How to change the encryption key on (rooted) Android 9? In Android 6, you could change the disk encryption key using the vdc command with

vdc cryptfs changepw NEWPW


In Android 9, you get a message, that raw commands are no longer supported. 

During rooting and installing Lineage OS 16 and installing different stuff, I got different PIN and encryption keys. This means, that when I change the lockscreen PIN, the encryption key is no longer changed.

In principle, this is what I wanted to achieve, but the problem is that I currently do not know how to change the encryption key at all. I would like to have a rather short lockscreen pin and a longer encryption key, that I can change from time to time. On Android 6 this was no problem on the shell and with different Apps, but the Apps seem to depend on the vdc command as well.

I already tried to change the lockscreen PIN back to the current encryption password in the hope, that the next change of the PIN then would change the encryption as well, because I thought maybe the encryption was not changed because the new API needs a correct old password before changing the key to the new password. But this did not work as well.

Is there any App, command line tool or function in Lineage OS 16, that can change the encryption key?
I don't think is documented anywhere the syntax but looking at this code
https://review.lineageos.org/c/LineageOS/android_system_vold/+/258179
I was able to set a different password.
Initially I used a PIN for unlocking, so the command to run on a terminal on lineageos 17.1 as root is:
vdc cryptfs changepw TYPEOFNEWPASSWORD OLDPASSWORD NEWPASSWORD

Where type of password can be:

password
pin
pattern