systemd-cryptsetup

SYSTEMD-CRYPTSETUP@.SERVICsystemd-cryptsetup@.seSYSTEMD-CRYPTSETUP@.SERVICE(8)

NAME
       systemd-cryptsetup@.service, systemd-cryptsetup - Full disk decryption
       logic

SYNOPSIS
       systemd-cryptsetup@.service

       system-systemd\x2dcryptsetup.slice

       /lib/systemd/systemd-cryptsetup

DESCRIPTION
       systemd-cryptsetup@.service is a service responsible for setting up
       encrypted block devices. It is instantiated for each device that
       requires decryption for access.

       systemd-cryptsetup@.service instances are part of the
       system-systemd\x2dcryptsetup.slice slice, which is destroyed only very
       late in the shutdown procedure. This allows the encrypted devices to
       remain up until filesystems have been unmounted.

       systemd-cryptsetup@.service will ask for hard disk passwords via the
       password agent logic[1], in order to query the user for the password
       using the right mechanism at boot and during runtime.

       At early boot and when the system manager configuration is reloaded,
       /etc/crypttab is translated into systemd-cryptsetup@.service units by
       systemd-cryptsetup-generator(8).

       In order to unlock a volume a password or binary key is required.
       systemd-cryptsetup@.service tries to acquire a suitable password or
       binary key via the following mechanisms, tried in order:

        1. If a key file is explicitly configured (via the third column in
           /etc/crypttab), a key read from it is used. If a PKCS#11 token,
           FIDO2 token or TPM2 device is configured (using the pkcs11-uri=,
           fido2-device=, tpm2-device= options) the key is decrypted before
           use.

        2. If no key file is configured explicitly this way, a key file is
           automatically loaded from /etc/cryptsetup-keys.d/volume.key and
           /run/cryptsetup-keys.d/volume.key, if present. Here too, if a
           PKCS#11/FIDO2/TPM2 token/device is configured, any key found this
           way is decrypted before use.

        3. If the try-empty-password option is specified it is then attempted
           to unlock the volume with an empty password.

        4. The kernel keyring is then checked for a suitable cached password
           from previous attempts.

        5. Finally, the user is queried for a password, possibly multiple
           times, unless the headless option is set.

       If no suitable key may be acquired via any of the mechanisms describes
       above, volume activation fails.

SEE ALSO
       systemd(1), systemd-cryptsetup-generator(8), crypttab(5), systemd-
       cryptenroll(1), cryptsetup(8)

NOTES
        1. password agent logic
           https://systemd.io/PASSWORD_AGENTS/

systemd 249                                     SYSTEMD-CRYPTSETUP@.SERVICE(8)