1SYSTEMD-CRYPTSETUP@.SERVICEs(y8s)temd-cryptsetup@.serSvYiScTeEMD-CRYPTSETUP@.SERVICE(8)
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NAME

6       systemd-cryptsetup@.service, systemd-cryptsetup - Full disk decryption
7       logic
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SYNOPSIS

10       systemd-cryptsetup@.service
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12       system-systemd\x2dcryptsetup.slice
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14       /usr/lib/systemd/systemd-cryptsetup
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DESCRIPTION

17       systemd-cryptsetup@.service is a service responsible for setting up
18       encrypted block devices. It is instantiated for each device that
19       requires decryption for access.
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21       systemd-cryptsetup@.service instances are part of the
22       system-systemd\x2dcryptsetup.slice slice, which is destroyed only very
23       late in the shutdown procedure. This allows the encrypted devices to
24       remain up until filesystems have been unmounted.
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26       systemd-cryptsetup@.service will ask for hard disk passwords via the
27       password agent logic[1], in order to query the user for the password
28       using the right mechanism at boot and during runtime.
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30       At early boot and when the system manager configuration is reloaded,
31       /etc/crypttab is translated into systemd-cryptsetup@.service units by
32       systemd-cryptsetup-generator(8).
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34       In order to unlock a volume a password or binary key is required.
35       systemd-cryptsetup@.service tries to acquire a suitable password or
36       binary key via the following mechanisms, tried in order:
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38        1. If a key file is explicitly configured (via the third column in
39           /etc/crypttab), a key read from it is used. If a PKCS#11 token,
40           FIDO2 token or TPM2 device is configured (using the pkcs11-uri=,
41           fido2-device=, tpm2-device= options) the key is decrypted before
42           use.
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44        2. If no key file is configured explicitly this way, a key file is
45           automatically loaded from /etc/cryptsetup-keys.d/volume.key and
46           /run/cryptsetup-keys.d/volume.key, if present. Here too, if a
47           PKCS#11/FIDO2/TPM2 token/device is configured, any key found this
48           way is decrypted before use.
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50        3. If the try-empty-password option is specified it is then attempted
51           to unlock the volume with an empty password.
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53        4. The kernel keyring is then checked for a suitable cached password
54           from previous attempts.
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56        5. Finally, the user is queried for a password, possibly multiple
57           times, unless the headless option is set.
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59       If no suitable key may be acquired via any of the mechanisms describes
60       above, volume activation fails.
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SEE ALSO

63       systemd(1), systemd-cryptsetup-generator(8), crypttab(5), systemd-
64       cryptenroll(1), cryptsetup(8)
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NOTES

67        1. password agent logic
68           https://systemd.io/PASSWORD_AGENTS/
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72systemd 250                                     SYSTEMD-CRYPTSETUP@.SERVICE(8)
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