How to check if custom ROM supports encryption? First solution which is coming to my mind is install custom ROM and encrypt /data partition. But it always take time. I'm wondering if there's quicker method like download custom ROM, extract system image, then extract files from system image file and looking for encryption support in system files like *.rc which are in root file system. Is there any other way to checking?
I you would install a custom rom you can ask the maintainer of your rom, usually all custom roms from Android 5 and above Support it, nur maybe your device doesnt Support it in a custom rom. Normally the maintainer of your rom wrote a bug list in the XDA Thread, if that's too uncertain ask the maintainer.