Best way to check password against hash

[chilliger]

Using the -rfbauth option the password is stored obscured with a fixed key. I want to overcome this by storing the password as a SHA256 hash and check against that one. What is the best way to do that?

-passwdfile with "custom:" prefix seems not to receive the inputed client password: https://www.linuxquestions.org/questions/linux-software-2/how-to-decode-des-encrypted-string-4175617903/

-unixpw_cmd: Judging by the source code the client needs also to provide a valid username before the command is run. Username is not relevant in my use case. Using TightVNC as a client directly teminates with an error. https://unix.stackexchange.com/questions/222726/x11vnc-and-unixpw-cmd-option

There seems to be no simple way to do that today?