Systemd 246 has been released. There is an incredibly long list of new features, many of which have to do with support for encrypted and signed disk volumes. "Various command line parameters and configuration file settings that configure key or certificate files now optionally take paths to AF_UNIX sockets in the file system. If configured that way a stream connection is made to the socket and the required data read from it. This is a simple and natural extension to the existing regular file logic, and permits other software to provide keys or certificates via simple IPC services, for example when unencrypted storage on disk is not desired."