1CRYPTSETUP-LUKSCONVERTKEY(8) Maintenance Commands CRYPTSETUP-LUKSCONVERTKEY(8)
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6 cryptsetup-luksConvertKey - converts an existing LUKS2 keyslot to new
7 PBKDF parameters
8
10 cryptsetup luksConvertKey [<options>] <device>
11
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.
17 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.
24 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 <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].
33
35 --hash, -h <hash-spec>
36 The specified hash is used for PBKDF2 and AF splitter.
37 --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.
42 --key-file, -d name
44 Read the passphrase from file.
45 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 With LUKS, the passphrase supplied via --key-file is always the
50 existing passphrase requested by a command, except in the case of
51 luksFormat where --key-file is equivalent to the positional key
52 file argument.
53 If you want to set a new passphrase via key file, you have to use a
55 positional argument to luksAddKey.
56 See section NOTES ON PASSPHRASE PROCESSING in cryptsetup(8) for
58 more information.
59 --keyfile-offset value
61 Skip value bytes at the beginning of the key file.
62 --keyfile-size, -l value
64 Read a maximum of value bytes from the key file. The default is to
65 read the whole file up to the compiled-in maximum that can be
66 queried with --help. Supplying more data than the compiled-in
67 maximum aborts the operation.
68 This option is useful to cut trailing newlines, for example. If
70 --keyfile-offset is also given, the size count starts after the
71 offset.
72 --new-keyfile-offset value
74 Skip value bytes at the start when adding a new passphrase from key
75 file with luksAddKey.
76 --new-keyfile-size value
78 Read a maximum of value bytes when adding a new passphrase from key
79 file with luksAddKey. The default is to read the whole file up to
80 the compiled-in maximum length that can be queried with --help.
81 Supplying more than the compiled in maximum aborts the operation.
82 When --new-keyfile-offset is also given, reading starts after the
83 offset.
84 --key-slot, -S <0-N>
86 For LUKS operations that add key material, this option allows you
87 to specify which key slot is selected for the new key.
88 The maximum number of key slots depends on the LUKS version. LUKS1
90 can have up to 8 key slots. LUKS2 can have up to 32 key slots based
91 on key slot area size and key size, but a valid key slot ID can
92 always be between 0 and 31 for LUKS2.
93 --pbkdf <PBKDF spec>
95 Set Password-Based Key Derivation Function (PBKDF) algorithm for
96 LUKS keyslot. The PBKDF can be: pbkdf2 (for PBKDF2 according to
97 RFC2898), argon2i for Argon2i or argon2id for Argon2id (see Argon2
98 <https://www.cryptolux.org/index.php/Argon2> for more info).
99 For LUKS1, only PBKDF2 is accepted (no need to use this option).
101 The default PBKDF for LUKS2 is set during compilation time and is
102 available in cryptsetup --help output.
103 A PBKDF is used for increasing dictionary and brute-force attack
105 cost for keyslot passwords. The parameters can be time, memory and
106 parallel cost.
107 For PBKDF2, only time cost (number of iterations) applies. For
109 Argon2i/id, there is also memory cost (memory required during the
110 process of key derivation) and parallel cost (number of threads
111 that run in parallel during the key derivation.
112 Note that increasing memory cost also increases time, so the final
114 parameter values are measured by a benchmark. The benchmark tries
115 to find iteration time (--iter-time) with required memory cost
116 --pbkdf-memory. If it is not possible, the memory cost is decreased
117 as well. The parallel cost --pbkdf-parallel is constant and is
118 checked against available CPU cores.
119 You can see all PBKDF parameters for particular LUKS2 keyslot with
121 cryptsetup-luksDump(8) command.
122 NOTE: If you do not want to use benchmark and want to specify all
124 parameters directly, use --pbkdf-force-iterations with
125 --pbkdf-memory and --pbkdf-parallel. This will override the values
126 without benchmarking. Note it can cause extremely long unlocking
127 time. Use only in specific cases, for example, if you know that the
128 formatted device will be used on some small embedded system.
129 MINIMAL AND MAXIMAL PBKDF COSTS: For PBKDF2, the minimum iteration
131 count is 1000 and maximum is 4294967295 (maximum for 32bit unsigned
132 integer). Memory and parallel costs are unused for PBKDF2. For
133 Argon2i and Argon2id, minimum iteration count (CPU cost) is 4 and
134 maximum is 4294967295 (maximum for 32bit unsigned integer). Minimum
135 memory cost is 32 KiB and maximum is 4 GiB. (Limited by addressable
136 memory on some CPU platforms.) If the memory cost parameter is
137 benchmarked (not specified by a parameter) it is always in range
138 from 64 MiB to 1 GiB. The parallel cost minimum is 1 and maximum 4
139 (if enough CPUs cores are available, otherwise it is decreased).
140 --iter-time, -i <number of milliseconds>
142 The number of milliseconds to spend with PBKDF passphrase
143 processing. Specifying 0 as parameter selects the compiled-in
144 default.
145 --pbkdf-memory <number>
147 Set the memory cost for PBKDF (for Argon2i/id the number represents
148 kilobytes). Note that it is maximal value, PBKDF benchmark or
149 available physical memory can decrease it. This option is not
150 available for PBKDF2.
151 --pbkdf-parallel <number>
153 Set the parallel cost for PBKDF (number of threads, up to 4). Note
154 that it is maximal value, it is decreased automatically if CPU
155 online count is lower. This option is not available for PBKDF2.
156 --pbkdf-force-iterations <num>
158 Avoid PBKDF benchmark and set time cost (iterations) directly. It
159 can be used for LUKS/LUKS2 device only. See --pbkdf option for more
160 info.
161 --timeout, -t <number of seconds>
163 The number of seconds to wait before timeout on passphrase input
164 via terminal. It is relevant every time a passphrase is asked. It
165 has no effect if used in conjunction with --key-file.
166 This option is useful when the system should not stall if the user
168 does not input a passphrase, e.g. during boot. The default is a
169 value of 0 seconds, which means to wait forever.
170 --header <device or file storing the LUKS header>
172 Use a detached (separated) metadata device or file where the LUKS
173 header is stored. This option allows one to store ciphertext and
174 LUKS header on different devices.
175 For commands that change the LUKS header (e.g. luksAddKey), specify
177 the device or file with the LUKS header directly as the LUKS
178 device.
179 --force-password
181 Do not use password quality checking for new LUKS passwords.
182 This option is ignored if cryptsetup is built without password
184 quality checking support.
185 For more info about password quality check, see the manual page for
187 pwquality.conf(5) and passwdqc.conf(5).
188 --disable-locks
190 Disable lock protection for metadata on disk. This option is valid
191 only for LUKS2 and ignored for other formats.
192 WARNING: Do not use this option unless you run cryptsetup in a
194 restricted environment where locking is impossible to perform
195 (where /run directory cannot be used).
196 --keyslot-cipher <cipher-spec>
198 This option can be used to set specific cipher encryption for the
199 LUKS2 keyslot area.
200 --keyslot-key-size <bits>
202 This option can be used to set specific key size for the LUKS2
203 keyslot area.
204 --batch-mode, -q
206 Suppresses all confirmation questions. Use with care!
207 If the --verify-passphrase option is not specified, this option
209 also switches off the passphrase verification.
210 --debug or --debug-json
212 Run in debug mode with full diagnostic logs. Debug output lines are
213 always prefixed by #.
214 If --debug-json is used, additional LUKS2 JSON data structures are
216 printed.
217 --version, -V
219 Show the program version.
220 --usage
222 Show short option help.
223 --help, -?
225 Show help text and default parameters.
226
228 Report bugs at cryptsetup mailing list <cryptsetup@lists.linux.dev> or
229 in Issues project section
230 <https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.
231 Please attach output of the failed command with --debug option added.
233
235 Cryptsetup FAQ
236 <https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions>
237 cryptsetup(8), integritysetup(8) and veritysetup(8)
239
241 Part of cryptsetup project <https://gitlab.com/cryptsetup/cryptsetup/>.
242cryptsetup 2.5.0 2022-07-28 CRYPTSETUP-LUKSCONVERTKEY(8)