
537 My personal advice is to use one USB disk (low value date) or three
538 disks (high value data) in rotating order for backups, and either
539 use different passphrases or keep them easily accessible in case
540 you need to disable a key-slot. If you do network-backup or
541 tape-backup, I strongly recommend to go the public-key path,
542 especially as you typically cannot reliably delete data in these
543 scenarios. (Well, you can burn the tape if it is under your
547 * What happens if I overwrite the start of a LUKS partition or
548 damage the LUKS header or key-slots?
550 There are two critical components for decryption: The salt values
551 in the header itself and the key-slots. If the salt values are
552 overwritten or changed, nothing (in the cryptographically strong
553 sense) can be done to access the data, unless there is a backup of
554 the LUKS header. If a key-slot is damaged, the data can still be
555 read with a different key-slot, if there is a remaining undamaged
556 and used key-slot. Note that in order to make a key-slot
557 unrecoverable in a cryptographically strong sense, changing about
558 4-6 bits in random locations of its 128kiB size is quite enough.
561 * What happens if I (quick) format a LUKS partition?
563 I have not tried the different ways to do this, but very likely you
564 will have written a new boot-sector, which in turn overwrites the
565 LUKS header, including the salts. You may also damage the key-slots
566 in part or in full. See also last item.
569 * What does the on-disk structure of dm-crypt look like?
571 There is none. dm-crypt takes a block device and gives encrypted
572 access to each of its blocks with a key derived from the passphrase
573 given. If you use a cipher different than the default, you have to
574 specify that as a parameter to cryptsetup too. If you want to
575 change the password, you basically have to create a second
576 encrypted device with the new passphrase and copy your data over.
577 On the plus side, if you accidentally overwrite any part of a
578 dm-crypt device, the damage will be limited to the are you
582 * What does the on-disk structure of LUKS look like?
584 A LUKS partition consists of a header, followed by 8 key-slot
585 descriptors, followed by 8 key slots, followed by the encrypted
588 Header and key-slot descriptors fill the first 592 bytes. The
589 key-slot size depends on the creation parameters, namely on the
590 number of anti-forensic stripes and on key block alignment.
592 With 4000 stripes (the default), each key-slot is a bit less than
593 128kiB in size. Due to sector alignment of the key-slot start,
594 that means the key block 0 is at offset 0x1000-0x20400, key block
595 1 at offset 0x21000-0x40400, and key block 7 at offset
596 0xc1000-0xe0400. The space to the next full sector address is
597 padded with zeros. Never used key-slots are filled with what the
598 disk originally contained there, a key-slot removed with
599 "luksRemoveKey" or "luksKillSlot" gets filled with 0xff. Start of
600 bulk data (with the default 4000 stripes and 8 key-slots) is at
601 0x101000, i.e. at 1'052'672 bytes, i.e. at 1MiB + 4096 bytes from
602 the start of the partition. This is also the value given by command
603 "luksDump" with "Payload offset: 2056", just multiply by the sector
604 size (512 bytes). Incidentally, "luksHeaderBackup" dumps exactly
605 the first 1'052'672 bytes to file and "luksHeaderRestore" restores
608 The exact specification of the format is here:
609 http://code.google.com/p/cryptsetup/wiki/Specification
612 * How do I backup a LUKS header?
614 While you could just copy the appropriate number of bytes from the
615 start of the LUKS partition, the best way is to use command option
616 "luksHeaderBackup" of cryptsetup. This protects also against errors
617 when non-standard parameters have been used in LUKS partition
621 cryptsetup luksHeaderBackup --header-backup-file h_bak /dev/mapper/c1
624 * How do I backup a LUKS partition?
626 You do a sector-image of the whole partition. This will contain the
627 LUKS header, the keys-slots and the data ares. It can be done
628 under Linux e.g. with dd_rescue (for a direct image copy) and with
629 "cat" or "dd". Example:
631 cat /dev/sda10 > sda10.img
632 dd_rescue /dev/sda10 sda10.img
634 You can also use any other backup software that is capable of making
635 a sector image of a partition. Note that compression is
636 ineffective for encrypted data, hence it does not sense to use it.
639 * Do I need a backup of the full partition? Would the header and
640 key-slots not be enough?
642 Backup protects you against two things: Disk loss or corruption and
643 user error. By far the most questions on the dm-crypt mailing list
644 about how to recover a damaged LUKS partition are related to user
645 error. For example, if you create a new filesystem on a LUKS
646 partition, chances are good that all data is lost permanently.
648 For this case, a header+key-slot backup would often be enough. But
649 keep in mind that a HDD has roughly a failure risk of 5% per year.
650 It is highly advisable to have a complete backup to protect against
654 * Are there security risks from a backup of the LUKS header or a
655 whole LUKS partition?
657 Yes. One risk is that if you remove access rights for specific
658 key-slots by deleting their contents, the data can still be
659 accessed with invalidated passphrase and the backup. The other risk
660 is that if you erase a LUKS partition, a backup could still grant
661 access, especially if you only erased the LUKS header and not the
665 * I think this is overly complicated. Is there an alternative?
667 Yes, you can use plain dm-crypt. It does not allow multiple
668 passphrases, but on the plus side, it has zero on disk description
669 and if you overwrite some part of a plain dm-crypt partition,
670 exactly the overwritten parts are lost (rounded up to sector
674 7. Issues with Specific Versions of cryptsetup
677 * When using the create command for plain dm-crypt with cryptsetup
678 1.1.x, the mapping is incompatible and my data is not accessible
681 With cryptsetup 1.1.x, the distro maintainer can define different
682 default encryption modes for LUKS and plain devices. You can check
683 these compiled-in defaults using "cryptsetup --help". Moreover, the
684 plain device default changed because the old IV mode was
685 vulnerable to a watermarking attack.
687 If you are using a plain device and you need a compatible mode, just
688 specify cipher, key size and hash algorithm explicitly. For
689 compatibility with cryptsetup 1.0.x defaults, simple use the
692 cryptsetup create -c aes-cbc-plain -s 256 -h ripemd160 <name> <device>
694 LUKS stores cipher and mode in the metadata on disk, avoiding this
698 * cryptsetup on SLED 10 has problems...
700 SLED 10 is missing an essential kernel patch for dm-crypt, which
701 is broken in its kernel as a result. There may be a very old
702 version of cryptsetup (1.0.x) provided by SLED, which should also
703 not be used anymore as well. My advice would be to drop SLED 10.
705 A. Contributors In no particular order: