Does "adb backup" also backup /data/misc/vold - the Encryption Key for Adoptable SD card? I want to make sure that using adb backup -apk -shared -all -f ~/backup.ab will also save /data/misc/vold? 

I am trying to backup before rooting, in order to be able to gain access to the encryption key in /data/misc/vold (got corrupted SD card adopted as internal). So I want to make sure ih something bad happens during the rooting, I could still access the backup version of /data/misc/vold?

Thanks!
My solution to Matifow problem was ...

I cannot extract the token because my device was not rooted.

I bought a new microSD and clone in it the microSD from my device.

https://askubuntu.com/questions/227924/sd-card-cloning-using-the-dd-command

When i put this new card the phone recognize as the old one.

I recover photos, media from whatsapp, apps installed ...

I lost some files ( the corrupted I assume) but can recover the most.