1CRYPTSETUP-LUKSCONVERTKEY(8) Maintenance Commands CRYPTSETUP-LUKSCONVERTKEY(8)
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NAME

6       cryptsetup-luksConvertKey - converts an existing LUKS2 keyslot to new
7       PBKDF parameters
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SYNOPSIS

10       cryptsetup luksConvertKey [<options>] <device>
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DESCRIPTION

13       Converts an existing LUKS2 keyslot to new PBKDF parameters. The
14       passphrase for keyslot to be converted must be supplied interactively
15       or via --key-file. If no --pbkdf parameters are specified LUKS2 default
16       PBKDF values will apply.
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18       If a keyslot is specified (via --key-slot), the passphrase for that
19       keyslot must be given. If no keyslot is specified and there is still a
20       free keyslot, then the new parameters will be put into a free keyslot
21       before the keyslot containing the old parameters is purged. If there is
22       no free keyslot, then the keyslot with the old parameters is
23       overwritten directly.
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25       WARNING: If a keyslot is overwritten, a media failure during this
26       operation can cause the overwrite to fail after the old parameters have
27       been wiped and make the LUKS container inaccessible.
28
29       <options> can be [--key-file, --keyfile-offset, --keyfile-size,
30       --key-slot, --hash, --header, --disable-locks, --iter-time, --pbkdf,
31       --pbkdf-force-iterations, --pbkdf-memory, --pbkdf-parallel,
32       --keyslot-cipher, --keyslot-key-size, --timeout, --verify-passphrase].
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OPTIONS

35       --hash, -h <hash-spec>
36           The specified hash is used for PBKDF2 and AF splitter.
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38       --verify-passphrase, -y
39           When interactively asking for a passphrase, ask for it twice and
40           complain if both inputs do not match. Ignored on input from file or
41           stdin.
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43       --key-file, -d name
44           Read the passphrase from file.
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46           If the name given is "-", then the passphrase will be read from
47           stdin. In this case, reading will not stop at newline characters.
48
49           See section NOTES ON PASSPHRASE PROCESSING in cryptsetup(8) for
50           more information.
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52       --keyfile-offset value
53           Skip value bytes at the beginning of the key file.
54
55       --keyfile-size, -l value
56           Read a maximum of value bytes from the key file. The default is to
57           read the whole file up to the compiled-in maximum that can be
58           queried with --help. Supplying more data than the compiled-in
59           maximum aborts the operation.
60
61           This option is useful to cut trailing newlines, for example. If
62           --keyfile-offset is also given, the size count starts after the
63           offset.
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65       --new-keyfile-offset value
66           Skip value bytes at the start when adding a new passphrase from key
67           file.
68
69       --new-keyfile-size value
70           Read a maximum of value bytes when adding a new passphrase from key
71           file. The default is to read the whole file up to the compiled-in
72           maximum length that can be queried with --help. Supplying more than
73           the compiled in maximum aborts the operation. When
74           --new-keyfile-offset is also given, reading starts after the
75           offset.
76
77       --key-slot, -S <0-N>
78           For LUKS operations that add key material, this option allows you
79           to specify which key slot is selected for the new key.
80
81           The maximum number of key slots depends on the LUKS version. LUKS1
82           can have up to 8 key slots. LUKS2 can have up to 32 key slots based
83           on key slot area size and key size, but a valid key slot ID can
84           always be between 0 and 31 for LUKS2.
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86       --pbkdf <PBKDF spec>
87           Set Password-Based Key Derivation Function (PBKDF) algorithm for
88           LUKS keyslot. The PBKDF can be: pbkdf2 (for PBKDF2 according to
89           RFC2898), argon2i for Argon2i or argon2id for Argon2id (see Argon2
90           <https://www.cryptolux.org/index.php/Argon2> for more info).
91
92           For LUKS1, only PBKDF2 is accepted (no need to use this option).
93           The default PBKDF for LUKS2 is set during compilation time and is
94           available in cryptsetup --help output.
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96           A PBKDF is used for increasing dictionary and brute-force attack
97           cost for keyslot passwords. The parameters can be time, memory and
98           parallel cost.
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100           For PBKDF2, only time cost (number of iterations) applies. For
101           Argon2i/id, there is also memory cost (memory required during the
102           process of key derivation) and parallel cost (number of threads
103           that run in parallel during the key derivation.
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105           Note that increasing memory cost also increases time, so the final
106           parameter values are measured by a benchmark. The benchmark tries
107           to find iteration time (--iter-time) with required memory cost
108           --pbkdf-memory. If it is not possible, the memory cost is decreased
109           as well. The parallel cost --pbkdf-parallel is constant and is
110           checked against available CPU cores.
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112           You can see all PBKDF parameters for particular LUKS2 keyslot with
113           cryptsetup-luksDump(8) command.
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115           NOTE: If you do not want to use benchmark and want to specify all
116           parameters directly, use --pbkdf-force-iterations with
117           --pbkdf-memory and --pbkdf-parallel. This will override the values
118           without benchmarking. Note it can cause extremely long unlocking
119           time. Use only in specific cases, for example, if you know that the
120           formatted device will be used on some small embedded system.
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122           MINIMAL AND MAXIMAL PBKDF COSTS: For PBKDF2, the minimum iteration
123           count is 1000 and maximum is 4294967295 (maximum for 32bit unsigned
124           integer). Memory and parallel costs are unused for PBKDF2. For
125           Argon2i and Argon2id, minimum iteration count (CPU cost) is 4 and
126           maximum is 4294967295 (maximum for 32bit unsigned integer). Minimum
127           memory cost is 32 KiB and maximum is 4 GiB. (Limited by addressable
128           memory on some CPU platforms.) If the memory cost parameter is
129           benchmarked (not specified by a parameter) it is always in range
130           from 64 MiB to 1 GiB. The parallel cost minimum is 1 and maximum 4
131           (if enough CPUs cores are available, otherwise it is decreased).
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133       --iter-time, -i <number of milliseconds>
134           The number of milliseconds to spend with PBKDF passphrase
135           processing. Specifying 0 as parameter selects the compiled-in
136           default.
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138       --pbkdf-memory <number>
139           Set the memory cost for PBKDF (for Argon2i/id the number represents
140           kilobytes). Note that it is maximal value, PBKDF benchmark or
141           available physical memory can decrease it. This option is not
142           available for PBKDF2.
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144       --pbkdf-parallel <number>
145           Set the parallel cost for PBKDF (number of threads, up to 4). Note
146           that it is maximal value, it is decreased automatically if CPU
147           online count is lower. This option is not available for PBKDF2.
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149       --pbkdf-force-iterations <num>
150           Avoid PBKDF benchmark and set time cost (iterations) directly. It
151           can be used for LUKS/LUKS2 device only. See --pbkdf option for more
152           info.
153
154       --timeout, -t <number of seconds>
155           The number of seconds to wait before timeout on passphrase input
156           via terminal. It is relevant every time a passphrase is asked. It
157           has no effect if used in conjunction with --key-file.
158
159           This option is useful when the system should not stall if the user
160           does not input a passphrase, e.g. during boot. The default is a
161           value of 0 seconds, which means to wait forever.
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163       --header <device or file storing the LUKS header>
164           Use a detached (separated) metadata device or file where the LUKS
165           header is stored. This option allows one to store ciphertext and
166           LUKS header on different devices.
167
168           For commands that change the LUKS header (e.g. luksAddKey), specify
169           the device or file with the LUKS header directly as the LUKS
170           device.
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172       --force-password
173           Do not use password quality checking for new LUKS passwords.
174
175           This option is ignored if cryptsetup is built without password
176           quality checking support.
177
178           For more info about password quality check, see the manual page for
179           pwquality.conf(5) and passwdqc.conf(5).
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181       --disable-locks
182           Disable lock protection for metadata on disk. This option is valid
183           only for LUKS2 and ignored for other formats.
184
185           WARNING: Do not use this option unless you run cryptsetup in a
186           restricted environment where locking is impossible to perform
187           (where /run directory cannot be used).
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189       --keyslot-cipher <cipher-spec>
190           This option can be used to set specific cipher encryption for the
191           LUKS2 keyslot area.
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193       --keyslot-key-size <bits>
194           This option can be used to set specific key size for the LUKS2
195           keyslot area.
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197       --batch-mode, -q
198           Suppresses all confirmation questions. Use with care!
199
200           If the --verify-passphrase option is not specified, this option
201           also switches off the passphrase verification.
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203       --debug or --debug-json
204           Run in debug mode with full diagnostic logs. Debug output lines are
205           always prefixed by #.
206
207           If --debug-json is used, additional LUKS2 JSON data structures are
208           printed.
209
210       --version, -V
211           Show the program version.
212
213       --usage
214           Show short option help.
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216       --help, -?
217           Show help text and default parameters.
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REPORTING BUGS

220       Report bugs at cryptsetup mailing list <cryptsetup@lists.linux.dev> or
221       in Issues project section
222       <https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.
223
224       Please attach output of the failed command with --debug option added.
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SEE ALSO

227       Cryptsetup FAQ
228       <https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions>
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230       cryptsetup(8), integritysetup(8) and veritysetup(8)
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CRYPTSETUP

233       Part of cryptsetup project <https://gitlab.com/cryptsetup/cryptsetup/>.
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237cryptsetup 2.6.1                  2023-02-10      CRYPTSETUP-LUKSCONVERTKEY(8)
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