{ "mode": "man", "parameter": "cryptsetup-reencrypt", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/cryptsetup-reencrypt/8/json", "generated": "2026-10-06T15:37:07Z", "synopsis": "cryptsetup reencrypt [] or --active-name []", "sections": { "NAME": { "content": "cryptsetup-reencrypt - reencrypt LUKS encrypted volumes in-place\n", "subsections": [] }, "SYNOPSIS": { "content": "cryptsetup reencrypt [] or --active-name []\n", "subsections": [] }, "DESCRIPTION": { "content": "Run LUKS device reencryption.\n\nThere are 3 basic modes of operation:\n\n• device reencryption (reencrypt)\n\n• device encryption (reencrypt --encrypt/--new/-N)\n\n• device decryption (reencrypt --decrypt)\n\n or --active-name (LUKS2 only) is mandatory parameter.\n\nCryptsetup reencrypt action can be used to change reencryption parameters which otherwise\nrequire full on-disk data change (re-encryption). The reencrypt action reencrypts data on\nLUKS device in-place.\n\nYou can regenerate volume key (the real key used in on-disk encryption unlocked by\npassphrase), cipher, cipher mode or encryption sector size (LUKS2 only).\n\nReencryption process may be safely interrupted by a user via SIGINT signal (ctrl+c). Same\napplies to SIGTERM signal (i.e. issued by systemd during system shutdown).\n\nFor in-place encryption mode, the reencrypt action additionally takes all options available\nfor luksFormat action for respective LUKS version (see cryptsetup-luksFormat man page for\nmore details). See cryptsetup-luksFormat(8).\n\nNOTE that for encrypt and decrypt mode, the whole device must be treated as unencrypted —\nthere are no guarantees of confidentiality as part of the device contains plaintext.\n", "subsections": [ { "name": "ALWAYS BE SURE YOU HAVE RELIABLE BACKUP BEFORE USING THIS ACTION ON LUKS DEVICE.", "content": " can be [--batch-mode, --block-size, --cipher, --debug, --debug-json, --decrypt,\n--device-size, --disable-locks, --encrypt, --force-offline-reencrypt, --hash, --header,\n--hotzone-size, --iter-time, --init-only, --keep-key, --key-file, --key-size, --key-slot,\n--keyfile-offset, --keyfile-size, --tries, --timeout, --pbkdf, --pbkdf-force-iterations,\n--pbkdf-memory, --pbkdf-parallel, --progress-frequency, --progress-json,\n--reduce-device-size, --resilience, --resilience-hash, --resume-only, --sector-size,\n--use-directio, --use-random, --use-urandom, --use-fsync, --uuid, --verbose,\n--volume-key-file, --write-log].\n" } ] }, "LUKS2 REENCRYPTION": { "content": "With parameter cryptsetup looks up active dm mapping. If no active mapping\nis detected, it starts offline LUKS2 reencryption otherwise online reencryption takes place.\n\nTo resume already initialized or interrupted reencryption, just run the cryptsetup reencrypt\ncommand again to continue the reencryption operation. Reencryption may be resumed with\ndifferent --resilience or --hotzone-size unless implicit datashift resilience mode is used:\neither encrypt mode with --reduce-device-size option or decrypt mode with original LUKS2\nheader exported in --header file.\n\nIf the reencryption process was interrupted abruptly (reencryption process crash, system\ncrash, poweroff) it may require recovery. The recovery is currently run automatically on next\nactivation (action open) when needed or explicitly by user (action repair).\n\nOptional parameter takes effect only with encrypt option and it activates device\n immediately after encryption initialization gets finished. That’s useful when\ndevice needs to be ready as soon as possible and mounted (used) before full data area\nencryption is completed.\n", "subsections": [] }, "LUKS1 REENCRYPTION": { "content": "Current working directory must be writable and temporary files created during reencryption\nmust be present. During reencryption process the LUKS1 device is marked unavailable and must\nbe offline (no dm-crypt mapping or mounted filesystem).\n\nWARNING: The LUKS1 reencryption code is not resistant to hardware or kernel failures during\nreencryption (you can lose your data in this case).\n", "subsections": [] }, "OPTIONS": { "content": "--block-size value (LUKS1 only)\nUse re-encryption block size of value in MiB.\n\nValues can be between 1 and 64 MiB.\n", "subsections": [ { "name": "--use-directio (LUKS1 only)", "content": "Use direct-io (ODIRECT) for all read/write data operations related to block device\nundergoing reencryption.\n\nUseful if direct-io operations perform better than normal buffered operations (e.g. in\nvirtual environments).\n", "long": "--use-directio" }, { "name": "--use-fsync (LUKS1 only)", "content": "Use fsync call after every written block. This applies for reencryption log files as\nwell.\n", "long": "--use-fsync" }, { "name": "--write-log (LUKS1 only)", "content": "Update log file after every block write. This can slow down reencryption but will\nminimize data loss in the case of system crash.\n", "long": "--write-log" }, { "name": "--type ", "content": "Specifies required (encryption mode) or expected (other modes) LUKS format. Accepts only\nluks1 or luks2.\n\n--hash, -h \nLUKS1: Specifies the hash used in the LUKS1 key setup scheme and volume key digest.\n\nNOTE: if this parameter is not specified, default hash algorithm is always used for new\nLUKS1 device header.\n\nLUKS2: Ignored unless new keyslot pbkdf algorithm is set to PBKDF2 (see --pbkdf).\n\n--cipher, -c \nLUKS2: Set the cipher specification string for data segment only.\n\nLUKS1: Set the cipher specification string for data segment and keyslots.\n\nNOTE: In encrypt mode, if cipher specification is omitted the default cipher is applied.\nIn reencrypt mode, if no new cipher specification is requested, the existing cipher will\nremain in use. Unless the existing cipher was \"ciphernull\". In that case default cipher\nwould be applied as in encrypt mode.\n\ncryptsetup --help shows the compiled-in defaults.\n\nIf a hash is part of the cipher specification, then it is used as part of the IV\ngeneration. For example, ESSIV needs a hash function, while \"plain64\" does not and hence\nnone is specified.\n\nFor XTS mode you can optionally set a key size of 512 bits with the -s option. Key size\nfor XTS mode is twice that for other modes for the same security level.\n", "long": "--type", "arg": "" }, { "name": "--verify-passphrase, -y", "content": "When interactively asking for a passphrase, ask for it twice and complain if both inputs\ndo not match. Ignored on input from file or stdin.\n\n--key-file, -d name\nRead the passphrase from file.\n\nIf the name given is \"-\", then the passphrase will be read from stdin. In this case,\nreading will not stop at newline characters.\n\nWARNING: --key-file option can be used only if there is only one active keyslot, or\nalternatively, also if --key-slot option is specified (then all other keyslots will be\ndisabled in new LUKS device).\n\nIf this option is not used, cryptsetup will ask for all active keyslot passphrases.\n\n--keyfile-offset value\nSkip value bytes at the beginning of the key file.\n\n--keyfile-size, -l value\nRead a maximum of value bytes from the key file. The default is to read the whole file up\nto the compiled-in maximum that can be queried with --help. Supplying more data than the\ncompiled-in maximum aborts the operation.\n\nThis option is useful to cut trailing newlines, for example. If --keyfile-offset is also\ngiven, the size count starts after the offset.\n", "flag": "-y", "long": "--verify-passphrase" }, { "name": "--volume-key-file, --master-key-file (OBSOLETE alias)", "content": "Use (set) new volume key stored in a file.\nWARNING: If you create your own volume key, you need to make sure to do it right.\nOtherwise, you can end up with a low-entropy or otherwise partially predictable volume\nkey which will compromise security.\n\n--use-random, --use-urandom\nDefine which kernel random number generator will be used to create the volume key.\n", "long": "--master-key-file" }, { "name": "--keep-key", "content": "LUKS2: Do not change effective volume key and change other parameters provided it is\nrequested.\n\nLUKS1: Reencrypt only the LUKS1 header and keyslots. Skips data in-place reencryption.\n", "long": "--keep-key" }, { "name": "--key-slot, -S <0-N>", "content": "For LUKS operations that add key material, this option allows you to specify which key\nslot is selected for the new key.\n\nFor reencryption mode it selects specific keyslot (and passphrase) that can be used to\nunlock new volume key. If used all other keyslots get removed after reencryption\noperation is finished.\n\nThe maximum number of key slots depends on the LUKS version. LUKS1 can have up to 8 key\nslots. LUKS2 can have up to 32 key slots based on key slot area size and key size, but a\nvalid key slot ID can always be between 0 and 31 for LUKS2.\n\n--key-size, -s bits\nSets key size in bits. The argument has to be a multiple of 8. The possible key-sizes are\nlimited by the cipher and mode used.\n\nSee /proc/crypto for more information. Note that key-size in /proc/crypto is stated in\nbytes.\n\nLUKS1: If you are increasing key size, there must be enough space in the LUKS header for\nenlarged keyslots (data offset must be large enough) or reencryption cannot be performed.\n\nIf there is not enough space for keyslots with new key size, you can destructively shrink\ndevice with --reduce-device-size option.\n", "flag": "-S", "long": "--key-slot", "arg": "<0-N>" }, { "name": "--offset, -o ", "content": "Start offset in the backend device in 512-byte sectors. This option is only relevant for\nthe encrypt mode.\n\nThe --offset option sets the data offset (payload) of data device and must be aligned to\n4096-byte sectors (must be multiple of 8). This option cannot be combined with\n--align-payload option.\n\n--device-size size[units]\nInstead of real device size, use specified value. It means that only specified area (from\nthe start of the device to the specified size) will be reencrypted.\n\nWARNING: This is destructive operation. Data beyond --device-size limit may be lost after\noperation gets finished.\n\nIf no unit suffix is specified, the size is in bytes.\n\nUnit suffix can be S for 512 byte sectors, K/M/G/T (or KiB,MiB,GiB,TiB) for units with\n1024 base or KB/MB/GB/TB for 1000 base (SI scale).\n", "flag": "-o", "long": "--offset" }, { "name": "--pbkdf ", "content": "Set Password-Based Key Derivation Function (PBKDF) algorithm for LUKS keyslot. The PBKDF\ncan be: pbkdf2 (for PBKDF2 according to RFC2898), argon2i for Argon2i or argon2id for\nArgon2id (see Argon2 for more info).\n\nFor LUKS1, only PBKDF2 is accepted (no need to use this option). The default PBKDF for\nLUKS2 is set during compilation time and is available in cryptsetup --help output.\n\nA PBKDF is used for increasing dictionary and brute-force attack cost for keyslot\npasswords. The parameters can be time, memory and parallel cost.\n\nFor PBKDF2, only time cost (number of iterations) applies. For Argon2i/id, there is also\nmemory cost (memory required during the process of key derivation) and parallel cost\n(number of threads that run in parallel during the key derivation.\n\nNote that increasing memory cost also increases time, so the final parameter values are\nmeasured by a benchmark. The benchmark tries to find iteration time (--iter-time) with\nrequired memory cost --pbkdf-memory. If it is not possible, the memory cost is decreased\nas well. The parallel cost --pbkdf-parallel is constant and is checked against available\nCPU cores.\n\nYou can see all PBKDF parameters for particular LUKS2 keyslot with cryptsetup-luksDump(8)\ncommand.\n\nNOTE: If you do not want to use benchmark and want to specify all parameters directly,\nuse --pbkdf-force-iterations with --pbkdf-memory and --pbkdf-parallel. This will override\nthe values without benchmarking. Note it can cause extremely long unlocking time or cause\nout-of-memory conditions with unconditional process termination. Use only in specific\ncases, for example, if you know that the formatted device will be used on some small\nembedded system.\n\nMINIMAL AND MAXIMAL PBKDF COSTS: For PBKDF2, the minimum iteration count is 1000 and\nmaximum is 4294967295 (maximum for 32bit unsigned integer). Memory and parallel costs are\nunused for PBKDF2. For Argon2i and Argon2id, minimum iteration count (CPU cost) is 4 and\nmaximum is 4294967295 (maximum for 32bit unsigned integer). Minimum memory cost is 32 KiB\nand maximum is 4 GiB. (Limited by addressable memory on some CPU platforms.) If the\nmemory cost parameter is benchmarked (not specified by a parameter) it is always in range\nfrom 64 MiB to 1 GiB. The parallel cost minimum is 1 and maximum 4 (if enough CPUs cores\nare available, otherwise it is decreased).\n", "long": "--pbkdf" }, { "name": "--iter-time, -i ", "content": "The number of milliseconds to spend with PBKDF passphrase processing for the new LUKS\nheader.\n", "flag": "-i", "long": "--iter-time" }, { "name": "--pbkdf-memory ", "content": "Set the memory cost for PBKDF (for Argon2i/id the number represents kilobytes). Note that\nit is maximal value, PBKDF benchmark or available physical memory can decrease it. This\noption is not available for PBKDF2.\n", "long": "--pbkdf-memory", "arg": "" }, { "name": "--pbkdf-parallel ", "content": "Set the parallel cost for PBKDF (number of threads, up to 4). Note that it is maximal\nvalue, it is decreased automatically if CPU online count is lower. This option is not\navailable for PBKDF2.\n", "long": "--pbkdf-parallel", "arg": "" }, { "name": "--pbkdf-force-iterations ", "content": "Avoid PBKDF benchmark and set time cost (iterations) directly. It can be used for\nLUKS/LUKS2 device only. See --pbkdf option for more info.\n\n--progress-frequency seconds\nPrint separate line every seconds with reencryption progress.\n", "long": "--pbkdf-force-iterations", "arg": "" }, { "name": "--progress-json", "content": "Prints progress data in JSON format suitable mostly for machine processing. It prints\nseparate line every half second (or based on --progress-frequency value). The JSON output\nlooks as follows during progress (except it’s compact single line):\n\n{\n\"device\":\"/dev/sda\" // backing device or file\n\"devicebytes\":\"8192\", // bytes of I/O so far\n\"devicesize\":\"44040192\", // total bytes of I/O to go\n\"speed\":\"126877696\", // calculated speed in bytes per second (based on progress so far)\n\"etams\":\"2520012\" // estimated time to finish an operation in milliseconds\n\"timems\":\"5561235\" // total time spent in IO operation in milliseconds\n}\n\nNote on numbers in JSON output: Due to JSON parsers limitations all numbers are\nrepresented in a string format due to need of full 64bit unsigned integers.\n", "long": "--progress-json" }, { "name": "--timeout, -t ", "content": "The number of seconds to wait before timeout on passphrase input via terminal. It is\nrelevant every time a passphrase is asked. It has no effect if used in conjunction with\n--key-file.\n\nThis option is useful when the system should not stall if the user does not input a\npassphrase, e.g. during boot. The default is a value of 0 seconds, which means to wait\nforever.\n", "flag": "-t", "long": "--timeout" }, { "name": "--tries, -T", "content": "How often the input of the passphrase shall be retried. The default is 3 tries.\n", "flag": "-T", "long": "--tries" }, { "name": "--align-payload ", "content": "Align payload at a boundary of value 512-byte sectors.\n\nIf not specified, cryptsetup tries to use the topology info provided by the kernel for\nthe underlying device to get the optimal alignment. If not available (or the calculated\nvalue is a multiple of the default) data is by default aligned to a 1MiB boundary (i.e.\n2048 512-byte sectors).\n\nFor a detached LUKS header, this option specifies the offset on the data device. See also\nthe --header option.\n\nWARNING: This option is DEPRECATED and has often unexpected impact to the data offset and\nkeyslot area size (for LUKS2) due to the complex rounding. For fixed data device offset\nuse --offset option instead.\n", "long": "--align-payload" }, { "name": "--uuid ", "content": "When used in encryption mode use the provided UUID for the new LUKS header instead of\ngenerating a new one.\n\nLUKS1 (only in decryption mode): To find out what UUID to pass look for temporary files\nLUKS-UUID.[|log|org|new] of the interrupted decryption process.\n\nThe UUID must be provided in the standard UUID format, e.g.\n12345678-1234-1234-1234-123456789abc.\n", "long": "--uuid", "arg": "" }, { "name": "--header ", "content": "Use a detached (separated) metadata device or file where the LUKS header is stored. This\noption allows one to store ciphertext and LUKS header on different devices.\n\nIf used with --encrypt/--new option, the header file will be created (or overwritten).\nUse with care.\n\nLUKS2: For decryption mode the option may be used to export original LUKS2 header to a\ndetached file. The passed future file must not exist at the time of initializing the\ndecryption operation. This frees space in head of data device so that data can be moved\nat original LUKS2 header location. Later on decryption operation continues as if the\nordinary detached header was passed.\n\nWARNING: Never put exported header file in a filesystem on top of device you are about to\ndecrypt! It would cause a deadlock.\n", "long": "--header", "arg": "LUKS" }, { "name": "--force-offline-reencrypt (LUKS2 only)", "content": "Bypass active device auto-detection and enforce offline reencryption.\n\nThis option is useful especially for reencryption of LUKS2 images put in files\n(auto-detection is not reliable in this scenario).\n\nIt may also help in case active device auto-detection on particular data device does not\nwork or report errors.\n\nWARNING: Use with extreme caution! This may destroy data if the device is activated\nand/or actively used.\n", "long": "--force-offline-reencrypt" }, { "name": "--force-password", "content": "Do not use password quality checking for new LUKS passwords.\n\nThis option is ignored if cryptsetup is built without password quality checking support.\n\nFor more info about password quality check, see the manual page for pwquality.conf(5) and\npasswdqc.conf(5).\n", "long": "--force-password" }, { "name": "--disable-blkid", "content": "Disable use of blkid library for checking and wiping on-disk signatures.\n", "long": "--disable-blkid" }, { "name": "--disable-locks", "content": "Disable lock protection for metadata on disk. This option is valid only for LUKS2 and\nignored for other formats.\n\nNOTE: With locking disabled LUKS2 images in files can be fully (re)encrypted offline\nwithout need for super user privileges provided used block ciphers are available in\ncrypto backend.\n\nWARNING: Do not use this option unless you run cryptsetup in a restricted environment\nwhere locking is impossible to perform (where /run directory cannot be used).\n", "long": "--disable-locks" }, { "name": "--disable-keyring", "content": "Do not load volume key in kernel keyring and store it directly in the dm-crypt target\ninstead. This option is supported only for the LUKS2 type.\n\n--sector-size bytes (LUKS2 only)\nReencrypt device with new encryption sector size enforced.\n\nWARNING: Increasing encryption sector size may break hosted filesystem. Do not run\nreencryption with --force-offline-reencrypt if unsure what block size was filesystem\nformatted with.\n", "long": "--disable-keyring" }, { "name": "--label