systemd-cryptsetup@.service(8) — Linux manual page



NAME         top

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

SYNOPSIS         top



DESCRIPTION         top

       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 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

       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.

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

SEE ALSO         top

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

NOTES         top

        1. password agent logic

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
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       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-12-18.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2020-12-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       (which is not part of the original manual page), send a mail to

systemd 247                               SYSTEMD-CRYPTSETUP@.SERVICE(8)

Pages that refer to this page: systemd-cryptenroll(1)crypttab(5)systemd.directives(7)systemd.index(7)systemd-cryptsetup-generator(8)systemd-gpt-auto-generator(8)