systemd-boot-password is systemd-boot boot manager with password-protected editor.
The gnu-efi library and GNU autotools should be installed.
Run ./autogen.sh && ./configure && make && sudo make install to build and install systemd-boot-password to your system.
Arch Linux users can install systemd-boot-password package from AUR.
You can install boot manager using sudo sbp-install $esp.
In $esp/loader/loader.conf you can add editor 1 to enable kernel parameters editor (enabled by default).
For password protection, run sbp-generate and enter desired password. This tool will generate SHA-512 hash sum which you can add to loader.conf file: password $sha512sum. Boot manager will prompt password when you try to open editor with e key.
This program is licensed with LGPLv2.1+.