1SYSTEMD-CRYPTSETUP@.SERVICEs(y8s)temd-cryptsetup@.serSvYiScTeEMD-CRYPTSETUP@.SERVICE(8)
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6 systemd-cryptsetup@.service, systemd-cryptsetup - Full disk decryption
7 logic
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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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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.
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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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63 systemd(1), systemd-cryptsetup-generator(8), crypttab(5), systemd-
64 cryptenroll(1), cryptsetup(8)
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67 1. password agent logic
68 https://systemd.io/PASSWORD_AGENTS/
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72systemd 248 SYSTEMD-CRYPTSETUP@.SERVICE(8)