/lib/systemd/systemd-cryptsetup
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 m[blue]password agent logicm[][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).
systemd(1), systemd-cryptsetup-generator(8), crypttab(5), cryptsetup(8)