cryptsetup-luksDump - dump the header information of a LUKS device

Cryptsetup

       Part of cryptsetupproject <https://gitlab.com/cryptsetup/cryptsetup/>.

cryptsetup 2.8.0                                   2025-07-25                             CRYPTSETUP-LUKSDUMP(8)

Description

Dump the header information of a LUKS device.

If the --dump-volume-key option is used, the LUKS device volume key is dumped instead of the keyslot
info. Together with the --volume-key-file option, volume key is dumped to a file instead of standard
output. Beware that the volume key cannot be changed without reencryption and can be used to decrypt the
data stored in the LUKS container without a passphrase and even without the LUKS header. This means that
if the volume key is compromised, the whole device has to be erased or reencrypted to prevent further
access. Use this option carefully.

To dump the volume key, a passphrase has to be supplied, either interactively or via --key-file.

To dump unbound key (LUKS2 format only), --unbound parameter, specific --key-slot id and proper
passphrase has to be supplied, either interactively or via --key-file. Optional --volume-key-file
parameter enables unbound keyslot dump to a file.

To dump LUKS2 JSON metadata (without basic header information like UUID) use --dump-json-metadata option.

<options> can be [--dump-volume-key, --dump-json-metadata, --key-file, --keyfile-offset, --keyfile-size,
--header, --disable-locks, --volume-key-file, --type, --unbound, --key-slot, --timeout,
--external-tokens-path].

WARNING: If --dump-volume-key is used with --key-file and the argument to --key-file is '-', no
validation question will be asked and no warning given.

Name

       cryptsetup-luksDump - dump the header information of a LUKS device

Options

--batch-mode,-q
           Suppresses all confirmation questions. Use with care!

           If the --verify-passphrase option is not specified, this option also switches off the passphrase
           verification.

       --debugor--debug-json
           Run in debug mode with full diagnostic logs. Debug output lines are always prefixed by #.

           If --debug-json is used, additional LUKS2 JSON data structures are printed.

       --disable-locks
           Disable lock protection for metadata on disk. This option is valid only for LUKS2 and ignored for
           other formats.

           WARNING: Do not use this option unless you run cryptsetup in a restricted environment where locking
           is impossible to perform (where /run directory cannot be used).

       --dump-json-metadata
           For luksDump (LUKS2 only) this option prints content of LUKS2 header JSON metadata area.

       --dump-volume-key,--dump-master-key(OBSOLETEalias)
           Print the volume key in the displayed information. Use with care, as the volume key can be used to
           bypass the passphrases, see also option --volume-key-file.

       --external-tokens-pathabsolute_path
           Override system directory path where cryptsetup searches for external token handlers (or token
           plugins). It must be absolute path (starting with '/' character).

       --header<deviceorfilestoringtheLUKSheader>
           Use a detached (separated) metadata device or file where the LUKS header is stored. This option
           allows one to store ciphertext and LUKS header on different devices.

           For commands that change the LUKS header (e.g. luksAddKey), specify the device or file with the LUKS
           header directly as the LUKS device.

       --help,-?
           Show help text and default parameters.

       --key-description<text>
           Set key description in keyring that will be used for passphrase retrieval.

       --key-file,-dname
           Read the passphrase from file.

           If the name given is "-", then the passphrase will be read from stdin. In this case, reading will not
           stop at newline characters.

           See section NOTESONPASSPHRASEPROCESSING in cryptsetup(8) for more information.

       --keyfile-offsetvalue
           Skip value bytes at the beginning of the key file.

       --keyfile-size,-lvalue
           Read a maximum of value bytes from the key file. The default is to read the whole file up to the
           compiled-in maximum that can be queried with --help. Supplying more data than the compiled-in maximum
           aborts the operation.

           This option is useful to cut trailing newlines, for example. If --keyfile-offset is also given, the
           size count starts after the offset.

       --key-slot,-S<0-N>
           For LUKS operations that add key material, this option allows you to specify which key slot is
           selected for the new key.

           The maximum number of key slots depends on the LUKS version. LUKS1 can have up to 8 key slots. LUKS2
           can have up to 32 key slots based on key slot area size and key size, but a valid key slot ID can
           always be between 0 and 31 for LUKS2.

       --timeout,-t<numberofseconds>
           The number of seconds to wait before timeout on passphrase input via terminal. It is relevant every
           time a passphrase is asked. It has no effect if used in conjunction with --key-file.

           This option is useful when the system should not stall if the user does not input a passphrase, e.g.
           during boot. The default is a value of 0 seconds, which means to wait forever.

       --type<device-type>
           Specifies required device type, for more info read BASICACTIONS section in cryptsetup(8).

       --unbound
           Dumps existing LUKS2 unbound keyslot.

       --usage
           Show short option help.

       --version,-V
           Show the program version.

       --volume-key-file,--master-key-file(OBSOLETEalias)
           Use a volume key stored in a file. The volume key is stored in a file instead of being printed out to
           standard output.

Reporting Bugs

       Report bugs at cryptsetupmailinglist <cryptsetup@lists.linux.dev> or in Issuesprojectsection
       <https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.

       Please attach output of the failed command with --debug option added.