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Manual: systemd-cryptsetup@.service

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SYSTEMD-CRYPTSETUP(8)				     systemd-cryptsetup				       SYSTEMD-CRYPTSETUP(8)

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

SYNOPSIS

       systemd-cryptsetup [OPTIONS...] attach VOLUME SOURCE-DEVICE [KEY-FILE] [CRYPTTAB-OPTIONS]

       systemd-cryptsetup [OPTIONS...] detach VOLUME

       systemd-cryptsetup@.service

       system-systemd\x2dcryptsetup.slice

DESCRIPTION
       systemd-cryptsetup is used to set up (with attach) and tear down (with detach) access to an encrypted block device.
       It is primarily used via systemd-cryptsetup@.service during early boot, but may also be called manually. The
       positional arguments VOLUME, SOURCE-DEVICE, KEY-FILE, and CRYPTTAB-OPTIONS have the same meaning as the fields in
       crypttab(5).

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

       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 then unlocking the volume with an empty password is attempted.

	4. If the password-cache= option is set to "yes" or "read-only", 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.

CREDENTIALS
       systemd-cryptsetup supports the service credentials logic as implemented by
       ImportCredential=/LoadCredential=/SetCredential= (see systemd.exec(5) for details). The following credentials are
       used by "systemd-crypsetup@root.service" (generated by systemd-gpt-auto-generator) when passed in:

       cryptsetup.passphrase
	   This credential specifies the passphrase of the LUKS volume.

	   Added in version 256.

       cryptsetup.tpm2-pin
	   This credential specifies the TPM pin.

	   Added in version 256.

       cryptsetup.fido2-pin
	   This credential specifies the FIDO2 token pin.

	   Added in version 256.

       cryptsetup.pkcs11-pin
	   This credential specifies the PKCS11 token pin.

	   Added in version 256.

       cryptsetup.luks2-pin
	   This credential specifies the pin requested by generic LUKS2 token modules.

	   Added in version 256.

SEE ALSO
       systemd(1), systemd-cryptsetup-generator(8), crypttab(5), systemd-cryptenroll(1), cryptsetup(8), TPM2 PCR
       Measurements Made by systemd[2]

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

	2. TPM2 PCR Measurements Made by systemd
	   https://systemd.io/TPM2_PCR_MEASUREMENTS

systemd 259.5											       SYSTEMD-CRYPTSETUP(8)

Related Commands:

systemd systemd-cryptenroll SYSTEMD-CRYPTSETUP systemd-cryptsetup-generator systemd.exec
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